Added disjoint context class which manages disjoints within gpu timing.

gpu/command_buffer/service/gpu_timing.h

Index: gpu/command_buffer/service/gpu_timing.h
diff --git a/gpu/command_buffer/service/gpu_timing.h b/gpu/command_buffer/service/gpu_timing.h
index 1d9ecf690902e2725ff14f97a96f129ee95e1e2b..9c8b8cc40d0b2656568108d3ff8bf12d7e610ee5 100644
--- a/gpu/command_buffer/service/gpu_timing.h
+++ b/gpu/command_buffer/service/gpu_timing.h
@@ -5,6 +5,8 @@
 #ifndef GPU_COMMAND_BUFFER_SERVICE_GPU_TIMING_H_
 #define GPU_COMMAND_BUFFER_SERVICE_GPU_TIMING_H_
 
+#include <vector>
+
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "gpu/gpu_export.h"
@@ -38,6 +40,33 @@ class GPU_EXPORT GPUTimer {
   DISALLOW_COPY_AND_ASSIGN(GPUTimer);
 };
 
+// DisjointContext keeps track of disjoint conditions which invalidate
+// timing values. Each GPUTiming class can keep track of multiple
+// DisjointContexts so that a single GL Context can support multiple
+// tracings.
+class GPU_EXPORT DisjointContext : public base::RefCounted<DisjointContext> {
+ public:
+  // CheckAndResetTimerErrors has to be called before reading timestamps
+  // from GPUTimers instances and after making sure all the timers
+  // were available.
+  // If the returned value is false, all the previous timers should be
+  // discarded.
+  bool CheckAndResetTimerErrors();
+
+ protected:
+  DisjointContext(GPUTiming* gpu_timing, bool disjoint_value);
+  virtual ~DisjointContext();
+  friend class base::RefCounted<DisjointContext>;
+
+ private:
+  void ResetParentGPUTiming();
+  void SetDisjoint();
+
+  GPUTiming* gpu_timing_;
+  bool disjoint_value_;
+  friend class GPUTiming;
+};
+
 // GPUTiming contains all the gl timing logic that is not specific
 // to a single GPUTimer.
 class GPU_EXPORT GPUTiming {
@@ -55,12 +84,8 @@ class GPU_EXPORT GPUTiming {
   bool Initialize(gfx::GLContext* context);
   bool IsAvailable();
 
-  // CheckAndResetTimerErrors has to be called before reading timestamps
-  // from GPUTimers instances and after making sure all the timers
-  // were available.
-  // If the returned value is false, all the previous timers should be
-  // discarded.
-  bool CheckAndResetTimerErrors();
+  scoped_refptr<DisjointContext> CreateDisjointContext();
+  size_t GetDisjointContextsCount() { return disjoint_contexts_.size(); }
 
   const char* GetTimerTypeName() const;
 
@@ -73,11 +98,17 @@ class GPU_EXPORT GPUTiming {
   void SetTimerTypeForTesting(TimerType type);
 
  private:
+  void UpdateDisjointContexts();
+  void RemoveDisjointContext(DisjointContext* context);
+
   TimerType timer_type_ = kTimerTypeInvalid;
   int64 offset_ = 0;  // offset cache when timer_type_ == kTimerTypeARB
   bool offset_valid_ = false;
+  bool disjoint_occurred_ = false;
+  std::vector<DisjointContext*> disjoint_contexts_;

[Daniele Castagna, 2015/02/19 18:15:32]

How many disjoint contexts do you think there are going to be?

[David Yen, 2015/02/19 19:00:47]

Most likely only a few, but going from 2 to n does not really add any complexity
IMHO.

   base::Callback<int64(void)> cpu_time_for_testing_;
   friend class GPUTimer;
+  friend class DisjointContext;
   DISALLOW_COPY_AND_ASSIGN(GPUTiming);
 };
 }  // namespace gpu