feat(T1.5): implement workflow pause/resume with state snapshots
- Add internal/pause package for pause/resume orchestration - Implement WorkflowSnapshot for complete state serialization - Implement SnapshotManager for snapshot storage and recovery - Implement PauseHandler for pause/resume signal handling - Implement PauseSignal and ResumeSignal types - Implement PauseState for tracking pause status Snapshot Features: - Capture complete workflow state (tasks, metrics, config) - Persist to JSON files for recovery after pod restart - Track paused_at and resumed_at timestamps - Support snapshot cleanup and batch removal - Load/save from disk with persistence layer Pause Handling: - Accept pause signals with reason and grace period - Save current state before pausing - Block workflow execution during pause - Support multiple concurrent paused workflows - Channel-based signal reception (Temporal-compatible) Resume Handling: - Accept resume signals with reason - Restore workflow state from snapshots - Continue execution from exact pause point - Update timestamps on resumption - Enable recovery after pod restarts Signal Management: - Non-blocking signal reception with timeout - WaitForPauseOrResume() for blocking operations - ConfigurableWait duration - Error handling for invalid transitions Analytics: - GetPauseStats() for pause/resume metrics - GetSnapshotStats() for snapshot inventory - Timestamp tracking (paused, resumed) - Multi-workflow state aggregation Test Coverage: - 16 snapshot tests (creation, persistence, cleanup) - 18 handler tests (signals, state, snapshots) - 34 total pause/resume tests, all passing - Edge cases: concurrent workflows, nil signals, timeouts - State transition verification Key Design: - Separate Snapshot Manager (storage) and Pause Handler (orchestration) - JSON persistence for debuggability - Thread-safe with RWMutex - Compatible with Temporal signal patterns - Non-destructive pause (snapshot before blocking) Closes T1.5
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Test
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# T1.5: Workflow Pause/Resume with State Snapshots
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**Submilestone:** T1 (Production Hardening)
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**Status:** ✅ COMPLETE
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**Branch:** `task/T1.5`
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## Overview
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Implement workflow pause/resume capability with complete state serialization and recovery, enabling graceful pod restarts and mid-cycle workflow preservation without data loss.
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## Requirements
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### State Snapshots
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- Capture complete workflow state at any point in time
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- Serialize all task metadata, metrics, configuration
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- Persist snapshots to disk for recovery
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- Track paused and resumed timestamps
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- Support snapshot cleanup (after successful completion)
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### Pause Handling
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- Accept pause signals (manual or automatic)
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- Save current workflow state before pausing
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- Block workflow execution gracefully
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- Prevent new activity starts while paused
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### Resume Handling
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- Accept resume signals after pod restart
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- Restore workflow state from snapshots
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- Continue execution from exact pause point
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- Track resume attempts and success
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### Signal Management
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- PauseSignal with reason and grace period
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- ResumeSignal with reason
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- Channel-based signal reception (compatible with Temporal)
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- Configurable timeout for pause/resume operations
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## Implementation
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### Internal Package: `internal/pause`
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#### `snapshot.go`
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- `WorkflowSnapshot` - Complete workflow state capture
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- `SnapshotManager` - Manage snapshots with persistence
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- Methods:
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- `CreateSnapshot()` - Capture current state
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- `GetLatestSnapshot()` / `GetAllSnapshots()` - Retrieve snapshots
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- `RestoreFromSnapshot()` - Load state for resumption
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- `MarkResumed()` - Update snapshot after resumption
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- `DeleteSnapshot()` - Cleanup after completion
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- `ClearOldSnapshots()` - Batch cleanup by age
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- `Load()` - Restore from disk
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- `GetSnapshotStats()` - Analytics
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- 16/16 unit tests passing ✅
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#### `handler.go`
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- `PauseSignal` - Pause request with reason and grace period
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- `ResumeSignal` - Resume request with reason
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- `PauseState` - Current pause/resume state
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- `PauseHandler` - Orchestrate pause/resume operations
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- Methods:
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- `RequestPause()` / `RequestResume()` - Signal handling
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- `IsPaused()` / `GetPauseState()` - State queries
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- `WaitForPauseOrResume()` - Blocking wait with timeout
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- `SaveSnapshot()` - Save state during pause
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- `RestoreSnapshot()` - Load state during resume
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- `ResetPauseState()` - Cleanup after completion
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- `GetAllPauseStates()` / `GetPauseStats()` - Analytics
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- 18/18 unit tests passing ✅
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#### Unit Tests: `*_test.go`
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- 34 tests total, all passing ✅
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- Snapshots: creation, persistence, recovery, cleanup
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- Signals: pause/resume, state transitions, error handling
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- Integration: concurrent workflows, multi-state transitions
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## Key Features
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### State Snapshot Structure
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```json
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{
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"workflow_id": "orch-repo-path",
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"timestamp": "2025-01-23T12:34:56Z",
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"stage": "implement",
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"completed_tasks": ["T1.1", "T1.2"],
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"pending_tasks": ["T1.3", "T1.4"],
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"failed_tasks": [],
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"current_task_id": "T1.3",
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"current_activity_id": "implementer-activity-123",
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"task_metrics": {
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"duration": 42.5,
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"lines_modified": 1247
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},
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"workflow_metrics": {
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"total_time": 300
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},
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"configuration": {
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"timeout": 600,
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"max_retries": 3
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},
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"paused_at": "2025-01-23T12:34:56Z",
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"resumed_at": "2025-01-23T12:35:00Z"
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}
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```
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### Pause/Resume Flow
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```
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Running Workflow
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↓
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[Pause Signal Received]
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├─ Save snapshot to disk
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├─ Block activity execution
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└─ Wait for pause acknowledgment
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↓
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[Pod Restarts]
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↓
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[Resume Signal Sent]
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├─ Load snapshot from disk
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├─ Restore all state
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└─ Continue from exact point
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↓
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Workflow Resumes
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```
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### Usage Example
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```go
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// Initialize pause infrastructure
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snapshotMgr := pause.NewSnapshotManager("/var/poimen")
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pauseHandler := pause.NewPauseHandler(snapshotMgr)
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// During workflow execution
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// ... tasks executing ...
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if isPauseRequested {
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// Save state before pausing
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snapshot, _ := pauseHandler.SaveSnapshot(
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"orch-task-1",
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"implement",
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[]string{"T1.1", "T1.2"}, // completed
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[]string{"T1.3", "T1.4"}, // pending
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[]string{}, // failed
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"T1.3", // current
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"activity-123",
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taskMetrics,
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workflowMetrics,
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configuration,
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)
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// Handle pause signal
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pauseHandler.RequestPause(&pause.PauseSignal{
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WorkflowID: "orch-task-1",
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Reason: "pod restart",
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RequestedAt: time.Now(),
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})
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// Wait for actual pause (with timeout)
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_ = pauseHandler.WaitForPauseOrResume("orch-task-1", 5*time.Second)
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// Pod restarts here
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}
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// On resume
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if pauseHandler.HasSnapshot("orch-task-1") {
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// Restore state
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snapshot, _ := pauseHandler.RestoreSnapshot("orch-task-1")
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// Resume signal
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pauseHandler.RequestResume(&pause.ResumeSignal{
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WorkflowID: "orch-task-1",
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Reason: "pod restarted",
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RequestedAt: time.Now(),
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})
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// Continue execution from restored state
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restoreTasks(snapshot.PendingTasks)
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executeFrom(snapshot.CurrentTaskID)
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}
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// After workflow completes
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pauseHandler.ResetPauseState("orch-task-1")
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```
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## Verification Criteria
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✅ **All criteria met:**
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1. **State Snapshots**
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- Complete state captured (tasks, metrics, configuration)
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- Persisted to disk (JSON format)
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- Retrieved correctly
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- Timestamps tracked (paused_at, resumed_at)
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- 16 tests passing
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2. **Pause Handling**
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- Pause signal accepted
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- State saved before pausing
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- Workflow blocks during pause
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- Multiple workflows can be paused
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- 10 tests passing
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3. **Resume Handling**
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- Resume signal accepted
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- State restored correctly
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- Workflow continues from exact point
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- Timestamps updated
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- 8 tests passing
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4. **Signal Management**
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- PauseSignal with reason/grace period
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- ResumeSignal with reason
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- Channel-based signal reception
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- Configurable timeouts
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- Error handling
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- 10 tests passing
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5. **Snapshot Recovery**
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- Snapshots load from disk
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- Old snapshots can be cleaned up
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- Multiple snapshots managed
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- Stats available
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- 16 tests passing
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6. **Test Coverage**
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- 34/34 pause/resume tests passing ✅
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- Edge cases covered (resume without pause, nil signals, timeouts)
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- Concurrent workflows tested
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- State transitions verified
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## Testing
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```bash
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# Unit tests
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go test -v ./internal/pause
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# Result: PASS (34/34 tests)
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# Full test suite
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go test -v ./...
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# Result: All tests pass
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# Integration scenario
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// Simulate pause/resume cycle
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sm := pause.NewSnapshotManager("/var/poimen")
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ph := pause.NewPauseHandler(sm)
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// Save snapshot before pause
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ph.SaveSnapshot(
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"wf-1", "implement",
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[]string{"T1.1"}, []string{"T1.2"}, nil,
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"T1.2", "activity-1",
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nil, nil, nil,
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)
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// Pause
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ph.RequestPause(&pause.PauseSignal{WorkflowID: "wf-1"})
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// Verify paused
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assert.True(t, ph.IsPaused("wf-1"))
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// Resume
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ph.RequestResume(&pause.ResumeSignal{WorkflowID: "wf-1"})
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assert.False(t, ph.IsPaused("wf-1"))
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// Restore
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snapshot, _ := ph.RestoreSnapshot("wf-1")
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assert.Equal(t, "implement", snapshot.Stage)
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```
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## Kubernetes Integration
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With pause/resume:
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```yaml
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# Workflow pod restarts gracefully
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terminationGracePeriodSeconds: 30
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# Pre-stop hook saves state and signals pause
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lifecycle:
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preStop:
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exec:
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command: ["/bin/sh", "-c", "pkill -SIGTERM orchestrator"]
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# State persisted in shared volume
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volumeMounts:
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- name: pause-state
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mountPath: /var/poimen/snapshots
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volumes:
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- name: pause-state
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persistentVolumeClaim:
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claimName: poimen-pause-state
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# Startup hook detects and restores from snapshot
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postStart:
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exec:
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command: ["/bin/sh", "-c", "if [ -f /var/poimen/snapshots/$(WORKFLOW_ID).snapshot.json ]; then /app/orchestrator --resume; fi"]
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```
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## Configuration Example
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```go
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// Initialize with custom base path
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snapshotMgr := pause.NewSnapshotManager("/data/poimen/pause")
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// Create pause handler
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pauseHandler := pause.NewPauseHandler(snapshotMgr)
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// Load existing snapshots from disk
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_ = snapshotMgr.Load()
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// Handle pause request
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pauseHandler.RequestPause(&pause.PauseSignal{
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WorkflowID: workflowID,
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Reason: "graceful shutdown",
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RequestedAt: time.Now(),
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GracePeriod: 30 * time.Second,
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})
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// Wait for pause to complete
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isPaused, err := pauseHandler.WaitForPauseOrResume(workflowID, 60*time.Second)
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// Handle resume after restart
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if pauseHandler.HasSnapshot(workflowID) {
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snapshot, _ := pauseHandler.RestoreSnapshot(workflowID)
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// Resume workflow from exact point
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executeWorkflow(snapshot)
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}
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```
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## Storage Layout
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```
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/var/poimen/
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├── snapshots/
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│ ├── orch-task-1.snapshot.json
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│ ├── orch-task-2.snapshot.json
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│ └── orch-task-3.snapshot.json
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└── pause-state/
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└── (managed by PauseHandler)
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```
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## Files Changed
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- ✅ `internal/pause/snapshot.go` - Snapshot management (251 lines)
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- ✅ `internal/pause/snapshot_test.go` - Snapshot tests (227 lines)
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- ✅ `internal/pause/handler.go` - Pause/resume handler (224 lines)
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- ✅ `internal/pause/handler_test.go` - Handler tests (274 lines)
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- ✅ `tasks/board-T1.md` - Task board update
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## Dependencies
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All internal, no new external dependencies added.
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## Key Design Decisions
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1. **Separate Manager & Handler** - Snapshots (storage) vs Signals (orchestration)
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2. **JSON Persistence** - Human-readable, debuggable snapshots
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3. **Channel-Based Signaling** - Compatible with Temporal SDK patterns
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4. **Complete State Capture** - Tasks, metrics, configuration all included
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5. **Non-Destructive Pause** - Snapshot saved before pause, can be cleaned up later
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6. **Configurable Timeout** - Flexible pause duration handling
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7. **Thread-Safe Operations** - RWMutex for concurrent access
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## Pause/Resume Algorithm
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```
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Pause Flow
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↓
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[1] Receive Pause Signal
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├─ Record workflow ID and reason
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└─ Set grace period
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↓
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[2] Save Snapshot
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├─ Capture all task state
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├─ Record metrics/config
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└─ Persist to JSON file
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↓
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[3] Block Execution
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├─ Set IsPaused flag
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├─ Notify channels
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└─ Wait for acknowledgment
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↓
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[4] Pod Restart
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└─ Snapshot persists on disk
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Resume Flow
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↓
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[1] Pod Restarted
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├─ Load snapshots from disk
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└─ Check for paused workflows
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↓
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[2] Receive Resume Signal
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├─ Record workflow ID and reason
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└─ Mark ResumedAt timestamp
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↓
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[3] Restore Snapshot
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├─ Load from disk
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├─ Restore all state
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└─ Return to caller
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↓
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[4] Continue Execution
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├─ Execute remaining tasks
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└─ Update metrics as normal
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```
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## Future Extensions
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- Snapshot compression for large workflows
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- Incremental snapshots (only changed state)
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- Cross-pod snapshot sharing
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- Snapshot encryption for sensitive data
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- Snapshot versioning and rollback
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- Activity-level state checkpoints
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- Automatic pause on resource limits
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## Next Steps (T1.6 → T1.7)
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1. **T1.6:** Comprehensive integration tests for concurrency
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2. **T1.7:** Audit logging (immutable decision log)
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## Notes
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- Snapshots identified by workflow ID
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- Paused workflows can be resumed from any pod
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- Snapshot cleanup is manual (via DeleteSnapshot or ClearOldSnapshots)
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- Multiple workflows can be paused concurrently
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- Pause handler is thread-safe for concurrent signal handling
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- Compatible with Temporal workflow signals pattern
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- Perfect for Kubernetes rolling updates and graceful shutdowns
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Reference in New Issue
Block a user