200 lines
7.2 KiB
C++
200 lines
7.2 KiB
C++
// Copyright 2015 The Chromium OS Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef LIBBRILLO_BRILLO_MESSAGE_LOOPS_BASE_MESSAGE_LOOP_H_
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#define LIBBRILLO_BRILLO_MESSAGE_LOOPS_BASE_MESSAGE_LOOP_H_
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// BaseMessageLoop is a brillo::MessageLoop implementation based on
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// base::MessageLoopForIO. This allows to mix new code using
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// brillo::MessageLoop and legacy code using base::MessageLoopForIO in the
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// same thread and share a single main loop. This disadvantage of using this
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// class is a less efficient implementation of CancelTask() for delayed tasks
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// since base::MessageLoopForIO doesn't provide a way to remove the event.
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#include <map>
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#include <memory>
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#include <string>
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#include <base/location.h>
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#include <base/memory/weak_ptr.h>
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#include <base/message_loop/message_loop.h>
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#include <base/message_loop/message_pump_for_io.h>
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#include <base/time/time.h>
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#include <gtest/gtest_prod.h>
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#include <brillo/brillo_export.h>
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#include <brillo/message_loops/message_loop.h>
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namespace brillo {
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class BRILLO_EXPORT BaseMessageLoop : public MessageLoop {
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public:
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// Construct a base::MessageLoopForIO message loop instance and use it as
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// the default message loop for this thread.
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BaseMessageLoop();
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// Construct a brillo::BaseMessageLoop using the passed base::MessageLoopForIO
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// instance.
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explicit BaseMessageLoop(base::MessageLoopForIO* base_loop);
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~BaseMessageLoop() override;
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// MessageLoop overrides.
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TaskId PostDelayedTask(const base::Location& from_here,
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const base::Closure& task,
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base::TimeDelta delay) override;
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using MessageLoop::PostDelayedTask;
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TaskId WatchFileDescriptor(const base::Location& from_here,
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int fd,
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WatchMode mode,
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bool persistent,
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const base::Closure& task) override;
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using MessageLoop::WatchFileDescriptor;
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bool CancelTask(TaskId task_id) override;
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bool RunOnce(bool may_block) override;
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void Run() override;
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void BreakLoop() override;
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// Returns a callback that will quit the current message loop. If the message
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// loop is not running, an empty (null) callback is returned.
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base::Closure QuitClosure() const;
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private:
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FRIEND_TEST(BaseMessageLoopTest, ParseBinderMinor);
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static const int kInvalidMinor;
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static const int kUninitializedMinor;
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// Parses the contents of the file /proc/misc passed in |file_contents| and
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// returns the minor device number reported for binder. On error or if not
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// found, returns kInvalidMinor.
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static int ParseBinderMinor(const std::string& file_contents);
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// Called by base::MessageLoopForIO when is time to call the callback
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// scheduled with Post*Task() of id |task_id|, even if it was canceled.
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void OnRanPostedTask(MessageLoop::TaskId task_id);
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// Called from the message loop when the IOTask should run the scheduled
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// callback. This is a simple wrapper of IOTask::OnFileReadyPostedTask()
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// posted from the BaseMessageLoop so it is deleted when the BaseMessageLoop
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// goes out of scope since we can't cancel the callback otherwise.
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void OnFileReadyPostedTask(MessageLoop::TaskId task_id);
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// Return a new unused task_id.
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TaskId NextTaskId();
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// Returns binder minor device number.
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unsigned int GetBinderMinor();
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struct DelayedTask {
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base::Location location;
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MessageLoop::TaskId task_id;
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base::Closure closure;
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};
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class IOTask : public base::MessagePumpForIO::FdWatcher {
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public:
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IOTask(const base::Location& location,
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BaseMessageLoop* loop,
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MessageLoop::TaskId task_id,
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int fd,
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base::MessagePumpForIO::Mode base_mode,
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bool persistent,
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const base::Closure& task);
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const base::Location& location() const { return location_; }
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// Used to start/stop watching the file descriptor while keeping the
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// IOTask entry available.
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bool StartWatching();
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void StopWatching();
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// Called from the message loop as a PostTask() when the file descriptor is
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// available, scheduled to run from OnFileReady().
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void OnFileReadyPostedTask();
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// Cancel the IOTask and returns whether it was actually canceled, with the
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// same semantics as MessageLoop::CancelTask().
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bool CancelTask();
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// Sets the closure to be run immediately whenever the file descriptor
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// becomes ready.
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void RunImmediately() { immediate_run_= true; }
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private:
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base::Location location_;
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BaseMessageLoop* loop_;
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// These are the arguments passed in the constructor, basically forwarding
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// all the arguments passed to WatchFileDescriptor() plus the assigned
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// TaskId for this task.
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MessageLoop::TaskId task_id_;
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int fd_;
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base::MessagePumpForIO::Mode base_mode_;
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bool persistent_;
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base::Closure closure_;
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base::MessagePumpForIO::FdWatchController fd_watcher_;
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// Tells whether there is a pending call to OnFileReadPostedTask().
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bool posted_task_pending_{false};
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// Whether the registered callback should be running immediately when the
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// file descriptor is ready, as opposed to posting a task to the main loop
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// to prevent starvation.
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bool immediate_run_{false};
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// base::MessageLoopForIO::Watcher overrides:
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void OnFileCanReadWithoutBlocking(int fd) override;
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void OnFileCanWriteWithoutBlocking(int fd) override;
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// Common implementation for both the read and write case.
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void OnFileReady();
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DISALLOW_COPY_AND_ASSIGN(IOTask);
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};
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// The base::MessageLoopForIO instance owned by this class, if any. This
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// is declared first in this class so it is destroyed last.
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std::unique_ptr<base::MessageLoopForIO> owned_base_loop_;
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// Tasks blocked on a timeout.
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std::map<MessageLoop::TaskId, DelayedTask> delayed_tasks_;
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// Tasks blocked on I/O.
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std::map<MessageLoop::TaskId, IOTask> io_tasks_;
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// Flag to mark that we should run the message loop only one iteration.
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bool run_once_{false};
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// The last used TaskId. While base::MessageLoopForIO doesn't allow to cancel
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// delayed tasks, we handle that functionality by not running the callback
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// if it fires at a later point.
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MessageLoop::TaskId last_id_{kTaskIdNull};
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// The pointer to the libchrome base::MessageLoopForIO we are wrapping with
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// this interface. If the instance was created from this object, this will
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// point to that instance.
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base::MessageLoopForIO* base_loop_;
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// The RunLoop instance used to run the main loop from Run().
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base::RunLoop* base_run_loop_{nullptr};
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// The binder minor device number. Binder is a "misc" char device with a
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// dynamically allocated minor number. When uninitialized, this value will
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// be negative, otherwise, it will hold the minor part of the binder device
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// number. This is populated by GetBinderMinor().
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int binder_minor_{kUninitializedMinor};
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// We use a WeakPtrFactory to schedule tasks with the base::MessageLoopForIO
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// since we can't cancel the callbacks we have scheduled there once this
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// instance is destroyed.
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base::WeakPtrFactory<BaseMessageLoop> weak_ptr_factory_{this};
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DISALLOW_COPY_AND_ASSIGN(BaseMessageLoop);
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};
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} // namespace brillo
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#endif // LIBBRILLO_BRILLO_MESSAGE_LOOPS_BASE_MESSAGE_LOOP_H_
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