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/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef INCLUDE_PERFETTO_EXT_BASE_UNIX_TASK_RUNNER_H_
#define INCLUDE_PERFETTO_EXT_BASE_UNIX_TASK_RUNNER_H_
#include "perfetto/base/build_config.h"
#include "perfetto/base/task_runner.h"
#include "perfetto/base/time.h"
#include "perfetto/ext/base/event_fd.h"
#include "perfetto/ext/base/scoped_file.h"
#include "perfetto/ext/base/thread_checker.h"
#include "perfetto/ext/base/thread_utils.h"
#include <poll.h>
#include <chrono>
#include <deque>
#include <map>
#include <mutex>
#include <vector>
namespace perfetto {
namespace base {
// Runs a task runner on the current thread.
//
// Implementation note: we currently assume (and enforce in debug builds) that
// Run() is called from the thread that constructed the UnixTaskRunner. This is
// not strictly necessary, and we could instead track the thread that invokes
// Run(). However, a related property that *might* be important to enforce is
// that the destructor runs on the task-running thread. Otherwise, if there are
// still-pending tasks at the time of destruction, we would destroy those
// outside of the task thread (which might be unexpected to the caller). On the
// other hand, the std::function task interface discourages use of any
// resource-owning tasks (as the callable needs to be copyable), so this might
// not be important in practice.
//
// TODO(rsavitski): consider adding a thread-check in the destructor, after
// auditing existing usages.
class UnixTaskRunner : public TaskRunner {
public:
UnixTaskRunner();
~UnixTaskRunner() override;
// Start executing tasks. Doesn't return until Quit() is called. Run() may be
// called multiple times on the same task runner.
void Run();
void Quit();
// Checks whether there are any pending immediate tasks to run. Note that
// delayed tasks don't count even if they are due to run.
bool IsIdleForTesting();
// TaskRunner implementation:
void PostTask(std::function<void()>) override;
void PostDelayedTask(std::function<void()>, uint32_t delay_ms) override;
void AddFileDescriptorWatch(int fd, std::function<void()>) override;
void RemoveFileDescriptorWatch(int fd) override;
bool RunsTasksOnCurrentThread() const override;
// Returns true if the task runner is quitting, or has quit and hasn't been
// restarted since. Exposed primarily for ThreadTaskRunner, not necessary for
// normal use of this class.
bool QuitCalled();
private:
void WakeUp();
void UpdateWatchTasksLocked();
int GetDelayMsToNextTaskLocked() const;
void RunImmediateAndDelayedTask();
void PostFileDescriptorWatches();
void RunFileDescriptorWatch(int fd);
ThreadChecker thread_checker_;
PlatformThreadID created_thread_id_ = GetThreadId();
// On Linux, an eventfd(2) used to waking up the task runner when a new task
// is posted. Otherwise the read end of a pipe used for the same purpose.
EventFd event_;
std::vector<struct pollfd> poll_fds_;
// --- Begin lock-protected members ---
std::mutex lock_;
std::deque<std::function<void()>> immediate_tasks_;
std::multimap<TimeMillis, std::function<void()>> delayed_tasks_;
bool quit_ = false;
struct WatchTask {
std::function<void()> callback;
size_t poll_fd_index; // Index into |poll_fds_|.
};
std::map<int, WatchTask> watch_tasks_;
bool watch_tasks_changed_ = false;
// --- End lock-protected members ---
};
} // namespace base
} // namespace perfetto
#endif // INCLUDE_PERFETTO_EXT_BASE_UNIX_TASK_RUNNER_H_
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