feat: implement NatsClient connection handler with read/write pipeline
This commit is contained in:
Joseph Doherty
284
src/NATS.Server/NatsClient.cs
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284
src/NATS.Server/NatsClient.cs
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@@ -0,0 +1,284 @@
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using System.Buffers;
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using System.IO.Pipelines;
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using System.Net.Sockets;
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using System.Text;
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using System.Text.Json;
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using NATS.Server.Protocol;
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using NATS.Server.Subscriptions;
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namespace NATS.Server;
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public interface IMessageRouter
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{
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void ProcessMessage(string subject, string? replyTo, ReadOnlyMemory<byte> headers,
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ReadOnlyMemory<byte> payload, NatsClient sender);
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void RemoveClient(NatsClient client);
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}
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public interface ISubListAccess
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{
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SubList SubList { get; }
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}
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public sealed class NatsClient : IDisposable
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{
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private readonly Socket _socket;
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private readonly NetworkStream _stream;
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private readonly NatsOptions _options;
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private readonly ServerInfo _serverInfo;
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private readonly NatsParser _parser;
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private readonly SemaphoreSlim _writeLock = new(1, 1);
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private readonly Dictionary<string, Subscription> _subs = new();
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public ulong Id { get; }
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public ClientOptions? ClientOpts { get; private set; }
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public IMessageRouter? Router { get; set; }
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public bool ConnectReceived { get; private set; }
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// Stats
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public long InMsgs;
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public long OutMsgs;
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public long InBytes;
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public long OutBytes;
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public IReadOnlyDictionary<string, Subscription> Subscriptions => _subs;
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public NatsClient(ulong id, Socket socket, NatsOptions options, ServerInfo serverInfo)
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{
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Id = id;
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_socket = socket;
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_stream = new NetworkStream(socket, ownsSocket: false);
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_options = options;
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_serverInfo = serverInfo;
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_parser = new NatsParser(options.MaxPayload);
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}
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public async Task RunAsync(CancellationToken ct)
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{
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var pipe = new Pipe();
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try
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{
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// Send INFO
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await SendInfoAsync(ct);
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// Start read pump and command processing in parallel
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var fillTask = FillPipeAsync(pipe.Writer, ct);
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var processTask = ProcessCommandsAsync(pipe.Reader, ct);
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await Task.WhenAny(fillTask, processTask);
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}
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catch (OperationCanceledException) { }
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catch (Exception) { /* connection error -- clean up */ }
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finally
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{
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Router?.RemoveClient(this);
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}
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}
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private async Task FillPipeAsync(PipeWriter writer, CancellationToken ct)
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{
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try
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{
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while (!ct.IsCancellationRequested)
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{
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var memory = writer.GetMemory(4096);
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int bytesRead = await _stream.ReadAsync(memory, ct);
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if (bytesRead == 0)
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break;
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writer.Advance(bytesRead);
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var result = await writer.FlushAsync(ct);
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if (result.IsCompleted)
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break;
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}
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}
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finally
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{
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await writer.CompleteAsync();
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}
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}
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private async Task ProcessCommandsAsync(PipeReader reader, CancellationToken ct)
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{
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try
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{
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while (!ct.IsCancellationRequested)
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{
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var result = await reader.ReadAsync(ct);
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var buffer = result.Buffer;
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while (_parser.TryParse(ref buffer, out var cmd))
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{
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await DispatchCommandAsync(cmd, ct);
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}
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reader.AdvanceTo(buffer.Start, buffer.End);
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if (result.IsCompleted)
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break;
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}
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}
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finally
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{
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await reader.CompleteAsync();
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}
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}
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private async ValueTask DispatchCommandAsync(ParsedCommand cmd, CancellationToken ct)
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{
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switch (cmd.Type)
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{
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case CommandType.Connect:
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ProcessConnect(cmd);
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break;
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case CommandType.Ping:
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await WriteAsync(NatsProtocol.PongBytes, ct);
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break;
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case CommandType.Pong:
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// Update RTT tracking (placeholder)
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break;
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case CommandType.Sub:
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ProcessSub(cmd);
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break;
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case CommandType.Unsub:
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ProcessUnsub(cmd);
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break;
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case CommandType.Pub:
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case CommandType.HPub:
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ProcessPub(cmd);
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break;
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}
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}
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private void ProcessConnect(ParsedCommand cmd)
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{
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ClientOpts = JsonSerializer.Deserialize<ClientOptions>(cmd.Payload.Span)
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?? new ClientOptions();
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ConnectReceived = true;
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}
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private void ProcessSub(ParsedCommand cmd)
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{
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var sub = new Subscription
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{
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Subject = cmd.Subject!,
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Queue = cmd.Queue,
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Sid = cmd.Sid!,
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};
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_subs[cmd.Sid!] = sub;
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sub.Client = this;
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if (Router is ISubListAccess sl)
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sl.SubList.Insert(sub);
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}
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private void ProcessUnsub(ParsedCommand cmd)
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{
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if (!_subs.TryGetValue(cmd.Sid!, out var sub))
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return;
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if (cmd.MaxMessages > 0)
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{
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sub.MaxMessages = cmd.MaxMessages;
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// Will be cleaned up when MessageCount reaches MaxMessages
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return;
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}
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_subs.Remove(cmd.Sid!);
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if (Router is ISubListAccess sl)
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sl.SubList.Remove(sub);
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}
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private void ProcessPub(ParsedCommand cmd)
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{
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Interlocked.Increment(ref InMsgs);
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Interlocked.Add(ref InBytes, cmd.Payload.Length);
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ReadOnlyMemory<byte> headers = default;
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ReadOnlyMemory<byte> payload = cmd.Payload;
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if (cmd.Type == CommandType.HPub && cmd.HeaderSize > 0)
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{
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headers = cmd.Payload[..cmd.HeaderSize];
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payload = cmd.Payload[cmd.HeaderSize..];
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}
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Router?.ProcessMessage(cmd.Subject!, cmd.ReplyTo, headers, payload, this);
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}
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private async Task SendInfoAsync(CancellationToken ct)
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{
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var infoJson = JsonSerializer.Serialize(_serverInfo);
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var infoLine = Encoding.ASCII.GetBytes($"INFO {infoJson}\r\n");
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await WriteAsync(infoLine, ct);
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}
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public async Task SendMessageAsync(string subject, string sid, string? replyTo,
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ReadOnlyMemory<byte> headers, ReadOnlyMemory<byte> payload, CancellationToken ct)
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{
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Interlocked.Increment(ref OutMsgs);
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Interlocked.Add(ref OutBytes, payload.Length + headers.Length);
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byte[] line;
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if (headers.Length > 0)
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{
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int totalSize = headers.Length + payload.Length;
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line = Encoding.ASCII.GetBytes($"HMSG {subject} {sid} {(replyTo != null ? replyTo + " " : "")}{headers.Length} {totalSize}\r\n");
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}
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else
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{
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line = Encoding.ASCII.GetBytes($"MSG {subject} {sid} {(replyTo != null ? replyTo + " " : "")}{payload.Length}\r\n");
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}
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await _writeLock.WaitAsync(ct);
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try
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{
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await _stream.WriteAsync(line, ct);
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if (headers.Length > 0)
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await _stream.WriteAsync(headers, ct);
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if (payload.Length > 0)
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await _stream.WriteAsync(payload, ct);
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await _stream.WriteAsync(NatsProtocol.CrLf, ct);
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await _stream.FlushAsync(ct);
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}
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finally
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{
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_writeLock.Release();
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}
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}
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private async Task WriteAsync(byte[] data, CancellationToken ct)
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{
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await _writeLock.WaitAsync(ct);
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try
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{
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await _stream.WriteAsync(data, ct);
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await _stream.FlushAsync(ct);
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}
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finally
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{
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_writeLock.Release();
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}
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}
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public void RemoveAllSubscriptions(SubList subList)
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{
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foreach (var sub in _subs.Values)
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subList.Remove(sub);
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_subs.Clear();
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}
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public void Dispose()
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{
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_stream.Dispose();
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_socket.Dispose();
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_writeLock.Dispose();
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}
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}
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