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 10 namespace cc { 11 12 // When a change to the compositor's state/invalidation/whatever happens, a 13 // Swap Promise can be inserted into LayerTreeHost/LayerTreeImpl, to track 14 // whether the compositor's reply to the new state/invaliadtion/whatever is 15 // completed in the compositor, i.e. the compositor knows it has been sent 16 // to its output or not. 17 // 18 // If the new compositor state is sent to the output, SwapPromise::DidSwap() 19 // will be called, and if the compositor fails to send its new state to the 20 // output, SwapPromise::DidNotSwap() will be called. 21 // 22 // Client wishes to use SwapPromise should have a subclass that defines 23 // the behavior of DidSwap() and DidNotSwap(). Notice that the promise can 24 // be broken at either main or impl thread, e.g. commit fails on main thread, 25 // new frame data has no actual damage so LayerTreeHostImpl::SwapBuffers() 26 // bails out early on impl thread, so don't assume that DidSwap() and 27 // DidNotSwap() are called at a particular thread. It is better to let the 28 // subclass carry thread-safe member data and operate on that member data in 29 // DidSwap() and DidNotSwap(). 30 class CC_EXPORT SwapPromise { 31 public: 32 enum DidNotSwapReason { 33 DID_NOT_SWAP_UNKNOWN, 34 SWAP_FAILS, 35 COMMIT_FAILS, 36 COMMIT_NO_UPDATE, 37 }; 38 39 SwapPromise() {} 40 virtual ~SwapPromise() {} 41 42 virtual void DidSwap(CompositorFrameMetadata* metadata) = 0; 43 virtual void DidNotSwap(DidNotSwapReason reason) = 0; 44 45 // A non-zero trace id identifies a trace flow object that is embedded in the 46 // swap promise. This can be used for registering additional flow steps to 47 // visualize the object's path through the system. 48 virtual int64 TraceId() const = 0; 49 }; 50 51 } // namespace cc 52 53 #endif // CC_BASE_SWAP_PROMISE_H_ 54
