Reduce memory consumption of string values used in tracking what metadata we have sent for a ws connection by keeping a cache of shared string values for this. This will deduplicate the values and help with memory consumption with a large number of AIS targets and multiple ws connections.
The cache is purged every 30 minutes to get rid of data for AIS targets that have disappeared.
Fixes #1717.
Reduce memory consumption of string values used in tracking what metadata we have sent for a ws connection by keeping a cache of shared string values for this. This will deduplicate the values and help with memory consumption with a large number of AIS targets and multiple ws connections.
The cache is purged every 30 minutes to get rid of data for AIS targets that have disappeared.