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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.
*/
#pragma once
#include <list>
#include <memory>
#include "mongo/executor/task_executor.h"
#include "mongo/platform/condition_variable.h"
#include "mongo/platform/mutex.h"
#include "mongo/stdx/thread.h"
#include "mongo/transport/baton.h"
#include "mongo/util/fail_point_service.h"
namespace mongo {
class ThreadPoolInterface;
namespace executor {
extern FailPoint initialSyncFuzzerSynchronizationPoint1;
extern FailPoint initialSyncFuzzerSynchronizationPoint2;
struct ConnectionPoolStats;
class NetworkInterface;
/**
* Implementation of a TaskExecutor that uses a pool of threads to execute work items.
*/
class ThreadPoolTaskExecutor final : public TaskExecutor {
ThreadPoolTaskExecutor(const ThreadPoolTaskExecutor&) = delete;
ThreadPoolTaskExecutor& operator=(const ThreadPoolTaskExecutor&) = delete;
public:
/**
* Constructs an instance of ThreadPoolTaskExecutor that runs tasks in "pool" and uses "net"
* for network operations.
*/
ThreadPoolTaskExecutor(std::unique_ptr<ThreadPoolInterface> pool,
std::shared_ptr<NetworkInterface> net);
/**
* Destroys a ThreadPoolTaskExecutor.
*/
~ThreadPoolTaskExecutor();
void startup() override;
void shutdown() override;
void join() override;
void appendDiagnosticBSON(BSONObjBuilder* b) const override;
Date_t now() override;
StatusWith<EventHandle> makeEvent() override;
void signalEvent(const EventHandle& event) override;
StatusWith<CallbackHandle> onEvent(const EventHandle& event, CallbackFn&& work) override;
StatusWith<stdx::cv_status> waitForEvent(OperationContext* opCtx,
const EventHandle& event,
Date_t deadline) override;
void waitForEvent(const EventHandle& event) override;
StatusWith<CallbackHandle> scheduleWork(CallbackFn&& work) override;
StatusWith<CallbackHandle> scheduleWorkAt(Date_t when, CallbackFn&& work) override;
StatusWith<CallbackHandle> scheduleRemoteCommandOnAny(
const RemoteCommandRequestOnAny& request,
const RemoteCommandOnAnyCallbackFn& cb,
const BatonHandle& baton = nullptr) override;
void cancel(const CallbackHandle& cbHandle) override;
void wait(const CallbackHandle& cbHandle,
Interruptible* interruptible = Interruptible::notInterruptible()) override;
void appendConnectionStats(ConnectionPoolStats* stats) const override;
/**
* Drops all connections to the given host on the network interface.
*/
void dropConnections(const HostAndPort& hostAndPort);
private:
class CallbackState;
class EventState;
using WorkQueue = std::list<std::shared_ptr<CallbackState>>;
using EventList = std::list<std::shared_ptr<EventState>>;
/**
* Representation of the stage of life of a thread pool.
*
* A pool starts out in the preStart state, and ends life in the shutdownComplete state. Work
* may only be scheduled in the preStart and running states. Threads may only be started in the
* running state. In shutdownComplete, there are no remaining threads or pending tasks to
* execute.
*
* Diagram of legal transitions:
*
* preStart -> running -> joinRequired -> joining -> shutdownComplete
* \ ^
* \_____________/
*
* NOTE: The enumeration values below are compared using operator<, etc, with the expectation
* that a -> b in the diagram above implies that a < b in the enum below.
*/
enum State { preStart, running, joinRequired, joining, shutdownComplete };
/**
* Returns an EventList containing one unsignaled EventState. This is a helper function for
* performing allocations outside of _mutex, and should only be called by makeSingletonWork and
* makeEvent().
*/
static EventList makeSingletonEventList();
/**
* Returns an object suitable for passing to enqueueCallbackState_inlock that represents
* executing "work" no sooner than "when" (defaults to ASAP). This function may and should be
* called outside of _mutex.
*/
static WorkQueue makeSingletonWorkQueue(CallbackFn work,
const BatonHandle& baton,
Date_t when = {});
/**
* Moves the single callback in "wq" to the end of "queue". It is required that "wq" was
* produced via a call to makeSingletonWorkQueue().
*/
StatusWith<CallbackHandle> enqueueCallbackState_inlock(WorkQueue* queue, WorkQueue* wq);
/**
* Signals the given event.
*/
void signalEvent_inlock(const EventHandle& event, stdx::unique_lock<Latch> lk);
/**
* Schedules all items from "fromQueue" into the thread pool and moves them into
* _poolInProgressQueue.
*/
void scheduleIntoPool_inlock(WorkQueue* fromQueue, stdx::unique_lock<Latch> lk);
/**
* Schedules the given item from "fromQueue" into the thread pool and moves it into
* _poolInProgressQueue.
*/
void scheduleIntoPool_inlock(WorkQueue* fromQueue,
const WorkQueue::iterator& iter,
stdx::unique_lock<Latch> lk);
/**
* Schedules entries from "begin" through "end" in "fromQueue" into the thread pool
* and moves them into _poolInProgressQueue.
*/
void scheduleIntoPool_inlock(WorkQueue* fromQueue,
const WorkQueue::iterator& begin,
const WorkQueue::iterator& end,
stdx::unique_lock<Latch> lk);
/**
* Executes the callback specified by "cbState".
*/
void runCallback(std::shared_ptr<CallbackState> cbState);
bool _inShutdown_inlock() const;
void _setState_inlock(State newState);
stdx::unique_lock<Latch> _join(stdx::unique_lock<Latch> lk);
// The network interface used for remote command execution and waiting.
std::shared_ptr<NetworkInterface> _net;
// The thread pool that executes scheduled work items.
std::shared_ptr<ThreadPoolInterface> _pool;
// Mutex guarding all remaining fields.
mutable Mutex _mutex = MONGO_MAKE_LATCH("ThreadPoolTaskExecutor::_mutex");
// Queue containing all items currently scheduled into the thread pool but not yet completed.
WorkQueue _poolInProgressQueue;
// Queue containing all items currently scheduled into the network interface.
WorkQueue _networkInProgressQueue;
// Queue containing all items waiting for a particular point in time to execute.
WorkQueue _sleepersQueue;
// List of all events that have yet to be signaled.
EventList _unsignaledEvents;
// Lifecycle state of this executor.
stdx::condition_variable _stateChange;
State _state = preStart;
};
} // namespace executor
} // namespace mongo
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