src/developer/memory/metrics/watcher.h

// Copyright 2019 The Fuchsia 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 SRC_DEVELOPER_MEMORY_METRICS_WATCHER_H_
#define SRC_DEVELOPER_MEMORY_METRICS_WATCHER_H_

#include <lib/async/dispatcher.h>
#include <lib/fit/function.h>

#include "src/developer/memory/metrics/capture.h"

namespace memory {

// Watches memory usage and reports back when memory reaches a new high.
class Watcher {
 public:
  // Constructs a new Watcher which will check memory usage at the rate
  // specified by |poll_frequency|, using the |async_dispatcher|.
  // Each time usage increasess by at least |high_water_threshold| the
  // |high_water_cb| will be called.
  // |capture_cb| is used to access memory usage.
  Watcher(zx::duration poll_frequency, uint64_t high_water_threshold,
          async_dispatcher_t* dispatcher,
          fit::function<zx_status_t(Capture&, CaptureLevel)> capture_cb,
          fit::function<void(const Capture&)> high_water_cb);
  ~Watcher() = default;

  void Run();

 private:
  void CaptureMemory();
  void CaptureMemoryRepeatedly();

  uint64_t least_free_bytes_;
  zx::duration poll_frequency_;
  uint64_t high_water_threshold_;
  async_dispatcher_t* dispatcher_;
  fit::function<zx_status_t(Capture&, CaptureLevel level)> capture_cb_;
  fit::function<void(const Capture&)> high_water_cb_;
};

}  // namespace memory

#endif  // SRC_DEVELOPER_MEMORY_METRICS_WATCHER_H_