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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.
*/
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kDefault
#include "mongo/db/client_out_of_line_executor.h"
#include "mongo/base/error_codes.h"
#include "mongo/base/status.h"
#include "mongo/db/service_context.h"
#include "mongo/logv2/log.h"
#include "mongo/logv2/log_severity.h"
#include "mongo/logv2/log_severity_suppressor.h"
#include "mongo/util/clock_source.h"
#include "mongo/util/scopeguard.h"
namespace mongo {
// Per-instance implementation details that need not appear in the header.
class ClientOutOfLineExecutor::Impl {
public:
/** Returns Info(), then suppresses to `Debug(2)` for a second. */
logv2::SeveritySuppressor bumpedSeverity{
Seconds{1}, logv2::LogSeverity::Info(), logv2::LogSeverity::Debug(2)};
ClockSource::StopWatch stopWatch;
};
ClientOutOfLineExecutor::ClientOutOfLineExecutor() noexcept
: _impl{std::make_unique<Impl>()}, _taskQueue{std::make_shared<QueueType>()} {}
ClientOutOfLineExecutor::~ClientOutOfLineExecutor() noexcept {
if (!_requireShutdown.load())
return;
invariant(_isShutdown);
}
void ClientOutOfLineExecutor::shutdown() {
ON_BLOCK_EXIT([this]() mutable { _isShutdown = true; });
// Force producers to consume their tasks beyond this point.
_taskQueue->closeProducerEnd();
// Only call `tryPop()` when there's a task to pop to avoid lifetime issues with logging.
auto toCollect = _taskQueue->getStats().queueDepth;
while (toCollect) {
auto task = _taskQueue->tryPop();
invariant(task);
(*task)(Status(ErrorCodes::ClientDisconnect, "Client's executor has stopped"));
toCollect--;
}
invariant(toCollect == 0);
}
static const Client::Decoration<ClientOutOfLineExecutor> getClientExecutor =
Client::declareDecoration<ClientOutOfLineExecutor>();
ClientOutOfLineExecutor* ClientOutOfLineExecutor::get(const Client* client) noexcept {
return const_cast<ClientOutOfLineExecutor*>(&getClientExecutor(client));
}
void ClientOutOfLineExecutor::schedule(Task task) {
getHandle().schedule(std::move(task));
}
void ClientOutOfLineExecutor::consumeAllTasks() noexcept {
// This limit allows logging incidents that the executor consumes too much of the client's
// time running scheduled tasks. The value is only used for debugging, and should be an
// approximation of the acceptable overhead in the context of normal client operations.
static constexpr auto kTimeLimit = Microseconds(30);
_impl->stopWatch.restart();
while (auto maybeTask = _taskQueue->tryPop()) {
auto task = std::move(*maybeTask);
task(Status::OK());
}
auto elapsed = _impl->stopWatch.elapsed();
if (MONGO_unlikely(elapsed > kTimeLimit)) {
LOGV2_DEBUG(4651401,
_impl->bumpedSeverity().toInt(),
"Client's executor exceeded time limit",
"elapsed"_attr = elapsed,
"limit"_attr = kTimeLimit);
}
}
void ClientOutOfLineExecutor::QueueHandle::schedule(Task&& task) {
ScopeGuard guard(
[&task] { task(Status(ErrorCodes::CallbackCanceled, "Client no longer exists")); });
if (auto queue = _weakQueue.lock()) {
try {
queue->push(std::move(task));
guard.dismiss();
} catch (const ExceptionFor<ErrorCodes::ProducerConsumerQueueEndClosed>&) {
// The destructor for the out-of-line executor has already been called.
}
}
}
namespace {
/**
* The observer ensures that `ClientOutOfLineExecutor` is always stopped before the client object is
* destroyed. This is necessary to guarantee that `ClientOutOfLineExecutor::shutdown()` is executed
* before the client decorations are destroyed. See SERVER-48901 for more details.
*/
class ClientOutOfLineExecutorClientObserver final : public ServiceContext::ClientObserver {
void onCreateClient(Client*) {}
void onDestroyClient(Client* client) {
ClientOutOfLineExecutor::get(client)->shutdown();
}
void onCreateOperationContext(OperationContext*) {}
void onDestroyOperationContext(OperationContext*) {}
};
ServiceContext::ConstructorActionRegisterer
registerClientOutOfLineExecutorClientObserverConstructor{
"ClientOutOfLineExecutorClientObserverConstructor", [](ServiceContext* service) {
service->registerClientObserver(
std::make_unique<ClientOutOfLineExecutorClientObserver>());
}};
} // namespace
} // namespace mongo
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