Rarely, we find ourselves needing to explicitly delete some data, eg. something that shouldn't
have been public and should be removed from all records.
It would also be nice if we could "clean up" bad versions of the same segment,
which occasionally come up when downloaders have issues.
With our distributed segment database, this is actually rather difficult as deleting the data
from any one server would cause it to be restored from the others. It was only possible
by stopping all backfill, deleting the data on all servers, then starting backfill again.
Here we introduce a more practical approach. An operator creates an empty flag file
with the same name as the segment to be deleted, but with a `.tombstone` extension.
eg. to delete a file `/segments/desertbus/source/2019-11-13T02/45:51.608000-2.0-full-7IS92rssMzoSBQDIevHStbTNy-URRV3Vw-jzZ6pwOZM.ts`,
you would create a tombstone `/segments/desertbus/source/2019-11-13T02/45:51.608000-2.0-full-7IS92rssMzoSBQDIevHStbTNy-URRV3Vw-jzZ6pwOZM.tombstone`.
These tombstone files do two important things:
* They hide the segment from being listed, which both means:
* It can't be restreamed or put into a video
* It can't be backfilled to other nodes
* The tombstone files themselves do get backfilled to other nodes, so you only need to mark them on one server.
Once the tombstone has propagated to all nodes, the segment file can be deleted independently on each one.
We chose not to have a tombstone automatically trigger a segment deletion for safety reasons.
The restreamer spends most of its time iterating through segments (parsing them, determining the best one for each start time)
to serve large time ranges. Since this only depends on the list of filenames read from disk,
we can cache it for a given hour as long as that list is identical.
This is a little trickier than it sounds because best_segments_by_start is an iterator
and in most cases it won't be fully consumed. So we introduce a `CachedIterator` abstraction
that will both remember the previously yielded values, and keep track of the live iterator
so it can be resumed again if a previous invocation only partially consumed it.
This also has the nice side effect of merging simultaneous operations - if two requests come in
for the same hour at the same time, they'll share one iterator and both consume the results
as they come in.
We've seen cases where videos are not inserted even though the API call succeeded.
Our suspicion is that two concurrent insert calls for the same video are causing a race.
We try to avoid this by putting a lock around insert calls
The SQL args were the wrong way around, so we tried to set error to the id.
Thankfully this failed as the id queried is not a valid uuid.
Fix by making args named like every other usage of query()
* Add fullscreen functionality to Thrimbletrimmer video player
* Fix issue where clicking on fullscreen video pauses and unpauses instead of doing just one
The sheetsync loads playlist ids and tags into a new table `playlists`.
playlist manager reads this table and merges it with the playlists given on the command line.