Introducing grpc_executor, for all your threading needs
diff --git a/src/core/iomgr/executor.c b/src/core/iomgr/executor.c
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+++ b/src/core/iomgr/executor.c
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+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ * * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/iomgr/executor.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/sync.h>
+#include <grpc/support/thd.h>
+#include "src/core/iomgr/exec_ctx.h"
+
+typedef struct grpc_executor_data {
+ int busy; /**< is the thread currently running? */
+ int shutting_down; /**< has \a grpc_shutdown() been invoked? */
+ int pending_join; /**< has the thread finished but not been joined? */
+ grpc_closure_list closures; /**< collection of pending work */
+ gpr_thd_id tid; /**< thread id of the thread, only valid if \a busy or \a
+ pending_join are true */
+ gpr_thd_options options;
+ gpr_mu mu;
+} grpc_executor;
+
+static grpc_executor g_executor;
+
+void grpc_executor_init() {
+ memset(&g_executor, 0, sizeof(grpc_executor));
+ gpr_mu_init(&g_executor.mu);
+ g_executor.options = gpr_thd_options_default();
+ gpr_thd_options_set_joinable(&g_executor.options);
+}
+
+/* thread body */
+static void closure_exec_thread_func(void *ignored) {
+ grpc_closure *closure;
+
+ grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+ while (1) {
+ gpr_mu_lock(&g_executor.mu);
+ if (g_executor.shutting_down != 0) {
+ gpr_mu_unlock(&g_executor.mu);
+ break;
+ }
+ closure = grpc_closure_list_pop(&g_executor.closures);
+ if (closure == NULL) {
+ /* no more work, time to die */
+ GPR_ASSERT(g_executor.busy == 1);
+ g_executor.busy = 0;
+ gpr_mu_unlock(&g_executor.mu);
+ break;
+ }
+ gpr_mu_unlock(&g_executor.mu);
+ closure->cb(&exec_ctx, closure->cb_arg, closure->success);
+ }
+ grpc_exec_ctx_finish(&exec_ctx);
+}
+
+/* Spawn the thread if new work has arrived a no thread is up */
+static void maybe_spawn_locked() {
+ if (grpc_closure_list_empty(g_executor.closures) == 1) {
+ return;
+ }
+ if (g_executor.shutting_down == 1) {
+ return;
+ }
+
+ if (g_executor.busy != 0) {
+ /* Thread still working. New work will be picked up by already running
+ * thread. Not spawning anything. */
+ return;
+ } else if (g_executor.pending_join != 0) {
+ /* Pickup the remains of the previous incarnations of the thread. */
+ gpr_thd_join(g_executor.tid);
+ g_executor.pending_join = 0;
+ }
+
+ /* All previous instances of the thread should have been joined at this point.
+ * Spawn time! */
+ g_executor.busy = 1;
+ gpr_thd_new(&g_executor.tid, closure_exec_thread_func, NULL,
+ &g_executor.options);
+ g_executor.pending_join = 1;
+}
+
+void grpc_executor_enqueue(grpc_closure *closure, int success) {
+ gpr_mu_lock(&g_executor.mu);
+ if (g_executor.shutting_down == 0) {
+ grpc_closure_list_add(&g_executor.closures, closure, success);
+ maybe_spawn_locked();
+ }
+ gpr_mu_unlock(&g_executor.mu);
+}
+
+void grpc_executor_shutdown() {
+ gpr_thd_id tid;
+ int pending_join;
+ grpc_closure *closure;
+ grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+
+ gpr_mu_lock(&g_executor.mu);
+ pending_join = g_executor.pending_join;
+ tid = g_executor.tid;
+ g_executor.shutting_down = 1;
+ gpr_mu_unlock(&g_executor.mu);
+ /* we can release the lock at this point despite the access to the closure
+ * list below because we aren't accepting new work */
+
+ /* Execute pending callbacks, some may be performing cleanups */
+ while ((closure = grpc_closure_list_pop(&g_executor.closures)) != NULL) {
+ closure->cb(&exec_ctx, closure->cb_arg, closure->success);
+ }
+ grpc_exec_ctx_finish(&exec_ctx);
+ GPR_ASSERT(grpc_closure_list_empty(g_executor.closures));
+ if (pending_join) {
+ gpr_thd_join(g_executor.tid);
+ }
+ gpr_mu_destroy(&g_executor.mu);
+}