WIP GPU scheduler + delayed activation / tile draw

gpu/ipc/service/gpu_scheduler.h

Index: gpu/ipc/service/gpu_scheduler.h
diff --git a/gpu/ipc/service/gpu_scheduler.h b/gpu/ipc/service/gpu_scheduler.h
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index 0000000000000000000000000000000000000000..6c540b00380621d5bb3134be9be059c2c56acc50
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+++ b/gpu/ipc/service/gpu_scheduler.h
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+// Copyright (c) 2016 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 GPU_IPC_SERVICE_GPU_SCHEDULER_H_
+#define GPU_IPC_SERVICE_GPU_SCHEDULER_H_
+
+#include <deque>
+#include <set>
+#include <vector>
+
+#include "base/cancelable_callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/thread_checker.h"
+#include "base/time/time.h"
+#include "gpu/command_buffer/common/preemption_flag.h"
+#include "gpu/gpu_export.h"
+#include "gpu/ipc/common/gpu_stream_constants.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace gpu {
+
+class GpuCommandStream;
+
+struct GPU_EXPORT GpuSchedulerSettings {
+  base::TimeDelta min_time_slice;
+  base::TimeDelta max_time_slice;
+};
+
+class GPU_EXPORT GpuScheduler {
+ public:
+  // Create with default settings.
+  static std::unique_ptr<GpuScheduler> Create(
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+
+  GpuScheduler(const GpuSchedulerSettings& settings,
+               scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+
+  virtual ~GpuScheduler();
+
+  void AddStream(GpuCommandStream* stream, GpuStreamPriority priority);
+  void RemoveStream(GpuCommandStream* stream);
+
+  // Returns true if current stream should yield. Called on the main thread.
+  bool ShouldYield();
+
+  // Called when stream becomes ready.
+  void ScheduleStream(GpuCommandStream* stream);
+
+  // Called when a stream stops being ready.
+  void DescheduleStream(GpuCommandStream* stream);
+
+ protected:
+  virtual base::TimeTicks Now();  // for testing
+
+ private:
+  struct StreamInfo {
+    GpuCommandStream* stream = nullptr;
+    GpuStreamPriority priority = GpuStreamPriority::LAST;
+    bool ready = false;
+  };
+
+  struct ScheduledStream {
+    GpuCommandStream* stream = nullptr;
+    GpuStreamPriority priority = GpuStreamPriority::LAST;
+
+    bool operator<(const ScheduledStream& other) const {
+      return std::tie(priority, stream) >
+             std::tie(other.priority, other.stream);
+    }
+  };
+
+  std::vector<StreamInfo>::iterator FindStream(GpuCommandStream* stream);
+  std::vector<ScheduledStream>::iterator FindScheduledStream(
+      GpuCommandStream* stream);
+
+  void BuildWorkQueue();
+  ScheduledStream GetNextStream();
+  void RunNextStream();
+
+  const GpuSchedulerSettings settings_;
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  // The following are protected by |lock_|.
+  bool running_ = false;
+  // If we need to reschedule
+  bool needs_rescheduling_ = false;
+  // List of streams and associated information.
+  std::vector<StreamInfo> streams_;
+  // Priority queue of streams that are scheduled to run.
+  std::vector<ScheduledStream> work_queue_;
+  // Protects the above variables.
+  base::Lock lock_;
+
+  // Time when current stream started running.
+  base::TimeTicks running_stream_start_time_;
+
+  // Used to ensure that methods (except ScheduleStream) are called on the main
+  // thread.
+  base::ThreadChecker thread_checker_;
+
+  base::WeakPtrFactory<GpuScheduler> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuScheduler);
+};
+
+}  // namespace gpu
+
+#endif  // GPU_IPC_SERVICE_GPU_SCHEDULER_H_