Merge pull request #13311 from ctiller/lfe3
Fix races in rolled-back LockfreeEvent code
diff --git a/src/core/lib/iomgr/ev_epoll1_linux.cc b/src/core/lib/iomgr/ev_epoll1_linux.cc
index 504c659..9e3643f 100644
--- a/src/core/lib/iomgr/ev_epoll1_linux.cc
+++ b/src/core/lib/iomgr/ev_epoll1_linux.cc
@@ -46,6 +46,7 @@
#include "src/core/lib/iomgr/lockfree_event.h"
#include "src/core/lib/iomgr/wakeup_fd_posix.h"
#include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/support/manual_constructor.h"
#include "src/core/lib/support/string.h"
static grpc_wakeup_fd global_wakeup_fd;
@@ -111,8 +112,8 @@
struct grpc_fd {
int fd;
- gpr_atm read_closure;
- gpr_atm write_closure;
+ grpc_core::ManualConstructor<grpc_core::LockfreeEvent> read_closure;
+ grpc_core::ManualConstructor<grpc_core::LockfreeEvent> write_closure;
struct grpc_fd* freelist_next;
@@ -264,8 +265,8 @@
}
new_fd->fd = fd;
- grpc_lfev_init(&new_fd->read_closure);
- grpc_lfev_init(&new_fd->write_closure);
+ new_fd->read_closure.Init();
+ new_fd->write_closure.Init();
gpr_atm_no_barrier_store(&new_fd->read_notifier_pollset, (gpr_atm)NULL);
new_fd->freelist_next = NULL;
@@ -297,12 +298,11 @@
* shutdown() syscall on that fd) */
static void fd_shutdown_internal(grpc_exec_ctx* exec_ctx, grpc_fd* fd,
grpc_error* why, bool releasing_fd) {
- if (grpc_lfev_set_shutdown(exec_ctx, &fd->read_closure,
- GRPC_ERROR_REF(why))) {
+ if (fd->read_closure->SetShutdown(exec_ctx, GRPC_ERROR_REF(why))) {
if (!releasing_fd) {
shutdown(fd->fd, SHUT_RDWR);
}
- grpc_lfev_set_shutdown(exec_ctx, &fd->write_closure, GRPC_ERROR_REF(why));
+ fd->write_closure->SetShutdown(exec_ctx, GRPC_ERROR_REF(why));
}
GRPC_ERROR_UNREF(why);
}
@@ -318,7 +318,7 @@
grpc_error* error = GRPC_ERROR_NONE;
bool is_release_fd = (release_fd != NULL);
- if (!grpc_lfev_is_shutdown(&fd->read_closure)) {
+ if (!fd->read_closure->IsShutdown()) {
fd_shutdown_internal(exec_ctx, fd,
GRPC_ERROR_CREATE_FROM_COPIED_STRING(reason),
is_release_fd);
@@ -335,8 +335,8 @@
GRPC_CLOSURE_SCHED(exec_ctx, on_done, GRPC_ERROR_REF(error));
grpc_iomgr_unregister_object(&fd->iomgr_object);
- grpc_lfev_destroy(&fd->read_closure);
- grpc_lfev_destroy(&fd->write_closure);
+ fd->read_closure.Destroy();
+ fd->write_closure.Destroy();
gpr_mu_lock(&fd_freelist_mu);
fd->freelist_next = fd_freelist;
@@ -351,28 +351,28 @@
}
static bool fd_is_shutdown(grpc_fd* fd) {
- return grpc_lfev_is_shutdown(&fd->read_closure);
+ return fd->read_closure->IsShutdown();
}
static void fd_notify_on_read(grpc_exec_ctx* exec_ctx, grpc_fd* fd,
grpc_closure* closure) {
- grpc_lfev_notify_on(exec_ctx, &fd->read_closure, closure, "read");
+ fd->read_closure->NotifyOn(exec_ctx, closure);
}
static void fd_notify_on_write(grpc_exec_ctx* exec_ctx, grpc_fd* fd,
grpc_closure* closure) {
- grpc_lfev_notify_on(exec_ctx, &fd->write_closure, closure, "write");
+ fd->write_closure->NotifyOn(exec_ctx, closure);
}
static void fd_become_readable(grpc_exec_ctx* exec_ctx, grpc_fd* fd,
grpc_pollset* notifier) {
- grpc_lfev_set_ready(exec_ctx, &fd->read_closure, "read");
+ fd->read_closure->SetReady(exec_ctx);
/* Use release store to match with acquire load in fd_get_read_notifier */
gpr_atm_rel_store(&fd->read_notifier_pollset, (gpr_atm)notifier);
}
static void fd_become_writable(grpc_exec_ctx* exec_ctx, grpc_fd* fd) {
- grpc_lfev_set_ready(exec_ctx, &fd->write_closure, "write");
+ fd->write_closure->SetReady(exec_ctx);
}
/*******************************************************************************
diff --git a/src/core/lib/iomgr/ev_epollex_linux.cc b/src/core/lib/iomgr/ev_epollex_linux.cc
index aafdd69..26ed1f6 100644
--- a/src/core/lib/iomgr/ev_epollex_linux.cc
+++ b/src/core/lib/iomgr/ev_epollex_linux.cc
@@ -48,6 +48,7 @@
#include "src/core/lib/iomgr/timer.h"
#include "src/core/lib/iomgr/wakeup_fd_posix.h"
#include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/support/manual_constructor.h"
#include "src/core/lib/support/spinlock.h"
// debug aid: create workers on the heap (allows asan to spot
@@ -153,8 +154,8 @@
gpr_mu pollable_mu;
pollable* pollable_obj;
- gpr_atm read_closure;
- gpr_atm write_closure;
+ grpc_core::ManualConstructor<grpc_core::LockfreeEvent> read_closure;
+ grpc_core::ManualConstructor<grpc_core::LockfreeEvent> write_closure;
struct grpc_fd* freelist_next;
grpc_closure* on_done_closure;
@@ -286,8 +287,8 @@
fd->freelist_next = fd_freelist;
fd_freelist = fd;
- grpc_lfev_destroy(&fd->read_closure);
- grpc_lfev_destroy(&fd->write_closure);
+ fd->read_closure.Destroy();
+ fd->write_closure.Destroy();
gpr_mu_unlock(&fd_freelist_mu);
}
@@ -347,8 +348,8 @@
new_fd->pollable_obj = NULL;
gpr_atm_rel_store(&new_fd->refst, (gpr_atm)1);
new_fd->fd = fd;
- grpc_lfev_init(&new_fd->read_closure);
- grpc_lfev_init(&new_fd->write_closure);
+ new_fd->read_closure.Init();
+ new_fd->write_closure.Init();
gpr_atm_no_barrier_store(&new_fd->read_notifier_pollset, (gpr_atm)NULL);
new_fd->freelist_next = NULL;
@@ -411,27 +412,26 @@
}
static bool fd_is_shutdown(grpc_fd* fd) {
- return grpc_lfev_is_shutdown(&fd->read_closure);
+ return fd->read_closure->IsShutdown();
}
/* Might be called multiple times */
static void fd_shutdown(grpc_exec_ctx* exec_ctx, grpc_fd* fd, grpc_error* why) {
- if (grpc_lfev_set_shutdown(exec_ctx, &fd->read_closure,
- GRPC_ERROR_REF(why))) {
+ if (fd->read_closure->SetShutdown(exec_ctx, GRPC_ERROR_REF(why))) {
shutdown(fd->fd, SHUT_RDWR);
- grpc_lfev_set_shutdown(exec_ctx, &fd->write_closure, GRPC_ERROR_REF(why));
+ fd->write_closure->SetShutdown(exec_ctx, GRPC_ERROR_REF(why));
}
GRPC_ERROR_UNREF(why);
}
static void fd_notify_on_read(grpc_exec_ctx* exec_ctx, grpc_fd* fd,
grpc_closure* closure) {
- grpc_lfev_notify_on(exec_ctx, &fd->read_closure, closure, "read");
+ fd->read_closure->NotifyOn(exec_ctx, closure);
}
static void fd_notify_on_write(grpc_exec_ctx* exec_ctx, grpc_fd* fd,
grpc_closure* closure) {
- grpc_lfev_notify_on(exec_ctx, &fd->write_closure, closure, "write");
+ fd->write_closure->NotifyOn(exec_ctx, closure);
}
/*******************************************************************************
@@ -702,7 +702,7 @@
static void fd_become_readable(grpc_exec_ctx* exec_ctx, grpc_fd* fd,
grpc_pollset* notifier) {
- grpc_lfev_set_ready(exec_ctx, &fd->read_closure, "read");
+ fd->read_closure->SetReady(exec_ctx);
/* Note, it is possible that fd_become_readable might be called twice with
different 'notifier's when an fd becomes readable and it is in two epoll
@@ -714,7 +714,7 @@
}
static void fd_become_writable(grpc_exec_ctx* exec_ctx, grpc_fd* fd) {
- grpc_lfev_set_ready(exec_ctx, &fd->write_closure, "write");
+ fd->write_closure->SetReady(exec_ctx);
}
static grpc_error* fd_get_or_become_pollable(grpc_fd* fd, pollable** p) {
diff --git a/src/core/lib/iomgr/ev_epollsig_linux.cc b/src/core/lib/iomgr/ev_epollsig_linux.cc
index d5f3122..9a12780 100644
--- a/src/core/lib/iomgr/ev_epollsig_linux.cc
+++ b/src/core/lib/iomgr/ev_epollsig_linux.cc
@@ -50,6 +50,7 @@
#include "src/core/lib/iomgr/timer.h"
#include "src/core/lib/iomgr/wakeup_fd_posix.h"
#include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/support/manual_constructor.h"
#define GRPC_POLLSET_KICK_BROADCAST ((grpc_pollset_worker*)1)
@@ -127,8 +128,8 @@
valid */
bool orphaned;
- gpr_atm read_closure;
- gpr_atm write_closure;
+ grpc_core::ManualConstructor<grpc_core::LockfreeEvent> read_closure;
+ grpc_core::ManualConstructor<grpc_core::LockfreeEvent> write_closure;
struct grpc_fd* freelist_next;
grpc_closure* on_done_closure;
@@ -766,8 +767,8 @@
fd_freelist = fd;
grpc_iomgr_unregister_object(&fd->iomgr_object);
- grpc_lfev_destroy(&fd->read_closure);
- grpc_lfev_destroy(&fd->write_closure);
+ fd->read_closure.Destroy();
+ fd->write_closure.Destroy();
gpr_mu_unlock(&fd_freelist_mu);
} else {
@@ -832,8 +833,8 @@
gpr_atm_rel_store(&new_fd->refst, (gpr_atm)1);
new_fd->fd = fd;
new_fd->orphaned = false;
- grpc_lfev_init(&new_fd->read_closure);
- grpc_lfev_init(&new_fd->write_closure);
+ new_fd->read_closure.Init();
+ new_fd->write_closure.Init();
gpr_atm_no_barrier_store(&new_fd->read_notifier_pollset, (gpr_atm)NULL);
new_fd->freelist_next = NULL;
@@ -924,27 +925,26 @@
}
static bool fd_is_shutdown(grpc_fd* fd) {
- return grpc_lfev_is_shutdown(&fd->read_closure);
+ return fd->read_closure->IsShutdown();
}
/* Might be called multiple times */
static void fd_shutdown(grpc_exec_ctx* exec_ctx, grpc_fd* fd, grpc_error* why) {
- if (grpc_lfev_set_shutdown(exec_ctx, &fd->read_closure,
- GRPC_ERROR_REF(why))) {
+ if (fd->read_closure->SetShutdown(exec_ctx, GRPC_ERROR_REF(why))) {
shutdown(fd->fd, SHUT_RDWR);
- grpc_lfev_set_shutdown(exec_ctx, &fd->write_closure, GRPC_ERROR_REF(why));
+ fd->write_closure->SetShutdown(exec_ctx, GRPC_ERROR_REF(why));
}
GRPC_ERROR_UNREF(why);
}
static void fd_notify_on_read(grpc_exec_ctx* exec_ctx, grpc_fd* fd,
grpc_closure* closure) {
- grpc_lfev_notify_on(exec_ctx, &fd->read_closure, closure, "read");
+ fd->read_closure->NotifyOn(exec_ctx, closure);
}
static void fd_notify_on_write(grpc_exec_ctx* exec_ctx, grpc_fd* fd,
grpc_closure* closure) {
- grpc_lfev_notify_on(exec_ctx, &fd->write_closure, closure, "write");
+ fd->write_closure->NotifyOn(exec_ctx, closure);
}
/*******************************************************************************
@@ -1108,7 +1108,7 @@
static void fd_become_readable(grpc_exec_ctx* exec_ctx, grpc_fd* fd,
grpc_pollset* notifier) {
- grpc_lfev_set_ready(exec_ctx, &fd->read_closure, "read");
+ fd->read_closure->SetReady(exec_ctx);
/* Note, it is possible that fd_become_readable might be called twice with
different 'notifier's when an fd becomes readable and it is in two epoll
@@ -1120,7 +1120,7 @@
}
static void fd_become_writable(grpc_exec_ctx* exec_ctx, grpc_fd* fd) {
- grpc_lfev_set_ready(exec_ctx, &fd->write_closure, "write");
+ fd->write_closure->SetReady(exec_ctx);
}
static void pollset_release_polling_island(grpc_exec_ctx* exec_ctx,
diff --git a/src/core/lib/iomgr/lockfree_event.cc b/src/core/lib/iomgr/lockfree_event.cc
index 443a837..40e2ed6 100644
--- a/src/core/lib/iomgr/lockfree_event.cc
+++ b/src/core/lib/iomgr/lockfree_event.cc
@@ -26,92 +26,96 @@
/* 'state' holds the to call when the fd is readable or writable respectively.
It can contain one of the following values:
- CLOSURE_READY : The fd has an I/O event of interest but there is no
+ kClosureReady : The fd has an I/O event of interest but there is no
closure yet to execute
- CLOSURE_NOT_READY : The fd has no I/O event of interest
+ kClosureNotReady : The fd has no I/O event of interest
closure ptr : The closure to be executed when the fd has an I/O
event of interest
- shutdown_error | FD_SHUTDOWN_BIT :
- 'shutdown_error' field ORed with FD_SHUTDOWN_BIT.
+ shutdown_error | kShutdownBit :
+ 'shutdown_error' field ORed with kShutdownBit.
This indicates that the fd is shutdown. Since all
memory allocations are word-aligned, the lower two
bits of the shutdown_error pointer are always 0. So
- it is safe to OR these with FD_SHUTDOWN_BIT
+ it is safe to OR these with kShutdownBit
Valid state transitions:
- <closure ptr> <-----3------ CLOSURE_NOT_READY ----1----> CLOSURE_READY
+ <closure ptr> <-----3------ kClosureNotReady -----1-------> kClosureReady
| | ^ | ^ | |
| | | | | | |
| +--------------4----------+ 6 +---------2---------------+ |
| | |
| v |
- +-----5-------> [shutdown_error | FD_SHUTDOWN_BIT] <----7---------+
+ +-----5-------> [shutdown_error | kShutdownBit] <-------7---------+
- For 1, 4 : See grpc_lfev_set_ready() function
- For 2, 3 : See grpc_lfev_notify_on() function
- For 5,6,7: See grpc_lfev_set_shutdown() function */
+ For 1, 4 : See SetReady() function
+ For 2, 3 : See NotifyOn() function
+ For 5,6,7: See SetShutdown() function */
-#define CLOSURE_NOT_READY ((gpr_atm)0)
-#define CLOSURE_READY ((gpr_atm)2)
+namespace grpc_core {
-#define FD_SHUTDOWN_BIT ((gpr_atm)1)
+LockfreeEvent::LockfreeEvent() {
+ /* Perform an atomic store to start the state machine.
-void grpc_lfev_init(gpr_atm* state) {
- gpr_atm_no_barrier_store(state, CLOSURE_NOT_READY);
+ Note carefully that LockfreeEvent *MAY* be used whilst in a destroyed
+ state, while a file descriptor is on a freelist. In such a state it may
+ be SetReady'd, and so we need to perform an atomic operation here to
+ ensure no races */
+ gpr_atm_no_barrier_store(&state_, kClosureNotReady);
}
-void grpc_lfev_destroy(gpr_atm* state) {
- gpr_atm curr = gpr_atm_no_barrier_load(state);
- if (curr & FD_SHUTDOWN_BIT) {
- GRPC_ERROR_UNREF((grpc_error*)(curr & ~FD_SHUTDOWN_BIT));
- } else {
- GPR_ASSERT(curr == CLOSURE_NOT_READY || curr == CLOSURE_READY);
- }
+LockfreeEvent::~LockfreeEvent() {
+ gpr_atm curr;
+ do {
+ curr = gpr_atm_no_barrier_load(&state_);
+ if (curr & kShutdownBit) {
+ GRPC_ERROR_UNREF((grpc_error*)(curr & ~kShutdownBit));
+ } else {
+ GPR_ASSERT(curr == kClosureNotReady || curr == kClosureReady);
+ }
+ /* we CAS in a shutdown, no error value here. If this event is interacted
+ with post-deletion (see the note in the constructor) we want the bit
+ pattern to prevent error retention in a deleted object */
+ } while (!gpr_atm_no_barrier_cas(&state_, curr,
+ kShutdownBit /* shutdown, no error */));
}
-bool grpc_lfev_is_shutdown(gpr_atm* state) {
- gpr_atm curr = gpr_atm_no_barrier_load(state);
- return (curr & FD_SHUTDOWN_BIT) != 0;
-}
-
-void grpc_lfev_notify_on(grpc_exec_ctx* exec_ctx, gpr_atm* state,
- grpc_closure* closure, const char* variable) {
+void LockfreeEvent::NotifyOn(grpc_exec_ctx* exec_ctx, grpc_closure* closure) {
while (true) {
- gpr_atm curr = gpr_atm_no_barrier_load(state);
+ gpr_atm curr = gpr_atm_no_barrier_load(&state_);
if (GRPC_TRACER_ON(grpc_polling_trace)) {
- gpr_log(GPR_ERROR, "lfev_notify_on[%s]: %p curr=%p closure=%p", variable,
- state, (void*)curr, closure);
+ gpr_log(GPR_ERROR, "LockfreeEvent::NotifyOn: %p curr=%p closure=%p", this,
+ (void*)curr, closure);
}
switch (curr) {
- case CLOSURE_NOT_READY: {
- /* CLOSURE_NOT_READY -> <closure>.
+ case kClosureNotReady: {
+ /* kClosureNotReady -> <closure>.
We're guaranteed by API that there's an acquire barrier before here,
so there's no need to double-dip and this can be a release-only.
The release itself pairs with the acquire half of a set_ready full
barrier. */
- if (gpr_atm_rel_cas(state, CLOSURE_NOT_READY, (gpr_atm)closure)) {
+ if (gpr_atm_rel_cas(&state_, kClosureNotReady, (gpr_atm)closure)) {
return; /* Successful. Return */
}
break; /* retry */
}
- case CLOSURE_READY: {
- /* Change the state to CLOSURE_NOT_READY. Schedule the closure if
+ case kClosureReady: {
+ /* Change the state to kClosureNotReady. Schedule the closure if
successful. If not, the state most likely transitioned to shutdown.
We should retry.
This can be a no-barrier cas since the state is being transitioned to
- CLOSURE_NOT_READY; set_ready and set_shutdown do not schedule any
+ kClosureNotReady; set_ready and set_shutdown do not schedule any
closure when transitioning out of CLOSURE_NO_READY state (i.e there
is no other code that needs to 'happen-after' this) */
- if (gpr_atm_no_barrier_cas(state, CLOSURE_READY, CLOSURE_NOT_READY)) {
+ if (gpr_atm_no_barrier_cas(&state_, kClosureReady, kClosureNotReady)) {
GRPC_CLOSURE_SCHED(exec_ctx, closure, GRPC_ERROR_NONE);
return; /* Successful. Return */
}
@@ -123,8 +127,8 @@
/* 'curr' is either a closure or the fd is shutdown(in which case 'curr'
contains a pointer to the shutdown-error). If the fd is shutdown,
schedule the closure with the shutdown error */
- if ((curr & FD_SHUTDOWN_BIT) > 0) {
- grpc_error* shutdown_err = (grpc_error*)(curr & ~FD_SHUTDOWN_BIT);
+ if ((curr & kShutdownBit) > 0) {
+ grpc_error* shutdown_err = (grpc_error*)(curr & ~kShutdownBit);
GRPC_CLOSURE_SCHED(exec_ctx, closure,
GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
"FD Shutdown", &shutdown_err, 1));
@@ -133,7 +137,8 @@
/* There is already a closure!. This indicates a bug in the code */
gpr_log(GPR_ERROR,
- "notify_on called with a previous callback still pending");
+ "LockfreeEvent::NotifyOn: notify_on called with a previous "
+ "callback still pending");
abort();
}
}
@@ -142,22 +147,22 @@
GPR_UNREACHABLE_CODE(return );
}
-bool grpc_lfev_set_shutdown(grpc_exec_ctx* exec_ctx, gpr_atm* state,
- grpc_error* shutdown_err) {
- gpr_atm new_state = (gpr_atm)shutdown_err | FD_SHUTDOWN_BIT;
+bool LockfreeEvent::SetShutdown(grpc_exec_ctx* exec_ctx,
+ grpc_error* shutdown_err) {
+ gpr_atm new_state = (gpr_atm)shutdown_err | kShutdownBit;
while (true) {
- gpr_atm curr = gpr_atm_no_barrier_load(state);
+ gpr_atm curr = gpr_atm_no_barrier_load(&state_);
if (GRPC_TRACER_ON(grpc_polling_trace)) {
- gpr_log(GPR_ERROR, "lfev_set_shutdown: %p curr=%p err=%s", state,
- (void*)curr, grpc_error_string(shutdown_err));
+ gpr_log(GPR_ERROR, "LockfreeEvent::SetShutdown: %p curr=%p err=%s",
+ &state_, (void*)curr, grpc_error_string(shutdown_err));
}
switch (curr) {
- case CLOSURE_READY:
- case CLOSURE_NOT_READY:
+ case kClosureReady:
+ case kClosureNotReady:
/* Need a full barrier here so that the initial load in notify_on
doesn't need a barrier */
- if (gpr_atm_full_cas(state, curr, new_state)) {
+ if (gpr_atm_full_cas(&state_, curr, new_state)) {
return true; /* early out */
}
break; /* retry */
@@ -166,7 +171,7 @@
/* 'curr' is either a closure or the fd is already shutdown */
/* If fd is already shutdown, we are done */
- if ((curr & FD_SHUTDOWN_BIT) > 0) {
+ if ((curr & kShutdownBit) > 0) {
GRPC_ERROR_UNREF(shutdown_err);
return false;
}
@@ -176,7 +181,7 @@
Needs an acquire to pair with setting the closure (and get a
happens-after on that edge), and a release to pair with anything
loading the shutdown state. */
- if (gpr_atm_full_cas(state, curr, new_state)) {
+ if (gpr_atm_full_cas(&state_, curr, new_state)) {
GRPC_CLOSURE_SCHED(exec_ctx, (grpc_closure*)curr,
GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
"FD Shutdown", &shutdown_err, 1));
@@ -193,26 +198,25 @@
GPR_UNREACHABLE_CODE(return false);
}
-void grpc_lfev_set_ready(grpc_exec_ctx* exec_ctx, gpr_atm* state,
- const char* variable) {
+void LockfreeEvent::SetReady(grpc_exec_ctx* exec_ctx) {
while (true) {
- gpr_atm curr = gpr_atm_no_barrier_load(state);
+ gpr_atm curr = gpr_atm_no_barrier_load(&state_);
if (GRPC_TRACER_ON(grpc_polling_trace)) {
- gpr_log(GPR_ERROR, "lfev_set_ready[%s]: %p curr=%p", variable, state,
+ gpr_log(GPR_ERROR, "LockfreeEvent::SetReady: %p curr=%p", &state_,
(void*)curr);
}
switch (curr) {
- case CLOSURE_READY: {
+ case kClosureReady: {
/* Already ready. We are done here */
return;
}
- case CLOSURE_NOT_READY: {
+ case kClosureNotReady: {
/* No barrier required as we're transitioning to a state that does not
involve a closure */
- if (gpr_atm_no_barrier_cas(state, CLOSURE_NOT_READY, CLOSURE_READY)) {
+ if (gpr_atm_no_barrier_cas(&state_, kClosureNotReady, kClosureReady)) {
return; /* early out */
}
break; /* retry */
@@ -220,14 +224,14 @@
default: {
/* 'curr' is either a closure or the fd is shutdown */
- if ((curr & FD_SHUTDOWN_BIT) > 0) {
+ if ((curr & kShutdownBit) > 0) {
/* The fd is shutdown. Do nothing */
return;
}
/* Full cas: acquire pairs with this cas' release in the event of a
spurious set_ready; release pairs with this or the acquire in
notify_on (or set_shutdown) */
- else if (gpr_atm_full_cas(state, curr, CLOSURE_NOT_READY)) {
+ else if (gpr_atm_full_cas(&state_, curr, kClosureNotReady)) {
GRPC_CLOSURE_SCHED(exec_ctx, (grpc_closure*)curr, GRPC_ERROR_NONE);
return;
}
@@ -239,3 +243,5 @@
}
}
}
+
+} // namespace grpc_core
diff --git a/src/core/lib/iomgr/lockfree_event.h b/src/core/lib/iomgr/lockfree_event.h
index 75526d6..c667dcd 100644
--- a/src/core/lib/iomgr/lockfree_event.h
+++ b/src/core/lib/iomgr/lockfree_event.h
@@ -25,24 +25,30 @@
#include "src/core/lib/iomgr/exec_ctx.h"
-#ifdef __cplusplus
-extern "C" {
-#endif
+namespace grpc_core {
-void grpc_lfev_init(gpr_atm* state);
-void grpc_lfev_destroy(gpr_atm* state);
-bool grpc_lfev_is_shutdown(gpr_atm* state);
+class LockfreeEvent {
+ public:
+ LockfreeEvent();
+ ~LockfreeEvent();
-void grpc_lfev_notify_on(grpc_exec_ctx* exec_ctx, gpr_atm* state,
- grpc_closure* closure, const char* variable);
-/* Returns true on first successful shutdown */
-bool grpc_lfev_set_shutdown(grpc_exec_ctx* exec_ctx, gpr_atm* state,
- grpc_error* shutdown_err);
-void grpc_lfev_set_ready(grpc_exec_ctx* exec_ctx, gpr_atm* state,
- const char* variable);
+ LockfreeEvent(const LockfreeEvent&) = delete;
+ LockfreeEvent& operator=(const LockfreeEvent&) = delete;
-#ifdef __cplusplus
-}
-#endif
+ bool IsShutdown() const {
+ return (gpr_atm_no_barrier_load(&state_) & kShutdownBit) != 0;
+ }
+
+ void NotifyOn(grpc_exec_ctx* exec_ctx, grpc_closure* closure);
+ bool SetShutdown(grpc_exec_ctx* exec_ctx, grpc_error* error);
+ void SetReady(grpc_exec_ctx* exec_ctx);
+
+ private:
+ enum State { kClosureNotReady = 0, kClosureReady = 2, kShutdownBit = 1 };
+
+ gpr_atm state_;
+};
+
+} // namespace grpc_core
#endif /* GRPC_CORE_LIB_IOMGR_LOCKFREE_EVENT_H */