This commit changes the logic for managing the expiration of
objects in the database.
Before: There was a server-wide hashmap that stored the
collection key, id, and expiration timestamp for all objects
that had a TTL. The hashmap was occasionally probed at 20
random positions, looking for objects that have expired. Those
expired objects were immediately deleted, and if there was 5
or more objects deleted, then the probe happened again, with
no delay. If the number of objects was less than 5 then the
there was a 1/10th of a second delay before the next probe.
Now: Rather than a server-wide hashmap, each collection has
its own ordered priority queue that stores objects with TTLs.
Rather than probing, there is a background routine that
executes every 1/10th of a second, which pops the expired
objects from the collection queues, and deletes them.
The collection/queue method is a more stable approach than
the hashmap/probing method. With probing, we can run into
major cache misses for some cases where there is wide
TTL duration, such as in the hours or days. This may cause
the system to occasionally fall behind, leaving should-be
expired objects in memory. Using a queue, there is no
cache misses, all objects that should be expired will be
right away, regardless of the TTL durations.
Fixes#616
Prior to this commit roaming geofences only registered changes to
the SET command. Now it will work for SET/DEL/FSET, just like
non-roaming geofences.
To opt out of these events, explicitly choose which event you
would like to register when you create the geofences.
For example:
NEARBY fleet FENCE COMMANDS set,del ROAM fleet * 5000
Will only fire off events from SET and DEL command.
Closes#597
This commit fixes a case where a roaming geofence will not fire
a "faraway" event when it's supposed to.
The fix required rewriting the nearby/faraway detection logic. It
is now much more accurate and takes overall less memory, but it's
also a little slower per operation because each object proximity
is checked twice per update. Once to compare the old object's
surrounding, and once to evaulated the new object. The two lists
are then used to generate accurate "nearby" and "faraway" results.
This commit cleans up various Go code in the internal directory.
- Ensures comments on exported functions
- Changes all *Server receiver in all files to be "s", instead
of mixed "c", "s", "server", etc.
- Silenced Go warnings for if/else with returns.
- Cleaned up import ordering.
tidwall