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 trace_event {
  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     // Not a real type, but used by the IPC system. Should always remain the
  46     // *last* value in this enum.
  47     BEGIN_FRAME_ARGS_TYPE_MAX,
  48   };
  49   static const char* TypeToString(BeginFrameArgsType type);
  50
  51   // Creates an invalid set of values.
  52   BeginFrameArgs();
  53
  54 #ifdef NDEBUG
  55   typedef const void* CreationLocation;
  56 #else
  57   typedef const tracked_objects::Location& CreationLocation;
  58   tracked_objects::Location created_from;
  59 #endif
  60
  61   // You should be able to find all instances where a BeginFrame has been
  62   // created by searching for "BeginFrameArgs::Create".
  63   // The location argument should **always** be BEGINFRAME_FROM_HERE macro.
  64   static BeginFrameArgs Create(CreationLocation location,
  65                                base::TimeTicks frame_time,
  66                                base::TimeTicks deadline,
  67                                base::TimeDelta interval,
  68                                BeginFrameArgsType type);
  69
  70   // This is the default delta that will be used to adjust the deadline when
  71   // proper draw-time estimations are not yet available.
  72   static base::TimeDelta DefaultEstimatedParentDrawTime();
  73
  74   // This is the default interval to use to avoid sprinkling the code with
  75   // magic numbers.
  76   static base::TimeDelta DefaultInterval();
  77
  78   bool IsValid() const { return interval >= base::TimeDelta(); }
  79
  80   scoped_refptr<base::trace_event::ConvertableToTraceFormat> AsValue() const;
  81   void AsValueInto(base::trace_event::TracedValue* dict) const;
  82
  83   base::TimeTicks frame_time;
  84   base::TimeTicks deadline;
  85   base::TimeDelta interval;
  86   BeginFrameArgsType type;
  87
  88  private:
  89   BeginFrameArgs(base::TimeTicks frame_time,
  90                  base::TimeTicks deadline,
  91                  base::TimeDelta interval,
  92                  BeginFrameArgsType type);
  93 };
  94
  95 }  // namespace cc
  96
  97 #endif  // CC_OUTPUT_BEGIN_FRAME_ARGS_H_