clean up Writer interface slightly

src/dir.rs

@@ -122,12 +122,11 @@ impl SampleFileDir {
     /// directory has sufficient space for a couple recordings per camera in addition to the
     /// cameras' total `retain_bytes`.
     ///
-    /// The new recording will start at `prev_end` if specified; this should be the end time
-    /// of the previous segment of the same run. `run_offset` should be the offset of this segment
-    /// within the run; 0 iff `prev_end` is None.
-    pub fn create_writer<'a>(&self, channel: &'a SyncerChannel, prev_end: Option<recording::Time>,
-                             run_offset: i32, camera_id: i32,
-                             video_sample_entry_id: i32) -> Result<Writer<'a>, Error> {
+    /// The new recording will continue from `prev` if specified; this should be as returned from
+    /// a previous `close` call.
+    pub fn create_writer<'a>(&self, channel: &'a SyncerChannel, prev: Option<PreviousWriter>,
+                             camera_id: i32, video_sample_entry_id: i32)
+                             -> Result<Writer<'a>, Error> {
         // Grab the next uuid. Typically one is cached—a sync has usually completed since the last
         // writer was created, and syncs ensure `next_uuid` is filled while performing their
         // transaction. But if not, perform an extra database transaction to reserve a new one.
@@ -150,7 +149,7 @@ impl SampleFileDir {
                 return Err(e.into());
             },
         };
-        Writer::open(f, uuid, prev_end, run_offset, camera_id, video_sample_entry_id, channel)
+        Writer::open(f, uuid, prev, camera_id, video_sample_entry_id, channel)
     }
 
     /// Opens a sample file within this directory with the given flags and (if creating) mode.
@@ -458,11 +457,16 @@ struct UnflushedSample {
     is_key: bool,
 }
 
+#[derive(Copy, Clone)]
+pub struct PreviousWriter {
+    end_time: recording::Time,
+    run_offset: i32,
+}
+
 impl<'a> Writer<'a> {
     /// Opens the writer; for use by `SampleFileDir` (which should supply `f`).
-    fn open(f: fs::File, uuid: Uuid, prev_end: Option<recording::Time>,
-            run_offset: i32, camera_id: i32, video_sample_entry_id: i32,
-            syncer_channel: &'a SyncerChannel) -> Result<Self, Error> {
+    fn open(f: fs::File, uuid: Uuid, prev: Option<PreviousWriter>, camera_id: i32,
+            video_sample_entry_id: i32, syncer_channel: &'a SyncerChannel) -> Result<Self, Error> {
         Ok(Writer(Some(InnerWriter{
             syncer_channel: syncer_channel,
             f: f,
@@ -470,11 +474,11 @@ impl<'a> Writer<'a> {
             uuid: uuid,
             corrupt: false,
             hasher: hash::Hasher::new(hash::Type::SHA1)?,
-            prev_end: prev_end,
+            prev_end: prev.map(|p| p.end_time),
             local_start: None,
             camera_id: camera_id,
             video_sample_entry_id: video_sample_entry_id,
-            run_offset: run_offset,
+            run_offset: prev.map(|p| p.run_offset).unwrap_or(0),
             unflushed_sample: None,
         })))
     }
@@ -519,7 +523,7 @@ impl<'a> Writer<'a> {
     /// Cleanly closes the writer, using a supplied pts of the next sample for the last sample's
     /// duration (if known). If `close` is not called, the `Drop` trait impl will close the trait,
     /// swallowing errors and using a zero duration for the last sample.
-    pub fn close(mut self, next_pts: Option<i64>) -> Result<recording::Time, Error> {
+    pub fn close(mut self, next_pts: Option<i64>) -> Result<PreviousWriter, Error> {
         self.0.take().unwrap().close(next_pts)
     }
 }
@@ -533,7 +537,7 @@ impl<'a> InnerWriter<'a> {
         }
     }
 
-    fn close(mut self, next_pts: Option<i64>) -> Result<recording::Time, Error> {
+    fn close(mut self, next_pts: Option<i64>) -> Result<PreviousWriter, Error> {
         if self.corrupt {
             self.syncer_channel.async_abandon_recording(self.uuid);
             return Err(Error::new(format!("recording {} is corrupt", self.uuid)));
@@ -565,7 +569,10 @@ impl<'a> InnerWriter<'a> {
             flags: 0,  // TODO
         };
         self.syncer_channel.async_save_recording(recording, self.f);
-        Ok(end)
+        Ok(PreviousWriter{
+            end_time: end,
+            run_offset: self.run_offset,
+        })
     }
 }
 

src/streamer.rs

@@ -122,8 +122,7 @@ impl<'a, C, S> Streamer<'a, C, S> where C: 'a + Clock, S: 'a + stream::Stream {
         let mut seen_key_frame = false;
         let mut state: Option<WriterState> = None;
         let mut transformed = Vec::new();
-        let mut prev_end = None;
-        let mut run_index = -1;
+        let mut prev = None;
         while !self.shutdown.load(Ordering::SeqCst) {
             let pkt = stream.get_next()?;
             let pts = pkt.pts().ok_or_else(|| Error::new("packet with no pts".to_owned()))?;
@@ -138,7 +137,7 @@ impl<'a, C, S> Streamer<'a, C, S> where C: 'a + Clock, S: 'a + stream::Stream {
             state = if let Some(s) = state {
                 if frame_realtime.sec > s.rotate && pkt.is_key() {
                     trace!("{}: write on normal rotation", self.short_name);
-                    prev_end = Some(s.writer.close(Some(pts))?);
+                    prev = Some(s.writer.close(Some(pts))?);
                     None
                 } else {
                     Some(s)
@@ -156,10 +155,7 @@ impl<'a, C, S> Streamer<'a, C, S> where C: 'a + Clock, S: 'a + stream::Stream {
                     let r = r + if r <= sec { /*2**/self.rotate_interval_sec }
                                 else { 0/*self.rotate_interval_sec*/ };
 
-                    run_index += 1;
-
-                    let w = self.dir.create_writer(&self.syncer_channel, prev_end,
-                                                   run_index, self.camera_id,
+                    let w = self.dir.create_writer(&self.syncer_channel, prev, self.camera_id,
                                                    video_sample_entry_id)?;
                     WriterState{
                         writer: w,