cc/output/begin_frame_args.h

   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_OUTPUT_BEGIN_FRAME_ARGS_H_
   6 #define CC_OUTPUT_BEGIN_FRAME_ARGS_H_
   7
   8 #include "base/location.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/time/time.h"
  11 #include "base/values.h"
  12 #include "cc/base/cc_export.h"
  13
  14 namespace base {
  15 namespace debug {
  16 class ConvertableToTraceFormat;
  17 class TracedValue;
  18 }
  19 }
  20
  21 /**
  22  * In debug builds we trace the creation origin of BeginFrameArgs objects. We
  23  * reuse the tracked_objects::Location system to do that.
  24  *
  25  * However, in release builds we don't want this as it doubles the size of the
  26  * BeginFrameArgs object. As well it adds a number of largish strings to the
  27  * binary. Despite the argument being unused, most compilers are unable to
  28  * optimise it away even when unused. Instead we use the BEGINFRAME_FROM_HERE
  29  * macro to prevent the data even getting referenced.
  30  */
  31 #ifdef NDEBUG
  32 #define BEGINFRAME_FROM_HERE nullptr
  33 #else
  34 #define BEGINFRAME_FROM_HERE FROM_HERE
  35 #endif
  36
  37 namespace cc {
  38
  39 struct CC_EXPORT BeginFrameArgs {
  40   enum BeginFrameArgsType {
  41     INVALID,
  42     NORMAL,
  43     SYNCHRONOUS,
  44     MISSED,
  45   };
  46   static const char* TypeToString(BeginFrameArgsType type);
  47
  48   // Creates an invalid set of values.
  49   BeginFrameArgs();
  50
  51 #ifdef NDEBUG
  52   typedef const void* CreationLocation;
  53 #else
  54   typedef const tracked_objects::Location& CreationLocation;
  55   tracked_objects::Location created_from;
  56 #endif
  57
  58   // You should be able to find all instances where a BeginFrame has been
  59   // created by searching for "BeginFrameArgs::Create".
  60   // The location argument should **always** be BEGINFRAME_FROM_HERE macro.
  61   static BeginFrameArgs Create(CreationLocation location,
  62                                base::TimeTicks frame_time,
  63                                base::TimeTicks deadline,
  64                                base::TimeDelta interval,
  65                                BeginFrameArgsType type);
  66
  67   // This is the default delta that will be used to adjust the deadline when
  68   // proper draw-time estimations are not yet available.
  69   static base::TimeDelta DefaultEstimatedParentDrawTime();
  70
  71   // This is the default interval to use to avoid sprinkling the code with
  72   // magic numbers.
  73   static base::TimeDelta DefaultInterval();
  74
  75   // This is the default amount of time after the frame_time to retroactively
  76   // send a BeginFrame that had been skipped. This only has an effect if the
  77   // deadline has passed, since the deadline is also used to trigger BeginFrame
  78   // retroactively.
  79   static base::TimeDelta DefaultRetroactiveBeginFramePeriod();
  80
  81   bool IsValid() const { return interval >= base::TimeDelta(); }
  82
  83   scoped_refptr<base::debug::ConvertableToTraceFormat> AsValue() const;
  84   void AsValueInto(base::debug::TracedValue* dict) const;
  85
  86   base::TimeTicks frame_time;
  87   base::TimeTicks deadline;
  88   base::TimeDelta interval;
  89   BeginFrameArgsType type;
  90
  91  private:
  92   BeginFrameArgs(base::TimeTicks frame_time,
  93                  base::TimeTicks deadline,
  94                  base::TimeDelta interval,
  95                  BeginFrameArgsType type);
  96 };
  97
  98 }  // namespace cc
  99
 100 #endif  // CC_OUTPUT_BEGIN_FRAME_ARGS_H_