gpu: GPU service scheduler.

gpu/command_buffer/service/scheduler.h

+// Copyright (c) 2017 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_COMMAND_BUFFER_SERVICE_SCHEDULER_H_
+#define GPU_COMMAND_BUFFER_SERVICE_SCHEDULER_H_
+
+#include <queue>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/containers/flat_map.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 "gpu/command_buffer/common/scheduling_priority.h"
+#include "gpu/command_buffer/common/sync_token.h"
+#include "gpu/command_buffer/service/sequence_id.h"
+#include "gpu/gpu_export.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+namespace trace_event {
+class ConvertableToTraceFormat;
+}
+}
+
+namespace gpu {
+class SyncPointManager;
+
+class GPU_EXPORT Scheduler {
+ public:
+  Scheduler(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+            SyncPointManager* sync_point_manager);
+
+  virtual ~Scheduler();
+
+  // Create a sequence with given priority. Returns an identifier for the
+  // sequence that can be used with SyncPonintManager for creating sync point
+  // release clients. Sequences start off as enabled (see |EnableSequence|).
+  SequenceId CreateSequence(SchedulingPriority priority);
+
+  // Destroy the sequence and run any scheduled tasks immediately.
+  void DestroySequence(SequenceId sequence_id);
+
+  // Enables the sequence so that its tasks may be scheduled.
+  void EnableSequence(SequenceId sequence_id);
+
+  // Disables the sequence.
+  void DisableSequence(SequenceId sequence_id);
+
+  // Schedules task (closure) to run on the sequence. The task is blocked until
+  // the sync token fences are released or determined to be invalid. Tasks are
+  // run in the order in which they are submitted.
+  void ScheduleTask(SequenceId sequence_id,
+                    base::OnceClosure closure,
+                    const std::vector<SyncToken>& sync_token_fences);
+
+  // Continue running task on the sequence with the closure. This must be called
+  // while running a previously scheduled task.
+  void ContinueTask(SequenceId sequence_id, base::OnceClosure closure);
+
+  // If the sequence should yield so that a higher priority sequence may run.
+  bool ShouldYield(SequenceId sequence_id);
+
+ private:
+  class Sequence;
+
+  struct SchedulingState {
+    static bool Comparator(const SchedulingState& lhs,
+                           const SchedulingState& rhs) {
+      return rhs.RunsBefore(lhs);
+    }
+
+    SchedulingState();
+    SchedulingState(const SchedulingState& other);
+    ~SchedulingState();
+
+    bool RunsBefore(const SchedulingState& other) const {
+      return std::tie(priority, order_num) <
+             std::tie(other.priority, other.order_num);
+    }
+
+    std::unique_ptr<base::trace_event::ConvertableToTraceFormat> AsValue()
+        const;
+
+    SequenceId sequence_id;
+    SchedulingPriority priority = SchedulingPriority::kLowest;
+    uint32_t order_num = 0;
+  };
+
+  void SyncTokenFenceReleased(const SyncToken& sync_token,
+                              uint32_t order_num,
+                              SequenceId release_sequence_id,
+                              SequenceId waiting_sequence_id);
+
+  void TryScheduleSequence(Sequence* sequence);
+
+  void RebuildSchedulingQueue();
+
+  Sequence* GetSequence(SequenceId sequence_id);
+
+  void RunNextTask();
+
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  SyncPointManager* const sync_point_manager_;
+
+  mutable base::Lock lock_;
+
+  // The following are protected by |lock_|.
+  bool running_ = false;
+
+  base::flat_map<SequenceId, std::unique_ptr<Sequence>> sequences_;
+
+  // Used as a priority queue for scheduling sequences. Min heap of
+  // SchedulingState with highest priority (lowest order) in front.
+  std::vector<SchedulingState> scheduling_queue_;
+
+  // If the running sequence should yield so that a higher priority sequence can
+  // run.
+  bool should_yield_ = false;
+
+  // If the scheduling queue needs to be rebuild because a sequence changed
+  // priority.
+  bool rebuild_scheduling_queue_ = false;
+
+  base::ThreadChecker thread_checker_;
+
+  base::WeakPtrFactory<Scheduler> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(Scheduler);
+};
+
+}  // namespace gpu
+
+#endif  // GPU_COMMAND_BUFFER_SERVICE_SCHEDULER_H_