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feat: implemented LRU caching for flagd provider (#47)
Signed-off-by: Florian Bacher <[email protected]>
1 parent 04bdae0 commit f4d2142

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7 files changed

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7 files changed

+922
-50
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Diff for: ‎src/OpenFeature.Contrib.Providers.Flagd/Cache.cs

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using System.Collections.Generic;
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using System.Runtime.CompilerServices;
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[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]
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namespace OpenFeature.Contrib.Providers.Flagd
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{
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internal interface ICache<TKey, TValue>
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{
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void Add(TKey key, TValue value);
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TValue TryGet(TKey key);
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void Delete(TKey key);
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void Purge();
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}
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class LRUCache<TKey, TValue> : ICache<TKey, TValue> where TValue : class
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{
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private readonly int _capacity;
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private readonly Dictionary<TKey, Node> _map;
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private Node _head;
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private Node _tail;
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private System.Threading.Mutex _mtx;
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public LRUCache(int capacity)
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{
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_capacity = capacity;
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_map = new Dictionary<TKey, Node>();
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_mtx = new System.Threading.Mutex();
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}
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public TValue TryGet(TKey key)
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{
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using (var mtx = new Mutex(ref _mtx))
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{
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mtx.Lock();
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if (_map.TryGetValue(key, out Node node))
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{
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MoveToFront(node);
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return node.Value;
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}
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return default(TValue);
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}
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}
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public void Add(TKey key, TValue value)
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{
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using (var mtx = new Mutex(ref _mtx))
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{
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mtx.Lock();
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if (_map.TryGetValue(key, out Node node))
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{
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node.Value = value;
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MoveToFront(node);
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}
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else
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{
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if (_map.Count >= _capacity)
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{
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_map.Remove(_tail.Key);
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RemoveTail();
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}
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node = new Node(key, value);
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_map.Add(key, node);
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AddToFront(node);
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}
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}
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}
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public void Delete(TKey key)
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{
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using (var mtx = new Mutex(ref _mtx))
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{
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mtx.Lock();
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if (_map.TryGetValue(key, out Node node))
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{
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if (node == _head)
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{
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_head = node.Next;
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}
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else
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{
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node.Prev.Next = node.Next;
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}
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if (node.Next != null)
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{
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node.Next.Prev = node.Prev;
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}
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_map.Remove(key);
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}
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}
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}
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public void Purge()
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{
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using (var mtx = new Mutex(ref _mtx))
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{
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mtx.Lock();
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_map.Clear();
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}
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}
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private void MoveToFront(Node node)
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{
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if (node == _head)
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return;
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node.Prev.Next = node.Next;
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if (node == _tail)
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_tail = node.Prev;
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else
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node.Next.Prev = node.Prev;
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AddToFront(node);
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}
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private void AddToFront(Node node)
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{
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if (_head == null)
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{
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_head = node;
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_tail = node;
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return;
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}
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node.Next = _head;
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_head.Prev = node;
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_head = node;
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}
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private void RemoveTail()
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{
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_tail = _tail.Prev;
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if (_tail != null)
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_tail.Next = null;
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else
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_head = null;
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}
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private class Node
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{
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public TKey Key;
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public TValue Value;
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public Node Next;
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public Node Prev;
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public Node(TKey key, TValue value)
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{
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Key = key;
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Value = value;
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}
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}
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private class Mutex : System.IDisposable
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{
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public System.Threading.Mutex _mtx;
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public Mutex(ref System.Threading.Mutex mtx)
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{
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_mtx = mtx;
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}
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public void Lock()
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{
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_mtx.WaitOne();
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}
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public void Dispose()
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{
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_mtx.ReleaseMutex();
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}
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}
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}
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}
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Diff for: ‎src/OpenFeature.Contrib.Providers.Flagd/FlagdConfig.cs

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using System;
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namespace OpenFeature.Contrib.Providers.Flagd
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{
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internal class FlagdConfig
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{
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internal const string EnvVarHost = "FLAGD_HOST";
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internal const string EnvVarPort = "FLAGD_PORT";
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internal const string EnvVarTLS = "FLAGD_TLS";
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internal const string EnvVarSocketPath = "FLAGD_SOCKET_PATH";
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internal const string EnvVarCache = "FLAGD_CACHE";
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internal const string EnvVarMaxCacheSize = "FLAGD_MAX_CACHE_SIZE";
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internal const string EnvVarMaxEventStreamRetries = "FLAGD_MAX_EVENT_STREAM_RETRIES";
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internal static int CacheSizeDefault = 10;
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internal string Host
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{
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get { return _host; }
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}
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internal bool CacheEnabled
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{
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get { return _cache; }
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set { _cache = value; }
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}
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internal int MaxCacheSize
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{
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get { return _maxCacheSize; }
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}
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internal int MaxEventStreamRetries
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{
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get { return _maxEventStreamRetries; }
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set { _maxEventStreamRetries = value; }
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}
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private string _host;
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private string _port;
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private bool _useTLS;
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private string _socketPath;
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private bool _cache;
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private int _maxCacheSize;
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private int _maxEventStreamRetries;
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internal FlagdConfig()
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{
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_host = Environment.GetEnvironmentVariable(EnvVarHost) ?? "localhost";
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_port = Environment.GetEnvironmentVariable(EnvVarPort) ?? "8013";
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_useTLS = bool.Parse(Environment.GetEnvironmentVariable(EnvVarTLS) ?? "false");
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_socketPath = Environment.GetEnvironmentVariable(EnvVarSocketPath) ?? "";
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var cacheStr = Environment.GetEnvironmentVariable(EnvVarCache) ?? "";
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if (cacheStr.ToUpper().Equals("LRU"))
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{
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_cache = true;
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_maxCacheSize = int.Parse(Environment.GetEnvironmentVariable(EnvVarMaxCacheSize) ?? $"{CacheSizeDefault}");
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_maxEventStreamRetries = int.Parse(Environment.GetEnvironmentVariable(EnvVarMaxEventStreamRetries) ?? "3");
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}
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}
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internal Uri GetUri()
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{
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Uri uri;
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if (_socketPath != "")
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{
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uri = new Uri("unix://" + _socketPath);
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}
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else
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{
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var protocol = "http";
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if (_useTLS)
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{
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protocol = "https";
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}
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uri = new Uri(protocol + "://" + _host + ":" + _port);
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}
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return uri;
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}
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}
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}

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