Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[Unreleased]

Changed

• Security: production configs now default to verifying TLS. Config.production/1 sets verify: :verify_peer, and a :production endpoint built without ssl/credentials no longer silently downgrades to plaintext h2c — it raises a clear configuration error.
• Narrowed several broad rescue/catch clauses (Pool.scale_up/scale_down, Worker.send_ping, TelemetryReporter) so unexpected errors surface instead of being swallowed; demoted expected reconnect/retry logs to :debug.

Fixed

• Documentation: replaced README examples referencing a non-existent GrpcConnectionPool.execute/1 with the real get_channel/1 + stub-call pattern; corrected the stale install snippet and the :get_channel telemetry/strategy docs.

[0.3.5] - 2026-06-01

Fixed

• Slot-claim race in the hot path — slot claim/release are now serialized through PoolState (register_channel/3, unregister_channel/2). Concurrent worker connects/disconnects could previously collide on a slot, leaving :channel_count higher than the populated channels so get_channel/1 returned :not_connected on a healthy pool.
• get_channel/1 now returns {:error, :not_connected} (instead of raising) when the pool is not started or PoolState is restarting.

Changed

• Hot-path performance: collapsed the per-call ETS table-name rebuild + two persistent_term lookups into one combined term; RoundRobin uses unsigned atomics (no abs/1); PowerOfTwo now tracks load in lock-free :atomics counters (least-frequently-used) instead of writing a timestamp to ETS on every selection.
• Per-call :get_channel telemetry is configurable via telemetry_sample_rate (default 1 = emit every call; 0 disables; N samples ~1-in-N).
• The pid => slot map moved from ETS into PoolState state (slot claim is now O(1)).

[0.3.0] - 2026-03-24

Added

• Zero GenServer.call hot path — channels stored directly in ETS for O(1) indexed access, eliminating the GenServer.call bottleneck on every get_channel request
• Pluggable connection strategies via GrpcConnectionPool.Strategy behaviour:
  • :round_robin (default) — lock-free atomics-based round-robin
  • :random — random selection, good for avoiding hot-spotting
  • :power_of_two — power-of-two-choices with least-recently-used tiebreak
  • Custom strategies supported via behaviour implementation
• :persistent_term for pool config — zero-copy reads for configuration data
• ETS with read/write concurrency — optimized concurrent access flags
• PoolState GenServer — dedicated ETS table owner for crash resilience
• TelemetryReporter GenServer — replaced recursive :timer.sleep telemetry loop with a proper GenServer using Process.send_after
• await_ready/2 — blocks until at least one channel is connected or timeout, useful for application startup
• Stale scaling lock detection — scaling locks older than 30 seconds are automatically released
• max_reconnect_attempts config — workers crash after N consecutive connection failures instead of the fragile crash_after_reconnect_attempt timer
• Benchee benchmarks — bench/get_channel_bench.exs for measuring hot path performance
• Strategy tests — comprehensive tests for all three built-in strategies
• CI/CD pipeline — GitHub Actions with compile, format, credo, test, dialyzer, and auto-publish to Hex on tag push

Changed

• 4.3x–5.8x faster get_channel — single-process throughput improved from ~470K ips to ~2M ips
• O(n) scaling eliminated — pool_size=25 was 38% slower than pool_size=5, now only 2% slower
• 44–58% lower latency under concurrency — 100 concurrent callers: median 553μs → 312μs, p99 1035μs → 439μs
• 28–56% less memory per call — memory now constant regardless of pool size (was O(n))
• Pool.status 2.5x faster — reads from ETS channel_count instead of Registry.lookup
• Pool supervision tree restructured: PoolState starts first, then Registry, DynamicSupervisor, workers, and TelemetryReporter

Removed

• crash_after_reconnect_attempt message — replaced by max_reconnect_attempts config with clean {:stop, reason, state} on exhaustion

[0.2.3] - 2026-01-29

Added

• Enhanced telemetry events for better observability:
  • [:grpc_connection_pool, :pool, :init] - Pool initialization with size and endpoint
  • [:grpc_connection_pool, :channel, :ping] - Ping health check with duration and result
  • [:grpc_connection_pool, :channel, :gun_down] - Gun connection down events with reason and protocol
  • [:grpc_connection_pool, :channel, :gun_error] - Gun error events with reason
  • [:grpc_connection_pool, :channel, :reconnect_scheduled] - Reconnection scheduling with delay and attempt count
• Reconnect attempt tracking in worker state
• Comprehensive telemetry documentation in README
• Telemetry test suite

[0.2.2] - 2026-01-29

Added

• Support for gRPC client interceptors in endpoint configuration (thanks @arctarus)
• Comprehensive tests for interceptors feature
• CHANGELOG.md file

[0.2.1] - 2025-11-22

Fixed

• Handle GRPC v0.11.5 FunctionClauseError during disconnect

[0.2.0] - 2025-11-22

Added

• Dynamic pool scaling feature

[0.1.6] - 2025-11-22

Fixed

• Handle GenServer exit gracefully in connection cleanup

[0.1.5] - 2025-11-21

Changed

• Refactored to replace Poolex with DynamicSupervisor
• Added conn_grpc features
• Fixed documentation LICENSE reference warnings

[0.1.4] - 2025-11-19

Changed

• Updated dependencies: poolex to 1.4.2, grpc to 0.11.5
• Changed gRPC connection logs from info to debug level

Added

• suppress_connection_errors config option for GCP endpoints

[0.1.3] - 2025-11-18

Added

• License file

[0.1.2] - 2025-11-18

Added

• Comprehensive README with complete configuration examples and architecture details

[0.1.0] - 2025-11-18

Added

• Initial release: Complete GrpcConnectionPool library
• Configuration module with support for production, local, and custom environments
• Connection pooling with DynamicSupervisor
• Automatic connection warming and health monitoring
• Retry logic with exponential backoff and jitter
• Telemetry integration for metrics