The treeCache in SnapshotsDir was never cleared when snapshots were
reloaded. This caused the "latest" symlink to keep pointing to the
previous snapshot even after new snapshots were added.
Add a generation counter to SnapshotsDirStructure that is incremented
whenever the directory structure is rebuilt (in makeDirs). The
treeCache checks this generation on each lookup and resets itself
when the generation changes, ensuring cached nodes (including symlinks)
are refreshed after a snapshot reload.
This turns snapshotFilterOptions from cmd into a restic.SnapshotFilter
type and makes restic.FindFilteredSnapshot and FindFilteredSnapshots
methods on that type. This fixes#4211 by ensuring that hosts and paths
are named struct fields instead of unnamed function arguments in long
lists of such.
Timestamp limits are also included in the new type. To avoid too much
pointer handling, the convention is that time zero means no limit.
That's January 1st, year 1, 00:00 UTC, which is so unlikely a date that
we can sacrifice it for simpler code.
We previously checked whether the set of snapshots might have changed
based only on their number, which fails when as many snapshots are
forgotten as are added. Check for the SHA-256 of their id's instead.
FindFilteredSnapshots no longer prints errors during snapshot loading on
stderr, but instead passes the error to the callback to allow the caller
to decide on what to do.
In addition, it moves the logic to handle an explicit snapshot list from
the main package to restic.
Cleanly separate the directory presentation and the snapshot directory
structure. SnapshotsDir now translates the dirStruct into a format
usable by the fuse library and contains only minimal special case rules.
All decisions have moved into SnapshotsDirStructure which now creates a
fully preassembled tree data structure.