| // Copyright 2014 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. |
| |
| #ifndef CC_SCHEDULER_BEGIN_FRAME_TRACKER_H_ |
| #define CC_SCHEDULER_BEGIN_FRAME_TRACKER_H_ |
| |
| #include <set> |
| #include <string> |
| |
| #include "base/location.h" |
| #include "base/trace_event/trace_event.h" |
| #include "base/trace_event/trace_event_argument.h" |
| #include "cc/output/begin_frame_args.h" |
| |
| #define BEGINFRAMETRACKER_FROM_HERE FROM_HERE_WITH_EXPLICIT_FUNCTION("") |
| |
| namespace cc { |
| |
| // Microclass to trace and check properties for correct BeginFrameArgs (BFA) |
| // usage and provide a few helper methods. |
| // |
| // With DCHECKs enable, this class checks the following "invariants"; |
| // * BFA are monotonically increasing. |
| // * BFA is valid. |
| // * The BFA is only used inside a given period. |
| // * A new BFA isn't used before the last BFA is finished with. |
| // |
| // With the tracing category "cc.debug.scheduler.frames" enabled the tracker |
| // will output the following trace information; |
| // * Time period for which the BFA is in usage. |
| // * The flow of BFA as they are passed between tracking objects. |
| // |
| // TODO(mithro): Record stats about the BeginFrameArgs |
| class CC_EXPORT BeginFrameTracker { |
| public: |
| explicit BeginFrameTracker(const tracked_objects::Location& location); |
| ~BeginFrameTracker(); |
| |
| // The Start and Finish methods manage the period that a BFA should be |
| // accessed for. This allows tight control over the BFA and prevents |
| // accidental usage in the wrong period when code is split across multiple |
| // locations. |
| |
| // Start using a new BFA value and check invariant properties. |
| // **Must** only be called after finishing with any previous BFA. |
| void Start(BeginFrameArgs new_args); |
| // Finish using the current BFA. |
| // **Must** only be called while still using a BFA. |
| void Finish(); |
| |
| // The two accessors methods allow access to the BFA stored inside the |
| // tracker. They are mutually exclusive, at any time it is only valid to call |
| // one or the other. This makes sure you understand exactly which BFA you are |
| // intending to use and verifies that is the case. |
| |
| // Get the current BFA object. |
| // **Must** only be called between the start and finish methods calls. |
| const BeginFrameArgs& Current() const; |
| // Get the last used BFA. |
| // **Must** only be called when **not** between the start and finish method |
| // calls. |
| const BeginFrameArgs& Last() const; |
| |
| // Helper method to try and return a valid interval property. Defaults to |
| // BFA::DefaultInterval() is no other interval can be found. Can be called at |
| // any time. |
| base::TimeDelta Interval() const; |
| |
| void AsValueInto(base::trace_event::TracedValue* dict) const; |
| |
| // The following methods violate principles of how BeginFrameArgs should be |
| // used. These methods should only be used when there is no other choice. |
| bool DangerousMethodHasStarted() const { |
| return !current_updated_at_.is_null(); |
| } |
| bool DangerousMethodHasFinished() const { return HasFinished(); } |
| const BeginFrameArgs& DangerousMethodCurrentOrLast() const; |
| |
| private: |
| // Return if currently not between the start/end period. This method should |
| // be used extremely sparingly and normal indicates incorrect management of |
| // the BFA object. Can be called at any time. |
| bool HasFinished() const { return !current_finished_at_.is_null(); } |
| |
| const tracked_objects::Location location_; |
| const std::string location_string_; |
| |
| base::TimeTicks current_updated_at_; |
| BeginFrameArgs current_args_; |
| base::TimeTicks current_finished_at_; |
| }; |
| |
| } // namespace cc |
| |
| #endif // CC_SCHEDULER_BEGIN_FRAME_TRACKER_H_ |