chore: initial project import

backend/fleet/src/Fleet.Server.Link/FleetLinkHost.cs

@@ -0,0 +1,170 @@
+using System.Collections.Concurrent;
+using System.Net.WebSockets;
+using System.Text.Json;
+using System.Text.Json.Serialization.Metadata;
+using Fleet.Core;
+using Fleet.Rpc;
+using Microsoft.Extensions.Logging;
+
+namespace Fleet.Server;
+
+/// <summary>
+/// 服务端连接宿主：在线表 + 服务端发起的调用 + 状态推送通知。每个 WebSocket 对应一个 <see cref="NodeConnection"/>。
+/// </summary>
+public sealed class FleetLinkHost : IFleetConnections, IStateNotifier
+{
+    private readonly ConcurrentDictionary<NodeId, NodeConnection> _connections = new();
+
+    internal FleetLinkHost(
+        IFleetStore store,
+        FleetServerOptions options,
+        TimeProvider time,
+        ILogger<FleetLinkHost> logger,
+        IEnumerable<IStateProvider> stateProviders,
+        IEnumerable<IInbox> inboxes,
+        IEnumerable<INodeEventSink> sinks,
+        FleetRouter router)
+    {
+        Store = store;
+        Options = options;
+        Time = time;
+        Logger = logger;
+        StateProviders = [.. stateProviders];
+        Inboxes = inboxes.ToDictionary(i => i.Channel);
+        Sinks = [.. sinks];
+        Router = router.Inner;
+    }
+
+    internal IFleetStore Store { get; }
+
+    internal FleetServerOptions Options { get; }
+
+    internal TimeProvider Time { get; }
+
+    internal ILogger<FleetLinkHost> Logger { get; }
+
+    internal IReadOnlyList<IStateProvider> StateProviders { get; }
+
+    internal IReadOnlyDictionary<byte, IInbox> Inboxes { get; }
+
+    internal IReadOnlyList<INodeEventSink> Sinks { get; }
+
+    internal RpcRouter<NodeCallContext> Router { get; }
+
+    public IReadOnlyCollection<NodeId> OnlineNodes => [.. _connections.Keys];
+
+    public bool IsOnline(NodeId node) => _connections.ContainsKey(node);
+
+    public NodeSessionInfo? GetSession(NodeId node) =>
+        _connections.TryGetValue(node, out NodeConnection? c) ? c.Session : null;
+
+    /// <summary>处理一条 WebSocket 连接，直到连接结束。</summary>
+    public async Task RunConnectionAsync(WebSocket socket, CancellationToken ct)
+    {
+        using var connection = new NodeConnection(this, socket);
+        await connection.RunAsync(ct);
+    }
+
+    /// <summary>返回被替换掉的旧连接（如果有）。</summary>
+    internal NodeConnection? Register(NodeConnection connection)
+    {
+        NodeConnection? replaced = null;
+        _connections.AddOrUpdate(
+            connection.NodeId,
+            connection,
+            (_, existing) =>
+            {
+                replaced = existing;
+                return connection;
+            });
+        return replaced;
+    }
+
+    internal void Unregister(NodeConnection connection) =>
+        _connections.TryRemove(new KeyValuePair<NodeId, NodeConnection>(connection.NodeId, connection));
+
+    public async ValueTask<Result<TResult>> RequestAsync<TParams, TResult>(
+        NodeId node,
+        string method,
+        TParams parameters,
+        JsonTypeInfo<TParams> paramsInfo,
+        JsonTypeInfo<TResult> resultInfo,
+        CancellationToken ct)
+    {
+        if (!_connections.TryGetValue(node, out NodeConnection? connection))
+        {
+            return Result<TResult>.Fail(FleetErrors.NodeOffline, "node is not connected");
+        }
+
+        Result<JsonElement> raw = await connection.RequestAsync(method, JsonSerializer.SerializeToElement(parameters, paramsInfo), ct);
+        if (!raw.TryGet(out JsonElement value, out FleetError? error))
+        {
+            return Result<TResult>.Fail(error);
+        }
+
+        try
+        {
+            TResult? result = value.Deserialize(resultInfo);
+            return result is null
+                ? Result<TResult>.Fail(FleetErrors.Internal, "empty result")
+                : Result<TResult>.Ok(result);
+        }
+        catch (JsonException)
+        {
+            return Result<TResult>.Fail(FleetErrors.Internal, "result could not be parsed");
+        }
+    }
+
+    public async ValueTask<bool> NotifyAsync<TParams>(NodeId node, string method, TParams parameters, JsonTypeInfo<TParams> paramsInfo, CancellationToken ct)
+    {
+        if (!_connections.TryGetValue(node, out NodeConnection? connection))
+        {
+            return false;
+        }
+
+        return await connection.SendAsync(RpcMessage.Notification(method, parameters, paramsInfo), ct);
+    }
+
+    public async ValueTask CloseAllAsync(string reason)
+    {
+        foreach (NodeConnection connection in _connections.Values.ToArray())
+        {
+            await connection.CloseAsync(reason);
+        }
+    }
+
+    public async ValueTask DisconnectAsync(NodeId node, string reason, CancellationToken ct)
+    {
+        if (_connections.TryGetValue(node, out NodeConnection? connection))
+        {
+            await connection.RevokeAsync(reason, ct);
+        }
+    }
+
+    public void NotifyChanged(NodeId node)
+    {
+        if (_connections.TryGetValue(node, out NodeConnection? connection))
+        {
+            connection.SignalStateChanged();
+        }
+    }
+
+    public void NotifyAllChanged()
+    {
+        foreach (NodeConnection connection in _connections.Values)
+        {
+            connection.SignalStateChanged();
+        }
+    }
+}
+
+/// <summary>产品注册的 RPC 方法路由。</summary>
+public sealed class FleetRouter
+{
+    public FleetRouter(RpcRouter<NodeCallContext> inner)
+    {
+        Inner = inner;
+    }
+
+    internal RpcRouter<NodeCallContext> Inner { get; }
+}