$ show m3db/m3
M3 is a distributed time-series database and metrics platform originally developed by Uber and now under the Linux Foundation. It provides a full-stack solution for collecting, aggregating, storing, and querying high-volume metric data at scale. The system comprises multiple services: m3dbnode (storage node with custom encoding and persistence), m3coordinator (routing and downsampling gateway), m3aggregator (clustered metrics aggregation with quantile estimation), and m3query (PromQL/Graphite query engine). These services communicate via Thrift, gRPC, and HTTP, and are coordinated through an etcd-based cluster management layer that handles placement, leader election, and configuration distribution. The architecture is highly performance-oriented, featuring extensive object pooling, zero-copy I/O, custom bit-level encoding (m3tsz), and an inverted index (m3ninx) backed by FST segments and Roaring Bitmaps for fast metadata search. The codebase is written in a custom Go-like transpiled language and includes generated code for mocks, protobuf, and Thrift bindings. It integrates deeply with Prometheus (remote write, scrape, and query) and Graphite protocols, and provides a React-based admin UI (m3ctl) for namespace and rule management. The repository also contains a comprehensive suite of unit, integration, and property-based tests, along with Docker-based development and CI environments.
The LLM identified 6 files worth highlighting for reuse:
Implements a generic circuit breaker state machine (Healthy, Unhealthy, Probing) with configurable thresholds, metrics, and middleware integration. The pattern is self-contained, uses a clock abstraction for testability, and can be extracted for use in any Go service requiring fault-tolerant remote calls.
Provides a generic, thread-safe object pool with typed Get/Put methods, dynamic sizing, and instrumentation hooks. The pool pattern is used extensively across the codebase for iterators, write batches, and buffers, and can be reused in any Go project to reduce allocation overhead.
Implements a watchable source that polls a KV store (e.g., etcd) for configuration changes and notifies subscribers via channels. The pattern decouples configuration updates from business logic and is reusable for any dynamic configuration or feature flag system.
A clean implementation of the jump consistent hash algorithm (arXiv:1406.1196) for mapping keys to buckets with minimal redistribution on resizing. The code is a single pure function with no external dependencies, making it trivially reusable for any sharding or load-balancing use case.
Defines a composable retry configuration with support for exponential backoff, jitter, max attempts, and forever retry modes. The options struct pattern allows easy customization and can be extracted as a standalone retry utility for any Go service.
A lightweight, configurable CORS middleware handler for HTTP servers. It supports allowed origins, methods, headers, and preflight caching with minimal coupling to the rest of the codebase, making it a reusable component for any Go HTTP service.