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// Copyright 2017 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 <vector>
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/single_thread_task_runner.h"
#include "ui/compositor/compositor_export.h"
namespace cc {
class ScopedDeferMainFrameUpdate;
namespace ui {
class Compositor;
class CompositorLock;
// Implemented by clients which take compositor lock. Used to notify the client
// when their lock times out.
class CompositorLockClient {
virtual ~CompositorLockClient() {}
// Called if the CompositorLock ends before being destroyed due to timeout.
virtual void CompositorLockTimedOut() = 0;
// A helper class used to manage compositor locks. Should be created/used by
// classes which want to provide out compositor locking.
class COMPOSITOR_EXPORT CompositorLockManager {
scoped_refptr<base::SingleThreadTaskRunner> task_runner);
// Creates a compositor lock. Returns NULL if it is not possible to lock at
// this time (i.e. we're waiting to complete a previous unlock). If the
// timeout is null, then no timeout is used.
std::unique_ptr<CompositorLock> GetCompositorLock(
CompositorLockClient* client,
base::TimeDelta timeout,
void set_allow_locks_to_extend_timeout(bool allowed) {
allow_locks_to_extend_timeout_ = allowed;
bool IsLocked() const { return !active_locks_.empty(); }
void TimeoutLocksForTesting() { TimeoutLocks(); }
friend class CompositorLock;
// Causes all active CompositorLocks to be timed out.
void TimeoutLocks();
// Called to perform the unlock operation.
void RemoveCompositorLock(CompositorLock*);
// The TaskRunner on which timeouts are run.
scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
// The estimated time that the locks will timeout.
base::TimeTicks scheduled_timeout_;
// If true, the |scheduled_timeout_| might be recalculated and extended.
bool allow_locks_to_extend_timeout_ = false;
// The set of locks that are held externally.
std::vector<CompositorLock*> active_locks_;
base::WeakPtrFactory<CompositorLockManager> weak_ptr_factory_{this};
base::WeakPtrFactory<CompositorLockManager> lock_timeout_weak_ptr_factory_{
// This class represents a lock on the compositor, that can be used to prevent
// commits to the compositor tree while we're waiting for an asynchronous
// event. The typical use case is when waiting for a renderer to produce a frame
// at the right size. The caller keeps a reference on this object, and drops the
// reference once it desires to release the lock.
// By default, the lock will be cancelled after a short timeout to ensure
// responsiveness of the UI, so the compositor tree should be kept in a
// "reasonable" state while the lock is held. The timeout length, or no timeout,
// can be requested at the time the lock is created.
// Don't instantiate this class directly, use Compositor::GetCompositorLock.
class COMPOSITOR_EXPORT CompositorLock {
// The |client| is informed about events from the CompositorLock. The
// |delegate| is used to perform actual unlocking. If |timeout| is zero then
// no timeout is scheduled, else a timeout is scheduled on the |task_runner|.
explicit CompositorLock(CompositorLockClient* client,
base::WeakPtr<CompositorLockManager> manager,
friend class CompositorLockManager;
// Causes the CompositorLock to end due to a timeout.
void TimeoutLock();
CompositorLockClient* const client_;
base::WeakPtr<CompositorLockManager> manager_;
} // namespace ui