gpu_tracer_mtl.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_RENDERER_BACKEND_METAL_GPU_TRACER_MTL_H_
#define FLUTTER_IMPELLER_RENDERER_BACKEND_METAL_GPU_TRACER_MTL_H_
 
#include <Metal/Metal.h>
 
#include <memory>
#include <optional>
#include "impeller/base/thread.h"
#include "impeller/base/thread_safety.h"
#include "impeller/geometry/scalar.h"
 
namespace impeller {
 
class ContextMTL;
 
/// @brief Approximate the GPU frame time by computing a difference between the
///        smallest GPUStartTime and largest GPUEndTime for all command buffers
///        submitted in a frame workload.
class GPUTracerMTL : public std::enable_shared_from_this<GPUTracerMTL> {
 public:
  GPUTracerMTL() = default;
 
  ~GPUTracerMTL() = default;
 
  /// @brief Record that the current frame has ended. Any additional cmd buffers
  ///        will be attributed to the "next" frame.
  void MarkFrameEnd();
 
  /// @brief Record the current cmd buffer GPU execution timestamps into an
  ///        aggregate frame workload metric.
  void RecordCmdBuffer(id<MTLCommandBuffer> buffer);
 
 private:
  struct GPUTraceState {
    Scalar smallest_timestamp = std::numeric_limits<float>::max();
    Scalar largest_timestamp = 0;
    size_t pending_buffers = 0;
  };
 
  mutable Mutex trace_state_mutex_;
  GPUTraceState trace_states_[16] IPLR_GUARDED_BY(trace_state_mutex_);
  size_t current_state_ IPLR_GUARDED_BY(trace_state_mutex_) = 0u;
};
 
}  // namespace impeller
 
#endif  // FLUTTER_IMPELLER_RENDERER_BACKEND_METAL_GPU_TRACER_MTL_H_