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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::kExecutor
#include "mongo/platform/basic.h"
#include "mongo/executor/network_interface_thread_pool.h"
#include "mongo/executor/network_interface.h"
#include "mongo/util/destructor_guard.h"
#include "mongo/util/log.h"
#include "mongo/util/scopeguard.h"
namespace mongo {
namespace executor {
NetworkInterfaceThreadPool::NetworkInterfaceThreadPool(NetworkInterface* net) : _net(net) {}
NetworkInterfaceThreadPool::~NetworkInterfaceThreadPool() {
DESTRUCTOR_GUARD(_dtorImpl());
}
void NetworkInterfaceThreadPool::_dtorImpl() {
{
stdx::unique_lock<stdx::mutex> lk(_mutex);
if (_tasks.empty())
return;
_inShutdown = true;
}
join();
invariant(_tasks.empty());
}
void NetworkInterfaceThreadPool::startup() {
stdx::unique_lock<stdx::mutex> lk(_mutex);
if (_started) {
severe() << "Attempting to start pool, but it has already started";
fassertFailed(34358);
}
_started = true;
_consumeTasks(std::move(lk));
}
void NetworkInterfaceThreadPool::shutdown() {
{
stdx::lock_guard<stdx::mutex> lk(_mutex);
_inShutdown = true;
}
_net->signalWorkAvailable();
}
void NetworkInterfaceThreadPool::join() {
{
stdx::unique_lock<stdx::mutex> lk(_mutex);
if (_joining) {
severe() << "Attempted to join pool more than once";
fassertFailed(34357);
}
_joining = true;
_started = true;
if (_consumeState == ConsumeState::kNeutral)
_consumeTasksInline(std::move(lk));
}
_net->signalWorkAvailable();
stdx::unique_lock<stdx::mutex> lk(_mutex);
_joiningCondition.wait(
lk, [&] { return _tasks.empty() && (_consumeState == ConsumeState::kNeutral); });
}
Status NetworkInterfaceThreadPool::schedule(Task task) {
stdx::unique_lock<stdx::mutex> lk(_mutex);
if (_inShutdown) {
return {ErrorCodes::ShutdownInProgress, "Shutdown in progress"};
}
_tasks.emplace_back(std::move(task));
if (_started)
_consumeTasks(std::move(lk));
return Status::OK();
}
/**
* Consumes available tasks.
*
* We distinguish between calls to consume on the networking thread and off of it. For off thread
* calls, we try to initiate a consume via schedule and invoke directly inside the executor. This
* allows us to use the network interface's threads as our own pool, which should reduce context
* switches if our tasks are getting scheduled by network interface tasks.
*/
void NetworkInterfaceThreadPool::_consumeTasks(stdx::unique_lock<stdx::mutex> lk) {
if ((_consumeState != ConsumeState::kNeutral) || _tasks.empty())
return;
auto shouldNotSchedule = _inShutdown || _net->onNetworkThread();
if (shouldNotSchedule) {
_consumeTasksInline(std::move(lk));
return;
}
_consumeState = ConsumeState::kScheduled;
lk.unlock();
auto ret = _net->schedule([this](Status status) {
stdx::unique_lock<stdx::mutex> lk(_mutex);
if (_consumeState != ConsumeState::kScheduled)
return;
_consumeTasksInline(std::move(lk));
});
invariant(ret.isOK() || ErrorCodes::isShutdownError(ret.code()));
}
void NetworkInterfaceThreadPool::_consumeTasksInline(stdx::unique_lock<stdx::mutex> lk) {
_consumeState = ConsumeState::kConsuming;
const auto consumingTasksGuard = makeGuard([&] { _consumeState = ConsumeState::kNeutral; });
decltype(_tasks) tasks;
while (_tasks.size()) {
using std::swap;
swap(tasks, _tasks);
lk.unlock();
const auto lkGuard = makeGuard([&] { lk.lock(); });
for (auto&& task : tasks) {
try {
task();
} catch (...) {
severe() << "Exception escaped task in network interface thread pool";
std::terminate();
}
}
tasks.clear();
}
if (_joining)
_joiningCondition.notify_one();
}
} // namespace executor
} // namespace mongo
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