Also: support a "cli" env var value, that does not determine
the implementation from the env var, but rather from cli options (similar to as it was before adding BORG_CACHE_IMPL).
- skip test_cache_chunks if there is no persistent chunks cache file
- init self.chunks for AdHocCache
- remove warning output from AdHocCache.__init__, it gets mixed with JSON output and fails the JSON decoder.
Add new borg create option '--prefer-adhoc-cache' to prefer the
AdHocCache over the NewCache implementation.
Adjust a test to match the previous default behaviour (== use the
AdHocCache) with --no-cache-sync.
removed some code borg had for backwards compatibility with
old borg versions (that had timestamp only in the cache).
now the manifest timestamp is only checked against the manifest-timestamp
file in the security dir, simplifying the code.
removed some code borg had for backwards compatibility with
old borg versions (that had key_type only in the cache).
now the repo key_type is only checked against the key-type
file in the security dir, simplifying the code.
removed some code borg had for backwards compatibility with
old borg versions (that had previous_location only in the
cache).
now the repo location is only checked against the location
file in the security dir, simplifying the code and also
fixing a related test failure with NewCache.
also improved test_repository_move to test for aborting in
case the repo location changed unexpectedly.
NewCache does not do precise refcounting, thus chunks won't be deleted
from the repo at "borg delete" time.
"borg check --repair" would remove such chunks IF they are orphans.
if we use AdHocCache or NewCache, we do not have precise refcounting.
thus, we do not delete repo objects as their refcount does not go to zero.
check --repair will just remove the orphans.
incref: returns (id, size), so it needs the size if it can't
get it from the chunks index. also needed for updating stats.
decref: caller does not always have the chunk size (e.g. for
metadata chunks),
as we consider 0 to be an invalid size, we call with size == 1
in that case. thus, stats might be slightly off.
the files cache used to have only the chunk ids,
so it had to rely on the chunks index having the
size information - which is problematic with e.g.
the AdhocCache (has size==0 for all not new chunks) and blocked using the files cache there.
