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* master: return 503/Unavailable during topology warmup after leader change After a master restart or leader change, the topology is empty until volume servers reconnect and send heartbeats. During this warmup window (3 heartbeat intervals = 15 seconds), volume lookups that fail now return 503 Service Unavailable (HTTP) or gRPC Unavailable instead of 404 Not Found, signaling clients to retry with other masters. * master: skip warmup 503 on fresh start and single-master setups - Check MaxVolumeId > 0 to distinguish restart from fresh start (MaxVolumeId is Raft-persisted, so 0 means no prior data) - Check peer count > 1 so single-master deployments aren't affected (no point suggesting "retry with other masters" if there are none) * master: address review feedback and block assigns during warmup - Protect LastLeaderChangeTime with dedicated mutex (fix data race) - Extract warmup multiplier as WarmupPulseMultiplier constant - Derive Retry-After header from pulse config instead of hardcoding - Only trigger warmup 503 for "not found" errors, not parse errors - Return nil response (not partial) on gRPC Unavailable - Add doc comments to IsWarmingUp, getter/setter, WarmupDuration - Block volume assign requests (HTTP and gRPC) during warmup, since the topology is incomplete and assignments would be unreliable - Skip warmup behavior for single-master setups (no peers to retry) * master: apply warmup to all setups, skip only on fresh start Single-master restarts still have an empty topology until heartbeats arrive, so warmup protection should apply there too. The only case to skip is a fresh cluster start (MaxVolumeId == 0), which already has no volumes to look up. - Remove GetMasterCount() > 1 guard from all warmup checks - Remove now-unused GetMasterCount helper - Update error messages to "topology is still loading" (not "retry with other masters" which doesn't apply to single-master) * master: add client-side retry on Unavailable for lookup and assign The server-side 503/Unavailable during warmup needs client cooperation. Previously, LookupVolumeIds and Assign would immediately propagate the error without retry. Now both paths retry with exponential backoff (1s -> 1.5s -> ... up to 6s) when receiving Unavailable, respecting context cancellation. This covers the warmup window where the master's topology is still loading after a restart or leader change. * master: seed warmup timestamp in legacy raft path at setup The legacy raft path only set lastLeaderChangeTime inside the event listener callback, which could fire after IsLeader() was already observed as true in SetRaftServer. Seed the timestamp at setup time (matching the hashicorp path) so IsWarmingUp() is active immediately. * master: fix assign retry loop to cover full warmup window The retry loop used waitTime <= maxWaitTime as a stop condition, causing it to give up after ~13s while warmup lasts 15s. Now cap each individual sleep at maxWaitTime but keep retrying until the context is cancelled. * master: preserve gRPC status in lookup retry and fix retry window Return the raw gRPC error instead of wrapping with fmt.Errorf so status.FromError() can extract the status code. Use proper gRPC status check (codes.Unavailable) instead of string matching. Also cap individual sleep at maxWaitTime while retrying until ctx is done. * master: use gRPC status code instead of string matching in assign retry Use status.FromError/codes.Unavailable instead of brittle strings.Contains for detecting retriable gRPC errors in the assign retry loop. * master: use remaining warmup duration for Retry-After header Set Retry-After to the remaining warmup time instead of the full warmup duration, so clients don't wait longer than necessary. * master: reset ret.Replicas before populating from assign response Clear Replicas slice before appending to prevent duplicate entries when the assign response is retried or when alternative requests are attempted. * master: add unit tests for warmup retry behavior Test that Assign() and LookupVolumeIds() retry on codes.Unavailable and stop promptly when the context is cancelled. * master: record leader change time before initialization work Move SetLastLeaderChangeTime() to fire immediately when the leader change event is received, before DoBarrier(), EnsureTopologyId(), and updatePeers(), so the warmup clock starts at the true moment of leadership transition. * master: use topology warmup duration in volume growth wait loop Replace hardcoded constants.VolumePulsePeriod * 2 with topo.IsWarmingUp() and topo.WarmupDuration() so the growth wait stays in sync with the configured warmup window. Remove unused constants import. * master: resolve master before creating RPC timeout context Move GetMaster() call before context.WithTimeout() so master resolution blocking doesn't consume the gRPC call timeout. * master: use NotFound flag instead of string matching for volume lookup Add a NotFound field to LookupResult and set it in findVolumeLocation when a volume is genuinely missing. Update HTTP and gRPC warmup checks to use this flag instead of strings.Contains on the error message. * master: bound assign retry loop to 30s for deadline-free contexts Without a context deadline, the Unavailable retry loop could spin forever. Add a maxRetryDuration of 30s so the loop gives up even when no context deadline is set. * master: strengthen assign retry cancellation test Verify the retry loop actually retried (callCount > 1) and that the returned error is context.DeadlineExceeded, not just any error. * master: extract shared retry-with-backoff utility Add util.RetryWithBackoff for context-aware, bounded retry with exponential backoff. Refactor both Assign() and LookupVolumeIds() to use it instead of duplicating the retry/sleep/backoff logic. * master: cap waitTime in RetryWithBackoff to prevent unbounded growth Cap the backoff waitTime at maxWaitTime so it doesn't grow indefinitely in long-running retry scenarios. * master: only return Unavailable during warmup when all lookups failed For batched LookupVolume requests, return partial results when some volumes are found. Only return codes.Unavailable when no volumes were successfully resolved, so clients benefit from partial results instead of retrying unnecessarily. * master: set retriable error message in 503 response body When returning 503 during warmup, replace the "not found" error in the JSON body with "service warming up, please retry" so clients don't treat it as a permanent error. * master: guard empty master address in LookupVolumeIds If GetMaster() returns empty (no master found or ctx cancelled), return an appropriate error instead of dialing an empty address. Returns ctx.Err() if context is done, otherwise codes.Unavailable to trigger retry. * master: add comprehensive tests for RetryWithBackoff Test success after retries, non-retryable error handling, context cancellation, and maxDuration cap with context.Background(). * master: enforce hard maxDuration bound in RetryWithBackoff Use a deadline instead of elapsed-time check so the last sleep is capped to remaining time. This prevents the total retry duration from overshooting maxDuration by up to one full backoff interval. * master: respect fresh-start bypass in RemainingWarmupDuration Check IsWarmingUp() first (which returns false when MaxVolumeId==0) so RemainingWarmupDuration returns 0 on fresh clusters. * master: round up Retry-After seconds to avoid underestimating Use math.Ceil so fractional remaining seconds (e.g. 1.9s) round up to the next integer (2) instead of flooring down (1). * master: tighten batch lookup warmup to all-NotFound only Only return codes.Unavailable when every requested volume ID was a transient not-found. Mixed cases with non-NotFound errors now return the response with per-volume error details preserved. * master: reduce retry log noise and fix timer leak Lower per-attempt retry log from V(0) to V(1) to reduce noise during warmup. Replace time.After with time.NewTimer to avoid lingering timers when context is cancelled. * master: add per-attempt timeout for assign RPC Use a 10s per-attempt timeout so a single slow RPC can't consume the entire 30s retry budget when ctx has no deadline. * master: share single 30s retry deadline across assign request entries The Assign() function iterates over primary and fallback requests, previously giving each its own 30s RetryWithBackoff budget. With a primary + fallback, the total could reach 60s. Compute one deadline up front and pass the remaining budget to each RetryWithBackoff call so the entire Assign() call stays within a single 30s cap. * master: strengthen context-cancel test with DeadlineExceeded and retry assertions Assert errors.Is(err, context.DeadlineExceeded) to verify the error is specifically from the context deadline, and check callCount > 1 to prove retries actually occurred before cancellation. Mirrors the pattern used in TestAssignStopsOnContextCancel. * master: bound GetMaster with per-attempt timeout in LookupVolumeIds GetMaster() calls WaitUntilConnected() which can block indefinitely if no master is available. Previously it used the outer ctx, so a slow master resolution could consume the entire RetryWithBackoff budget in a single attempt. Move the per-attempt timeoutCtx creation before the GetMaster call so both master resolution and the gRPC LookupVolume RPC share one grpcTimeout-bounded attempt. * master: use deadline-aware context for assign retry budget The shared 30s deadline only limited RetryWithBackoff's internal wall-clock tracking, but per-attempt contexts were still derived from the original ctx and could run for up to 10s even when the budget was nearly exhausted. Create a deadlineCtx from the computed deadline and derive both RetryWithBackoff and per-attempt timeouts from it so all operations honor the shared 30s cap. * master: skip warmup gate for empty lookup requests When VolumeOrFileIds is empty, notFoundCount == len(req.VolumeOrFileIds) is 0 == 0 which is true, causing empty lookup batches during warmup to return codes.Unavailable and be retried endlessly. Add a len(req.VolumeOrFileIds) > 0 guard so empty requests pass through. * master: validate request fields before warmup gate in Assign Move Replication and Ttl parsing before the IsWarmingUp() check so invalid inputs get a proper validation error instead of being masked by codes.Unavailable during warmup. Pure syntactic validation does not depend on topology state and should run first. * master: check deadline and context before starting retry attempt RetryWithBackoff only checked the deadline and context after an attempt completed or during the sleep select. If the deadline expired or context was canceled during sleep, the next iteration would still call operation() before detecting it. Add pre-operation checks so no new attempt starts after the budget is exhausted. * master: always return ctx.Err() on context cancellation in RetryWithBackoff When ctx.Err() is non-nil, the pre-operation check was returning lastErr instead of ctx.Err(). This broke callers checking errors.Is(err, context.DeadlineExceeded) and contradicted the documented contract. Always return ctx.Err() so the cancellation reason is properly surfaced. * master: handle warmup errors in StreamAssign without killing the stream StreamAssign was returning codes.Unavailable errors from Assign directly, which terminates the gRPC stream and breaks pooled connections. Instead, return transient errors as in-band error responses so the stream survives warmup periods. Also reset assignClient in doAssign on Send/Recv failures so a broken stream doesn't leave the proxy permanently dead. * master: wait for warmup before slot search in findAndGrow findEmptySlotsForOneVolume was called before the warmup wait loop, selecting slots from an incomplete topology. Move the warmup wait before slot search so volume placement uses the fully warmed-up topology with all servers registered. * master: add Retry-After header to /dir/assign warmup response The /dir/lookup handler already sets Retry-After during warmup but /dir/assign did not, leaving HTTP clients without guidance on when to retry. Add the same header using RemainingWarmupDuration(). * master: only seed warmup timestamp on leader at startup SetLastLeaderChangeTime was called unconditionally for both leader and follower nodes. Followers don't need warmup state, and the leader change event listener handles real elections. Move the seed into the IsLeader() block so only the startup leader gets warmup initialized. * master: preserve codes.Unavailable for StreamAssign warmup errors in doAssign StreamAssign returns transient warmup errors as in-band AssignResponse.Error messages. doAssign was converting these to plain fmt.Errorf, losing the codes.Unavailable classification needed for the caller's retry logic. Detect warmup error messages and wrap them as status.Error(codes.Unavailable) so RetryWithBackoff can retry.master
Chris Lu
7 hours ago
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14 changed files with 627 additions and 100 deletions
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