1 files changed, 127 insertions, 0 deletions
diff --git a/Libs/VNLib.Plugins.Essentials.Sessions/MemorySessionStore.cs b/Libs/VNLib.Plugins.Essentials.Sessions/MemorySessionStore.cs
new file mode 100644
index 0000000..15c3002
--- /dev/null
+++ b/Libs/VNLib.Plugins.Essentials.Sessions/MemorySessionStore.cs
@@ -0,0 +1,127 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Collections.Generic;
+
+using VNLib.Hashing;
+using VNLib.Net.Http;
+using VNLib.Net.Sessions;
+using VNLib.Utils;
+using VNLib.Utils.Async;
+using VNLib.Utils.Extensions;
+using VNLib.Plugins.Essentials.Extensions;
+
+
+namespace VNLib.Plugins.Essentials.Sessions.Memory
+{
+
+    /// <summary>
+    /// An <see cref="ISessionProvider"/> for in-process-memory backed sessions
+    /// </summary>
+    internal sealed class MemorySessionStore : ISessionProvider
+    {
+        private readonly Dictionary<string, MemorySession> SessionsStore;
+
+        internal readonly MemorySessionConfig Config;
+
+        public MemorySessionStore(MemorySessionConfig config)
+        {
+            Config = config;
+            SessionsStore = new(config.MaxAllowedSessions, StringComparer.Ordinal);
+        }
+        
+        ///<inheritdoc/>
+        public async ValueTask<SessionHandle> GetSessionAsync(IHttpEvent entity, CancellationToken cancellationToken)
+        {
+            
+            static ValueTask SessionHandleClosedAsync(ISession session, IHttpEvent ev)
+            {
+                return (session as MemorySession).UpdateAndRelease(true, ev);
+            }
+            
+            //Check for previous session cookie
+            if (entity.Server.RequestCookies.TryGetNonEmptyValue(Config.SessionCookieID, out string sessionId))
+            {
+                //Try to get the old record or evict it
+                ERRNO result = SessionsStore.TryGetOrEvictRecord(sessionId, out MemorySession session);
+                if(result > 0)
+                {
+                    //Valid, now wait for exclusive access
+                    await session.WaitOneAsync(cancellationToken);
+                    return new (session, SessionHandleClosedAsync);
+                }
+                //Continue creating a new session
+            }
+            
+            //Dont service non browsers for new sessions
+            if (!entity.Server.IsBrowser())
+            {
+                return SessionHandle.Empty;
+            }
+            
+            //try to cleanup expired records
+            SessionsStore.CollectRecords();
+            //Make sure there is enough room to add a new session
+            if (SessionsStore.Count >= Config.MaxAllowedSessions)
+            {
+                entity.Server.SetNoCache();
+                //Set 503 when full
+                entity.CloseResponse(System.Net.HttpStatusCode.ServiceUnavailable);
+                //Cannot service new session
+                return new(null, FileProcessArgs.VirtualSkip, null);
+            }
+            //Initialze a new session
+            MemorySession ms = new(entity.Server.GetTrustedIp(), this);
+            //Set session cookie 
+            SetSessionCookie(entity, ms);
+            //Increment the semaphore
+            (ms as IWaitHandle).WaitOne();
+            //store the session in cache while holding semaphore, and set its expiration
+            SessionsStore.StoreRecord(ms.SessionID, ms, Config.SessionTimeout);
+            //Init new session handle
+            return new SessionHandle(ms, SessionHandleClosedAsync);
+        }
+
+        /// <summary>
+        /// Gets a new unique sessionid for sessions
+        /// </summary>
+        internal string NewSessionID => RandomHash.GetRandomHex((int)Config.SessionIdSizeBytes);
+
+        internal void UpdateRecord(string newSessId, MemorySession session)
+        {
+            lock (SessionsStore)
+            {
+                //Remove old record from the store
+                SessionsStore.Remove(session.SessionID);
+                //Insert the new session
+                SessionsStore.Add(newSessId, session);
+            }
+        }
+        /// <summary>
+        /// Sets a standard session cookie for an entity/connection
+        /// </summary>
+        /// <param name="entity">The entity to set the cookie on</param>
+        /// <param name="session">The session attached to the </param>
+        internal void SetSessionCookie(IHttpEvent entity, MemorySession session)
+        {
+            //Set session cookie 
+            entity.Server.SetCookie(Config.SessionCookieID, session.SessionID, null, "/", Config.SessionTimeout, CookieSameSite.Lax, true, true);
+        }
+        /// <summary>
+        /// Evicts all sessions from the current store
+        /// </summary>
+        public void Cleanup()
+        {
+            //Expire all old records to cleanup all entires
+            this.SessionsStore.CollectRecords(DateTime.MaxValue);
+        }
+        /// <summary>
+        /// Collects all expired records from the current store
+        /// </summary>
+        public void GC()
+        {
+            //collect expired records
+            this.SessionsStore.CollectRecords();
+        }
+    }
+}