* filer: expose metadata events and list snapshots
* mount: invalidate hot directory caches
* mount: read hot directories directly from filer
* mount: add sequenced metadata cache applier
* mount: apply metadata responses through cache applier
* mount: replay snapshot-consistent directory builds
* mount: dedupe self metadata events
* mount: factor directory build cleanup
* mount: replace proto marshal dedup with composite key and ring buffer
The dedup logic was doing a full deterministic proto.Marshal on every
metadata event just to produce a dedup key. Replace with a cheap
composite string key (TsNs|Directory|OldName|NewName).
Also replace the sliding-window slice (which leaked the backing array
unboundedly) with a fixed-size ring buffer that reuses the same array.
* filer: remove mutex and proto.Clone from request-scoped MetadataEventSink
MetadataEventSink is created per-request and only accessed by the
goroutine handling the gRPC call. The mutex and double proto.Clone
(once in Record, once in Last) were unnecessary overhead on every
filer write operation. Store the pointer directly instead.
* mount: skip proto.Clone for caller-owned metadata events
Add ApplyMetadataResponseOwned that takes ownership of the response
without cloning. Local metadata events (mkdir, create, flush, etc.)
are freshly constructed and never shared, so the clone is unnecessary.
* filer: only populate MetadataEvent on successful DeleteEntry
Avoid calling eventSink.Last() on error paths where the sink may
contain a partial event from an intermediate child deletion during
recursive deletes.
* mount: avoid map allocation in collectDirectoryNotifications
Replace the map with a fixed-size array and linear dedup. There are
at most 3 directories to notify (old parent, new parent, new child
if directory), so a 3-element array avoids the heap allocation on
every metadata event.
* mount: fix potential deadlock in enqueueApplyRequest
Release applyStateMu before the blocking channel send. Previously,
if the channel was full (cap 128), the send would block while holding
the mutex, preventing Shutdown from acquiring it to set applyClosed.
* mount: restore signature-based self-event filtering as fast path
Re-add the signature check that was removed when content-based dedup
was introduced. Checking signatures is O(1) on a small slice and
avoids enqueuing and processing events that originated from this
mount instance. The content-based dedup remains as a fallback.
* filer: send snapshotTsNs only in first ListEntries response
The snapshot timestamp is identical for every entry in a single
ListEntries stream. Sending it in every response message wastes
wire bandwidth for large directories. The client already reads
it only from the first response.
* mount: exit read-through mode after successful full directory listing
MarkDirectoryRefreshed was defined but never called, so directories
that entered read-through mode (hot invalidation threshold) stayed
there permanently, hitting the filer on every readdir even when cold.
Call it after a complete read-through listing finishes.
* mount: include event shape and full paths in dedup key
The previous dedup key only used Names, which could collapse distinct
rename targets. Include the event shape (C/D/U/R), source directory,
new parent path, and both entry names so structurally different events
are never treated as duplicates.
* mount: drain pending requests on shutdown in runApplyLoop
After receiving the shutdown sentinel, drain any remaining requests
from applyCh non-blockingly and signal each with errMetaCacheClosed
so callers waiting on req.done are released.
* mount: include IsDirectory in synthetic delete events
metadataDeleteEvent now accepts an isDirectory parameter so the
applier can distinguish directory deletes from file deletes. Rmdir
passes true, Unlink passes false.
* mount: fall back to synthetic event when MetadataEvent is nil
In mknod and mkdir, if the filer response omits MetadataEvent (e.g.
older filer without the field), synthesize an equivalent local
metadata event so the cache is always updated.
* mount: make Flush metadata apply best-effort after successful commit
After filer_pb.CreateEntryWithResponse succeeds, the entry is
persisted. Don't fail the Flush syscall if the local metadata cache
apply fails — log and invalidate the directory cache instead.
Also fall back to a synthetic event when MetadataEvent is nil.
* mount: make Rename metadata apply best-effort
The rename has already succeeded on the filer by the time we apply
the local metadata event. Log failures instead of returning errors
that would be dropped by the caller anyway.
* mount: make saveEntry metadata apply best-effort with fallback
After UpdateEntryWithResponse succeeds, treat local metadata apply
as non-fatal. Log and invalidate the directory cache on failure.
Also fall back to a synthetic event when MetadataEvent is nil.
* filer_pb: preserve snapshotTsNs on error in ReadDirAllEntriesWithSnapshot
Return the snapshot timestamp even when the first page fails, so
callers receive the snapshot boundary when partial data was received.
* filer: send snapshot token for empty directory listings
When no entries are streamed, send a final ListEntriesResponse with
only SnapshotTsNs so clients always receive the snapshot boundary.
* mount: distinguish not-found vs transient errors in lookupEntry
Return fuse.EIO for non-not-found filer errors instead of
unconditionally returning ENOENT, so transient failures don't
masquerade as missing entries.
* mount: make CacheRemoteObject metadata apply best-effort
The file content has already been cached successfully. Don't fail
the read if the local metadata cache update fails.
* mount: use consistent snapshot for readdir in direct mode
Capture the SnapshotTsNs from the first loadDirectoryEntriesDirect
call and store it on the DirectoryHandle. Subsequent batch loads
pass this stored timestamp so all batches use the same snapshot.
Also export DoSeaweedListWithSnapshot so mount can use it directly
with snapshot passthrough.
* filer_pb: fix test fake to send SnapshotTsNs only on first response
Match the server behavior: only the first ListEntriesResponse in a
page carries the snapshot timestamp, subsequent entries leave it zero.
* Fix nil pointer dereference in ListEntries stream consumers
Remove the empty-directory snapshot-only response from ListEntries
that sent a ListEntriesResponse with Entry==nil, which crashed every
raw stream consumer that assumed resp.Entry is always non-nil.
Also add defensive nil checks for resp.Entry in all raw ListEntries
stream consumers across: S3 listing, broker topic lookup, broker
topic config, admin dashboard, topic retention, hybrid message
scanner, Kafka integration, and consumer offset storage.
* Add nil guards for resp.Entry in remaining ListEntries stream consumers
Covers: S3 object lock check, MQ management dashboard (version/
partition/offset loops), and topic retention version loop.
* Make applyLocalMetadataEvent best-effort in Link and Symlink
The filer operations already succeeded; failing the syscall because
the local cache apply failed is wrong. Log a warning and invalidate
the parent directory cache instead.
* Make applyLocalMetadataEvent best-effort in Mkdir/Rmdir/Mknod/Unlink
The filer RPC already committed; don't fail the syscall when the
local metadata cache apply fails. Log a warning and invalidate the
parent directory cache to force a re-fetch on next access.
* flushFileMetadata: add nil-fallback for metadata event and best-effort apply
Synthesize a metadata event when resp.GetMetadataEvent() is nil
(matching doFlush), and make the apply best-effort with cache
invalidation on failure.
* Prevent double-invocation of cleanupBuild in doEnsureVisited
Add a cleanupDone guard so the deferred cleanup and inline error-path
cleanup don't both call DeleteFolderChildren/AbortDirectoryBuild.
* Fix comment: signature check is O(n) not O(1)
* Prevent deferred cleanup after successful CompleteDirectoryBuild
Set cleanupDone before returning from the success path so the
deferred context-cancellation check cannot undo a published build.
* Invalidate parent directory caches on rename metadata apply failure
When applyLocalMetadataEvent fails during rename, invalidate the
source and destination parent directory caches so subsequent accesses
trigger a re-fetch from the filer.
* Add event nil-fallback and cache invalidation to Link and Symlink
Synthesize metadata events when the server doesn't return one, and
invalidate parent directory caches on apply failure.
* Match requested partition when scanning partition directories
Parse the partition range format (NNNN-NNNN) and match against the
requested partition parameter instead of using the first directory.
* Preserve snapshot timestamp across empty directory listings
Initialize actualSnapshotTsNs from the caller-requested value so it
isn't lost when the server returns no entries. Re-add the server-side
snapshot-only response for empty directories (all raw stream consumers
now have nil guards for Entry).
* Fix CreateEntry error wrapping to support errors.Is/errors.As
Use errors.New + %w instead of %v for resp.Error so callers can
unwrap the underlying error.
* Fix object lock pagination: only advance on non-nil entries
Move entriesReceived inside the nil check so nil entries don't
cause repeated ListEntries calls with the same lastFileName.
* Guard Attributes nil check before accessing Mtime in MQ management
* Do not send nil-Entry response for empty directory listings
The snapshot-only ListEntriesResponse (with Entry == nil) for empty
directories breaks consumers that treat any received response as an
entry (Java FilerClient, S3 listing). The Go client-side
DoSeaweedListWithSnapshot already preserves the caller-requested
snapshot via actualSnapshotTsNs initialization, so the server-side
send is unnecessary.
* Fix review findings: subscriber dedup, invalidation normalization, nil guards, shutdown race
- Remove self-signature early-return in processEventFn so all events
flow through the applier (directory-build buffering sees self-originated
events that arrive after a snapshot)
- Normalize NewParentPath in collectEntryInvalidations to avoid duplicate
invalidations when NewParentPath is empty (same-directory update)
- Guard resp.Entry.Attributes for nil in admin_server.go and
topic_retention.go to prevent panics on entries without attributes
- Fix enqueueApplyRequest race with shutdown by using select on both
applyCh and applyDone, preventing sends after the apply loop exits
- Add cleanupDone check to deferred cleanup in meta_cache_init.go for
clarity alongside the existing guard in cleanupBuild
- Add empty directory test case for snapshot consistency
* Propagate authoritative metadata event from CacheRemoteObjectToLocalCluster and generate client-side snapshot for empty directories
- Add metadata_event field to CacheRemoteObjectToLocalClusterResponse
proto so the filer-emitted event is available to callers
- Use WithMetadataEventSink in the server handler to capture the event
from NotifyUpdateEvent and return it on the response
- Update filehandle_read.go to prefer the RPC's metadata event over
a locally fabricated one, falling back to metadataUpdateEvent when
the server doesn't provide one (e.g., older filers)
- Generate a client-side snapshot cutoff in DoSeaweedListWithSnapshot
when the server sends no snapshot (empty directory), so callers like
CompleteDirectoryBuild get a meaningful boundary for filtering
buffered events
* Skip directory notifications for dirs being built to prevent mid-build cache wipe
When a metadata event is buffered during a directory build,
applyMetadataSideEffects was still firing noteDirectoryUpdate for the
building directory. If the directory accumulated enough updates to
become "hot", markDirectoryReadThrough would call DeleteFolderChildren,
wiping entries that EnsureVisited had already inserted. The build would
then complete and mark the directory cached with incomplete data.
Fix by using applyMetadataSideEffectsSkippingBuildingDirs for buffered
events, which suppresses directory notifications for dirs currently in
buildingDirs while still applying entry invalidations.
* Add test for directory notification suppression during active build
TestDirectoryNotificationsSuppressedDuringBuild verifies that metadata
events targeting a directory under active EnsureVisited build do NOT
fire onDirectoryUpdate for that directory. In production, this prevents
markDirectoryReadThrough from calling DeleteFolderChildren mid-build,
which would wipe entries already inserted by the listing.
The test inserts an entry during a build, sends multiple metadata events
for the building directory, asserts no notifications fired for it,
verifies the entry survives, and confirms buffered events are replayed
after CompleteDirectoryBuild.
* Fix create invalidations, build guard, event shape, context, and snapshot error path
- collectEntryInvalidations: invalidate FUSE kernel cache on pure
create events (OldEntry==nil && NewEntry!=nil), not just updates
and deletes
- completeDirectoryBuildNow: only call markCachedFn when an active
build existed (state != nil), preventing an unpopulated directory
from being marked as cached
- Add metadataCreateEvent helper that produces a create-shaped event
(NewEntry only, no OldEntry) and use it in mkdir, mknod, symlink,
and hardlink create fallback paths instead of metadataUpdateEvent
which incorrectly set both OldEntry and NewEntry
- applyMetadataResponseEnqueue: use context.Background() for the
queued mutation so a cancelled caller context cannot abort the
apply loop mid-write
- DoSeaweedListWithSnapshot: move snapshot initialization before
ListEntries call so the error path returns the preserved snapshot
instead of 0
* Fix review findings: test loop, cache race, context safety, snapshot consistency
- Fix build test loop starting at i=1 instead of i=0, missing new-0.txt verification
- Re-check IsDirectoryCached after cache miss to avoid ENOENT race with markDirectoryReadThrough
- Use context.Background() in enqueueAndWait so caller cancellation can't abort build/complete mid-way
- Pass dh.snapshotTsNs in skip-batch loadDirectoryEntriesDirect for snapshot consistency
- Prefer resp.MetadataEvent over fallback in Unlink event derivation
- Add comment on MetadataEventSink.Record single-event assumption
* Fix empty-directory snapshot clock skew and build cancellation race
Empty-directory snapshot: Remove client-side time.Now() synthesis when
the server returns no entries. Instead return snapshotTsNs=0, and in
completeDirectoryBuildNow replay ALL buffered events when snapshot is 0.
This eliminates the clock-skew bug where a client ahead of the filer
would filter out legitimate post-list events.
Build cancellation: Use context.Background() for BeginDirectoryBuild
and CompleteDirectoryBuild calls in doEnsureVisited, so errgroup
cancellation doesn't cause enqueueAndWait to return early and trigger
cleanupBuild while the operation is still queued.
* Add tests for empty-directory build replay and cancellation resilience
TestEmptyDirectoryBuildReplaysAllBufferedEvents: verifies that when
CompleteDirectoryBuild receives snapshotTsNs=0 (empty directory, no
server snapshot), ALL buffered events are replayed regardless of their
TsNs values — no clock-skew-sensitive filtering occurs.
TestBuildCompletionSurvivesCallerCancellation: verifies that once
CompleteDirectoryBuild is enqueued, a cancelled caller context does not
prevent the build from completing. The apply loop runs with
context.Background(), so the directory becomes cached and buffered
events are replayed even when the caller gives up waiting.
* Fix directory subtree cleanup, Link rollback, test robustness
- applyMetadataResponseLocked: when a directory entry is deleted or
moved, call DeleteFolderChildren on the old path so cached descendants
don't leak as stale entries.
- Link: save original HardLinkId/Counter before mutation. If
CreateEntryWithResponse fails after the source was already updated,
rollback the source entry to its original state via UpdateEntry.
- TestBuildCompletionSurvivesCallerCancellation: replace fixed
time.Sleep(50ms) with a deadline-based poll that checks
IsDirectoryCached in a loop, failing only after 2s timeout.
- TestReadDirAllEntriesWithSnapshotEmptyDirectory: assert that
ListEntries was actually invoked on the mock client so the test
exercises the RPC path.
- newMetadataEvent: add early return when both oldEntry and newEntry are
nil to avoid emitting events with empty Directory.
---------
Co-authored-by: Copilot <copilot@github.com>
SeaweedMQ Message Queue on SeaweedFS (WIP, not ready)
What are the use cases it is designed for?
Message queues are like water pipes. Messages flow in the pipes to their destinations.
However, what if a flood comes? Of course, you can increase the number of partitions, add more brokers, restart,
and watch the traffic level closely.
Sometimes the flood is expected. For example, backfill some old data in batch, and switch to online messages.
You may want to ensure enough brokers to handle the data and reduce them later to cut cost.
SeaweedMQ is designed for use cases that need to:
Receive and save large number of messages.
Handle spike traffic automatically.
What is special about SeaweedMQ?
Separate computation and storage nodes to scale independently.
Unlimited storage space by adding volume servers.
Unlimited message brokers to handle incoming messages.
Offline messages can be operated as normal files.
Scale up and down with auto split and merge message topics.
Topics can automatically split into segments when traffic increases, and vice verse.
Pass messages by reference instead of copying.
Clients can optionally upload the messages first and just submit the references.
Drastically reduce the broker load.
Stateless brokers
All brokers are equal. One broker is dynamically picked as the leader.
Add brokers at any time.
Allow rolling restart brokers or remove brokers at a pace.
Design
How it works?
Brokers are just computation nodes without storage. When a broker starts, it reports itself to masters.
Among all the brokers, one of them will be selected as the leader by the masters.
A topic needs to define its partition key on its messages.
Messages for a topic are divided into segments. One segment can cover a range of partitions. A segment can
be split into 2 segments, or 2 neighboring segments can be merged back to one segment.
During write time, the client will ask the broker leader for a few brokers to process the segment.
The broker leader will check whether the segment already has assigned the brokers. If not, select a few brokers based
on their loads, save the selection into filer, and tell the client.
The client will write the messages for this segment to the selected brokers.
Failover
The broker leader does not contain any state. If it fails, the masters will select a different broker.
For a segment, if any one of the selected brokers is down, the remaining brokers should try to write received messages
to the filer, and close the segment to the clients.
Then the clients should start a new segment. The masters should assign other healthy brokers to handle the new segment.
So any brokers can go down without losing data.
Auto Split or Merge
(The idea is learned from Pravega.)
The brokers should report its traffic load to the broker leader periodically.
If any segment has too much load, the broker leader will ask the brokers to tell the client to
close current one and create two new segments.
If 2 neighboring segments have the combined load below average load per segment, the broker leader will ask
the brokers to tell the client to close this 2 segments and create a new segment.
Chris Lu
3f946fc0c0