Skip long-polling if any requested topic does not exist.
Only long-poll when MinBytes > 0, data isn’t available yet, and all topics exist.
Cap the long-polling wait to 1s in tests to prevent hanging on shutdown.
Busy fetch loop: Implemented basic long-polling in Fetch. If no data and min_bytes>0 with max_wait_ms>0, we wait up to max_wait_ms, and populate throttle_time_ms accordingly. This stops the rapid loop for kafka-go on empty partitions.
- Added centralized errors.go with complete Kafka error code definitions
- Implemented timeout detection and network error classification
- Enhanced connection handling with configurable timeouts and better error reporting
- Added comprehensive error handling test suite with 21 test cases
- Unified error code usage across all protocol handlers
- Improved request/response timeout handling with graceful fallbacks
- All protocol and E2E tests passing with robust error handling
- Added flexible_versions.go with utilities for Kafka flexible versions (v3+)
- Implemented ParseRequestHeader for compact string parsing and tagged fields
- Added fallback mechanism in handler.go for backward compatibility
- Updated handleApiVersions to support flexible version responses
- Added comprehensive tests for flexible version utilities
- All protocol tests passing with robust error handling
Multi-batch Fetch support completed:
## Core Features
- **MaxBytes compliance**: Respects fetch request MaxBytes limits to prevent oversized responses
- **Multi-batch concatenation**: Properly concatenates multiple record batches in single response
- **Size estimation**: Pre-estimates batch sizes to optimize MaxBytes usage before construction
- **Kafka-compliant behavior**: Always returns at least one batch even if it exceeds MaxBytes (first batch rule)
## Implementation Details
- **MultiBatchFetcher**: New dedicated class for multi-batch operations
- **Intelligent batching**: Adapts record count per batch based on available space (10-50 records)
- **Proper concatenation format**: Each batch maintains independent headers and structure
- **Fallback support**: Graceful fallback to single batch if multi-batch fails
## Advanced Features
- **Compression ready**: Basic support for compressed record batches (GZIP placeholder)
- **Size tracking**: Tracks total response size and batch count across operations
- **Edge case handling**: Handles large single batches, empty responses, partial batches
## Integration & Testing
- **Fetch API integration**: Seamlessly integrated with existing handleFetch pipeline
- **17 comprehensive tests**: Multi-batch scenarios, size limits, concatenation format validation
- **E2E compatibility**: Sarama tests pass with no regressions
- **Performance validation**: Benchmarks for batch construction and multi-fetch operations
## Performance Improvements
- **Better bandwidth utilization**: Fills available MaxBytes space efficiently
- **Reduced round trips**: Multiple batches in single response
- **Adaptive sizing**: Smaller batches when space limited, larger when space available
Ready for Phase 6: Basic flexible versions support
ApiVersions Matrix Accuracy completed:
## Critical Fixes
- **OffsetFetch API**: Updated advertised from v0-v2 to v0-v5 (MAJOR fix)
- Implementation already supported v3+ throttle_time_ms and v5+ leader_epoch
- Clients can now use advanced OffsetFetch features
- **CreateTopics API**: Updated advertised from v0-v4 to v0-v5 (minor fix)
- Implementation already routed v5 requests to v2+ handler
- Better client compatibility for v5 CreateTopics requests
## Implementation
- **handleApiVersions()**: Corrected advertised max versions
- **validateAPIVersion()**: Updated validation ranges to match advertisements
- **Consistency**: Eliminated mismatch between advertised vs implemented versions
## Testing & Verification
- **Comprehensive test suite**: 6 new tests in api_versions_test.go
- **Version validation tests**: OffsetFetch v3-v5 and CreateTopics v5 now accepted
- **End-to-end verification**: E2E tests still pass, no regressions
- **API audit documentation**: Complete version matrix in API_VERSION_MATRIX.md
## Impact
- **Client compatibility**: Higher-version clients can now connect properly
- **Feature utilization**: Advanced features like leader epoch, throttle time accessible
- **Protocol compliance**: Advertised versions now match actual implementation
- **Future-proofing**: Clear process for managing API version accuracy
Ready for Phase 4: Consumer group protocol metadata parsing
CreateTopics Protocol Compliance completed:
## Implementation
- Implement handleCreateTopicsV0V1() with proper v0/v1 request parsing
- Support regular array/string format (not compact) for v0/v1
- Parse topic name, partitions, replication factor, assignments, configs
- Handle timeout_ms and validate_only fields correctly
- Maintain existing v2+ compact format support
- Wire to SeaweedMQ handler for actual topic creation
## Key Features
- Full v0-v5 CreateTopics API version support
- Proper error handling (TOPIC_ALREADY_EXISTS, INVALID_PARTITIONS, etc.)
- Partition count validation and enforcement
- Compatible with existing SeaweedMQ topic management
## Tests
- Comprehensive unit tests for v0/v1/v2+ parsing
- Error condition testing (duplicate topics, invalid partitions)
- Multi-topic creation support
- Integration tests across all API versions
- Performance benchmarks for CreateTopics operations
## Verification
- All protocol tests pass (v0-v5 CreateTopics)
- E2E Sarama tests continue to work
- Real topics created with specified partition counts
- Proper error responses for edge cases
Ready for Phase 3: ApiVersions matrix accuracy
Core SeaweedMQ Integration completed:
## Implementation
- Implement SeaweedMQHandler.GetStoredRecords() to retrieve actual records from SeaweedMQ
- Add SeaweedSMQRecord wrapper implementing offset.SMQRecord interface
- Wire Fetch API to use real SMQ records instead of synthetic batches
- Support both agent and broker client connections for record retrieval
## Key Features
- Proper Kafka offset mapping from SeaweedMQ records
- Respects maxRecords limit and batch size constraints
- Graceful error handling for missing topics/partitions
- High water mark boundary checking
## Tests
- Unit tests for SMQRecord interface compliance
- Edge case testing (empty topics, offset boundaries, limits)
- Integration with existing end-to-end Kafka tests
- Benchmark tests for record accessor performance
## Verification
- All integration tests pass
- E2E Sarama test shows 'Found X SMQ records' debug output
- GetStoredRecords now returns real data instead of TODO placeholder
Ready for Phase 2: CreateTopics protocol compliance
chrislu