Large project reorder and consolidation

1 files changed, 263 insertions, 0 deletions

diff --git a/lib/VNLib.Data.Caching.ObjectCache/src/ObjectCacheStore.cs b/lib/VNLib.Data.Caching.ObjectCache/src/ObjectCacheStore.cs
new file mode 100644
index 0000000..514d00b
--- /dev/null
+++ b/lib/VNLib.Data.Caching.ObjectCache/src/ObjectCacheStore.cs
@@ -0,0 +1,263 @@
+/*
+* Copyright (c) 2022 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: VNLib.Data.Caching.ObjectCache
+* File: ObjectCacheStore.cs 
+*
+* ObjectCacheStore.cs is part of VNLib.Data.Caching.ObjectCache which is part of the larger 
+* VNLib collection of libraries and utilities.
+*
+* VNLib.Data.Caching.ObjectCache 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.Data.Caching.ObjectCache 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.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+using VNLib.Utils.Async;
+using VNLib.Utils.Memory;
+using VNLib.Utils.Logging;
+using VNLib.Utils.Extensions;
+using VNLib.Net.Messaging.FBM.Server;
+using static VNLib.Data.Caching.Constants;
+
+namespace VNLib.Data.Caching.ObjectCache
+{
+    public delegate ReadOnlySpan<byte> GetBodyDataCallback<T>(T state);
+
+    /// <summary>
+    /// A <see cref="FBMListener"/> implementation of a <see cref="CacheListener"/>
+    /// </summary>
+    public class ObjectCacheStore : CacheListener, IDisposable
+    {
+        private readonly SemaphoreSlim StoreLock;
+        private bool disposedValue;
+
+        ///<inheritdoc/>
+        protected override ILogProvider Log { get; }
+
+        /// <summary>
+        /// A queue that stores update and delete events
+        /// </summary>
+        public AsyncQueue<ChangeEvent> EventQueue { get; }
+
+        /// <summary>
+        /// Initialzies a new <see cref="ObjectCacheStore"/>
+        /// </summary>
+        /// <param name="dir">The <see cref="DirectoryInfo"/> to store blob files to</param>
+        /// <param name="cacheMax"></param>
+        /// <param name="log"></param>
+        /// <param name="heap"></param>
+        /// <param name="singleReader">A value that indicates if a single thread is processing events</param>
+        public ObjectCacheStore(DirectoryInfo dir, int cacheMax, ILogProvider log, IUnmangedHeap heap, bool singleReader)
+        {
+            Log = log;
+            //We can use a single writer and single reader in this context
+            EventQueue = new(true, singleReader);
+            InitCache(dir, cacheMax, heap);
+            InitListener(heap);
+            StoreLock = new(1,1);
+        }
+
+        ///<inheritdoc/>
+        protected override async Task ProcessAsync(FBMContext context, object? userState, CancellationToken cancellationToken)
+        {
+            try
+            {
+                //Get the action header
+                string action = context.Method();
+                //Optional newid header
+                string? alternateId = context.NewObjectId();
+
+                switch (action)
+                {
+                    case Actions.Get:
+                        {
+                            //Get the object-id header
+                            string objectId = context.ObjectId();
+                            //Take lock on store 
+                            using SemSlimReleaser rel = await StoreLock.GetReleaserAsync(cancellationToken: cancellationToken);
+                            if (Cache!.TryGetValue(objectId, out MemoryHandle<byte>? data))
+                            {
+                                //Set the status code and write the buffered data to the response buffer
+                                context.CloseResponse(ResponseCodes.Okay);
+                                //Copy data to response buffer
+                                context.Response.WriteBody(data.Span);
+                            }
+                            else
+                            {
+                                context.CloseResponse(ResponseCodes.NotFound);
+                            }
+                        }
+                        break;
+                    case Actions.AddOrUpdate:
+                        {
+                            //Get the object-id header
+                            string objectId = context.ObjectId();
+                            //Add/update a blob async
+                            await AddOrUpdateBlobAsync(objectId, alternateId, static context => context.Request.BodyData, context);
+                            //Notify update the event bus
+                            await EventQueue.EnqueueAsync(new(objectId, alternateId, false), cancellationToken);
+                            //Set status code
+                            context.CloseResponse(ResponseCodes.Okay);                           
+                        }
+                        break;
+                    case Actions.Delete:
+                        {
+                            //Get the object-id header
+                            string objectId = context.ObjectId();
+                           
+                            if (await DeleteItemAsync(objectId))
+                            {
+                                //Notify deleted
+                                await EventQueue.EnqueueAsync(new(objectId, null, true), cancellationToken);
+                                //Set status header
+                                context.CloseResponse(ResponseCodes.Okay);
+                            }
+                            else
+                            {
+                                //Set status header
+                                context.CloseResponse(ResponseCodes.NotFound);
+                            }
+                        }
+                        break;
+                    // event queue dequeue request
+                    case Actions.Dequeue:
+                        {
+                            //If no event bus is registered, then this is not a legal command
+                            if (userState is not AsyncQueue<ChangeEvent> eventBus)
+                            {
+                                context.CloseResponse(ResponseCodes.NotFound);
+                                break;
+                            }
+                            //Wait for a new message to process
+                            ChangeEvent ev = await eventBus.DequeueAsync(cancellationToken);
+                            if (ev.Deleted)
+                            {
+                                context.CloseResponse("deleted");
+                                context.Response.WriteHeader(ObjectId, ev.CurrentId);
+                            }
+                            else
+                            {
+                                //Changed
+                                context.CloseResponse("modified");
+                                context.Response.WriteHeader(ObjectId, ev.CurrentId);
+                                //Set old id if an old id is set
+                                if (ev.CurrentId != null)
+                                {
+                                    context.Response.WriteHeader(NewObjectId, ev.AlternateId);
+                                }
+                            }
+                        }
+                        break;
+                }
+            }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
+            catch(Exception ex)
+            {
+                //Log error and set error status code
+                Log.Error(ex);
+                context.CloseResponse(ResponseCodes.Error);
+            }
+        }
+
+        /// <summary>
+        /// Asynchronously deletes a previously stored item
+        /// </summary>
+        /// <param name="id">The id of the object to delete</param>
+        /// <returns>A task that completes when the item has been deleted</returns>
+        public async Task<bool> DeleteItemAsync(string id)
+        {
+            using SemSlimReleaser rel = await StoreLock.GetReleaserAsync();
+            return Cache!.Remove(id);
+        }
+        
+        /// <summary>
+        /// Asynchronously adds or updates an object in the store and optionally update's its id
+        /// </summary>
+        /// <param name="objectId">The current (or old) id of the object</param>
+        /// <param name="alternateId">An optional id to update the blob to</param>
+        /// <param name="bodyData">A callback that returns the data for the blob</param>
+        /// <param name="state">The state parameter to pass to the data callback</param>
+        /// <returns></returns>
+        public async Task AddOrUpdateBlobAsync<T>(string objectId, string? alternateId, GetBodyDataCallback<T> bodyData, T state)
+        {
+            MemoryHandle<byte>? blob;
+            //See if new/alt session id was specified
+            if (string.IsNullOrWhiteSpace(alternateId))
+            {
+                //Take lock on store 
+                using SemSlimReleaser rel = await StoreLock.GetReleaserAsync();
+                //See if blob exists
+                if (!Cache!.TryGetValue(objectId, out blob))
+                {
+                    //If not, create new blob and add to store
+                    blob = Heap.AllocAndCopy(bodyData(state));
+                    Cache.Add(objectId, blob);
+                }
+                else
+                {
+                    //Reset the buffer state
+                    blob.WriteAndResize(bodyData(state));
+                }
+            }
+            //Need to change the id of the record
+            else
+            {
+                //Take lock on store 
+                using SemSlimReleaser rel = await StoreLock.GetReleaserAsync();
+                //Try to change the blob key
+                if (!Cache!.TryChangeKey(objectId, alternateId, out blob))
+                {
+                    //Blob not found, create new blob
+                    blob = Heap.AllocAndCopy(bodyData(state));
+                    Cache.Add(alternateId, blob);
+                }
+                else
+                {
+                    //Reset the buffer state
+                    blob.WriteAndResize(bodyData(state));
+                }
+            }
+        }
+        
+        ///<inheritdoc/>
+        protected virtual void Dispose(bool disposing)
+        {
+            if (!disposedValue)
+            {
+                if (disposing)
+                {
+                    Cache?.Clear();
+                }
+                
+                StoreLock.Dispose();
+                
+                disposedValue = true;
+            }
+        }
+        ///<inheritdoc/>
+        public void Dispose()
+        {
+            // Do not change this code. Put cleanup code in 'Dispose(bool disposing)' method
+            Dispose(disposing: true);
+            GC.SuppressFinalize(this);
+        }
+    }
+}