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Diffstat (limited to 'libs/VNLib.Plugins.Sessions.Cache.Client/src/SessionCacheClient.cs')
| -rw-r--r-- | libs/VNLib.Plugins.Sessions.Cache.Client/src/SessionCacheClient.cs | 251 |
1 files changed, 0 insertions, 251 deletions
diff --git a/libs/VNLib.Plugins.Sessions.Cache.Client/src/SessionCacheClient.cs b/libs/VNLib.Plugins.Sessions.Cache.Client/src/SessionCacheClient.cs deleted file mode 100644 index 20ea947..0000000 --- a/libs/VNLib.Plugins.Sessions.Cache.Client/src/SessionCacheClient.cs +++ /dev/null @@ -1,251 +0,0 @@ -/* -* Copyright (c) 2022 Vaughn Nugent -* -* Library: VNLib -* Package: VNLib.Plugins.Sessions.Cache.Client -* File: SessionCacheClient.cs -* -* SessionCacheClient.cs is part of VNLib.Plugins.Sessions.Cache.Client which is part of the larger -* VNLib collection of libraries and utilities. -* -* VNLib.Plugins.Sessions.Cache.Client is free software: you can redistribute it and/or modify -* it under the terms of the GNU Affero General Public License as -* published by the Free Software Foundation, either version 3 of the -* License, or (at your option) any later version. -* -* VNLib.Plugins.Sessions.Cache.Client is distributed in the hope that it will be useful, -* but WITHOUT ANY WARRANTY; without even the implied warranty of -* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -* GNU Affero General Public License for more details. -* -* You should have received a copy of the GNU Affero General Public License -* along with this program. If not, see https://www.gnu.org/licenses/. -*/ - -using System; -using System.Threading; -using System.Threading.Tasks; -using System.Collections.Generic; -using System.Diagnostics.CodeAnalysis; - -using VNLib.Net.Http; -using VNLib.Utils.Async; -using VNLib.Utils.Logging; -using VNLib.Utils.Memory.Caching; -using VNLib.Plugins.Essentials.Sessions; - -namespace VNLib.Plugins.Sessions.Cache.Client -{ - - /// <summary> - /// A client that allows access to sessions located on external servers - /// </summary> - public abstract class SessionCacheClient : ICacheHolder - { - public class LRUSessionStore<T> : LRUCache<string, T>, ICacheHolder where T : ISession - { - internal AsyncQueue<T> ExpiredSessions { get; } - - ///<inheritdoc/> - public override bool IsReadOnly => false; - ///<inheritdoc/> - protected override int MaxCapacity { get; } - - - public LRUSessionStore(int maxCapacity) : base(StringComparer.Ordinal) - { - MaxCapacity = maxCapacity; - ExpiredSessions = new (true, true); - } - - ///<inheritdoc/> - protected override bool CacheMiss(string key, [NotNullWhen(true)] out T? value) - { - value = default; - return false; - } - - ///<inheritdoc/> - protected override void Evicted(ref KeyValuePair<string, T> evicted) - { - //add to queue, the list lock should be held during this operatio - _ = ExpiredSessions.TryEnque(evicted.Value); - } - - ///<inheritdoc/> - public void CacheClear() - { - foreach (KeyValuePair<string, T> value in List) - { - KeyValuePair<string, T> onStack = value; - - Evicted(ref onStack); - } - - Clear(); - } - - ///<inheritdoc/> - public void CacheHardClear() - { - CacheClear(); - } - } - - protected readonly LRUSessionStore<RemoteSession> CacheTable; - protected readonly object CacheLock; - protected readonly int MaxLoadedEntires; - - /// <summary> - /// The client used to communicate with the cache server - /// </summary> - protected IRemoteCacheStore Store { get; } - - /// <summary> - /// Gets a value that determines if the backing <see cref="IRemoteCacheStore"/> is connected - /// to a server - /// </summary> - public bool IsConnected => Store.IsConnected; - - /// <summary> - /// Initializes a new <see cref="SessionCacheClient"/> - /// </summary> - /// <param name="client"></param> - /// <param name="maxCacheItems">The maximum number of sessions to keep in memory</param> - protected SessionCacheClient(IRemoteCacheStore client, int maxCacheItems) - { - MaxLoadedEntires = maxCacheItems; - CacheLock = new(); - CacheTable = new(maxCacheItems); - Store = client; - } - - private ulong _waitingCount; - - /// <summary> - /// The number of pending connections waiting for results from the cache server - /// </summary> - public ulong WaitingConnections => _waitingCount; - - /// <summary> - /// Attempts to get a session from the cache identified by its sessionId asynchronously - /// </summary> - /// <param name="entity">The connection/request to attach the session to</param> - /// <param name="sessionId">The ID of the session to retrieve</param> - /// <param name="cancellationToken">A token to cancel the operation</param> - /// <returns>A <see cref="ValueTask"/> that resolves the remote session</returns> - /// <exception cref="SessionException"></exception> - public virtual async ValueTask<RemoteSession> GetSessionAsync(IHttpEvent entity, string sessionId, CancellationToken cancellationToken) - { - try - { - RemoteSession? session; - //Aquire lock on cache - lock (CacheLock) - { - //See if session is loaded into cache - if (!CacheTable.TryGetValue(sessionId, out session)) - { - //Init new record - session = SessionCtor(sessionId); - //Add to cache - CacheTable.Add(session.SessionID, session); - } - //Valid entry found in cache - } - - //Inc waiting count - Interlocked.Increment(ref _waitingCount); - - try - { - //Load session-data - await session.WaitAndLoadAsync(entity, cancellationToken); - return session; - } - catch - { - //Remove the invalid cached session - lock (CacheLock) - { - _ = CacheTable.Remove(sessionId); - } - throw; - } - finally - { - //Dec waiting count - Interlocked.Decrement(ref _waitingCount); - } - } - catch (SessionException) - { - throw; - } - catch (OperationCanceledException) - { - throw; - } - //Wrap exceptions - catch (Exception ex) - { - throw new SessionException("An unhandled exception was raised", ex); - } - } - - /// <summary> - /// Gets a new <see cref="RemoteSession"/> instances for the given sessionId, - /// and places it a the head of internal cache - /// </summary> - /// <param name="sessionId">The session identifier</param> - /// <returns>The new session for the given ID</returns> - protected abstract RemoteSession SessionCtor(string sessionId); - - /// <summary> - /// Begins waiting for expired sessions to be evicted from the cache table that - /// may have pending synchronization operations - /// </summary> - /// <param name="log"></param> - /// <param name="token"></param> - /// <returns></returns> - public async Task CleanupExpiredSessionsAsync(ILogProvider log, CancellationToken token) - { - while (true) - { - try - { - //Wait for expired session and dispose it - using RemoteSession session = await CacheTable.ExpiredSessions.DequeueAsync(token); - - //Obtain lock on session - await session.WaitOneAsync(CancellationToken.None); - - log.Verbose("Removed expired session {id}", session.SessionID); - } - catch (OperationCanceledException) - { - break; - } - catch(Exception ex) - { - log.Error(ex); - } - } - } - - ///<inheritdoc/> - public void CacheClear() - { - - } - ///<inheritdoc/> - public void CacheHardClear() - { - //Cleanup cache when disconnected - lock (CacheLock) - { - CacheTable.CacheHardClear(); - } - } - } -} |