2 Commits

Include renames

Author	SHA1	Message	Date
3 people	b747e0d3b1	cluster: bound each DistributedLock attempt with a timeout (#12113) ... * cluster: bound each DistributedLock attempt with a timeout An unreachable lock owner blocked the attempt on the connection timeout. Bound it so the write fails fast; a timed-out attempt keeps no renew token. * cluster: keep renewToken across failed lock attempts A request may have renewed the lease server-side before its response was lost, so the last token can still be valid on the next attempt. Clearing it on any transport failure strands a live lease until its TTL expires. A definitive rejection still clears the token through the response's empty RenewToken, and falling back to the seed filer no longer abandons the lease either. * cluster: bound each lock attempt by the remaining route window The 15s unavailability window started only after the first failure, so three 10s attempts plus sleeps outlasted it: the third failure selected the seed fallback at the same moment the loop gave up, and a reachable seed route was never tried. Start the clock before the first attempt and cap each attempt at what the window has left. When the window is spent on a non-seed target, fall back to the seed filer — it can forward to the real owner — and give that route its own window, so the fallback is always exercised before acquisition fails. * cluster: bound DistributedUnlock by the lock RPC timeout The unlock used context.Background(), so Stop against an unreachable lock server could wait on the TCP connect timeout far past the renewal goroutine's bounded shutdown wait. A timed-out unlock is harmless: the lease expires via its TTL regardless. * dlm: replay the current token on a lost renewal's retry A renewal rotates the token server-side before the response is sent. When that response is lost the client only knows the superseded token: retries mismatched, the token was cleared, and the holder conflicted with its own lease until it expired. The lock now remembers the superseded token, so a retry from the same owner replays the current token, and a superseded token can still release its own lock. Generated with [Devin](https://devin.ai) Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com> * cluster: give the seed lock fallback one fresh window per acquisition The seed can redirect back to a dead primary via LockHostMovedTo, so refilling the retry window on every return to the seed made the primary->seed->primary cycle unbounded. The first seed fallback keeps its fresh window; later returns to the seed keep the running deadline. * cluster: advance the lock seq when a lost-renewal replay extends the lease A retry of a renewal whose response was lost updates ExpiredAtNs in place but returned the existing Seq, so the replicated extension was rejected by InsertBackupLock as a stale mutation. A promoted backup would then grant the lock when the old expiry passed even though the holder still believes the lease is renewed. Bump Seq on the replay so the backup accepts the new expiry. * cluster: carry the superseded lock token through replication and transfer A renewal rotates the lock token and keeps the superseded one in PrevToken so a holder whose renewal response was lost can still recover. That recovery broke as soon as the lock moved: neither the replicated backup copy nor a transferred lock carried PrevToken, so a new primary rejected retries of the old token until the lease expired. Add prev_renew_token to the Lock and ReplicateLockRequest messages and thread it through ReplicateLock, TransferLocks, InsertBackupLock and InsertLock. * cluster: count clean lock redirects against the retry window A bare LockHostMovedTo response (no error, no token) returns nil from attemptToLockWithin, and retryUntilLocked reset the retry window on every nil result. Two ring-disagreeing filers forwarding to each other therefore bounced the client in an unbounded loop; the spent-window exit could also return a nil error with no token, handing callers an unacquired lock. * cluster: do not mark a lock held or hot-loop on tokenless attempts A bare LockHostMovedTo redirect returns nil with no renewToken; the attempt previously flipped isLocked to 1 anyway and retried immediately. Gate the flag on a granted token and pace the retry like other outcomes. * cluster: keep renewToken across bare lock redirects A LockHostMovedTo response carries no token and no error; overwriting renewToken with it dropped a held token, so the next renewal re-acquired fresh and could contend against its own still-live lease until TTL. * cluster: poll for replicated backup state in lock tests Replication runs in a goroutine, so a fixed sleep followed by an immediate backup read is racy. Wait for the expected backup state with require.Eventually instead. * cluster: mark a lock held only on a grant verdict A bare LockHostMovedTo redirect with a saved token left isLocked set without the redirected filer granting anything, and retryUntilLocked could exit on a stale token with no attempt made. doLock now reports whether the response was a grant, and both the retry loop and isLocked follow that verdict. --------- Co-authored-by: chrislusf <chrislusf@users.noreply.github.com> Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>	2026-10-26 20:53:46 -07:00
Chris LuandCopilot	75a6a34528	dlm: resilient distributed locks via consistent hashing + backup replication (#8860) ... * dlm: replace modulo hashing with consistent hash ring Introduce HashRing with virtual nodes (CRC32-based consistent hashing) to replace the modulo-based hashKeyToServer. When a filer node is removed, only keys that hashed to that node are remapped to the next server on the ring, leaving all other mappings stable. This is the foundation for backup replication — the successor on the ring is always the natural takeover node. * dlm: add Generation and IsBackup fields to Lock Lock now carries IsBackup (whether this node holds the lock as a backup replica) and Generation (a monotonic fencing token that increments on each fresh acquisition, stays the same on renewal). Add helper methods: AllLocks, PromoteLock, DemoteLock, InsertBackupLock, RemoveLock, GetLock. * dlm: add ReplicateLock RPC and generation/is_backup proto fields Add generation field to LockResponse for fencing tokens. Add generation and is_backup fields to Lock message. Add ReplicateLock RPC for primary-to-backup lock replication. Add ReplicateLockRequest/ReplicateLockResponse messages. * dlm: add async backup replication to DistributedLockManager Route lock/unlock via consistent hash ring's GetPrimaryAndBackup(). After a successful lock or unlock on the primary, asynchronously replicate the operation to the backup server via ReplicateFunc callback. Single-server deployments skip replication. * dlm: add ReplicateLock handler and backup-aware topology changes Add ReplicateLock gRPC handler for primary-to-backup replication. Revise OnDlmChangeSnapshot to handle three cases on topology change: - Promote backup locks when this node becomes primary - Demote primary locks when this node becomes backup - Transfer locks when this node is neither primary nor backup Wire up SetupDlmReplication during filer server initialization. * dlm: expose generation fencing token in lock client LiveLock now captures the generation from LockResponse and exposes it via Generation() method. Consumers can use this as a fencing token to detect stale lock holders. * dlm: update empty folder cleaner to use consistent hash ring Replace local modulo-based hashKeyToServer with LockRing.GetPrimary() which uses the shared consistent hash ring for folder ownership. * dlm: add unit tests for consistent hash ring Test basic operations, consistency on server removal (only keys from removed server move), backup-is-successor property (backup becomes new primary when primary is removed), and key distribution balance. * dlm: add integration tests for lock replication failure scenarios Test cases: - Primary crash with backup promotion (backup has valid token) - Backup crash with primary continuing - Both primary and backup crash (lock lost, re-acquirable) - Rolling restart across all nodes - Generation fencing token increments on new acquisition - Replication failure (primary still works independently) - Unlock replicates deletion to backup - Lock survives server addition (topology change) - Consistent hashing minimal disruption (only removed server's keys move) * dlm: address PR review findings 1. Causal replication ordering: Add per-lock sequence number (Seq) that increments on every mutation. Backup rejects incoming mutations with seq <= current seq, preventing stale async replications from overwriting newer state. Unlock replication also carries seq and is rejected if stale. 2. Demote-after-handoff: OnDlmChangeSnapshot now transfers the lock to the new primary first and only demotes to backup after a successful TransferLocks RPC. If the transfer fails, the lock stays as primary on this node. 3. SetSnapshot candidateServers leak: Replace the candidateServers map entirely instead of appending, so removed servers don't linger. 4. TransferLocks preserves Generation and Seq: InsertLock now accepts generation and seq parameters. After accepting a transferred lock, the receiving node re-replicates to its backup. 5. Rolling restart test: Add re-replication step after promotion and assert survivedCount > 0. Add TestDLM_StaleReplicationRejected. 6. Mixed-version upgrade note: Add comment on HashRing documenting that all filer nodes must be upgraded together. * dlm: serve renewals locally during transfer window on node join When a new node joins and steals hash ranges from surviving nodes, there's a window between ring update and lock transfer where the client gets redirected to a node that doesn't have the lock yet. Fix: if the ring says primary != self but we still hold the lock locally (non-backup, matching token), serve the renewal/unlock here rather than redirecting. The lock will be transferred by OnDlmChangeSnapshot, and subsequent requests will go to the new primary once the transfer completes. Add tests: - TestDLM_NodeDropAndJoin_OwnershipDisruption: measures disruption when a node drops and a new one joins (14/100 surviving-node locks disrupted, all handled by transfer logic) - TestDLM_RenewalDuringTransferWindow: verifies renewal succeeds on old primary during the transfer window * dlm: master-managed lock ring with stabilization batching The master now owns the lock ring membership. Instead of filers independently reacting to individual ClusterNodeUpdate add/remove events, the master: 1. Tracks filer membership in LockRingManager 2. Batches rapid changes with a 1-second stabilization timer (e.g., a node drop + join within 1 second → single ring update) 3. Broadcasts the complete ring snapshot atomically via the new LockRingUpdate message in KeepConnectedResponse Filers receive the ring as a complete snapshot and apply it via SetSnapshot, ensuring all filers converge to the same ring state without intermediate churn. This eliminates the double-churn problem where a rapid drop+join would fire two separate ring mutations, each triggering lock transfers and disrupting ownership on surviving nodes. * dlm: track ring version, reject stale updates, remove dead code SetSnapshot now takes a version parameter from the master. Stale updates (version < current) are rejected, preventing reordered messages from overwriting a newer ring state. Version 0 is always accepted for bootstrap. Remove AddServer/RemoveServer from LockRing — the ring is now exclusively managed by the master via SetSnapshot. Remove the candidateServers map that was only used by those methods. * dlm: fix SelectLocks data race, advance generation on backup insert - SelectLocks: change RLock to Lock since the function deletes map entries, which is a write operation and causes a data race under RLock. - InsertBackupLock: advance nextGeneration to at least the incoming generation so that after failover promotion, new lock acquisitions get a generation strictly greater than any replicated lock. - Bump replication failure log from V(1) to Warningf for production visibility. * dlm: fix SetSnapshot race, test reliability, timer edge cases - SetSnapshot: hold LockRing lock through both version update and Ring.SetServers() so they're atomic. Prevents a concurrent caller from seeing the new version but applying stale servers. - Transfer window test: search for a key that actually moves primary when filer4 joins, instead of relying on a fixed key that may not. - renewLock redirect: pass the existing token to the new primary instead of empty string, so redirected renewals work correctly. - scheduleBroadcast: check timer.Stop() return value. If the timer already fired, the callback picks up latest state. - FlushPending: only broadcast if timer.Stop() returns true (timer was still pending). If false, the callback is already running. - Fix test comment: "idempotent" → "accepted, state-changing". * dlm: use wall-clock nanoseconds for lock ring version The lock ring version was an in-memory counter that reset to 0 on master restart. A filer that had seen version 5 would reject version 1 from the restarted master. Fix: use time.Now().UnixNano() as the version. This survives master restarts without persistence — the restarted master produces a version greater than any pre-restart value. * dlm: treat expired lock owners as missing Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> * dlm: reject stale lock transfers Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> * dlm: order replication by generation Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> * dlm: bootstrap lock ring on reconnect Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> --------- Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>	2026-03-30 23:29:56 -07:00