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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kControl;
#include "mongo/platform/basic.h"
#include "mongo/util/exit.h"
#include <boost/optional.hpp>
#include <stack>
#include "mongo/stdx/condition_variable.h"
#include "mongo/stdx/functional.h"
#include "mongo/stdx/mutex.h"
#include "mongo/stdx/thread.h"
#include "mongo/util/log.h"
#include "mongo/util/quick_exit.h"
namespace mongo {
namespace {
stdx::mutex shutdownMutex;
stdx::condition_variable shutdownTasksComplete;
boost::optional<ExitCode> shutdownExitCode;
bool shutdownTasksInProgress = false;
AtomicWord<unsigned> shutdownFlag;
std::stack<unique_function<void(const ShutdownTaskArgs&)>> shutdownTasks;
stdx::thread::id shutdownTasksThreadId;
void runTasks(decltype(shutdownTasks) tasks, const ShutdownTaskArgs& shutdownArgs) noexcept {
while (!tasks.empty()) {
const auto& task = tasks.top();
task(shutdownArgs);
tasks.pop();
}
}
// The logAndQuickExit_inlock() function should be called while holding the 'shutdownMutex' to
// prevent multiple threads from attempting to log that they are exiting. The quickExit() function
// has its own 'quickExitMutex' to prohibit multiple threads from attempting to call _exit().
MONGO_COMPILER_NORETURN void logAndQuickExit_inlock() {
ExitCode code = shutdownExitCode.get();
log() << "shutting down with code:" << code;
quickExit(code);
}
void setShutdownFlag() {
shutdownFlag.fetchAndAdd(1);
}
} // namespace
bool globalInShutdownDeprecated() {
return shutdownFlag.loadRelaxed() != 0;
}
ExitCode waitForShutdown() {
stdx::unique_lock<stdx::mutex> lk(shutdownMutex);
shutdownTasksComplete.wait(lk, [] {
const auto shutdownStarted = static_cast<bool>(shutdownExitCode);
return shutdownStarted && !shutdownTasksInProgress;
});
return shutdownExitCode.get();
}
void registerShutdownTask(unique_function<void(const ShutdownTaskArgs&)> task) {
stdx::lock_guard<stdx::mutex> lock(shutdownMutex);
invariant(!globalInShutdownDeprecated());
shutdownTasks.emplace(std::move(task));
}
void shutdown(ExitCode code, const ShutdownTaskArgs& shutdownArgs) {
decltype(shutdownTasks) localTasks;
{
stdx::unique_lock<stdx::mutex> lock(shutdownMutex);
if (shutdownTasksInProgress) {
// Someone better have called shutdown in some form already.
invariant(globalInShutdownDeprecated());
// Re-entrant calls to shutdown are not allowed.
invariant(shutdownTasksThreadId != stdx::this_thread::get_id());
ExitCode originallyRequestedCode = shutdownExitCode.get();
if (code != originallyRequestedCode) {
log() << "While running shutdown tasks with the intent to exit with code "
<< originallyRequestedCode << ", an additional shutdown request arrived with "
"the intent to exit with a different exit code "
<< code << "; ignoring the conflicting exit code";
}
// Wait for the shutdown tasks to complete
while (shutdownTasksInProgress)
shutdownTasksComplete.wait(lock);
logAndQuickExit_inlock();
}
setShutdownFlag();
shutdownExitCode.emplace(code);
shutdownTasksInProgress = true;
shutdownTasksThreadId = stdx::this_thread::get_id();
localTasks.swap(shutdownTasks);
}
runTasks(std::move(localTasks), shutdownArgs);
{
stdx::lock_guard<stdx::mutex> lock(shutdownMutex);
shutdownTasksInProgress = false;
shutdownTasksComplete.notify_all();
logAndQuickExit_inlock();
}
}
void shutdownNoTerminate(const ShutdownTaskArgs& shutdownArgs) {
decltype(shutdownTasks) localTasks;
{
stdx::lock_guard<stdx::mutex> lock(shutdownMutex);
if (globalInShutdownDeprecated())
return;
setShutdownFlag();
shutdownTasksInProgress = true;
shutdownTasksThreadId = stdx::this_thread::get_id();
localTasks.swap(shutdownTasks);
}
runTasks(std::move(localTasks), shutdownArgs);
{
stdx::lock_guard<stdx::mutex> lock(shutdownMutex);
shutdownTasksInProgress = false;
shutdownExitCode.emplace(EXIT_CLEAN);
}
shutdownTasksComplete.notify_all();
}
} // namespace mongo
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