C Core API cleanup.

Simplify grpc_event into something that can be non-heap allocated.
Deprecate grpc_event_finish.
Remove grpc_op_error - use an int as this is more idiomatic C style.
diff --git a/include/grpc/grpc.h b/include/grpc/grpc.h
index 91e3d30..eee55e9 100644
--- a/include/grpc/grpc.h
+++ b/include/grpc/grpc.h
@@ -140,14 +140,6 @@
   GRPC_CALL_ERROR_INVALID_FLAGS
 } grpc_call_error;
 
-/* Result of a grpc operation */
-typedef enum grpc_op_error {
-  /* everything went ok */
-  GRPC_OP_OK = 0,
-  /* something failed, we don't know what */
-  GRPC_OP_ERROR
-} grpc_op_error;
-
 /* Write Flags: */
 /* Hint that the write may be buffered and need not go out on the wire
    immediately. GRPC is free to buffer the message until the next non-buffered
@@ -196,22 +188,15 @@
 } grpc_metadata;
 
 typedef enum grpc_completion_type {
-  GRPC_QUEUE_SHUTDOWN,       /* Shutting down */
-  GRPC_OP_COMPLETE,          /* operation completion */
-  GRPC_SERVER_SHUTDOWN,      /* The server has finished shutting down */
-  GRPC_COMPLETION_DO_NOT_USE /* must be last, forces users to include
-                                a default: case */
+  GRPC_QUEUE_SHUTDOWN, /* Shutting down */
+  GRPC_QUEUE_TIMEOUT,  /* No event before timeout */
+  GRPC_OP_COMPLETE     /* operation completion */
 } grpc_completion_type;
 
 typedef struct grpc_event {
   grpc_completion_type type;
+  int success;
   void *tag;
-  grpc_call *call;
-  /* Data associated with the completion type. Field names match the type of
-     completion as listed in grpc_completion_type. */
-  union {
-    grpc_op_error op_complete;
-  } data;
 } grpc_event;
 
 typedef struct {
@@ -352,8 +337,8 @@
 
    Callers must not call grpc_completion_queue_next and
    grpc_completion_queue_pluck simultaneously on the same completion queue. */
-grpc_event *grpc_completion_queue_next(grpc_completion_queue *cq,
-                                       gpr_timespec deadline);
+grpc_event grpc_completion_queue_next(grpc_completion_queue *cq,
+                                      gpr_timespec deadline);
 
 /* Blocks until an event with tag 'tag' is available, the completion queue is
    being shutdown or deadline is reached. Returns NULL on timeout, or a pointer
@@ -362,11 +347,8 @@
 
    Callers must not call grpc_completion_queue_next and
    grpc_completion_queue_pluck simultaneously on the same completion queue. */
-grpc_event *grpc_completion_queue_pluck(grpc_completion_queue *cq, void *tag,
-                                        gpr_timespec deadline);
-
-/* Clean up any data owned by the event */
-void grpc_event_finish(grpc_event *event);
+grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cq, void *tag,
+                                       gpr_timespec deadline);
 
 /* Begin destruction of a completion queue. Once all possible events are
    drained then grpc_completion_queue_next will start to produce
diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index 070be1b..3b8d514 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -62,7 +62,7 @@
 typedef struct {
   grpc_ioreq_completion_func on_complete;
   void *user_data;
-  grpc_op_error status;
+  int success;
 } completed_request;
 
 /* See request_set in grpc_call below for a description */
@@ -74,7 +74,7 @@
 typedef struct {
   /* Overall status of the operation: starts OK, may degrade to
      non-OK */
-  grpc_op_error status;
+  int success;
   /* Completion function to call at the end of the operation */
   grpc_ioreq_completion_func on_complete;
   void *user_data;
@@ -239,7 +239,6 @@
     y = temp;            \
   } while (0)
 
-static void do_nothing(void *ignored, grpc_op_error also_ignored) {}
 static void set_deadline_alarm(grpc_call *call, gpr_timespec deadline);
 static void call_on_done_recv(void *call, int success);
 static void call_on_done_send(void *call, int success);
@@ -460,7 +459,7 @@
 
   if (completing_requests > 0) {
     for (i = 0; i < completing_requests; i++) {
-      completed_requests[i].on_complete(call, completed_requests[i].status,
+      completed_requests[i].on_complete(call, completed_requests[i].success,
                                         completed_requests[i].user_data);
     }
     lock(call);
@@ -520,7 +519,7 @@
 }
 
 static void finish_live_ioreq_op(grpc_call *call, grpc_ioreq_op op,
-                                 grpc_op_error status) {
+                                 int success) {
   completed_request *cr;
   gpr_uint8 master_set = call->request_set[op];
   reqinfo_master *master;
@@ -528,8 +527,8 @@
   /* ioreq is live: we need to do something */
   master = &call->masters[master_set];
   master->complete_mask |= 1u << op;
-  if (status != GRPC_OP_OK) {
-    master->status = status;
+  if (!success) {
+    master->success = 0;
   }
   if (master->complete_mask == master->need_mask) {
     for (i = 0; i < GRPC_IOREQ_OP_COUNT; i++) {
@@ -540,7 +539,7 @@
       switch ((grpc_ioreq_op)i) {
         case GRPC_IOREQ_RECV_MESSAGE:
         case GRPC_IOREQ_SEND_MESSAGE:
-          if (master->status == GRPC_OP_OK) {
+          if (master->success) {
             call->request_set[i] = REQSET_EMPTY;
           } else {
             call->write_state = WRITE_STATE_WRITE_CLOSED;
@@ -575,33 +574,31 @@
       }
     }
     cr = &call->completed_requests[call->num_completed_requests++];
-    cr->status = master->status;
+    cr->success = master->success;
     cr->on_complete = master->on_complete;
     cr->user_data = master->user_data;
   }
 }
 
-static void finish_ioreq_op(grpc_call *call, grpc_ioreq_op op,
-                            grpc_op_error status) {
+static void finish_ioreq_op(grpc_call *call, grpc_ioreq_op op, int success) {
   if (is_op_live(call, op)) {
-    finish_live_ioreq_op(call, op, status);
+    finish_live_ioreq_op(call, op, success);
   }
 }
 
 static void call_on_done_send(void *pc, int success) {
   grpc_call *call = pc;
-  grpc_op_error error = success ? GRPC_OP_OK : GRPC_OP_ERROR;
   lock(call);
   if (call->last_send_contains & (1 << GRPC_IOREQ_SEND_INITIAL_METADATA)) {
-    finish_ioreq_op(call, GRPC_IOREQ_SEND_INITIAL_METADATA, error);
+    finish_ioreq_op(call, GRPC_IOREQ_SEND_INITIAL_METADATA, success);
   }
   if (call->last_send_contains & (1 << GRPC_IOREQ_SEND_MESSAGE)) {
-    finish_ioreq_op(call, GRPC_IOREQ_SEND_MESSAGE, error);
+    finish_ioreq_op(call, GRPC_IOREQ_SEND_MESSAGE, success);
   }
   if (call->last_send_contains & (1 << GRPC_IOREQ_SEND_CLOSE)) {
-    finish_ioreq_op(call, GRPC_IOREQ_SEND_TRAILING_METADATA, error);
-    finish_ioreq_op(call, GRPC_IOREQ_SEND_STATUS, error);
-    finish_ioreq_op(call, GRPC_IOREQ_SEND_CLOSE, GRPC_OP_OK);
+    finish_ioreq_op(call, GRPC_IOREQ_SEND_TRAILING_METADATA, success);
+    finish_ioreq_op(call, GRPC_IOREQ_SEND_STATUS, success);
+    finish_ioreq_op(call, GRPC_IOREQ_SEND_CLOSE, 1);
   }
   call->last_send_contains = 0;
   call->sending = 0;
@@ -720,12 +717,12 @@
     }
     finish_read_ops(call);
   } else {
-    finish_ioreq_op(call, GRPC_IOREQ_RECV_MESSAGE, GRPC_OP_ERROR);
-    finish_ioreq_op(call, GRPC_IOREQ_RECV_STATUS, GRPC_OP_ERROR);
-    finish_ioreq_op(call, GRPC_IOREQ_RECV_CLOSE, GRPC_OP_ERROR);
-    finish_ioreq_op(call, GRPC_IOREQ_RECV_TRAILING_METADATA, GRPC_OP_ERROR);
-    finish_ioreq_op(call, GRPC_IOREQ_RECV_INITIAL_METADATA, GRPC_OP_ERROR);
-    finish_ioreq_op(call, GRPC_IOREQ_RECV_STATUS_DETAILS, GRPC_OP_ERROR);
+    finish_ioreq_op(call, GRPC_IOREQ_RECV_MESSAGE, 0);
+    finish_ioreq_op(call, GRPC_IOREQ_RECV_STATUS, 0);
+    finish_ioreq_op(call, GRPC_IOREQ_RECV_CLOSE, 0);
+    finish_ioreq_op(call, GRPC_IOREQ_RECV_TRAILING_METADATA, 0);
+    finish_ioreq_op(call, GRPC_IOREQ_RECV_INITIAL_METADATA, 0);
+    finish_ioreq_op(call, GRPC_IOREQ_RECV_STATUS_DETAILS, 0);
   }
   call->recv_ops.nops = 0;
   unlock(call);
@@ -877,7 +874,7 @@
         (NULL == (*call->request_data[GRPC_IOREQ_RECV_MESSAGE].recv_message =
                       grpc_bbq_pop(&call->incoming_queue)));
     if (!empty) {
-      finish_live_ioreq_op(call, GRPC_IOREQ_RECV_MESSAGE, GRPC_OP_OK);
+      finish_live_ioreq_op(call, GRPC_IOREQ_RECV_MESSAGE, 1);
       empty = grpc_bbq_empty(&call->incoming_queue);
     }
   } else {
@@ -887,19 +884,19 @@
   switch (call->read_state) {
     case READ_STATE_STREAM_CLOSED:
       if (empty) {
-        finish_ioreq_op(call, GRPC_IOREQ_RECV_CLOSE, GRPC_OP_OK);
+        finish_ioreq_op(call, GRPC_IOREQ_RECV_CLOSE, 1);
       }
     /* fallthrough */
     case READ_STATE_READ_CLOSED:
       if (empty) {
-        finish_ioreq_op(call, GRPC_IOREQ_RECV_MESSAGE, GRPC_OP_OK);
+        finish_ioreq_op(call, GRPC_IOREQ_RECV_MESSAGE, 1);
       }
-      finish_ioreq_op(call, GRPC_IOREQ_RECV_STATUS, GRPC_OP_OK);
-      finish_ioreq_op(call, GRPC_IOREQ_RECV_STATUS_DETAILS, GRPC_OP_OK);
-      finish_ioreq_op(call, GRPC_IOREQ_RECV_TRAILING_METADATA, GRPC_OP_OK);
+      finish_ioreq_op(call, GRPC_IOREQ_RECV_STATUS, 1);
+      finish_ioreq_op(call, GRPC_IOREQ_RECV_STATUS_DETAILS, 1);
+      finish_ioreq_op(call, GRPC_IOREQ_RECV_TRAILING_METADATA, 1);
     /* fallthrough */
     case READ_STATE_GOT_INITIAL_METADATA:
-      finish_ioreq_op(call, GRPC_IOREQ_RECV_INITIAL_METADATA, GRPC_OP_OK);
+      finish_ioreq_op(call, GRPC_IOREQ_RECV_INITIAL_METADATA, 1);
     /* fallthrough */
     case READ_STATE_INITIAL:
       /* do nothing */
@@ -910,13 +907,13 @@
 static void early_out_write_ops(grpc_call *call) {
   switch (call->write_state) {
     case WRITE_STATE_WRITE_CLOSED:
-      finish_ioreq_op(call, GRPC_IOREQ_SEND_MESSAGE, GRPC_OP_ERROR);
-      finish_ioreq_op(call, GRPC_IOREQ_SEND_STATUS, GRPC_OP_ERROR);
-      finish_ioreq_op(call, GRPC_IOREQ_SEND_TRAILING_METADATA, GRPC_OP_ERROR);
-      finish_ioreq_op(call, GRPC_IOREQ_SEND_CLOSE, GRPC_OP_OK);
+      finish_ioreq_op(call, GRPC_IOREQ_SEND_MESSAGE, 0);
+      finish_ioreq_op(call, GRPC_IOREQ_SEND_STATUS, 0);
+      finish_ioreq_op(call, GRPC_IOREQ_SEND_TRAILING_METADATA, 0);
+      finish_ioreq_op(call, GRPC_IOREQ_SEND_CLOSE, 1);
     /* fallthrough */
     case WRITE_STATE_STARTED:
-      finish_ioreq_op(call, GRPC_IOREQ_SEND_INITIAL_METADATA, GRPC_OP_ERROR);
+      finish_ioreq_op(call, GRPC_IOREQ_SEND_INITIAL_METADATA, 0);
     /* fallthrough */
     case WRITE_STATE_INITIAL:
       /* do nothing */
@@ -957,7 +954,7 @@
   }
 
   master = &call->masters[set];
-  master->status = GRPC_OP_OK;
+  master->success = 1;
   master->need_mask = have_ops;
   master->complete_mask = 0;
   master->on_complete = completion;
@@ -1144,8 +1141,8 @@
   *(grpc_status_code *)dest = (status != GRPC_STATUS_OK);
 }
 
-static void finish_batch(grpc_call *call, grpc_op_error result, void *tag) {
-  grpc_cq_end_op(call->cq, tag, call, do_nothing, NULL, GRPC_OP_OK);
+static void finish_batch(grpc_call *call, int success, void *tag) {
+  grpc_cq_end_op(call->cq, tag, call, 1);
 }
 
 grpc_call_error grpc_call_start_batch(grpc_call *call, const grpc_op *ops,
@@ -1159,8 +1156,8 @@
   GRPC_CALL_LOG_BATCH(GPR_INFO, call, ops, nops, tag);
 
   if (nops == 0) {
-    grpc_cq_begin_op(call->cq, call, GRPC_OP_COMPLETE);
-    grpc_cq_end_op(call->cq, tag, call, do_nothing, NULL, GRPC_OP_OK);
+    grpc_cq_begin_op(call->cq, call);
+    grpc_cq_end_op(call->cq, tag, call, 1);
     return GRPC_CALL_OK;
   }
 
@@ -1251,7 +1248,7 @@
     }
   }
 
-  grpc_cq_begin_op(call->cq, call, GRPC_OP_COMPLETE);
+  grpc_cq_begin_op(call->cq, call);
 
   return grpc_call_start_ioreq_and_call_back(call, reqs, out, finish_batch,
                                              tag);
diff --git a/src/core/surface/call.h b/src/core/surface/call.h
index 2d4c7f6..30d9c86 100644
--- a/src/core/surface/call.h
+++ b/src/core/surface/call.h
@@ -80,8 +80,7 @@
   grpc_ioreq_data data;
 } grpc_ioreq;
 
-typedef void (*grpc_ioreq_completion_func)(grpc_call *call,
-                                           grpc_op_error status,
+typedef void (*grpc_ioreq_completion_func)(grpc_call *call, int success,
                                            void *user_data);
 
 grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
diff --git a/src/core/surface/completion_queue.c b/src/core/surface/completion_queue.c
index 3e90318..2f1d81e 100644
--- a/src/core/surface/completion_queue.c
+++ b/src/core/surface/completion_queue.c
@@ -51,8 +51,6 @@
    function (on_finish) that is hidden from outside this module */
 typedef struct event {
   grpc_event base;
-  grpc_event_finish_func on_finish;
-  void *on_finish_user_data;
   struct event *queue_next;
   struct event *queue_prev;
   struct event *bucket_next;
@@ -78,16 +76,8 @@
   event *queue;
   /* Fixed size chained hash table of events for pluck() */
   event *buckets[NUM_TAG_BUCKETS];
-
-#ifndef NDEBUG
-  /* Debug support: track which operations are in flight at any given time */
-  gpr_atm pending_op_count[GRPC_COMPLETION_DO_NOT_USE];
-#endif
 };
 
-/* Default do-nothing on_finish function */
-static void null_on_finish(void *user_data, grpc_op_error error) {}
-
 grpc_completion_queue *grpc_completion_queue_create(void) {
   grpc_completion_queue *cc = gpr_malloc(sizeof(grpc_completion_queue));
   memset(cc, 0, sizeof(*cc));
@@ -124,15 +114,11 @@
    members can be filled in.
    Requires GRPC_POLLSET_MU(&cc->pollset) locked. */
 static event *add_locked(grpc_completion_queue *cc, grpc_completion_type type,
-                         void *tag, grpc_call *call,
-                         grpc_event_finish_func on_finish, void *user_data) {
+                         void *tag, grpc_call *call) {
   event *ev = gpr_malloc(sizeof(event));
   gpr_uintptr bucket = ((gpr_uintptr)tag) % NUM_TAG_BUCKETS;
   ev->base.type = type;
   ev->base.tag = tag;
-  ev->base.call = call;
-  ev->on_finish = on_finish ? on_finish : null_on_finish;
-  ev->on_finish_user_data = user_data;
   if (cc->queue == NULL) {
     cc->queue = ev->queue_next = ev->queue_prev = ev;
   } else {
@@ -152,22 +138,15 @@
   return ev;
 }
 
-void grpc_cq_begin_op(grpc_completion_queue *cc, grpc_call *call,
-                      grpc_completion_type type) {
+void grpc_cq_begin_op(grpc_completion_queue *cc, grpc_call *call) {
   gpr_ref(&cc->refs);
   if (call) GRPC_CALL_INTERNAL_REF(call, "cq");
-#ifndef NDEBUG
-  gpr_atm_no_barrier_fetch_add(&cc->pending_op_count[type], 1);
-#endif
 }
 
 /* Signal the end of an operation - if this is the last waiting-to-be-queued
    event, then enter shutdown mode */
 static void end_op_locked(grpc_completion_queue *cc,
                           grpc_completion_type type) {
-#ifndef NDEBUG
-  GPR_ASSERT(gpr_atm_full_fetch_add(&cc->pending_op_count[type], -1) > 0);
-#endif
   if (gpr_unref(&cc->refs)) {
     GPR_ASSERT(!cc->shutdown);
     GPR_ASSERT(cc->shutdown_called);
@@ -176,20 +155,12 @@
   }
 }
 
-void grpc_cq_end_server_shutdown(grpc_completion_queue *cc, void *tag) {
-  gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
-  add_locked(cc, GRPC_SERVER_SHUTDOWN, tag, NULL, NULL, NULL);
-  end_op_locked(cc, GRPC_SERVER_SHUTDOWN);
-  gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
-}
-
 void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, grpc_call *call,
-                    grpc_event_finish_func on_finish, void *user_data,
-                    grpc_op_error error) {
+                    int success) {
   event *ev;
   gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
-  ev = add_locked(cc, GRPC_OP_COMPLETE, tag, call, on_finish, user_data);
-  ev->base.data.op_complete = error;
+  ev = add_locked(cc, GRPC_OP_COMPLETE, tag, call);
+  ev->base.success = success;
   end_op_locked(cc, GRPC_OP_COMPLETE);
   gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
 }
@@ -198,15 +169,14 @@
 static event *create_shutdown_event(void) {
   event *ev = gpr_malloc(sizeof(event));
   ev->base.type = GRPC_QUEUE_SHUTDOWN;
-  ev->base.call = NULL;
   ev->base.tag = NULL;
-  ev->on_finish = null_on_finish;
   return ev;
 }
 
-grpc_event *grpc_completion_queue_next(grpc_completion_queue *cc,
-                                       gpr_timespec deadline) {
+grpc_event grpc_completion_queue_next(grpc_completion_queue *cc,
+                                      gpr_timespec deadline) {
   event *ev = NULL;
+  grpc_event ret;
 
   gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
   for (;;) {
@@ -240,12 +210,16 @@
     if (gpr_cv_wait(GRPC_POLLSET_CV(&cc->pollset),
                     GRPC_POLLSET_MU(&cc->pollset), deadline)) {
       gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
-      return NULL;
+      memset(&ret, 0, sizeof(ret));
+      ret.type = GRPC_QUEUE_TIMEOUT;
+      return ret;
     }
   }
   gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
-  GRPC_SURFACE_TRACE_RETURNED_EVENT(cc, &ev->base);
-  return &ev->base;
+  ret = ev->base;
+  gpr_free(ev);
+  GRPC_SURFACE_TRACE_RETURNED_EVENT(cc, &ret);
+  return ret;
 }
 
 static event *pluck_event(grpc_completion_queue *cc, void *tag) {
@@ -277,9 +251,10 @@
   return NULL;
 }
 
-grpc_event *grpc_completion_queue_pluck(grpc_completion_queue *cc, void *tag,
-                                        gpr_timespec deadline) {
+grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cc, void *tag,
+                                       gpr_timespec deadline) {
   event *ev = NULL;
+  grpc_event ret;
 
   gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
   for (;;) {
@@ -296,12 +271,16 @@
     if (gpr_cv_wait(GRPC_POLLSET_CV(&cc->pollset),
                     GRPC_POLLSET_MU(&cc->pollset), deadline)) {
       gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
-      return NULL;
+      memset(&ret, 0, sizeof(ret));
+      ret.type = GRPC_QUEUE_TIMEOUT;
+      return ret;
     }
   }
   gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
+  ret = ev->base;
+  gpr_free(ev);
   GRPC_SURFACE_TRACE_RETURNED_EVENT(cc, &ev->base);
-  return &ev->base;
+  return ret;
 }
 
 /* Shutdown simply drops a ref that we reserved at creation time; if we drop
@@ -324,30 +303,6 @@
   grpc_cq_internal_unref(cc);
 }
 
-void grpc_event_finish(grpc_event *base) {
-  event *ev = (event *)base;
-  ev->on_finish(ev->on_finish_user_data, GRPC_OP_OK);
-  if (ev->base.call) {
-    GRPC_CALL_INTERNAL_UNREF(ev->base.call, "cq", 1);
-  }
-  gpr_free(ev);
-}
-
-void grpc_cq_dump_pending_ops(grpc_completion_queue *cc) {
-#ifndef NDEBUG
-  char tmp[GRPC_COMPLETION_DO_NOT_USE * (1 + GPR_LTOA_MIN_BUFSIZE)];
-  char *p = tmp;
-  int i;
-
-  for (i = 0; i < GRPC_COMPLETION_DO_NOT_USE; i++) {
-    *p++ = ' ';
-    p += gpr_ltoa(cc->pending_op_count[i], p);
-  }
-
-  gpr_log(GPR_INFO, "pending ops:%s", tmp);
-#endif
-}
-
 grpc_pollset *grpc_cq_pollset(grpc_completion_queue *cc) {
   return &cc->pollset;
 }
diff --git a/src/core/surface/completion_queue.h b/src/core/surface/completion_queue.h
index a0d7eea..239bfe4 100644
--- a/src/core/surface/completion_queue.h
+++ b/src/core/surface/completion_queue.h
@@ -39,17 +39,12 @@
 #include "src/core/iomgr/pollset.h"
 #include <grpc/grpc.h>
 
-/* A finish func is executed whenever the event consumer calls
-   grpc_event_finish */
-typedef void (*grpc_event_finish_func)(void *user_data, grpc_op_error error);
-
 void grpc_cq_internal_ref(grpc_completion_queue *cc);
 void grpc_cq_internal_unref(grpc_completion_queue *cc);
 
 /* Flag that an operation is beginning: the completion channel will not finish
    shutdown until a corrensponding grpc_cq_end_* call is made */
-void grpc_cq_begin_op(grpc_completion_queue *cc, grpc_call *call,
-                      grpc_completion_type type);
+void grpc_cq_begin_op(grpc_completion_queue *cc, grpc_call *call);
 
 /* grpc_cq_end_* functions pair with a grpc_cq_begin_op
 
@@ -64,16 +59,11 @@
 
 /* Queue a GRPC_OP_COMPLETED operation */
 void grpc_cq_end_op(grpc_completion_queue *cc, void *tag, grpc_call *call,
-                    grpc_event_finish_func on_finish, void *user_data,
-                    grpc_op_error error);
-
-void grpc_cq_end_server_shutdown(grpc_completion_queue *cc, void *tag);
+                    int success);
 
 /* disable polling for some tests */
 void grpc_completion_queue_dont_poll_test_only(grpc_completion_queue *cc);
 
-void grpc_cq_dump_pending_ops(grpc_completion_queue *cc);
-
 grpc_pollset *grpc_cq_pollset(grpc_completion_queue *cc);
 
 void grpc_cq_hack_spin_pollset(grpc_completion_queue *cc);
diff --git a/src/core/surface/event_string.c b/src/core/surface/event_string.c
index 30bdff6..448bb11 100644
--- a/src/core/surface/event_string.c
+++ b/src/core/surface/event_string.c
@@ -40,23 +40,15 @@
 
 static void addhdr(gpr_strvec *buf, grpc_event *ev) {
   char *tmp;
-  gpr_asprintf(&tmp, "tag:%p call:%p", ev->tag, (void *)ev->call);
+  gpr_asprintf(&tmp, "tag:%p", ev->tag);
   gpr_strvec_add(buf, tmp);
 }
 
-static const char *errstr(grpc_op_error err) {
-  switch (err) {
-    case GRPC_OP_OK:
-      return "OK";
-    case GRPC_OP_ERROR:
-      return "ERROR";
-  }
-  return "UNKNOWN_UNKNOWN";
-}
+static const char *errstr(int success) { return success ? "OK" : "ERROR"; }
 
-static void adderr(gpr_strvec *buf, grpc_op_error err) {
+static void adderr(gpr_strvec *buf, int success) {
   char *tmp;
-  gpr_asprintf(&tmp, " err=%s", errstr(err));
+  gpr_asprintf(&tmp, " %s", errstr(success));
   gpr_strvec_add(buf, tmp);
 }
 
@@ -69,8 +61,8 @@
   gpr_strvec_init(&buf);
 
   switch (ev->type) {
-    case GRPC_SERVER_SHUTDOWN:
-      gpr_strvec_add(&buf, gpr_strdup("SERVER_SHUTDOWN"));
+    case GRPC_QUEUE_TIMEOUT:
+      gpr_strvec_add(&buf, gpr_strdup("QUEUE_TIMEOUT"));
       break;
     case GRPC_QUEUE_SHUTDOWN:
       gpr_strvec_add(&buf, gpr_strdup("QUEUE_SHUTDOWN"));
@@ -78,11 +70,7 @@
     case GRPC_OP_COMPLETE:
       gpr_strvec_add(&buf, gpr_strdup("OP_COMPLETE: "));
       addhdr(&buf, ev);
-      adderr(&buf, ev->data.op_complete);
-      break;
-    case GRPC_COMPLETION_DO_NOT_USE:
-      gpr_strvec_add(&buf, gpr_strdup("DO_NOT_USE (this is a bug)"));
-      addhdr(&buf, ev);
+      adderr(&buf, ev->success);
       break;
   }
 
diff --git a/src/core/surface/server.c b/src/core/surface/server.c
index 01644b4..0d81170 100644
--- a/src/core/surface/server.c
+++ b/src/core/surface/server.c
@@ -188,8 +188,6 @@
 #define SERVER_FROM_CALL_ELEM(elem) \
   (((channel_data *)(elem)->channel_data)->server)
 
-static void do_nothing(void *unused, grpc_op_error ignored) {}
-
 static void begin_call(grpc_server *server, call_data *calld,
                        requested_call *rc);
 static void fail_call(grpc_server *server, requested_call *rc);
@@ -538,8 +536,8 @@
   if (chand->server->shutdown && chand->server->lists[ALL_CALLS] == NULL) {
     for (i = 0; i < chand->server->num_shutdown_tags; i++) {
       for (j = 0; j < chand->server->cq_count; j++) {
-        grpc_cq_end_server_shutdown(chand->server->cqs[j],
-                                    chand->server->shutdown_tags[i]);
+        grpc_cq_end_op(chand->server->cqs[j], chand->server->shutdown_tags[i],
+                       NULL, 1);
       }
     }
   }
@@ -817,7 +815,7 @@
   gpr_mu_lock(&server->mu);
   if (have_shutdown_tag) {
     for (i = 0; i < server->cq_count; i++) {
-      grpc_cq_begin_op(server->cqs[i], NULL, GRPC_SERVER_SHUTDOWN);
+      grpc_cq_begin_op(server->cqs[i], NULL);
     }
     server->shutdown_tags =
         gpr_realloc(server->shutdown_tags,
@@ -867,7 +865,7 @@
   if (server->lists[ALL_CALLS] == NULL) {
     for (i = 0; i < server->num_shutdown_tags; i++) {
       for (j = 0; j < server->cq_count; j++) {
-        grpc_cq_end_server_shutdown(server->cqs[j], server->shutdown_tags[i]);
+        grpc_cq_end_op(server->cqs[j], server->shutdown_tags[i], NULL, 1);
       }
     }
   }
@@ -1018,7 +1016,7 @@
                                          grpc_completion_queue *cq_bind,
                                          void *tag) {
   requested_call rc;
-  grpc_cq_begin_op(server->unregistered_cq, NULL, GRPC_OP_COMPLETE);
+  grpc_cq_begin_op(server->unregistered_cq, NULL);
   rc.type = BATCH_CALL;
   rc.tag = tag;
   rc.data.batch.cq_bind = cq_bind;
@@ -1034,7 +1032,7 @@
     grpc_completion_queue *cq_bind, void *tag) {
   requested_call rc;
   registered_method *registered_method = rm;
-  grpc_cq_begin_op(registered_method->cq, NULL, GRPC_OP_COMPLETE);
+  grpc_cq_begin_op(registered_method->cq, NULL);
   rc.type = REGISTERED_CALL;
   rc.tag = tag;
   rc.data.registered.cq_bind = cq_bind;
@@ -1046,10 +1044,9 @@
   return queue_call_request(server, &rc);
 }
 
-static void publish_registered_or_batch(grpc_call *call, grpc_op_error status,
+static void publish_registered_or_batch(grpc_call *call, int success,
                                         void *tag);
-static void publish_was_not_set(grpc_call *call, grpc_op_error status,
-                                void *tag) {
+static void publish_was_not_set(grpc_call *call, int success, void *tag) {
   abort();
 }
 
@@ -1118,24 +1115,23 @@
     case BATCH_CALL:
       *rc->data.batch.call = NULL;
       rc->data.batch.initial_metadata->count = 0;
-      grpc_cq_end_op(server->unregistered_cq, rc->tag, NULL, do_nothing, NULL,
-                     GRPC_OP_ERROR);
+      grpc_cq_end_op(server->unregistered_cq, rc->tag, NULL, 0);
       break;
     case REGISTERED_CALL:
       *rc->data.registered.call = NULL;
       rc->data.registered.initial_metadata->count = 0;
       grpc_cq_end_op(rc->data.registered.registered_method->cq, rc->tag, NULL,
-                     do_nothing, NULL, GRPC_OP_ERROR);
+                     0);
       break;
   }
 }
 
-static void publish_registered_or_batch(grpc_call *call, grpc_op_error status,
+static void publish_registered_or_batch(grpc_call *call, int success,
                                         void *tag) {
   grpc_call_element *elem =
       grpc_call_stack_element(grpc_call_get_call_stack(call), 0);
   call_data *calld = elem->call_data;
-  grpc_cq_end_op(calld->cq_new, tag, call, do_nothing, NULL, status);
+  grpc_cq_end_op(calld->cq_new, tag, call, success);
 }
 
 const grpc_channel_args *grpc_server_get_channel_args(grpc_server *server) {
diff --git a/src/cpp/client/client_context.cc b/src/cpp/client/client_context.cc
index 70c9cb4..f38a694 100644
--- a/src/cpp/client/client_context.cc
+++ b/src/cpp/client/client_context.cc
@@ -49,15 +49,11 @@
     grpc_call_destroy(call_);
   }
   if (cq_) {
-    grpc_completion_queue_shutdown(cq_);
     // Drain cq_.
-    grpc_event* ev;
-    grpc_completion_type t;
-    do {
-      ev = grpc_completion_queue_next(cq_, gpr_inf_future);
-      t = ev->type;
-      grpc_event_finish(ev);
-    } while (t != GRPC_QUEUE_SHUTDOWN);
+    grpc_completion_queue_shutdown(cq_);
+    while (grpc_completion_queue_next(cq_, gpr_inf_future).type !=
+           GRPC_QUEUE_SHUTDOWN)
+      ;
     grpc_completion_queue_destroy(cq_);
   }
 }
diff --git a/src/cpp/common/completion_queue.cc b/src/cpp/common/completion_queue.cc
index 2b9000e..b2dd1ac 100644
--- a/src/cpp/common/completion_queue.cc
+++ b/src/cpp/common/completion_queue.cc
@@ -48,53 +48,41 @@
 
 void CompletionQueue::Shutdown() { grpc_completion_queue_shutdown(cq_); }
 
-// Helper class so we can declare a unique_ptr with grpc_event
-class EventDeleter {
- public:
-  void operator()(grpc_event* ev) {
-    if (ev) grpc_event_finish(ev);
-  }
-};
-
 CompletionQueue::NextStatus CompletionQueue::AsyncNextInternal(
     void** tag, bool* ok, gpr_timespec deadline) {
-  std::unique_ptr<grpc_event, EventDeleter> ev;
-
   for (;;) {
-    ev.reset(grpc_completion_queue_next(cq_, deadline));
-    if (!ev) { /* got a NULL back because deadline passed */
-      return TIMEOUT;
-    }
-    if (ev->type == GRPC_QUEUE_SHUTDOWN) {
-      return SHUTDOWN;
-    }
-    auto cq_tag = static_cast<CompletionQueueTag*>(ev->tag);
-    *ok = ev->data.op_complete == GRPC_OP_OK;
-    *tag = cq_tag;
-    if (cq_tag->FinalizeResult(tag, ok)) {
-      return GOT_EVENT;
+    auto ev = grpc_completion_queue_next(cq_, deadline);
+    switch (ev.type) {
+      case GRPC_QUEUE_TIMEOUT:
+        return TIMEOUT;
+      case GRPC_QUEUE_SHUTDOWN:
+        return SHUTDOWN;
+      case GRPC_OP_COMPLETE:
+        auto cq_tag = static_cast<CompletionQueueTag*>(ev.tag);
+        *ok = ev.success != 0;
+        *tag = cq_tag;
+        if (cq_tag->FinalizeResult(tag, ok)) {
+          return GOT_EVENT;
+        }
+        break;
     }
   }
 }
 
 bool CompletionQueue::Pluck(CompletionQueueTag* tag) {
-  std::unique_ptr<grpc_event, EventDeleter> ev;
-
-  ev.reset(grpc_completion_queue_pluck(cq_, tag, gpr_inf_future));
-  bool ok = ev->data.op_complete == GRPC_OP_OK;
+  auto ev = grpc_completion_queue_pluck(cq_, tag, gpr_inf_future);
+  bool ok = ev.success != 0;
   void* ignored = tag;
   GPR_ASSERT(tag->FinalizeResult(&ignored, &ok));
   GPR_ASSERT(ignored == tag);
   // Ignore mutations by FinalizeResult: Pluck returns the C API status
-  return ev->data.op_complete == GRPC_OP_OK;
+  return ev.success != 0;
 }
 
 void CompletionQueue::TryPluck(CompletionQueueTag* tag) {
-  std::unique_ptr<grpc_event, EventDeleter> ev;
-
-  ev.reset(grpc_completion_queue_pluck(cq_, tag, gpr_time_0));
-  if (!ev) return;
-  bool ok = ev->data.op_complete == GRPC_OP_OK;
+  auto ev = grpc_completion_queue_pluck(cq_, tag, gpr_time_0);
+  if (ev.type == GRPC_QUEUE_TIMEOUT) return;
+  bool ok = ev.success != 0;
   void* ignored = tag;
   // the tag must be swallowed if using TryPluck
   GPR_ASSERT(!tag->FinalizeResult(&ignored, &ok));
diff --git a/src/csharp/ext/grpc_csharp_ext.c b/src/csharp/ext/grpc_csharp_ext.c
index fb8b757..df812c8 100644
--- a/src/csharp/ext/grpc_csharp_ext.c
+++ b/src/csharp/ext/grpc_csharp_ext.c
@@ -63,8 +63,7 @@
   return bb;
 }
 
-typedef void(GPR_CALLTYPE *callback_funcptr)(grpc_op_error op_error,
-                                             void *batch_context);
+typedef void(GPR_CALLTYPE *callback_funcptr)(int success, void *batch_context);
 
 /*
  * Helper to maintain lifetime of batch op inputs and store batch op outputs.
@@ -302,27 +301,26 @@
 
 GPR_EXPORT grpc_completion_type GPR_CALLTYPE
 grpcsharp_completion_queue_next_with_callback(grpc_completion_queue *cq) {
-  grpc_event *ev;
+  grpc_event ev;
   grpcsharp_batch_context *batch_context;
   grpc_completion_type t;
   void(GPR_CALLTYPE * callback)(grpc_event *);
 
   ev = grpc_completion_queue_next(cq, gpr_inf_future);
-  t = ev->type;
-  if (t == GRPC_OP_COMPLETE && ev->tag) {
+  t = ev.type;
+  if (t == GRPC_OP_COMPLETE && ev.tag) {
     /* NEW API handler */
-    batch_context = (grpcsharp_batch_context *)ev->tag;
-    batch_context->callback(ev->data.op_complete, batch_context);
+    batch_context = (grpcsharp_batch_context *)ev.tag;
+    batch_context->callback(ev.success, batch_context);
     grpcsharp_batch_context_destroy(batch_context);
-  } else if (ev->tag) {
+  } else if (ev.tag) {
     /* call the callback in ev->tag */
     /* C forbids to cast object pointers to function pointers, so
      * we cast to intptr first.
      */
-    callback = (void(GPR_CALLTYPE *)(grpc_event *))(gpr_intptr)ev->tag;
-    (*callback)(ev);
+    callback = (void(GPR_CALLTYPE *)(grpc_event *))(gpr_intptr)ev.tag;
+    (*callback)(&ev);
   }
-  grpc_event_finish(ev);
 
   /* return completion type to allow some handling for events that have no
    * tag - such as GRPC_QUEUE_SHUTDOWN
@@ -789,7 +787,7 @@
 /* For testing */
 GPR_EXPORT void GPR_CALLTYPE
 grpcsharp_test_callback(callback_funcptr callback) {
-  callback(GRPC_OP_OK, NULL);
+  callback(1, NULL);
 }
 
 /* For testing */
diff --git a/src/node/ext/completion_queue_async_worker.cc b/src/node/ext/completion_queue_async_worker.cc
index 4e57121..4be208c 100644
--- a/src/node/ext/completion_queue_async_worker.cc
+++ b/src/node/ext/completion_queue_async_worker.cc
@@ -63,7 +63,7 @@
 
 void CompletionQueueAsyncWorker::Execute() {
   result = grpc_completion_queue_next(queue, gpr_inf_future);
-  if (result->data.op_complete != GRPC_OP_OK) {
+  if (!result.success) {
     SetErrorMessage("The batch encountered an error");
   }
 }
@@ -96,25 +96,21 @@
   } else {
     current_threads -= 1;
   }
-  NanCallback *callback = GetTagCallback(result->tag);
-  Handle<Value> argv[] = {NanNull(), GetTagNodeValue(result->tag)};
+  NanCallback *callback = GetTagCallback(result.tag);
+  Handle<Value> argv[] = {NanNull(), GetTagNodeValue(result.tag)};
   callback->Call(2, argv);
 
-  DestroyTag(result->tag);
-  grpc_event_finish(result);
-  result = NULL;
+  DestroyTag(result.tag);
 }
 
 void CompletionQueueAsyncWorker::HandleErrorCallback() {
   NanScope();
-  NanCallback *callback = GetTagCallback(result->tag);
+  NanCallback *callback = GetTagCallback(result.tag);
   Handle<Value> argv[] = {NanError(ErrorMessage())};
 
   callback->Call(1, argv);
 
-  DestroyTag(result->tag);
-  grpc_event_finish(result);
-  result = NULL;
+  DestroyTag(result.tag);
 }
 
 }  // namespace node
diff --git a/src/node/ext/completion_queue_async_worker.h b/src/node/ext/completion_queue_async_worker.h
index 5d52bbb..27fedf2 100644
--- a/src/node/ext/completion_queue_async_worker.h
+++ b/src/node/ext/completion_queue_async_worker.h
@@ -70,7 +70,7 @@
   void HandleErrorCallback();
 
  private:
-  grpc_event *result;
+  grpc_event result;
 
   static grpc_completion_queue *queue;
 
diff --git a/src/php/ext/grpc/call.c b/src/php/ext/grpc/call.c
index b1525e9..9cc4fd7 100644
--- a/src/php/ext/grpc/call.c
+++ b/src/php/ext/grpc/call.c
@@ -61,17 +61,12 @@
 /* Frees and destroys an instance of wrapped_grpc_call */
 void free_wrapped_grpc_call(void *object TSRMLS_DC) {
   wrapped_grpc_call *call = (wrapped_grpc_call *)object;
-  grpc_event *event;
   if (call->owned && call->wrapped != NULL) {
     if (call->queue != NULL) {
       grpc_completion_queue_shutdown(call->queue);
-      event = grpc_completion_queue_next(call->queue, gpr_inf_future);
-      while (event != NULL) {
-        if (event->type == GRPC_QUEUE_SHUTDOWN) {
-          break;
-        }
-        event = grpc_completion_queue_next(call->queue, gpr_inf_future);
-      }
+      while (grpc_completion_queue_next(call->queue, gpr_inf_future).type !=
+             GRPC_QUEUE_SHUTDOWN)
+        ;
       grpc_completion_queue_destroy(call->queue);
     }
     grpc_call_destroy(call->wrapped);
@@ -287,7 +282,7 @@
   grpc_byte_buffer *message;
   int cancelled;
   grpc_call_error error;
-  grpc_event *event;
+  grpc_event event;
   zval *result;
   char *message_str;
   size_t message_len;
@@ -422,7 +417,7 @@
   }
   event = grpc_completion_queue_pluck(call->queue, call->wrapped,
                                       gpr_inf_future);
-  if (event->data.op_complete != GRPC_OP_OK) {
+  if (!event.success) {
     zend_throw_exception(spl_ce_LogicException,
                          "The batch failed for some reason",
                          1 TSRMLS_CC);
diff --git a/src/php/ext/grpc/server.c b/src/php/ext/grpc/server.c
index dbb9425..c5defa4 100644
--- a/src/php/ext/grpc/server.c
+++ b/src/php/ext/grpc/server.c
@@ -61,16 +61,11 @@
 /* Frees and destroys an instance of wrapped_grpc_server */
 void free_wrapped_grpc_server(void *object TSRMLS_DC) {
   wrapped_grpc_server *server = (wrapped_grpc_server *)object;
-  grpc_event *event;
   if (server->queue != NULL) {
     grpc_completion_queue_shutdown(server->queue);
-    event = grpc_completion_queue_next(server->queue, gpr_inf_future);
-    while (event != NULL) {
-      if (event->type == GRPC_QUEUE_SHUTDOWN) {
-        break;
-      }
-      event = grpc_completion_queue_next(server->queue, gpr_inf_future);
-    }
+    while (grpc_completion_queue_next(server->queue, gpr_inf_future).type !=
+           GRPC_QUEUE_SHUTDOWN)
+      ;
     grpc_completion_queue_destroy(server->queue);
   }
   if (server->wrapped != NULL) {
@@ -141,7 +136,7 @@
   grpc_call_details details;
   grpc_metadata_array metadata;
   zval *result;
-  grpc_event *event;
+  grpc_event event;
   MAKE_STD_ZVAL(result);
   object_init(result);
   grpc_call_details_init(&details);
@@ -154,7 +149,7 @@
     goto cleanup;
   }
   event = grpc_completion_queue_pluck(server->queue, NULL, gpr_inf_future);
-  if (event->data.op_complete != GRPC_OP_OK) {
+  if (!event.success) {
     zend_throw_exception(spl_ce_LogicException,
                          "Failed to request a call for some reason",
                          1 TSRMLS_CC);
diff --git a/src/python/src/grpc/_adapter/_completion_queue.c b/src/python/src/grpc/_adapter/_completion_queue.c
index f616faf..23e5b47 100644
--- a/src/python/src/grpc/_adapter/_completion_queue.c
+++ b/src/python/src/grpc/_adapter/_completion_queue.c
@@ -349,7 +349,7 @@
   PyObject *deadline;
   double double_deadline;
   gpr_timespec deadline_timespec;
-  grpc_event *c_event;
+  grpc_event c_event;
 
   PyObject *event_args;
   PyObject *event;
@@ -378,15 +378,14 @@
       grpc_completion_queue_next(self->c_completion_queue, deadline_timespec);
   Py_END_ALLOW_THREADS;
 
-  if (c_event == NULL) {
-    Py_RETURN_NONE;
-  }
+  tag = (pygrpc_tag *)c_event.tag;
 
-  tag = (pygrpc_tag *)c_event->tag;
-
-  switch (c_event->type) {
+  switch (c_event.type) {
+    case GRPC_QUEUE_TIMEOUT:
+      Py_RETURN_NONE;
+      break;
     case GRPC_QUEUE_SHUTDOWN:
-      event_args = pygrpc_stop_event_args(c_event);
+      event_args = pygrpc_stop_event_args(&c_event);
       break;
     case GRPC_OP_COMPLETE: {
       if (!tag) {
@@ -398,28 +397,27 @@
           if (tag) {
             pygrpc_tag_destroy(tag);
           }
-          grpc_event_finish(c_event);
           return pygrpc_completion_queue_get(self, args);
         case PYGRPC_WRITE_ACCEPTED:
-          event_args = pygrpc_write_event_args(c_event);
+          event_args = pygrpc_write_event_args(&c_event);
           break;
         case PYGRPC_FINISH_ACCEPTED:
-          event_args = pygrpc_complete_event_args(c_event);
+          event_args = pygrpc_complete_event_args(&c_event);
           break;
         case PYGRPC_SERVER_RPC_NEW:
-          event_args = pygrpc_service_event_args(c_event);
+          event_args = pygrpc_service_event_args(&c_event);
           break;
         case PYGRPC_READ:
-          event_args = pygrpc_read_event_args(c_event);
+          event_args = pygrpc_read_event_args(&c_event);
           break;
         case PYGRPC_CLIENT_METADATA_READ:
-          event_args = pygrpc_metadata_event_args(c_event);
+          event_args = pygrpc_metadata_event_args(&c_event);
           break;
         case PYGRPC_FINISHED_CLIENT:
-          event_args = pygrpc_finished_client_event_args(c_event);
+          event_args = pygrpc_finished_client_event_args(&c_event);
           break;
         case PYGRPC_FINISHED_SERVER:
-          event_args = pygrpc_finished_server_event_args(c_event);
+          event_args = pygrpc_finished_server_event_args(&c_event);
           break;
         default:
           PyErr_SetString(PyExc_Exception, "Unrecognized op event type!");
diff --git a/test/core/end2end/cq_verifier.c b/test/core/end2end/cq_verifier.c
index f291e73..6648025 100644
--- a/test/core/end2end/cq_verifier.c
+++ b/test/core/end2end/cq_verifier.c
@@ -45,6 +45,8 @@
 #include <grpc/support/time.h>
 #include <grpc/support/useful.h>
 
+#define ROOT_EXPECTATION 1000
+
 /* a set of metadata we expect to find on an event */
 typedef struct metadata {
   size_t count;
@@ -60,9 +62,7 @@
   struct expectation *prev;
   grpc_completion_type type;
   void *tag;
-  union {
-    grpc_op_error op_complete;
-  } data;
+  int success;
 } expectation;
 
 /* the verifier itself */
@@ -75,7 +75,7 @@
 
 cq_verifier *cq_verifier_create(grpc_completion_queue *cq) {
   cq_verifier *v = gpr_malloc(sizeof(cq_verifier));
-  v->expect.type = GRPC_COMPLETION_DO_NOT_USE;
+  v->expect.type = ROOT_EXPECTATION;
   v->expect.tag = NULL;
   v->expect.next = &v->expect;
   v->expect.prev = &v->expect;
@@ -149,11 +149,9 @@
       abort();
       break;
     case GRPC_OP_COMPLETE:
-      GPR_ASSERT(e->data.op_complete == ev->data.op_complete);
+      GPR_ASSERT(e->success == ev->success);
       break;
-    case GRPC_SERVER_SHUTDOWN:
-      break;
-    case GRPC_COMPLETION_DO_NOT_USE:
+    case GRPC_QUEUE_TIMEOUT:
       gpr_log(GPR_ERROR, "not implemented");
       abort();
       break;
@@ -165,13 +163,10 @@
 
   switch (e->type) {
     case GRPC_OP_COMPLETE:
-      gpr_asprintf(&tmp, "GRPC_OP_COMPLETE result=%d", e->data.op_complete);
+      gpr_asprintf(&tmp, "GRPC_OP_COMPLETE result=%d", e->success);
       gpr_strvec_add(buf, tmp);
       break;
-    case GRPC_SERVER_SHUTDOWN:
-      gpr_strvec_add(buf, gpr_strdup("GRPC_SERVER_SHUTDOWN"));
-      break;
-    case GRPC_COMPLETION_DO_NOT_USE:
+    case GRPC_QUEUE_TIMEOUT:
     case GRPC_QUEUE_SHUTDOWN:
       gpr_log(GPR_ERROR, "not implemented");
       abort();
@@ -203,7 +198,7 @@
 
 void cq_verify(cq_verifier *v) {
   gpr_timespec deadline = GRPC_TIMEOUT_SECONDS_TO_DEADLINE(10);
-  grpc_event *ev;
+  grpc_event ev;
   expectation *e;
   char *s;
   gpr_strvec have_tags;
@@ -212,15 +207,16 @@
 
   while (v->expect.next != &v->expect) {
     ev = grpc_completion_queue_next(v->cq, deadline);
-    if (!ev) {
+    if (ev.type == GRPC_QUEUE_TIMEOUT) {
       fail_no_event_received(v);
+      break;
     }
 
     for (e = v->expect.next; e != &v->expect; e = e->next) {
       gpr_asprintf(&s, " %p", e->tag);
       gpr_strvec_add(&have_tags, s);
-      if (e->tag == ev->tag) {
-        verify_matches(e, ev);
+      if (e->tag == ev.tag) {
+        verify_matches(e, &ev);
         e->next->prev = e->prev;
         e->prev->next = e->next;
         gpr_free(e);
@@ -228,7 +224,7 @@
       }
     }
     if (e == &v->expect) {
-      s = grpc_event_string(ev);
+      s = grpc_event_string(&ev);
       gpr_log(GPR_ERROR, "event not found: %s", s);
       gpr_free(s);
       s = gpr_strvec_flatten(&have_tags, NULL);
@@ -237,8 +233,6 @@
       gpr_strvec_destroy(&have_tags);
       abort();
     }
-
-    grpc_event_finish(ev);
   }
 
   gpr_strvec_destroy(&have_tags);
@@ -246,13 +240,13 @@
 
 void cq_verify_empty(cq_verifier *v) {
   gpr_timespec deadline = gpr_time_add(gpr_now(), gpr_time_from_seconds(1));
-  grpc_event *ev;
+  grpc_event ev;
 
   GPR_ASSERT(v->expect.next == &v->expect && "expectation queue must be empty");
 
   ev = grpc_completion_queue_next(v->cq, deadline);
-  if (ev != NULL) {
-    char *s = grpc_event_string(ev);
+  if (ev.type != GRPC_QUEUE_TIMEOUT) {
+    char *s = grpc_event_string(&ev);
     gpr_log(GPR_ERROR, "unexpected event (expected nothing): %s", s);
     gpr_free(s);
     abort();
@@ -269,10 +263,6 @@
   return e;
 }
 
-void cq_expect_completion(cq_verifier *v, void *tag, grpc_op_error result) {
-  add(v, GRPC_OP_COMPLETE, tag)->data.op_complete = result;
-}
-
-void cq_expect_server_shutdown(cq_verifier *v, void *tag) {
-  add(v, GRPC_SERVER_SHUTDOWN, tag);
+void cq_expect_completion(cq_verifier *v, void *tag, int success) {
+  add(v, GRPC_OP_COMPLETE, tag)->success = success;
 }
diff --git a/test/core/end2end/cq_verifier.h b/test/core/end2end/cq_verifier.h
index bae3c6c..1ecd4db 100644
--- a/test/core/end2end/cq_verifier.h
+++ b/test/core/end2end/cq_verifier.h
@@ -57,8 +57,7 @@
    Any functions taking ... expect a NULL terminated list of key/value pairs
    (each pair using two parameter slots) of metadata that MUST be present in
    the event. */
-void cq_expect_completion(cq_verifier *v, void *tag, grpc_op_error result);
-void cq_expect_server_shutdown(cq_verifier *v, void *tag);
+void cq_expect_completion(cq_verifier *v, void *tag, int success);
 
 int byte_buffer_eq_string(grpc_byte_buffer *byte_buffer, const char *string);
 int contains_metadata(grpc_metadata_array *array, const char *key, const char *value);
diff --git a/test/core/end2end/dualstack_socket_test.c b/test/core/end2end/dualstack_socket_test.c
index 5e278ca..92bb49b 100644
--- a/test/core/end2end/dualstack_socket_test.c
+++ b/test/core/end2end/dualstack_socket_test.c
@@ -50,15 +50,10 @@
 }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, ms_from_now(5000));
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-    gpr_log(GPR_INFO, "Drained event type %d", type);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 void test_connect(const char *server_host, const char *client_host, int port,
@@ -159,7 +154,7 @@
                                                         &call_details,
                                                         &request_metadata_recv,
                                                         server_cq, tag(101)));
-    cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+    cq_expect_completion(v_server, tag(101), 1);
     cq_verify(v_server);
 
     op = ops;
@@ -177,10 +172,10 @@
     GPR_ASSERT(GRPC_CALL_OK ==
                grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-    cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+    cq_expect_completion(v_server, tag(102), 1);
     cq_verify(v_server);
 
-    cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+    cq_expect_completion(v_client, tag(1), 1);
     cq_verify(v_client);
 
     GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
@@ -192,7 +187,7 @@
     grpc_call_destroy(s);
   } else {
     /* Check for a failed connection. */
-    cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+    cq_expect_completion(v_client, tag(1), 1);
     cq_verify(v_client);
 
     GPR_ASSERT(status == GRPC_STATUS_DEADLINE_EXCEEDED);
diff --git a/test/core/end2end/no_server_test.c b/test/core/end2end/no_server_test.c
index b292620..bba9cd1 100644
--- a/test/core/end2end/no_server_test.c
+++ b/test/core/end2end/no_server_test.c
@@ -45,8 +45,6 @@
   gpr_timespec deadline = GRPC_TIMEOUT_SECONDS_TO_DEADLINE(2);
   grpc_completion_queue *cq;
   cq_verifier *cqv;
-  grpc_event *ev;
-  int done;
   grpc_op ops[6];
   grpc_op *op;
   grpc_metadata_array trailing_metadata_recv;
@@ -79,17 +77,15 @@
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(call, ops, op - ops, tag(1)));
   /* verify that all tags get completed */
-  cq_expect_completion(cqv, tag(1), GRPC_OP_OK);
+  cq_expect_completion(cqv, tag(1), 1);
   cq_verify(cqv);
 
   GPR_ASSERT(status == GRPC_STATUS_DEADLINE_EXCEEDED);
 
   grpc_completion_queue_shutdown(cq);
-  for (done = 0; !done;) {
-    ev = grpc_completion_queue_next(cq, gpr_inf_future);
-    done = ev->type == GRPC_QUEUE_SHUTDOWN;
-    grpc_event_finish(ev);
-  }
+  while (grpc_completion_queue_next(cq, gpr_inf_future).type !=
+         GRPC_QUEUE_SHUTDOWN)
+    ;
   grpc_completion_queue_destroy(cq);
   grpc_call_destroy(call);
   grpc_channel_destroy(chan);
diff --git a/test/core/end2end/tests/bad_hostname.c b/test/core/end2end/tests/bad_hostname.c
index 80922f3..c43dfff 100644
--- a/test/core/end2end/tests/bad_hostname.c
+++ b/test/core/end2end/tests/bad_hostname.c
@@ -69,14 +69,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -144,7 +140,7 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNAUTHENTICATED);
diff --git a/test/core/end2end/tests/cancel_after_accept.c b/test/core/end2end/tests/cancel_after_accept.c
index 2105796..3cd8114 100644
--- a/test/core/end2end/tests/cancel_after_accept.c
+++ b/test/core/end2end/tests/cancel_after_accept.c
@@ -68,14 +68,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -164,7 +160,7 @@
   GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
                                  f.server, &s, &call_details,
                                  &request_metadata_recv, f.server_cq, tag(2)));
-  cq_expect_completion(v_server, tag(2), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(2), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -184,10 +180,10 @@
 
   GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c));
 
-  cq_expect_completion(v_server, tag(3), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(3), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == mode.expect_status);
diff --git a/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c b/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
index f8733ef..57c696c 100644
--- a/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
+++ b/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
@@ -68,14 +68,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -166,7 +162,7 @@
   GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(
                                  f.server, &s, &call_details,
                                  &request_metadata_recv, f.server_cq, tag(2)));
-  cq_expect_completion(v_server, tag(2), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(2), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -186,10 +182,10 @@
 
   GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c));
 
-  cq_expect_completion(v_server, tag(3), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(3), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == mode.expect_status);
diff --git a/test/core/end2end/tests/cancel_after_invoke.c b/test/core/end2end/tests/cancel_after_invoke.c
index 592dfd4..33b1172 100644
--- a/test/core/end2end/tests/cancel_after_invoke.c
+++ b/test/core/end2end/tests/cancel_after_invoke.c
@@ -69,14 +69,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -160,7 +156,7 @@
 
   GPR_ASSERT(GRPC_CALL_OK == mode.initiate_cancel(c));
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == mode.expect_status);
diff --git a/test/core/end2end/tests/cancel_before_invoke.c b/test/core/end2end/tests/cancel_before_invoke.c
index 6e100db..cb7ba4d 100644
--- a/test/core/end2end/tests/cancel_before_invoke.c
+++ b/test/core/end2end/tests/cancel_before_invoke.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -157,7 +153,7 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, test_ops, tag(1)));
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_CANCELLED);
diff --git a/test/core/end2end/tests/cancel_in_a_vacuum.c b/test/core/end2end/tests/cancel_in_a_vacuum.c
index a88ca0b..84c0ad2 100644
--- a/test/core/end2end/tests/cancel_in_a_vacuum.c
+++ b/test/core/end2end/tests/cancel_in_a_vacuum.c
@@ -66,14 +66,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
diff --git a/test/core/end2end/tests/census_simple_request.c b/test/core/end2end/tests/census_simple_request.c
index 67c769c..a457574 100644
--- a/test/core/end2end/tests/census_simple_request.c
+++ b/test/core/end2end/tests/census_simple_request.c
@@ -75,14 +75,10 @@
 }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, n_seconds_time(5));
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void end_test(grpc_end2end_test_fixture *f) {
@@ -146,7 +142,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -163,10 +159,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/disappearing_server.c b/test/core/end2end/tests/disappearing_server.c
index c8e22ce..4ac36b8 100644
--- a/test/core/end2end/tests/disappearing_server.c
+++ b/test/core/end2end/tests/disappearing_server.c
@@ -55,14 +55,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -137,7 +133,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f->server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   /* should be able to shut down the server early
@@ -158,10 +154,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c b/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
index 2c2d2e8..90713d1 100644
--- a/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
+++ b/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -152,7 +148,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -164,10 +160,10 @@
   /* shutdown and destroy the server */
   shutdown_server(&f);
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNAVAILABLE);
diff --git a/test/core/end2end/tests/early_server_shutdown_finishes_tags.c b/test/core/end2end/tests/early_server_shutdown_finishes_tags.c
index 96978a8..5515bd8 100644
--- a/test/core/end2end/tests/early_server_shutdown_finishes_tags.c
+++ b/test/core/end2end/tests/early_server_shutdown_finishes_tags.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -120,7 +116,7 @@
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
   grpc_server_shutdown(f.server);
-  cq_expect_completion(v_server, tag(101), GRPC_OP_ERROR);
+  cq_expect_completion(v_server, tag(101), 0);
   cq_verify(v_server);
   GPR_ASSERT(s == NULL);
 
diff --git a/test/core/end2end/tests/empty_batch.c b/test/core/end2end/tests/empty_batch.c
index 6237e29..3b8e33c 100644
--- a/test/core/end2end/tests/empty_batch.c
+++ b/test/core/end2end/tests/empty_batch.c
@@ -69,14 +69,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -115,7 +111,7 @@
   GPR_ASSERT(c);
 
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, op, 0, tag(1)));
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   grpc_call_destroy(c);
diff --git a/test/core/end2end/tests/graceful_server_shutdown.c b/test/core/end2end/tests/graceful_server_shutdown.c
index d084530..eb853c9 100644
--- a/test/core/end2end/tests/graceful_server_shutdown.c
+++ b/test/core/end2end/tests/graceful_server_shutdown.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -151,7 +147,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   /* shutdown and destroy the server */
@@ -172,14 +168,14 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
   grpc_call_destroy(s);
-  cq_expect_server_shutdown(v_server, tag(0xdead));
+  cq_expect_completion(v_server, tag(0xdead), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/invoke_large_request.c b/test/core/end2end/tests/invoke_large_request.c
index d9d9e93..8d0b1fa 100644
--- a/test/core/end2end/tests/invoke_large_request.c
+++ b/test/core/end2end/tests/invoke_large_request.c
@@ -65,14 +65,10 @@
 }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, n_seconds_time(5));
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -169,7 +165,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -192,10 +188,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/max_concurrent_streams.c b/test/core/end2end/tests/max_concurrent_streams.c
index 6e95a6c..56d81a1 100644
--- a/test/core/end2end/tests/max_concurrent_streams.c
+++ b/test/core/end2end/tests/max_concurrent_streams.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -149,7 +145,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -166,10 +162,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
@@ -203,7 +199,7 @@
   gpr_timespec deadline;
   cq_verifier *v_client;
   cq_verifier *v_server;
-  grpc_event *ev;
+  grpc_event ev;
   grpc_call_details call_details;
   grpc_metadata_array request_metadata_recv;
   grpc_metadata_array initial_metadata_recv1;
@@ -303,20 +299,18 @@
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(c2, ops, op - ops, tag(402)));
 
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   ev = grpc_completion_queue_next(f.client_cq,
                                   GRPC_TIMEOUT_SECONDS_TO_DEADLINE(3));
-  GPR_ASSERT(ev);
-  GPR_ASSERT(ev->type == GRPC_OP_COMPLETE);
-  GPR_ASSERT(ev->data.op_complete == GRPC_OP_OK);
-  GPR_ASSERT(ev->tag == tag(301) || ev->tag == tag(401));
+  GPR_ASSERT(ev.type == GRPC_OP_COMPLETE);
+  GPR_ASSERT(ev.success);
+  GPR_ASSERT(ev.tag == tag(301) || ev.tag == tag(401));
   /* The /alpha or /beta calls started above could be invoked (but NOT both);
    * check this here */
   /* We'll get tag 303 or 403, we want 300, 400 */
-  live_call = ((int)(gpr_intptr)ev->tag) - 1;
-  grpc_event_finish(ev);
+  live_call = ((int)(gpr_intptr)ev.tag) - 1;
 
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
@@ -333,20 +327,20 @@
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(s1, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(live_call + 2), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(live_call + 2), 1);
   /* first request is finished, we should be able to start the second */
   live_call = (live_call == 300) ? 400 : 300;
-  cq_expect_completion(v_client, tag(live_call + 1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(live_call + 1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(GRPC_CALL_OK == grpc_server_request_call(f.server, &s2,
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(201)));
-  cq_expect_completion(v_server, tag(201), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(201), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -364,10 +358,10 @@
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(s2, ops, op - ops, tag(202)));
 
-  cq_expect_completion(v_client, tag(live_call + 2), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(live_call + 2), 1);
   cq_verify(v_client);
 
-  cq_expect_completion(v_server, tag(202), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(202), 1);
   cq_verify(v_server);
 
   cq_verifier_destroy(v_client);
diff --git a/test/core/end2end/tests/no_op.c b/test/core/end2end/tests/no_op.c
index 497bdcc..ec38924 100644
--- a/test/core/end2end/tests/no_op.c
+++ b/test/core/end2end/tests/no_op.c
@@ -65,14 +65,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
diff --git a/test/core/end2end/tests/ping_pong_streaming.c b/test/core/end2end/tests/ping_pong_streaming.c
index fe02f25..6fad1f6 100644
--- a/test/core/end2end/tests/ping_pong_streaming.c
+++ b/test/core/end2end/tests/ping_pong_streaming.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -157,7 +153,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(100)));
-  cq_expect_completion(v_server, tag(100), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(100), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -188,7 +184,7 @@
     op++;
     GPR_ASSERT(GRPC_CALL_OK ==
                grpc_call_start_batch(s, ops, op - ops, tag(102)));
-    cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+    cq_expect_completion(v_server, tag(102), 1);
     cq_verify(v_server);
 
     op = ops;
@@ -197,10 +193,10 @@
     op++;
     GPR_ASSERT(GRPC_CALL_OK ==
                grpc_call_start_batch(s, ops, op - ops, tag(103)));
-    cq_expect_completion(v_server, tag(103), GRPC_OP_OK);
+    cq_expect_completion(v_server, tag(103), 1);
     cq_verify(v_server);
 
-    cq_expect_completion(v_client, tag(2), GRPC_OP_OK);
+    cq_expect_completion(v_client, tag(2), 1);
     cq_verify(v_client);
 
     grpc_byte_buffer_destroy(request_payload);
@@ -225,12 +221,12 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(104)));
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
-  cq_expect_completion(v_client, tag(3), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
+  cq_expect_completion(v_client, tag(3), 1);
   cq_verify(v_client);
 
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
-  cq_expect_completion(v_server, tag(104), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
+  cq_expect_completion(v_server, tag(104), 1);
   cq_verify(v_server);
 
   grpc_call_destroy(c);
diff --git a/test/core/end2end/tests/registered_call.c b/test/core/end2end/tests/registered_call.c
index 05b7a1d..3ffcf00 100644
--- a/test/core/end2end/tests/registered_call.c
+++ b/test/core/end2end/tests/registered_call.c
@@ -69,14 +69,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -150,7 +146,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -167,10 +163,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
index 0169d52..2d65198 100644
--- a/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -185,7 +181,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -209,10 +205,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/request_response_with_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_metadata_and_payload.c
index dc49242..db766cf 100644
--- a/test/core/end2end/tests/request_response_with_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_metadata_and_payload.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -171,7 +167,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -195,10 +191,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/request_response_with_payload.c b/test/core/end2end/tests/request_response_with_payload.c
index 9203659..6c21db3 100644
--- a/test/core/end2end/tests/request_response_with_payload.c
+++ b/test/core/end2end/tests/request_response_with_payload.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -163,7 +159,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -186,10 +182,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
index b7834a1..0c3929f 100644
--- a/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
@@ -170,7 +170,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -195,10 +195,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/request_with_large_metadata.c b/test/core/end2end/tests/request_with_large_metadata.c
index c5b4e0c..1ed059e 100644
--- a/test/core/end2end/tests/request_with_large_metadata.c
+++ b/test/core/end2end/tests/request_with_large_metadata.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -167,7 +163,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -187,10 +183,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/request_with_payload.c b/test/core/end2end/tests/request_with_payload.c
index 63b7c5e..af57789 100644
--- a/test/core/end2end/tests/request_with_payload.c
+++ b/test/core/end2end/tests/request_with_payload.c
@@ -67,14 +67,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -158,7 +154,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -178,10 +174,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/simple_delayed_request.c b/test/core/end2end/tests/simple_delayed_request.c
index 0dbb35d..030e358 100644
--- a/test/core/end2end/tests/simple_delayed_request.c
+++ b/test/core/end2end/tests/simple_delayed_request.c
@@ -55,14 +55,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -145,7 +141,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f->server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -162,10 +158,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/end2end/tests/simple_request.c b/test/core/end2end/tests/simple_request.c
index 4d4d48a..aa6e506 100644
--- a/test/core/end2end/tests/simple_request.c
+++ b/test/core/end2end/tests/simple_request.c
@@ -69,14 +69,10 @@
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
 
 static void drain_cq(grpc_completion_queue *cq) {
-  grpc_event *ev;
-  grpc_completion_type type;
+  grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, five_seconds_time());
-    GPR_ASSERT(ev);
-    type = ev->type;
-    grpc_event_finish(ev);
-  } while (type != GRPC_QUEUE_SHUTDOWN);
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
 static void shutdown_server(grpc_end2end_test_fixture *f) {
@@ -151,7 +147,7 @@
                                                       &call_details,
                                                       &request_metadata_recv,
                                                       f.server_cq, tag(101)));
-  cq_expect_completion(v_server, tag(101), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(101), 1);
   cq_verify(v_server);
 
   op = ops;
@@ -168,10 +164,10 @@
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
-  cq_expect_completion(v_server, tag(102), GRPC_OP_OK);
+  cq_expect_completion(v_server, tag(102), 1);
   cq_verify(v_server);
 
-  cq_expect_completion(v_client, tag(1), GRPC_OP_OK);
+  cq_expect_completion(v_client, tag(1), 1);
   cq_verify(v_client);
 
   GPR_ASSERT(status == GRPC_STATUS_UNIMPLEMENTED);
diff --git a/test/core/fling/client.c b/test/core/fling/client.c
index 68164b1..37d787c 100644
--- a/test/core/fling/client.c
+++ b/test/core/fling/client.c
@@ -93,7 +93,7 @@
                                   "localhost", gpr_inf_future);
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(call, ops, op - ops, (void *)1));
-  grpc_event_finish(grpc_completion_queue_next(cq, gpr_inf_future));
+  grpc_completion_queue_next(cq, gpr_inf_future);
   grpc_call_destroy(call);
   grpc_byte_buffer_destroy(response_payload_recv);
   call = NULL;
@@ -106,7 +106,7 @@
   stream_init_op.data.send_initial_metadata.count = 0;
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(call, &stream_init_op, 1, (void *)1));
-  grpc_event_finish(grpc_completion_queue_next(cq, gpr_inf_future));
+  grpc_completion_queue_next(cq, gpr_inf_future);
 
   grpc_metadata_array_init(&initial_metadata_recv);
 
@@ -119,7 +119,7 @@
 static void step_ping_pong_stream(void) {
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(call, stream_step_ops, 2, (void *)1));
-  grpc_event_finish(grpc_completion_queue_next(cq, gpr_inf_future));
+  grpc_completion_queue_next(cq, gpr_inf_future);
   grpc_byte_buffer_destroy(response_payload_recv);
 }
 
@@ -147,7 +147,6 @@
   char *fake_argv[1];
 
   int payload_size = 1;
-  int done;
   int secure = 0;
   char *target = "localhost:443";
   gpr_cmdline *cl;
@@ -209,12 +208,9 @@
 
   grpc_channel_destroy(channel);
   grpc_completion_queue_shutdown(cq);
-  done = 0;
-  while (!done) {
-    grpc_event *ev = grpc_completion_queue_next(cq, gpr_inf_future);
-    done = (ev->type == GRPC_QUEUE_SHUTDOWN);
-    grpc_event_finish(ev);
-  }
+  while (grpc_completion_queue_next(cq, gpr_inf_future).type !=
+         GRPC_QUEUE_SHUTDOWN)
+    ;
   grpc_completion_queue_destroy(cq);
   grpc_byte_buffer_destroy(the_buffer);
   gpr_slice_unref(slice);
diff --git a/test/core/fling/server.c b/test/core/fling/server.c
index 63c7bd7..57e702e 100644
--- a/test/core/fling/server.c
+++ b/test/core/fling/server.c
@@ -169,7 +169,7 @@
 static void sigint_handler(int x) { _exit(0); }
 
 int main(int argc, char **argv) {
-  grpc_event *ev;
+  grpc_event ev;
   call_state *s;
   char *addr_buf = NULL;
   gpr_cmdline *cl;
@@ -233,9 +233,8 @@
     }
     ev = grpc_completion_queue_next(
         cq, gpr_time_add(gpr_now(), gpr_time_from_micros(1000000)));
-    if (!ev) continue;
-    s = ev->tag;
-    switch (ev->type) {
+    s = ev.tag;
+    switch (ev.type) {
       case GRPC_OP_COMPLETE:
         switch ((gpr_intptr)s) {
           case FLING_SERVER_NEW_REQUEST:
@@ -297,10 +296,9 @@
         GPR_ASSERT(shutdown_started);
         shutdown_finished = 1;
         break;
-      default:
-        GPR_ASSERT(0);
+      case GRPC_QUEUE_TIMEOUT:
+        break;
     }
-    grpc_event_finish(ev);
   }
   grpc_profiler_stop();
   grpc_call_details_destroy(&call_details);
diff --git a/test/core/surface/completion_queue_test.c b/test/core/surface/completion_queue_test.c
index 29fb7a9..3e84eaf 100644
--- a/test/core/surface/completion_queue_test.c
+++ b/test/core/surface/completion_queue_test.c
@@ -43,10 +43,6 @@
 
 #define LOG_TEST() gpr_log(GPR_INFO, "%s", __FUNCTION__)
 
-static void increment_int_on_finish(void *user_data, grpc_op_error error) {
-  ++*(int *)user_data;
-}
-
 static void *create_test_tag(void) {
   static gpr_intptr i = 0;
   return (void *)(++i);
@@ -54,12 +50,10 @@
 
 /* helper for tests to shutdown correctly and tersely */
 static void shutdown_and_destroy(grpc_completion_queue *cc) {
-  grpc_event *ev;
+  grpc_event ev;
   grpc_completion_queue_shutdown(cc);
   ev = grpc_completion_queue_next(cc, gpr_inf_past);
-  GPR_ASSERT(ev != NULL);
-  GPR_ASSERT(ev->type == GRPC_QUEUE_SHUTDOWN);
-  grpc_event_finish(ev);
+  GPR_ASSERT(ev.type == GRPC_QUEUE_SHUTDOWN);
   grpc_completion_queue_destroy(cc);
 }
 
@@ -75,42 +69,36 @@
   LOG_TEST();
 
   cc = grpc_completion_queue_create();
-  GPR_ASSERT(grpc_completion_queue_next(cc, gpr_now()) == NULL);
+  GPR_ASSERT(grpc_completion_queue_next(cc, gpr_now()).type ==
+             GRPC_QUEUE_TIMEOUT);
   shutdown_and_destroy(cc);
 }
 
 static void test_cq_end_op(void) {
-  grpc_event *ev;
+  grpc_event ev;
   grpc_completion_queue *cc;
-  int on_finish_called = 0;
   void *tag = create_test_tag();
 
   LOG_TEST();
 
   cc = grpc_completion_queue_create();
 
-  grpc_cq_begin_op(cc, NULL, GRPC_OP_COMPLETE);
-  grpc_cq_end_op(cc, tag, NULL, increment_int_on_finish, &on_finish_called,
-                 GRPC_OP_OK);
+  grpc_cq_begin_op(cc, NULL);
+  grpc_cq_end_op(cc, tag, NULL, 1);
 
   ev = grpc_completion_queue_next(cc, gpr_inf_past);
-  GPR_ASSERT(ev != NULL);
-  GPR_ASSERT(ev->type == GRPC_OP_COMPLETE);
-  GPR_ASSERT(ev->tag == tag);
-  GPR_ASSERT(ev->data.op_complete == GRPC_OP_OK);
-  GPR_ASSERT(on_finish_called == 0);
-  grpc_event_finish(ev);
-  GPR_ASSERT(on_finish_called == 1);
+  GPR_ASSERT(ev.type == GRPC_OP_COMPLETE);
+  GPR_ASSERT(ev.tag == tag);
+  GPR_ASSERT(ev.success);
 
   shutdown_and_destroy(cc);
 }
 
 static void test_pluck(void) {
-  grpc_event *ev;
+  grpc_event ev;
   grpc_completion_queue *cc;
   void *tags[128];
   unsigned i, j;
-  int on_finish_called = 0;
 
   LOG_TEST();
 
@@ -124,34 +112,26 @@
   cc = grpc_completion_queue_create();
 
   for (i = 0; i < GPR_ARRAY_SIZE(tags); i++) {
-    grpc_cq_begin_op(cc, NULL, GRPC_OP_COMPLETE);
-    grpc_cq_end_op(cc, tags[i], NULL, increment_int_on_finish,
-                   &on_finish_called, GRPC_OP_OK);
+    grpc_cq_begin_op(cc, NULL);
+    grpc_cq_end_op(cc, tags[i], NULL, 1);
   }
 
   for (i = 0; i < GPR_ARRAY_SIZE(tags); i++) {
     ev = grpc_completion_queue_pluck(cc, tags[i], gpr_inf_past);
-    GPR_ASSERT(ev->tag == tags[i]);
-    grpc_event_finish(ev);
+    GPR_ASSERT(ev.tag == tags[i]);
   }
 
-  GPR_ASSERT(on_finish_called == GPR_ARRAY_SIZE(tags));
-
   for (i = 0; i < GPR_ARRAY_SIZE(tags); i++) {
-    grpc_cq_begin_op(cc, NULL, GRPC_OP_COMPLETE);
-    grpc_cq_end_op(cc, tags[i], NULL, increment_int_on_finish,
-                   &on_finish_called, GRPC_OP_OK);
+    grpc_cq_begin_op(cc, NULL);
+    grpc_cq_end_op(cc, tags[i], NULL, 1);
   }
 
   for (i = 0; i < GPR_ARRAY_SIZE(tags); i++) {
     ev = grpc_completion_queue_pluck(cc, tags[GPR_ARRAY_SIZE(tags) - i - 1],
                                      gpr_inf_past);
-    GPR_ASSERT(ev->tag == tags[GPR_ARRAY_SIZE(tags) - i - 1]);
-    grpc_event_finish(ev);
+    GPR_ASSERT(ev.tag == tags[GPR_ARRAY_SIZE(tags) - i - 1]);
   }
 
-  GPR_ASSERT(on_finish_called == 2 * GPR_ARRAY_SIZE(tags));
-
   shutdown_and_destroy(cc);
 }
 
@@ -182,7 +162,7 @@
 
   gpr_log(GPR_INFO, "producer %d phase 1", opt->id);
   for (i = 0; i < TEST_THREAD_EVENTS; i++) {
-    grpc_cq_begin_op(opt->cc, NULL, GRPC_OP_COMPLETE);
+    grpc_cq_begin_op(opt->cc, NULL);
   }
 
   gpr_log(GPR_INFO, "producer %d phase 1 done", opt->id);
@@ -191,8 +171,7 @@
 
   gpr_log(GPR_INFO, "producer %d phase 2", opt->id);
   for (i = 0; i < TEST_THREAD_EVENTS; i++) {
-    grpc_cq_end_op(opt->cc, (void *)(gpr_intptr)1, NULL, NULL, NULL,
-                   GRPC_OP_OK);
+    grpc_cq_end_op(opt->cc, (void *)(gpr_intptr)1, NULL, 1);
     opt->events_triggered++;
   }
 
@@ -202,7 +181,7 @@
 
 static void consumer_thread(void *arg) {
   test_thread_options *opt = arg;
-  grpc_event *ev;
+  grpc_event ev;
 
   gpr_log(GPR_INFO, "consumer %d started", opt->id);
   gpr_event_set(&opt->on_started, (void *)(gpr_intptr) 1);
@@ -217,20 +196,17 @@
   gpr_log(GPR_INFO, "consumer %d phase 2", opt->id);
   for (;;) {
     ev = grpc_completion_queue_next(opt->cc, ten_seconds_time());
-    GPR_ASSERT(ev);
-    switch (ev->type) {
+    switch (ev.type) {
       case GRPC_OP_COMPLETE:
-        GPR_ASSERT(ev->data.op_complete == GRPC_OP_OK);
+        GPR_ASSERT(ev.success);
         opt->events_triggered++;
-        grpc_event_finish(ev);
         break;
       case GRPC_QUEUE_SHUTDOWN:
         gpr_log(GPR_INFO, "consumer %d phase 2 done", opt->id);
         gpr_event_set(&opt->on_finished, (void *)(gpr_intptr) 1);
-        grpc_event_finish(ev);
         return;
-      default:
-        gpr_log(GPR_ERROR, "Invalid event received: %d", ev->type);
+      case GRPC_QUEUE_TIMEOUT:
+        gpr_log(GPR_ERROR, "Invalid timeout received");
         abort();
     }
   }
diff --git a/test/core/surface/lame_client_test.c b/test/core/surface/lame_client_test.c
index 05e8f95..34d37f0 100644
--- a/test/core/surface/lame_client_test.c
+++ b/test/core/surface/lame_client_test.c
@@ -79,7 +79,7 @@
              grpc_call_start_batch(call, ops, op - ops, tag(1)));
 
   /* the call should immediately fail */
-  cq_expect_completion(cqv, tag(1), GRPC_OP_OK);
+  cq_expect_completion(cqv, tag(1), 1);
   cq_verify(cqv);
 
   grpc_call_destroy(call);