feat: add route hash storage for O(1) lookup (Gap 13.4)
Add ConcurrentDictionary<ulong, RouteConnection> _routesByHash with FNV-1a 64-bit hash key, RegisterRouteByHash/UnregisterRouteByHash/GetRouteByHash/ GetRouteByServerId methods, and HashedRouteCount property to RouteManager. Includes 10 unit tests covering determinism, distinct hashes, CRUD lifecycle, overwrite semantics, and no-op unregister.
This commit is contained in:
Joseph Doherty
199
tests/NATS.Server.Tests/Routes/RouteHashStorageTests.cs
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199
tests/NATS.Server.Tests/Routes/RouteHashStorageTests.cs
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// Reference: golang/nats-server/server/route.go — route hash map for O(1) server-ID lookup.
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// Tests for Gap 13.4: hash-based route storage added to RouteManager.
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using System.Net;
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using System.Net.Sockets;
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using Microsoft.Extensions.Logging.Abstractions;
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using NATS.Server;
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using NATS.Server.Configuration;
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using NATS.Server.Routes;
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namespace NATS.Server.Tests.Routes;
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/// <summary>
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/// Tests for the FNV-1a hash-based route storage on <see cref="RouteManager"/>.
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/// Covers <c>ComputeRouteHash</c>, <c>RegisterRouteByHash</c>,
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/// <c>UnregisterRouteByHash</c>, <c>GetRouteByHash</c>,
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/// <c>GetRouteByServerId</c>, and <c>HashedRouteCount</c>.
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/// Go reference: server/route.go — server-ID-keyed route hash map.
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/// </summary>
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public class RouteHashStorageTests
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{
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// Helper: build a RouteManager instance that is NOT started (no listener).
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// Only hash-map methods are exercised; StartAsync is never called.
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private static RouteManager CreateManager() =>
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new(
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new ClusterOptions { Host = "127.0.0.1", Port = 0 },
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new ServerStats(),
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serverId: Guid.NewGuid().ToString("N"),
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remoteSubSink: static _ => { },
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routedMessageSink: static _ => { },
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logger: NullLogger<RouteManager>.Instance);
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// Helper: create a RouteConnection backed by a loopback-connected socket.
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// RouteConnection's constructor wraps the socket in NetworkStream, which
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// requires a connected socket, so we use a listener/accept pair.
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private static RouteConnection MakeRouteConnection()
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{
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using var listener = new TcpListener(IPAddress.Loopback, 0);
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listener.Start();
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var client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
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client.Connect(IPAddress.Loopback, ((IPEndPoint)listener.LocalEndpoint).Port);
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// Accept server side so the TCP handshake completes; we hand the client
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// socket to RouteConnection and let the server-side socket be GC'd.
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_ = listener.AcceptSocket();
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return new RouteConnection(client);
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}
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// 1 -----------------------------------------------------------------------
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[Fact]
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public void ComputeRouteHash_Deterministic()
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{
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// Go reference: server/route.go — hash derivation must be stable across calls.
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const string serverId = "server-abc-123";
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var h1 = RouteManager.ComputeRouteHash(serverId);
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var h2 = RouteManager.ComputeRouteHash(serverId);
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var h3 = RouteManager.ComputeRouteHash(serverId);
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h1.ShouldBe(h2);
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h2.ShouldBe(h3);
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}
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// 2 -----------------------------------------------------------------------
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[Fact]
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public void ComputeRouteHash_DifferentInputs_DifferentHashes()
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{
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// Go reference: server/route.go — distinct server IDs must not collide.
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var h1 = RouteManager.ComputeRouteHash("server-1");
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var h2 = RouteManager.ComputeRouteHash("server-2");
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h1.ShouldNotBe(h2);
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}
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// 3 -----------------------------------------------------------------------
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[Fact]
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public void ComputeRouteHash_EmptyString_DoesNotThrow()
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{
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// Go reference: server/route.go — empty server ID is a degenerate but
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// valid input; the FNV offset basis is returned.
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var ex = Record.Exception(() => RouteManager.ComputeRouteHash(string.Empty));
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ex.ShouldBeNull();
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// The hash of an empty string equals the FNV-1a 64-bit offset basis.
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const ulong fnvOffsetBasis = 14695981039346656037UL;
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RouteManager.ComputeRouteHash(string.Empty).ShouldBe(fnvOffsetBasis);
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}
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// 4 -----------------------------------------------------------------------
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[Fact]
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public async Task RegisterRouteByHash_CanRetrieve()
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{
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// Go reference: server/route.go — after registration the connection must
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// be retrievable by its hash key.
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var mgr = CreateManager();
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await using var conn = MakeRouteConnection();
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mgr.RegisterRouteByHash("srv-A", conn);
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var hash = RouteManager.ComputeRouteHash("srv-A");
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mgr.GetRouteByHash(hash).ShouldBeSameAs(conn);
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}
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// 5 -----------------------------------------------------------------------
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[Fact]
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public async Task UnregisterRouteByHash_RemovesEntry()
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{
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// Go reference: server/route.go — deregistration removes the hash entry.
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var mgr = CreateManager();
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await using var conn = MakeRouteConnection();
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mgr.RegisterRouteByHash("srv-B", conn);
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mgr.UnregisterRouteByHash("srv-B");
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var hash = RouteManager.ComputeRouteHash("srv-B");
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mgr.GetRouteByHash(hash).ShouldBeNull();
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}
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// 6 -----------------------------------------------------------------------
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[Fact]
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public async Task GetRouteByServerId_FindsRegistered()
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{
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// Go reference: server/route.go — string-based lookup computes hash internally.
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var mgr = CreateManager();
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await using var conn = MakeRouteConnection();
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mgr.RegisterRouteByHash("srv-C", conn);
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mgr.GetRouteByServerId("srv-C").ShouldBeSameAs(conn);
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}
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// 7 -----------------------------------------------------------------------
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[Fact]
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public void GetRouteByServerId_NotRegistered_ReturnsNull()
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{
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// Go reference: server/route.go — unknown server ID yields null.
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var mgr = CreateManager();
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mgr.GetRouteByServerId("unknown-server").ShouldBeNull();
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}
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// 8 -----------------------------------------------------------------------
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[Fact]
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public async Task HashedRouteCount_MatchesRegistrations()
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{
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// Go reference: server/route.go — count reflects registered entries.
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var mgr = CreateManager();
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await using var c1 = MakeRouteConnection();
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await using var c2 = MakeRouteConnection();
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await using var c3 = MakeRouteConnection();
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mgr.HashedRouteCount.ShouldBe(0);
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mgr.RegisterRouteByHash("srv-1", c1);
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mgr.HashedRouteCount.ShouldBe(1);
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mgr.RegisterRouteByHash("srv-2", c2);
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mgr.HashedRouteCount.ShouldBe(2);
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mgr.RegisterRouteByHash("srv-3", c3);
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mgr.HashedRouteCount.ShouldBe(3);
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mgr.UnregisterRouteByHash("srv-2");
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mgr.HashedRouteCount.ShouldBe(2);
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}
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// 9 -----------------------------------------------------------------------
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[Fact]
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public async Task RegisterRouteByHash_OverwritesPrevious()
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{
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// Go reference: server/route.go — re-registering the same server ID
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// replaces the stale connection with the new one.
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var mgr = CreateManager();
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await using var old = MakeRouteConnection();
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await using var replacement = MakeRouteConnection();
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mgr.RegisterRouteByHash("srv-D", old);
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mgr.RegisterRouteByHash("srv-D", replacement);
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mgr.GetRouteByServerId("srv-D").ShouldBeSameAs(replacement);
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mgr.HashedRouteCount.ShouldBe(1);
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}
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// 10 ----------------------------------------------------------------------
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[Fact]
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public async Task UnregisterRouteByHash_NonExistent_NoOp()
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{
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// Go reference: server/route.go — removing a hash key that was never
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// registered must not throw and must not alter the count.
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var mgr = CreateManager();
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await using var conn = MakeRouteConnection();
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mgr.RegisterRouteByHash("srv-E", conn);
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var ex = Record.Exception(() => mgr.UnregisterRouteByHash("does-not-exist"));
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ex.ShouldBeNull();
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mgr.HashedRouteCount.ShouldBe(1);
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}
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}
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