Index: cc/scheduler/begin_frame_tracker.h |
diff --git a/cc/scheduler/begin_frame_tracker.h b/cc/scheduler/begin_frame_tracker.h |
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+++ b/cc/scheduler/begin_frame_tracker.h |
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+// 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::TimeTicks now, |
+ 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_ |