77 lines
3.0 KiB
C#
77 lines
3.0 KiB
C#
using Npgsql.Util;
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using System;
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using System.Collections.Concurrent;
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namespace Npgsql.Internal;
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/// <summary>
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/// Cache for cluster's state
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/// </summary>
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public static class ClusterStateCache
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{
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static readonly ConcurrentDictionary<ClusterIdentifier, ClusterInfo> Clusters = new();
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internal static ClusterState GetClusterState(string host, int port, bool ignoreExpiration)
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=> Clusters.TryGetValue(new(host, port), out var cs) && (ignoreExpiration || !cs.Timeout.HasExpired)
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? cs.State
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: ClusterState.Unknown;
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#if NETSTANDARD2_0
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internal static ClusterState UpdateClusterState(string host, int port, ClusterState state, DateTime timeStamp, TimeSpan stateExpiration)
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=> Clusters.AddOrUpdate(
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new ClusterIdentifier(host, port),
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new ClusterInfo(state, new NpgsqlTimeout(stateExpiration), timeStamp),
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(_, oldInfo) => oldInfo.TimeStamp >= timeStamp ? oldInfo : new ClusterInfo(state, new NpgsqlTimeout(stateExpiration), timeStamp)).State;
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#else
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internal static ClusterState UpdateClusterState(string host, int port, ClusterState state, DateTime timeStamp, TimeSpan stateExpiration)
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=> Clusters.AddOrUpdate(
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new ClusterIdentifier(host, port),
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static (_, newInfo) => newInfo,
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static (_, oldInfo, newInfo) => oldInfo.TimeStamp >= newInfo.TimeStamp ? oldInfo : newInfo,
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new ClusterInfo(state, new NpgsqlTimeout(stateExpiration), timeStamp)).State;
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#endif
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/// <summary>
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/// Removes the specified cluster's state from cache
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/// </summary>
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/// <param name="host">Host address</param>
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/// <param name="port">Host port</param>
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public static void RemoveClusterState(string host, int port)
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=> Clusters.TryRemove(new ClusterIdentifier(host, port), out _);
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/// <summary>
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/// Removes every cluster's state from cache
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/// </summary>
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public static void Clear() => Clusters.Clear();
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readonly struct ClusterIdentifier : IEquatable<ClusterIdentifier>
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{
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readonly string _host;
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readonly int _port;
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public ClusterIdentifier(string host, int port) => (_host, _port) = (host, port);
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public override bool Equals(object? obj) => obj is ClusterIdentifier other && Equals(other);
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public bool Equals(ClusterIdentifier other) => _port == other._port && _host == other._host;
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public override int GetHashCode() => HashCode.Combine(_host, _port);
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}
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readonly struct ClusterInfo
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{
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internal readonly ClusterState State;
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internal readonly NpgsqlTimeout Timeout;
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// While the TimeStamp is not strictly required, it does lower the risk of overwriting the current state with an old value
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internal readonly DateTime TimeStamp;
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public ClusterInfo(ClusterState state, NpgsqlTimeout timeout, DateTime timeStamp)
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=> (State, Timeout, TimeStamp) = (state, timeout, timeStamp);
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}
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}
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enum ClusterState : byte
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{
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Unknown = 0,
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Offline = 1,
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PrimaryReadWrite = 2,
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PrimaryReadOnly = 3,
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Standby = 4
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} |