mirror of https://github.com/grpc/grpc.git
EventEngine Forkables (#30473)
A (currently) pthread_atfork-based fork support mechanism, allowing EventEngines - or any other object that wants to implement the Forkable interface - respond to forks.pull/30546/head
AJ Heller
2 years ago
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GitHub
parent
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commit
0c5b6171ad
26 changed files with 501 additions and 20 deletions
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// Copyright 2022 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <grpc/support/port_platform.h> |
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#include "src/core/lib/event_engine/forkable.h" |
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#ifdef GRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK |
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#include <pthread.h> |
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#include "absl/container/flat_hash_set.h" |
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#include "src/core/lib/gprpp/sync.h" |
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namespace grpc_event_engine { |
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namespace experimental { |
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namespace { |
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grpc_core::Mutex g_mu; |
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bool g_registered{false}; |
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absl::flat_hash_set<Forkable*> g_forkables; |
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} // namespace
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Forkable::Forkable() { ManageForkable(this); } |
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Forkable::~Forkable() { StopManagingForkable(this); } |
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void RegisterForkHandlers() { |
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grpc_core::MutexLock lock(&g_mu); |
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GPR_ASSERT(!absl::exchange(g_registered, true)); |
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pthread_atfork(PrepareFork, PostforkParent, PostforkChild); |
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}; |
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void PrepareFork() { |
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grpc_core::MutexLock lock(&g_mu); |
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for (auto* forkable : g_forkables) { |
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forkable->PrepareFork(); |
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} |
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} |
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void PostforkParent() { |
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grpc_core::MutexLock lock(&g_mu); |
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for (auto* forkable : g_forkables) { |
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forkable->PostforkParent(); |
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} |
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} |
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void PostforkChild() { |
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grpc_core::MutexLock lock(&g_mu); |
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for (auto* forkable : g_forkables) { |
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forkable->PostforkChild(); |
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} |
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} |
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void ManageForkable(Forkable* forkable) { |
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grpc_core::MutexLock lock(&g_mu); |
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g_forkables.insert(forkable); |
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} |
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void StopManagingForkable(Forkable* forkable) { |
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grpc_core::MutexLock lock(&g_mu); |
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g_forkables.erase(forkable); |
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} |
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} // namespace experimental
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} // namespace grpc_event_engine
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#else // GRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK
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namespace grpc_event_engine { |
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namespace experimental { |
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Forkable::Forkable() {} |
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Forkable::~Forkable() {} |
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void RegisterForkHandlers() {} |
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void PrepareFork() {} |
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void PostforkParent() {} |
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void PostforkChild() {} |
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void ManageForkable(Forkable* /* forkable */) {} |
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void StopManagingForkable(Forkable* /* forkable */) {} |
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} // namespace experimental
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} // namespace grpc_event_engine
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#endif // GRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK
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// Copyright 2022 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef GRPC_CORE_LIB_EVENT_ENGINE_FORKABLE_H |
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#define GRPC_CORE_LIB_EVENT_ENGINE_FORKABLE_H |
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#include <grpc/support/port_platform.h> |
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namespace grpc_event_engine { |
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namespace experimental { |
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// Register fork handlers with the system, enabling fork support.
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//
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// This provides pthread-based support for fork events. Any objects that
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// implement Forkable can register themselves with this system using
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// ManageForkable, and their respective methods will be called upon fork.
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//
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// This should be called once upon grpc_initialization.
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void RegisterForkHandlers(); |
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// Global callback for pthread_atfork's *prepare argument
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void PrepareFork(); |
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// Global callback for pthread_atfork's *parent argument
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void PostforkParent(); |
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// Global callback for pthread_atfork's *child argument
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void PostforkChild(); |
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// An interface to be implemented by EventEngines that wish to have managed fork
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// support.
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class Forkable { |
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public: |
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Forkable(); |
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virtual ~Forkable(); |
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virtual void PrepareFork() = 0; |
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virtual void PostforkParent() = 0; |
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virtual void PostforkChild() = 0; |
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}; |
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// Add Forkables from the set of objects that are supported.
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// Upon fork, each forkable will have its respective fork hooks called on
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// the thread that invoked the fork.
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//
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// Relative ordering of fork callback operations is not guaranteed.
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void ManageForkable(Forkable* forkable); |
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// Remove a forkable from the managed set.
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void StopManagingForkable(Forkable* forkable); |
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} // namespace experimental
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} // namespace grpc_event_engine
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#endif // GRPC_CORE_LIB_EVENT_ENGINE_FORKABLE_H
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// Copyright 2022 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <grpc/support/port_platform.h> |
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#ifndef GRPC_ENABLE_FORK_SUPPORT |
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// Test nothing, everything is fine
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int main(int /* argc */, char** /* argv */) { return 0; } |
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#else // GRPC_ENABLE_FORK_SUPPORT
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#include <sys/wait.h> |
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#include <unistd.h> |
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#include <gtest/gtest.h> |
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#include "absl/time/clock.h" |
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#include <grpc/grpc.h> |
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#include <grpc/support/log.h> |
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#include "src/core/lib/event_engine/forkable.h" |
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namespace { |
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using ::grpc_event_engine::experimental::Forkable; |
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using ::grpc_event_engine::experimental::RegisterForkHandlers; |
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} // namespace
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class ForkableTest : public testing::Test {}; |
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#ifdef GRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK |
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TEST_F(ForkableTest, BasicPthreadAtForkOperations) { |
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class SomeForkable : public Forkable { |
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public: |
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void PrepareFork() override { prepare_called_ = true; } |
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void PostforkParent() override { parent_called_ = true; } |
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void PostforkChild() override { child_called_ = true; } |
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void CheckParent() { |
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EXPECT_TRUE(prepare_called_); |
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EXPECT_TRUE(parent_called_); |
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EXPECT_FALSE(child_called_); |
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} |
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void CheckChild() { |
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EXPECT_TRUE(prepare_called_); |
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EXPECT_FALSE(parent_called_); |
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EXPECT_TRUE(child_called_); |
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} |
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private: |
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bool prepare_called_ = false; |
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bool parent_called_ = false; |
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bool child_called_ = false; |
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}; |
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SomeForkable forkable; |
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int child_pid = fork(); |
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ASSERT_NE(child_pid, -1); |
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if (child_pid == 0) { |
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gpr_log(GPR_DEBUG, "I am child pid: %d", getpid()); |
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forkable.CheckChild(); |
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exit(testing::Test::HasFailure()); |
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} else { |
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gpr_log(GPR_DEBUG, "I am parent pid: %d", getpid()); |
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forkable.CheckParent(); |
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int status; |
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gpr_log(GPR_DEBUG, "Waiting for child pid: %d", child_pid); |
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do { |
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// retry on EINTR, and fail otherwise
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if (waitpid(child_pid, &status, 0) != -1) break; |
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ASSERT_EQ(errno, EINTR); |
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} while (true); |
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if (WIFEXITED(status)) { |
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ASSERT_EQ(WEXITSTATUS(status), 0); |
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} else { |
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// exited abnormally, fail and print the exit status
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ASSERT_EQ(-99, status); |
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} |
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} |
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} |
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#endif // GRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK
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int main(int argc, char** argv) { |
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testing::InitGoogleTest(&argc, argv); |
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RegisterForkHandlers(); |
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auto result = RUN_ALL_TESTS(); |
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return result; |
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} |
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#endif // GRPC_ENABLE_FORK_SUPPORT
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