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//
//
// 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_SRC_CORE_LIB_GPRPP_FORK_H
#define GRPC_SRC_CORE_LIB_GPRPP_FORK_H
#include <grpc/support/port_platform.h>
#include <atomic>
#include <set>
//
// NOTE: FORKING IS NOT GENERALLY SUPPORTED, THIS IS ONLY INTENDED TO WORK
// AROUND VERY SPECIFIC USE CASES.
//
namespace grpc_core {
class Fork {
public:
typedef void (*child_postfork_func)(void);
static void GlobalInit();
// Returns true if fork suppport is enabled, false otherwise
static bool Enabled();
// Increment the count of active ExecCtxs.
// Will block until a pending fork is complete if one is in progress.
static void IncExecCtxCount() {
if (GPR_UNLIKELY(support_enabled_.load(std::memory_order_relaxed))) {
DoIncExecCtxCount();
}
}
// Decrement the count of active ExecCtxs
static void DecExecCtxCount() {
if (GPR_UNLIKELY(support_enabled_.load(std::memory_order_relaxed))) {
DoDecExecCtxCount();
}
}
// Provide a function that will be invoked in the child's postfork handler to
// reset the polling engine's internal state.
// Returns true if reset_child_polling_engine was not previously registered,
// otherwise returns false and does nothing.
static bool RegisterResetChildPollingEngineFunc(
child_postfork_func reset_child_polling_engine);
static const std::set<child_postfork_func>& GetResetChildPollingEngineFunc();
// Check if there is a single active ExecCtx
// (the one used to invoke this function). If there are more,
// return false. Otherwise, return true and block creation of
// more ExecCtx s until AlloWExecCtx() is called
//
static bool BlockExecCtx();
static void AllowExecCtx();
// Increment the count of active threads.
static void IncThreadCount();
// Decrement the count of active threads.
static void DecThreadCount();
// Await all core threads to be joined.
static void AwaitThreads();
// Test only: overrides environment variables/compile flags
// Must be called before grpc_init()
static void Enable(bool enable);
private:
static void DoIncExecCtxCount();
static void DoDecExecCtxCount();
static std::atomic<bool> support_enabled_;
static bool override_enabled_;
static std::set<child_postfork_func>* reset_child_polling_engine_;
};
} // namespace grpc_core
#endif // GRPC_SRC_CORE_LIB_GPRPP_FORK_H
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