1// Copyright 2013 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#ifndef CC_BASE_SWAP_PROMISE_H_ 6#define CC_BASE_SWAP_PROMISE_H_ 7 8#include "cc/output/compositor_frame_metadata.h" 9 10namespace cc { 11 12const unsigned int kMaxQueuedSwapPromiseNumber = 100; 13 14// When a change to the compositor's state/invalidation/whatever happens, a 15// Swap Promise can be inserted into LayerTreeHost/LayerTreeImpl, to track 16// whether the compositor's reply to the new state/invaliadtion/whatever is 17// completed in the compositor, i.e. the compositor knows it has been sent 18// to its output or not. 19// 20// If the new compositor state is sent to the output, SwapPromise::DidSwap() 21// will be called, and if the compositor fails to send its new state to the 22// output, SwapPromise::DidNotSwap() will be called. 23// 24// Client wishes to use SwapPromise should have a subclass that defines 25// the behavior of DidSwap() and DidNotSwap(). Notice that the promise can 26// be broken at either main or impl thread, e.g. commit fails on main thread, 27// new frame data has no actual damage so LayerTreeHostImpl::SwapBuffers() 28// bails out early on impl thread, so don't assume that DidSwap() and 29// DidNotSwap() are called at a particular thread. It is better to let the 30// subclass carry thread-safe member data and operate on that member data in 31// DidSwap() and DidNotSwap(). 32class CC_EXPORT SwapPromise { 33 public: 34 enum DidNotSwapReason { 35 DID_NOT_SWAP_UNKNOWN, 36 SWAP_FAILS, 37 COMMIT_FAILS, 38 SWAP_PROMISE_LIST_OVERFLOW, 39 }; 40 41 SwapPromise() {} 42 virtual ~SwapPromise() {} 43 44 virtual void DidSwap(CompositorFrameMetadata* metadata) = 0; 45 virtual void DidNotSwap(DidNotSwapReason reason) = 0; 46}; 47 48} // namespace cc 49 50#endif // CC_BASE_SWAP_PROMISE_H_ 51