Merge branch 'v1.7.x' of https://github.com/grpc/grpc

5 files changed, 185 insertions, 0 deletions

diff --git a/src/core/lib/support/fork.cc b/src/core/lib/support/fork.cc
new file mode 100644
index 0000000000..2f29af899d
--- /dev/null
+++ b/src/core/lib/support/fork.cc
@@ -0,0 +1,62 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include "src/core/lib/support/fork.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/useful.h>
+
+#include "src/core/lib/support/env.h"
+
+/*
+ * NOTE: FORKING IS NOT GENERALLY SUPPORTED, THIS IS ONLY INTENDED TO WORK
+ *       AROUND VERY SPECIFIC USE CASES.
+ */
+
+static int override_fork_support_enabled = -1;
+static int fork_support_enabled;
+
+void grpc_fork_support_init() {
+#ifdef GRPC_ENABLE_FORK_SUPPORT
+  fork_support_enabled = 1;
+#else
+  fork_support_enabled = 0;
+  char *env = gpr_getenv("GRPC_ENABLE_FORK_SUPPORT");
+  if (env != NULL) {
+    static const char *truthy[] = {"yes",  "Yes",  "YES", "true",
+                                   "True", "TRUE", "1"};
+    for (size_t i = 0; i < GPR_ARRAY_SIZE(truthy); i++) {
+      if (0 == strcmp(env, truthy[i])) {
+        fork_support_enabled = 1;
+      }
+    }
+    gpr_free(env);
+  }
+#endif
+  if (override_fork_support_enabled != -1) {
+    fork_support_enabled = override_fork_support_enabled;
+  }
+}
+
+int grpc_fork_support_enabled() { return fork_support_enabled; }
+
+void grpc_enable_fork_support(int enable) {
+  override_fork_support_enabled = enable;
+}
diff --git a/src/core/lib/support/fork.h b/src/core/lib/support/fork.h
new file mode 100644
index 0000000000..215d4214a6
--- /dev/null
+++ b/src/core/lib/support/fork.h
@@ -0,0 +1,35 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SUPPORT_FORK_H
+#define GRPC_CORE_LIB_SUPPORT_FORK_H
+
+/*
+ * NOTE: FORKING IS NOT GENERALLY SUPPORTED, THIS IS ONLY INTENDED TO WORK
+ *       AROUND VERY SPECIFIC USE CASES.
+ */
+
+void grpc_fork_support_init(void);
+
+int grpc_fork_support_enabled(void);
+
+// Test only:  Must be called before grpc_init(), and overrides
+// environment variables/compile flags
+void grpc_enable_fork_support(int enable);
+
+#endif /* GRPC_CORE_LIB_SUPPORT_FORK_H */
diff --git a/src/core/lib/support/thd_internal.h b/src/core/lib/support/thd_internal.h
new file mode 100644
index 0000000000..38bffc847d
--- /dev/null
+++ b/src/core/lib/support/thd_internal.h
@@ -0,0 +1,30 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SUPPORT_THD_INTERNAL_H
+#define GRPC_CORE_LIB_SUPPORT_THD_INTERNAL_H
+
+#include <grpc/support/time.h>
+
+/* Internal interfaces between modules within the gpr support library.  */
+void gpr_thd_init();
+
+/* Wait for all outstanding threads to finish, up to deadline */
+int gpr_await_threads(gpr_timespec deadline);
+
+#endif /* GRPC_CORE_LIB_SUPPORT_THD_INTERNAL_H */
diff --git a/src/core/lib/support/thd_posix.cc b/src/core/lib/support/thd_posix.cc
index 02e3846be1..c2a4f4198f 100644
--- a/src/core/lib/support/thd_posix.cc
+++ b/src/core/lib/support/thd_posix.cc
@@ -24,22 +24,34 @@
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <grpc/support/sync.h>
 #include <grpc/support/thd.h>
 #include <grpc/support/useful.h>
 #include <pthread.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include "src/core/lib/support/fork.h"
+
+static gpr_mu g_mu;
+static gpr_cv g_cv;
+static int g_thread_count;
+static int g_awaiting_threads;
+
 struct thd_arg {
   void (*body)(void* arg); /* body of a thread */
   void* arg;               /* argument to a thread */
 };
 
+static void inc_thd_count();
+static void dec_thd_count();
+
 /* Body of every thread started via gpr_thd_new. */
 static void* thread_body(void* v) {
   struct thd_arg a = *(struct thd_arg*)v;
   free(v);
   (*a.body)(a.arg);
+  dec_thd_count();
   return nullptr;
 }
 
@@ -54,6 +66,7 @@ int gpr_thd_new(gpr_thd_id* t, void (*thd_body)(void* arg), void* arg,
   GPR_ASSERT(a != nullptr);
   a->body = thd_body;
   a->arg = arg;
+  inc_thd_count();
 
   GPR_ASSERT(pthread_attr_init(&attr) == 0);
   if (gpr_thd_options_is_detached(options)) {
@@ -68,6 +81,7 @@ int gpr_thd_new(gpr_thd_id* t, void (*thd_body)(void* arg), void* arg,
   if (!thread_started) {
     /* don't use gpr_free, as this was allocated using malloc (see above) */
     free(a);
+    dec_thd_count();
   }
   *t = (gpr_thd_id)p;
   return thread_started;
@@ -77,4 +91,46 @@ gpr_thd_id gpr_thd_currentid(void) { return (gpr_thd_id)pthread_self(); }
 
 void gpr_thd_join(gpr_thd_id t) { pthread_join((pthread_t)t, nullptr); }
 
+/*****************************************
+ * Only used when fork support is enabled
+ */
+
+static void inc_thd_count() {
+  if (grpc_fork_support_enabled()) {
+    gpr_mu_lock(&g_mu);
+    g_thread_count++;
+    gpr_mu_unlock(&g_mu);
+  }
+}
+
+static void dec_thd_count() {
+  if (grpc_fork_support_enabled()) {
+    gpr_mu_lock(&g_mu);
+    g_thread_count--;
+    if (g_awaiting_threads && g_thread_count == 0) {
+      gpr_cv_signal(&g_cv);
+    }
+    gpr_mu_unlock(&g_mu);
+  }
+}
+
+void gpr_thd_init() {
+  gpr_mu_init(&g_mu);
+  gpr_cv_init(&g_cv);
+  g_thread_count = 0;
+  g_awaiting_threads = 0;
+}
+
+int gpr_await_threads(gpr_timespec deadline) {
+  gpr_mu_lock(&g_mu);
+  g_awaiting_threads = 1;
+  int res = 0;
+  if (g_thread_count > 0) {
+    res = gpr_cv_wait(&g_cv, &g_mu, deadline);
+  }
+  g_awaiting_threads = 0;
+  gpr_mu_unlock(&g_mu);
+  return res == 0;
+}
+
 #endif /* GPR_POSIX_SYNC */
diff --git a/src/core/lib/support/thd_windows.cc b/src/core/lib/support/thd_windows.cc
index 5bda7f440c..0875c2f03e 100644
--- a/src/core/lib/support/thd_windows.cc
+++ b/src/core/lib/support/thd_windows.cc
@@ -50,6 +50,8 @@ static void destroy_thread(struct thd_info* t) {
   gpr_free(t);
 }
 
+void gpr_thd_init(void) {}
+
 /* Body of every thread started via gpr_thd_new. */
 static DWORD WINAPI thread_body(void* v) {
   g_thd_info = (struct thd_info*)v;