* volume: drop stale volume-location cache on under-replication
A replicated write looks up the volume's locations and caches them for 10
minutes. When the master briefly reports fewer replicas than the copy count
(e.g. a stale heartbeat drops a just-added volume), that under-replicated
result got cached, so every write failed with "replicating operations is less
than replication copy count" until the entry expired -- long after the master
re-registered the replica.
Invalidate the cached entry when the location count is below the copy count, so
the next write re-queries the master and recovers as soon as it heals.
* volume: mirror the replication copy-count guard in seaweed-volume
do_replicated_request accepted a write even when the master reported fewer
locations than the volume's copy count, silently under-replicating. Reject it,
matching Go's GetWritableRemoteReplications. lookup_volume is uncached, so the
next write recovers as soon as the missing replica re-registers.
VidCache.cache was a []VidInfo indexed directly by volume id, so caching
one volume with a large id grew the backing array to that many entries
(each 48 bytes), allocating a zeroed slot for every unused id below it. A
single id of 32M cost ~1.5GB resident, plus geometric realloc churn as the
append loop doubled the array.
Use map[uint32]VidInfo so memory scales with the number of volumes actually
cached rather than the largest id seen. Parse ids with ParseUint(.,32) so
values outside the uint32 volume-id range are rejected instead of silently
wrapping into a key.
Chris Lu