Move everything into a separate futatabi/ subdir, for the upcoming merge with Futatabi.

[nageru] / nageru / disk_space_estimator.h

diff --git a/nageru/disk_space_estimator.h b/nageru/disk_space_estimator.h
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+++ b/nageru/disk_space_estimator.h
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+#ifndef _DISK_SPACE_ESTIMATOR_H
+#define _DISK_SPACE_ESTIMATOR_H
+
+// A class responsible for measuring how much disk there is left when we
+// store our video to disk, and how much recording time that equates to.
+// It gets callbacks from the Mux writing the stream to disk (which also
+// knows which filesystem the file is going to), makes its calculations,
+// and calls back to the MainWindow, which shows it to the user.
+//
+// The bitrate is measured over a simple 30-second sliding window.
+
+#include <stdint.h>
+#include <sys/types.h>
+#include <atomic>
+#include <deque>
+#include <functional>
+#include <string>
+
+#include "timebase.h"
+
+class DiskSpaceEstimator
+{
+public:
+       typedef std::function<void(off_t free_bytes, double estimated_seconds_left)> callback_t;
+       DiskSpaceEstimator(callback_t callback);
+
+       // Report that a video frame with the given pts has just been written
+       // to the given file, so the estimator should stat the file and see
+       // by how much it grew since last time. Called by the Mux object
+       // responsible for writing to the stream on disk.
+       //
+       // If the filename changed since last time, the estimation is reset.
+       // <pts> is taken to be in TIMEBASE units (see timebase.h).
+       void report_write(const std::string &filename, uint64_t pts);
+
+private:
+       static constexpr int64_t window_length = 30 * TIMEBASE;
+
+       callback_t callback;
+       std::string last_filename;
+
+       struct MeasurePoint {
+               uint64_t pts;
+               off_t size;
+       };
+       std::deque<MeasurePoint> measure_points;
+       uint64_t last_pts_reported = 0;
+
+       // Metrics.
+       std::atomic<int64_t> metric_disk_free_bytes{-1};
+};
+
+extern DiskSpaceEstimator *global_disk_space_estimator;
+
+#endif  // !defined(_DISK_SPACE_ESTIMATOR_H)