feat: Buff middleware handlers

|
|  Added implicit support for middleware post processing of files before the filehandler closes the connection. Also cleaned up some project file stuff

1 files changed, 187 insertions, 0 deletions

diff --git a/lib/Plugins.Essentials/src/Endpoints/SemiConsistentVeTable.cs b/lib/Plugins.Essentials/src/Endpoints/SemiConsistentVeTable.cs
new file mode 100644
index 0000000..09ab151
--- /dev/null
+++ b/lib/Plugins.Essentials/src/Endpoints/SemiConsistentVeTable.cs
@@ -0,0 +1,187 @@
+/*
+* Copyright (c) 2024 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: VNLib.Plugins.Essentials
+* File: SemiConsistentVeTable.cs 
+*
+* SemiConsistentVeTable.cs is part of VNLib.Plugins.Essentials which 
+* is part of the larger VNLib collection of libraries and utilities.
+*
+* VNLib.Plugins.Essentials 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.Essentials 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.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Collections.Frozen;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+
+using VNLib.Net.Http;
+
+namespace VNLib.Plugins.Essentials.Endpoints
+{
+    internal sealed class SemiConsistentVeTable : IVirtualEndpointTable
+    {
+
+        /*
+        * The VE table is read-only for the processor and my only 
+        * be updated by the application via the methods below
+        * 
+        * Since it would be very inefficient to track endpoint users
+        * using locks, we can assume any endpoint that is currently 
+        * processing requests cannot be stopped, so we just focus on
+        * swapping the table when updates need to be made.
+        * 
+        * This means calls to modify the table will read the table 
+        * (clone it), modify the local copy, then exhange it for 
+        * the active table so new requests will be processed on the 
+        * new table.
+        * 
+        * To make the calls to modify the table thread safe, a lock is 
+        * held while modification operations run, then the updated
+        * copy is published. Any threads reading the old table
+        * will continue to use a stale endpoint. 
+       */
+
+        /// <summary>
+        /// A "lookup table" that represents virtual endpoints to be processed when an
+        /// incomming connection matches its path parameter
+        /// </summary>
+        private FrozenDictionary<string, IVirtualEndpoint<HttpEntity>> VirtualEndpoints =
+            new Dictionary<string, IVirtualEndpoint<HttpEntity>>(StringComparer.OrdinalIgnoreCase)
+            .ToFrozenDictionary();
+
+        private bool _isEmpty = true;
+
+        /*
+         * A lock that is held by callers that intend to 
+         * modify the vep table at the same time
+         */
+        private readonly object VeUpdateLock = new();
+
+        ///<inheritdoc/>
+        public bool IsEmpty => _isEmpty;
+
+
+        ///<inheritdoc/>
+        public void AddEndpoint(params IEndpoint[] endpoints)
+        {
+            //Check
+            ArgumentNullException.ThrowIfNull(endpoints);
+            //Make sure all endpoints specify a path
+            if (endpoints.Any(static e => string.IsNullOrWhiteSpace(e?.Path)))
+            {
+                throw new ArgumentException("Endpoints array contains one or more empty endpoints");
+            }
+
+            if (endpoints.Length == 0)
+            {
+                return;
+            }
+
+            //Get virtual endpoints
+            IEnumerable<IVirtualEndpoint<HttpEntity>> eps = endpoints
+                                        .Where(static e => e is IVirtualEndpoint<HttpEntity>)
+                                        .Select(static e => (IVirtualEndpoint<HttpEntity>)e);
+
+            //Get http event endpoints and create wrapper classes for conversion
+            IEnumerable<IVirtualEndpoint<HttpEntity>> evs = endpoints
+                                        .Where(static e => e is IVirtualEndpoint<IHttpEvent>)
+                                        .Select(static e => new EvEndpointWrapper((e as IVirtualEndpoint<IHttpEvent>)!));
+
+            //Uinion endpoints by their paths to combine them
+            IEnumerable<IVirtualEndpoint<HttpEntity>> allEndpoints = eps.UnionBy(evs, static s => s.Path);
+
+            //Only allow 1 thread at a time to mutate the table
+            lock (VeUpdateLock)
+            {
+                //Clone the current dictonary
+                Dictionary<string, IVirtualEndpoint<HttpEntity>> newTable = new(VirtualEndpoints, StringComparer.OrdinalIgnoreCase);
+                //Insert the new eps, and/or overwrite old eps
+                foreach (IVirtualEndpoint<HttpEntity> ep in allEndpoints)
+                {
+                    newTable.Add(ep.Path, ep);
+                }
+
+                //Update is-empty flag
+                _isEmpty = newTable.Count == 0;
+
+                //Create the new table and store the entire table
+                _ = Interlocked.Exchange(ref VirtualEndpoints, newTable.ToFrozenDictionary(StringComparer.OrdinalIgnoreCase));
+            }
+        }
+
+        ///<inheritdoc/>
+        public void RemoveEndpoint(params IEndpoint[] eps)
+        {
+            ArgumentNullException.ThrowIfNull(eps);
+            //Call remove on path
+            RemoveEndpoint(eps.Select(static s => s.Path).ToArray());
+        }
+
+        ///<inheritdoc/>
+        public void RemoveEndpoint(params string[] paths)
+        {
+            ArgumentNullException.ThrowIfNull(paths);
+
+            //Make sure all endpoints specify a path
+            if (paths.Any(static e => string.IsNullOrWhiteSpace(e)))
+            {
+                throw new ArgumentException("Paths array contains one or more empty strings");
+            }
+
+            if (paths.Length == 0)
+            {
+                return;
+            }
+
+            //take update lock
+            lock (VeUpdateLock)
+            {
+                //Clone the current dictonary
+                Dictionary<string, IVirtualEndpoint<HttpEntity>> newTable = new(VirtualEndpoints, StringComparer.OrdinalIgnoreCase);
+
+                foreach (string eps in paths)
+                {
+                    _ = newTable.Remove(eps);
+                }
+
+                //Update is-empty flag
+                _isEmpty = newTable.Count == 0;
+
+                //Store the new table
+                _ = Interlocked.Exchange(ref VirtualEndpoints, newTable.ToFrozenDictionary(StringComparer.OrdinalIgnoreCase));
+            }
+        }
+
+        ///<inheritdoc/>
+        public bool TryGetEndpoint(string path, [NotNullWhen(true)] out IVirtualEndpoint<HttpEntity>? endpoint)
+            => VirtualEndpoints.TryGetValue(path, out endpoint);
+
+
+        /* 
+         * Wrapper class for converting IHttpEvent endpoints to 
+         * httpEntityEndpoints
+         */
+        private sealed class EvEndpointWrapper(IVirtualEndpoint<IHttpEvent> Wrapped) : IVirtualEndpoint<HttpEntity>
+        {
+            string IEndpoint.Path => Wrapped.Path;
+
+            ValueTask<VfReturnType> IVirtualEndpoint<HttpEntity>.Process(HttpEntity entity) => Wrapped.Process(entity);
+        }
+    }
+}
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