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pingqiuandClaude Opus 4.6
d1a16fac03
Add host-side protocol state seam that derives per-replica execution state from V2 sender/session snapshots and blocks live-tail WAL shipping while an active recovery session is in progress. New file: weed/server/block_protocol_state.go - replicaProtocolExecutionState derived from engine snapshots - LiveEligible=false during active catch-up/rebuild sessions - bindProtocolExecutionPolicy wires policy into BlockVol - syncProtocolExecutionState called after assignments + core events Data plane changes: - WALShipper.Ship() checks liveShippingPolicy before dial/send - BlockVol.SetLiveShippingPolicy persists across shipper group rebuilds - ShipperGroup propagates policy to all shippers Design contract: sw-block/design/v2-protocol-aware-execution.md Scope: WAL-first rollout only. Prevents illegal live-tail delivery during active recovery. Does not change snapshot/build behavior or move backlog. Next wave: bounded WAL catch-up under same contract. Tests: 4 unit/component tests for phase gate behavior, plus bootstrap seam tests that confirmed the two pre-existing bugs locally. 13 files changed, 900 insertions, 69 deletions. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
91 lines
3.2 KiB
Markdown
91 lines
3.2 KiB
Markdown
# V2 Protocol-Aware Execution
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## Purpose
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Make host-side execution in `weed/server` and `weed/storage/blockvol` obey the
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existing V2 session contract explicitly. The engine remains the semantic source
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of truth. Host code owns only:
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- execution-state caching derived from sender/session snapshots
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- phase gating before data-plane I/O
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- observation routing back into core events
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## Host-Side Execution State
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For each primary volume and replica, the host caches a `replica protocol
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execution state` with these fields:
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- `ReplicaID`
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- `SenderState`
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- `SessionID`
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- `SessionKind`
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- `SessionPhase`
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- `StartLSN`
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- `TargetLSN`
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- `FrozenTargetLSN`
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- `RecoveredTo`
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- `SessionActive`
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- `LiveEligible`
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- `Reason`
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Rules:
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1. State is derived from `v2Orchestrator.Registry` snapshots only.
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2. `LiveEligible=false` whenever there is an active recovery session.
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3. Data-plane code must consult this cached state before shipping current live
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WAL entries.
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4. Heartbeat and publication remain projection-driven; they do not invent local
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session semantics.
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## WAL-First Rollout
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The first rollout is intentionally narrow:
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- cover `keepup` and WAL-based catch-up only
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- do not change snapshot/build policy
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- do not let fresh late-attached replicas consume current live-tail WAL while a
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bounded catch-up session is active
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Current implementation seam:
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- `weed/server/block_protocol_state.go`
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- derives host execution state from sender/session snapshots
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- binds a per-volume live-shipping policy back into `BlockVol`
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- `weed/storage/blockvol/blockvol.go`
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- carries the host-provided live-shipping policy across shipper-group rebuilds
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- `weed/storage/blockvol/wal_shipper.go`
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- checks the policy before any live-tail dial or send
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This is intentionally a phase gate, not a second source of truth.
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## Observation Seam
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Runtime observations should feed back through one server-side seam:
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- sender/session snapshots -> `syncProtocolExecutionState()`
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- host event application -> `applyCoreEvent()`
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- assignment processing -> `ApplyAssignments()`
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The rule is:
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1. engine chooses the protocol phase
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2. host derives execution state from engine snapshots
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3. data path obeys that state
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4. host emits observed facts back through `applyCoreEvent()`
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## Fast Test Roster
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The first fast-test roster for protocol-aware execution is:
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- `unit`: `TestWALShipper_LiveShippingPolicyBlocksBeforeDial`
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- proves phase gate happens before any transport dial
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- `unit`: `TestWALShipper_LiveShippingPolicyAllowsShip`
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- proves the gate does not block normal live shipping after eligibility
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- `component`: `TestBlockService_ProtocolExecutionState_ActiveCatchUpBlocksLiveShipping`
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- proves sender/session snapshots become host execution state and block live
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shipping during active catch-up
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- `component`: `TestBlockService_ProtocolExecutionState_InSyncSenderAllowsLiveShipping`
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- proves the host reopens live shipping after the recovery session is gone
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Next fast tests to add in later waves:
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- late attach with backlog must stay bounded until target reached
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- transport contact before barrier durability must not imply publish healthy
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- timeout with valid retention pin may replan WAL catch-up
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- timeout after retention loss must escalate to build
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