0ea71ace79
Design covers the minimal NATS server port: pub/sub with wildcards and queue groups over System.IO.Pipelines, targeting .NET 10.
117 lines
6.3 KiB
Markdown
117 lines
6.3 KiB
Markdown
# CLAUDE.md
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This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
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## Project Overview
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This project ports the [NATS server](https://github.com/nats-io/nats-server) from Go to .NET 10 / C#. The Go reference implementation lives in `golang/nats-server/`. The .NET port lives at the repository root.
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NATS is a high-performance publish-subscribe messaging system. It supports wildcards (`*` single token, `>` multi-token), queue groups for load balancing, request-reply, clustering (full-mesh routes, gateways, leaf nodes), and persistent streaming via JetStream.
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## Build & Test Commands
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```bash
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# Build the solution
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dotnet build
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# Run all tests
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dotnet test
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# Run a single test project
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dotnet test <path/to/TestProject.csproj>
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# Run a specific test by name
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dotnet test --filter "FullyQualifiedName~TestClassName.TestMethodName"
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# Run tests with verbose output
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dotnet test -v normal
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# Clean and rebuild
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dotnet clean && dotnet build
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```
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## Go Reference Commands
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```bash
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# Build the Go reference server
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cd golang/nats-server && go build
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# Run Go tests for a specific area
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cd golang/nats-server && go test -v -run TestName ./server/ -count=1 -timeout=30m
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# Run all Go server tests (slow, ~30min)
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cd golang/nats-server && go test -v ./server/ -count=1 -timeout=30m
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```
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## Architecture: NATS Server (Reference)
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The Go source in `golang/nats-server/server/` is the authoritative reference. Key files by subsystem:
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### Core Message Path
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- **`server.go`** — Server struct, startup lifecycle (`NewServer` → `Run` → `WaitForShutdown`), listener management
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- **`client.go`** (6700 lines) — Connection handling, `readLoop`/`writeLoop` goroutines, per-client subscription tracking, dynamic buffer sizing (512→65536 bytes), client types: `CLIENT`, `ROUTER`, `GATEWAY`, `LEAF`, `SYSTEM`
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- **`parser.go`** — Protocol state machine. Text protocol: `PUB`, `SUB`, `UNSUB`, `CONNECT`, `INFO`, `PING/PONG`, `MSG`. Extended: `HPUB/HMSG` (headers), `RPUB/RMSG` (routes). Control line limit: 4096 bytes. Default max payload: 1MB.
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- **`sublist.go`** — Trie-based subject matcher with wildcard support. Nodes have `psubs` (plain), `qsubs` (queue groups), special pointers for `*` and `>` wildcards. Results are cached with atomic generation IDs for invalidation.
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### Authentication & Accounts
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- **`auth.go`** — Auth mechanisms: username/password, token, NKeys (Ed25519), JWT, external auth callout, LDAP
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- **`accounts.go`** (137KB) — Multi-tenant account isolation. Each account has its own `Sublist`, client set, and subject namespace. Supports exports/imports between accounts, service latency tracking.
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- **`jwt.go`**, **`nkey.go`** — JWT claims parsing and NKey validation
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### Clustering
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- **`route.go`** — Full-mesh cluster routes. Route pooling (default 3 connections per peer). Account-specific dedicated routes. Protocol: `RS+`/`RS-` for subscribe propagation, `RMSG` for routed messages.
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- **`gateway.go`** (103KB) — Inter-cluster bridges. Interest-only mode optimizes traffic. Reply subject mapping (`_GR_.` prefix) avoids cross-cluster conflicts.
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- **`leafnode.go`** — Hub-and-spoke topology for edge deployments. Only subscribed subjects shared with hub. Loop detection via `$LDS.` prefix.
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### JetStream (Persistence)
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- **`jetstream.go`** — Orchestration, API subject handlers (`$JS.API.*`)
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- **`stream.go`** (8000 lines) — Stream lifecycle, retention policies (Limits, Interest, WorkQueue), subject transforms, mirroring/sourcing
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- **`consumer.go`** — Stateful readers. Push vs pull delivery. Ack policies: None, All, Explicit. Redelivery tracking, priority groups.
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- **`filestore.go`** (337KB) — Block-based persistent storage with S2 compression, encryption (ChaCha20/AES-GCM), indexing
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- **`memstore.go`** — In-memory storage with hash-wheel TTL expiration
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- **`raft.go`** — RAFT consensus for clustered JetStream. Meta-cluster for metadata, per-stream/consumer RAFT groups.
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### Configuration & Monitoring
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- **`opts.go`** — CLI flags + config file loading. CLI overrides config. Supports hot reload on signal.
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- **`monitor.go`** — HTTP endpoints: `/varz`, `/connz`, `/routez`, `/gatewayz`, `/jsz`, `/healthz`
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- **`conf/`** — Config file parser (custom format with includes)
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### Internal Data Structures
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- **`server/avl/`** — AVL tree for sparse sequence sets (ack tracking)
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- **`server/stree/`** — Subject tree for per-subject state in streams
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- **`server/gsl/`** — Generic subject list, optimized trie
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- **`server/thw/`** — Time hash wheel for efficient TTL expiration
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## Key Porting Considerations
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**Concurrency model:** Go uses goroutines (one per connection readLoop + writeLoop). Map to async/await with `Task`-based I/O. Use `Channel<T>` or `Pipe` for producer-consumer patterns where Go uses channels.
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**Locking:** Go `sync.RWMutex` maps to `ReaderWriterLockSlim`. Go `sync.Map` maps to `ConcurrentDictionary`. Go `atomic` operations map to `Interlocked` or `volatile`.
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**Subject matching:** The `Sublist` trie is performance-critical. Every published message triggers a `Match()` call. Cache invalidation uses atomic generation counters.
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**Protocol parsing:** The parser is a byte-by-byte state machine. In .NET, use `System.IO.Pipelines` for zero-copy parsing with `ReadOnlySequence<byte>`.
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**Buffer management:** Go uses `[]byte` slices with pooling. Map to `ArrayPool<byte>` and `Memory<T>`/`Span<T>`.
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**Compression:** NATS uses S2 (Snappy variant) for route/gateway compression. Use an equivalent .NET S2 library or IronSnappy.
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**Ports:** Client=4222, Cluster=6222, Monitoring=8222, Leaf=5222, Gateway=7222.
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## Message Flow Summary
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```
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Client PUB → parser → permission check → Sublist.Match() →
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├─ Local subscribers: MSG to each (queue subs: pick one per group)
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├─ Cluster routes: RMSG to peers (who deliver to their locals)
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├─ Gateways: forward to interested remote clusters
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└─ JetStream: if subject matches a stream, store + deliver to consumers
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```
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## Conventions
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- Reference the Go implementation file and line when porting a subsystem
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- Maintain protocol compatibility — the .NET server must interoperate with existing NATS clients and Go servers in a cluster
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- Use the same configuration file format as the Go server (parsed by `conf/` package)
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- Match the Go server's monitoring JSON response shapes for tooling compatibility
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