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/**
* Copyright (C) 2020-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.
*/
#include "mongo/util/thread_context.h"
#include "mongo/base/init.h"
#include "mongo/stdx/thread.h"
#include "mongo/util/assert_util.h"
namespace mongo {
namespace {
const auto kMainThreadId = stdx::this_thread::get_id();
AtomicWord<bool> gHasInitializedMain{false};
} // namespace
thread_local ThreadContext::Handle ThreadContext::_handle;
MONGO_INITIALIZER(ThreadContextsInitialized)(InitializerContext*) {
ThreadContext::initializeMain();
}
void ThreadContext::initializeMain() {
invariant(stdx::this_thread::get_id() == kMainThreadId,
"initializeMain() must be called on the main thread");
if (gHasInitializedMain.swap(true)) {
return;
}
_handle.init();
}
ThreadContext::Handle::Handle() {
if (!gHasInitializedMain.loadRelaxed()) {
// If we have not initialized main, then we delay until the MONGO_INITIALIZER runs.
return;
}
init();
}
void ThreadContext::Handle::init() {
// Note that construction happens before assignment to the thread_local.
instance = make_intrusive<ThreadContext>();
}
ThreadContext::Handle::~Handle() {
if (!instance) {
// If we don't have an instance, just skip. This is mostly going to be pre-main failures.
return;
}
// Remove from the thread local access, then destroy our pointer to it.
auto localInstance = std::exchange(instance, {});
localInstance->_isAlive.store(false);
localInstance.reset();
}
} // namespace mongo
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