v0.2.0

v0.2.0

Features

• Public embed API: amber.Open, Options, Cardinality, S3 config — stable surface for embedding amber into another binary.
• S3 segment tiering: SegmentStore interface with LocalStore and S3Store implementations, automatic upload on seal.
• Posting list index for trace_id — replaces bitmap for high-cardinality fields.
• Ribbon filter for segment-level pruning.
• Cardinality guard: caps attrs per entry, attr value length, and unique keys per service.
• Circuit breaker rejects writes after consecutive batch failures.
• Prometheus /metrics endpoint with ingest and WAL counters (hand-rolled exporter, no client_golang dependency).
• /readyz gate and per-request size limits on the HTTP API.
• Timing-safe API key comparison, gated pprof.

Performance

• Zero-copy block scan: ~100k allocations -> ~40 per segment scan.
• processBatch allocations halved via metric handles and zstd encoder reuse.

Bug fixes

• Segment header is now fsynced before WAL replay (fixes zero-byte segment after crash).
• WAL replay caps per-record size and surfaces corruption events.
• Writer state and activeSize correctly restored after restart.
• Atomic index writes; WAL checkpoint durability.
• Rotation no longer reopens readers; retention sort fixed; seal retry on failure.

Tests

• Real SIGKILL chaos test for WAL recovery (subprocess + atomic marker).
• Contract test for the public embed API (amber_example_test.go).
• White-box benchmarks for query, ingest, storage, and indexer paths.
• 10M-record self-tracking benchmark (loadbench) with write/memory/read metrics.
• Metrics exporter coverage: counters, escaping, exposition format.

Tooling

• loadbench, lokibench, vlbench, httpbench — apples-to-apples benchmarks against Loki and VictoriaLogs over HTTP.
• lefthook pre-commit and pre-push hooks (gofmt, govet, golangci-lint, tests).