gpu_submission_tracker.h

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// Copyright 2013 The Flutter 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 FLUTTER_IMPELLER_CORE_GPU_SUBMISSION_TRACKER_H_
#define FLUTTER_IMPELLER_CORE_GPU_SUBMISSION_TRACKER_H_
 
#include <cstdint>
#include <vector>
 
#include "impeller/base/thread.h"
 
namespace impeller {
 
/// @brief Tracks GPU completion of submitted command buffers as a monotonic
///        watermark.
///
/// Backends record an id for each submitted command buffer and mark it from
/// the command buffer's completion callback. Consumers compare ids against
/// [CompletedThrough] to find out whether the GPU is done with all work
/// submitted up to a point in time, regardless of the order in which
/// individual command buffers complete.
///
/// All methods are thread safe.
class GpuSubmissionTracker {
 public:
  /// Records a command buffer submission and returns its id.
  uint64_t RecordSubmission();
 
  /// Marks a previously recorded submission as completed by the GPU.
  void RecordCompletion(uint64_t id);
 
  /// Returns the highest id such that all submissions with ids up to and
  /// including it have completed.
  uint64_t CompletedThrough() const;
 
  /// Returns the id of the most recent submission.
  uint64_t LatestSubmission() const;
 
 private:
  mutable Mutex mutex_;
  uint64_t last_id_ IPLR_GUARDED_BY(mutex_) = 0;
  // Sorted, since ids are recorded in increasing order. The pending count
  // tracks GPU queue depth and stays small, so erasure is cheap and steady
  // state performs no heap allocation.
  std::vector<uint64_t> pending_ IPLR_GUARDED_BY(mutex_);
};
 
}  // namespace impeller
 
#endif  // FLUTTER_IMPELLER_CORE_GPU_SUBMISSION_TRACKER_H_