src/ReverseProxy/Configuration/InMemoryConfigProvider.cs - main - aprogrammer/reverse-proxy-ms-yarp

src/ReverseProxy/Configuration/InMemoryConfigProvider.cs
107 строк4 KB
Thomas Carlier
Typos (#2547)
23 июл 2024, 20:30
23 июл 2024, 20:30cb0cdec
// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

using System;
using System.Collections.Generic;
using System.Threading;
using Microsoft.Extensions.Primitives;

namespace Yarp.ReverseProxy.Configuration;

/// <summary>
/// Provides an implementation of IProxyConfigProvider to support config being generated by code.
/// </summary>
public sealed class InMemoryConfigProvider : IProxyConfigProvider
{
    // Marked as volatile so that updates are atomic
    private volatile InMemoryConfig _config;

    /// <summary>
    /// Creates a new instance.
    /// </summary>
    public InMemoryConfigProvider(IReadOnlyList<RouteConfig> routes, IReadOnlyList<ClusterConfig> clusters)
        : this(routes, clusters, Guid.NewGuid().ToString())
    { }

    /// <summary>
    /// Creates a new instance, specifying a revision id of the configuration.
    /// </summary>
    public InMemoryConfigProvider(IReadOnlyList<RouteConfig> routes, IReadOnlyList<ClusterConfig> clusters, string revisionId)
    {
        _config = new InMemoryConfig(routes, clusters, revisionId);
    }

    /// <summary>
    /// Implementation of the IProxyConfigProvider.GetConfig method to supply the current snapshot of configuration
    /// </summary>
    /// <returns>An immutable snapshot of the current configuration state</returns>
    public IProxyConfig GetConfig() => _config;

    /// <summary>
    /// Swaps the config state with a new snapshot of the configuration, then signals that the old one is outdated.
    /// </summary>
    public void Update(IReadOnlyList<RouteConfig> routes, IReadOnlyList<ClusterConfig> clusters)
    {
        var newConfig = new InMemoryConfig(routes, clusters);
        UpdateInternal(newConfig);
    }

    /// <summary>
    /// Swaps the config state with a new snapshot of the configuration, then signals that the old one is outdated.
    /// </summary>
    public void Update(IReadOnlyList<RouteConfig> routes, IReadOnlyList<ClusterConfig> clusters, string revisionId)
    {
        var newConfig = new InMemoryConfig(routes, clusters, revisionId);
        UpdateInternal(newConfig);
    }

    private void UpdateInternal(InMemoryConfig newConfig)
    {
        var oldConfig = Interlocked.Exchange(ref _config, newConfig);
        oldConfig.SignalChange();
    }

    /// <summary>
    /// Implementation of IProxyConfig which is a snapshot of the current config state. The data for this class should be immutable.
    /// </summary>
    private class InMemoryConfig : IProxyConfig
    {
        // Used to implement the change token for the state
        private readonly CancellationTokenSource _cts = new CancellationTokenSource();

        public InMemoryConfig(IReadOnlyList<RouteConfig> routes, IReadOnlyList<ClusterConfig> clusters)
            : this(routes, clusters, Guid.NewGuid().ToString())
        { }

        public InMemoryConfig(IReadOnlyList<RouteConfig> routes, IReadOnlyList<ClusterConfig> clusters, string revisionId)
        {
            RevisionId = revisionId ?? throw new ArgumentNullException(nameof(revisionId));
            Routes = routes;
            Clusters = clusters;
            ChangeToken = new CancellationChangeToken(_cts.Token);
        }

        /// <inheritdoc/>
        public string RevisionId { get; }

        /// <summary>
        /// A snapshot of the list of routes for the proxy
        /// </summary>
        public IReadOnlyList<RouteConfig> Routes { get; }

        /// <summary>
        /// A snapshot of the list of Clusters which are collections of interchangeable destination endpoints
        /// </summary>
        public IReadOnlyList<ClusterConfig> Clusters { get; }

        /// <summary>
        /// Fired to indicate the proxy state has changed, and that this snapshot is now stale
        /// </summary>
        public IChangeToken ChangeToken { get; }

        internal void SignalChange()
        {
            _cts.Cancel();
        }
    }
}