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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <memory>
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/message_loop/message_pump.h"
#include "base/message_loop/watchable_io_message_pump_posix.h"
#include "base/threading/thread_checker.h"
#include "base/time/time.h"
// Declare structs we need from libevent.h rather than including it
struct event_base;
struct event;
namespace base {
// Class to monitor sockets and issue callbacks when sockets are ready for I/O
// TODO(dkegel): add support for background file IO somehow
class BASE_EXPORT MessagePumpLibevent : public MessagePump,
public WatchableIOMessagePumpPosix {
class FdWatchController : public FdWatchControllerInterface {
explicit FdWatchController(const Location& from_here);
// Implicitly calls StopWatchingFileDescriptor.
~FdWatchController() override;
// FdWatchControllerInterface:
bool StopWatchingFileDescriptor() override;
friend class MessagePumpLibevent;
friend class MessagePumpLibeventTest;
// Called by MessagePumpLibevent.
void Init(std::unique_ptr<event> e);
// Used by MessagePumpLibevent to take ownership of |event_|.
std::unique_ptr<event> ReleaseEvent();
void set_pump(MessagePumpLibevent* pump) { pump_ = pump; }
MessagePumpLibevent* pump() const { return pump_; }
void set_watcher(FdWatcher* watcher) { watcher_ = watcher; }
void OnFileCanReadWithoutBlocking(int fd, MessagePumpLibevent* pump);
void OnFileCanWriteWithoutBlocking(int fd, MessagePumpLibevent* pump);
std::unique_ptr<event> event_;
MessagePumpLibevent* pump_ = nullptr;
FdWatcher* watcher_ = nullptr;
// If this pointer is non-NULL, the pointee is set to true in the
// destructor.
bool* was_destroyed_ = nullptr;
~MessagePumpLibevent() override;
bool WatchFileDescriptor(int fd,
bool persistent,
int mode,
FdWatchController* controller,
FdWatcher* delegate);
// MessagePump methods:
void Run(Delegate* delegate) override;
void Quit() override;
void ScheduleWork() override;
void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override;
friend class MessagePumpLibeventTest;
// Risky part of constructor. Returns true on success.
bool Init();
// Called by libevent to tell us a registered FD can be read/written to.
static void OnLibeventNotification(int fd, short flags, void* context);
// Unix pipe used to implement ScheduleWork()
// ... callback; called by libevent inside Run() when pipe is ready to read
static void OnWakeup(int socket, short flags, void* context);
// This flag is set to false when Run should return.
bool keep_running_;
// This flag is set when inside Run.
bool in_run_;
// This flag is set if libevent has processed I/O events.
bool processed_io_events_;
// The time at which we should call DoDelayedWork.
TimeTicks delayed_work_time_;
// Libevent dispatcher. Watches all sockets registered with it, and sends
// readiness callbacks when a socket is ready for I/O.
event_base* event_base_;
// ... write end; ScheduleWork() writes a single byte to it
int wakeup_pipe_in_;
// ... read end; OnWakeup reads it and then breaks Run() out of its sleep
int wakeup_pipe_out_;
// ... libevent wrapper for read end
event* wakeup_event_;
ThreadChecker watch_file_descriptor_caller_checker_;
} // namespace base