Performance : don't wait for tile persistence to send tile to request initiator

[AlexGacon]

Hi,

Would-it be possible to add an option in geowebcache to have the tile persistence done asynchronously from the reply of the request. Like this, the caller can directly have the tile without waiting for the storage, if the storage has performance issues.

[aaime]

Oh, this has been on my want-list for years now. Yes. Just find someone with time to code it.

[AlexGacon]

Isn't it enough to call the method on this line asynchronously ?

[aaime]

For the simple non meta-tiling case, the lock must be released once the file is written on disk, so that other threads find it and avoid computation. But the meta-tiling case needs to be taken care of as well, and that's more complicated, we might need two levels of locks, one for the meta-tile (block until computed), and one for each single tile (block until saved), with the single tile one released asynchronously.

[aaime]

This PR does exactly what's requested here (among other things), but it's targeting the GeoServer integration case only.

Some of the same code could be made more general and ported over to standalone GWC, eventually.

[AlexGacon]

Hi Andrea. Thank you for the update.