Implement an AWS S3 Bucket Cache - C# .NET

using System; 
using System.Collections.Generic; 
using System.IO; 
 
using Newtonsoft.Json; 
 
using Amazon.S3; 
using Amazon.S3.IO; 
using Amazon.S3.Model; 
 
using Leadtools.Caching; 
 
namespace Leadtools.Services.Tools.Cache 
{ 
 
    /// <summary>  
    /// Wraps an AWS S3 AmazonS3Client object to be used with the LEADTOOLS Document Library  
    /// </summary>  
    public class S3BucketCache: ObjectCache 
    { 
        private S3BucketCache() { } 
 
        //S3Client used to connect to S3 Instance 
        AmazonS3Client _client; 
        //Name of the bucket holding all cache entries 
        public string _bucketName; 
 
 
        // <summary> 
        // Initialized a LEADTOOLS Object Cache wrapper from a AWS S3 Client 
        // </summary> 
        // <param name="client">Fully-initialized AmazonS3DClient object ready to be used.</param> 
        // <param name="bucketName">Name of the bucket used for the cache in your S3 implementation.</param> 
        // </summary> 
        public S3BucketCache(AmazonS3Client client, string bucketName = "LeadBucket") 
        { 
            this._client = client; 
            //If you do not pass a bucketName, then "leadbucketcache" will be the default bucketname that will be used. 
            this._bucketName = bucketName; 
        } 
 
        //  
        // These members must be implemented by our class and are called by the Document toolkit  
        //  
 
        // Name of the Cache 
        public override string Name 
        { 
            get 
            { 
                return "S3BucketCache"; 
            } 
        } 
 
        //Use JSON serialization for our policy and data files 
        public override CacheSerializationMode PolicySerializationMode 
        { 
            get 
            { 
                return CacheSerializationMode.Json; 
            } 
 
            set 
            { 
                throw new NotSupportedException(); 
            } 
        } 
 
        public override CacheSerializationMode DataSerializationMode 
        { 
            get 
            { 
                return CacheSerializationMode.Json; 
            } 
 
            set 
            { 
                throw new NotSupportedException(); 
            } 
        } 
 
        // We have no special extra support  
        public override DefaultCacheCapabilities DefaultCacheCapabilities 
        { 
            get 
            { 
                return DefaultCacheCapabilities.None; 
            } 
        } 
 
        // Method called when a cache item is added.  
        // Must return the old value  
        public override CacheItem<T> AddOrGetExisting<T>(CacheItem<T> item, CacheItemPolicy policy) 
        { 
            if (item == null) 
                throw new ArgumentNullException("item"); 
 
            // Resolve the key, remember, we do not have regions  
            var resolvedKey = ResolveKey(item.RegionName, item.Key); 
 
            CacheItem<T> oldItem = null; 
 
            // Try to get the old value 
            S3FileInfo file = new S3FileInfo(_client, _bucketName, resolvedKey); 
            if (file.Exists) 
            { 
                var oldValue = GetFromCache<T>(item.RegionName, item.Key); 
                oldItem = new CacheItem<T>(item.Key, (T)oldValue, item.RegionName); 
 
            } 
 
            // Set the new data  
            AddToCache(item, policy); 
 
            // Return old item  
            return oldItem; 
        } 
         
        public override CacheItem<T> GetCacheItem<T>(string key, string regionName) 
        { 
            // If we have an item with this key, return it. Otherwise, return null  
 
            var resolvedKey = ResolveKey(regionName, key); 
 
            CacheItem<T> item = null; 
 
            S3FileInfo file = new S3FileInfo(_client, _bucketName, resolvedKey); 
            if (file.Exists) 
            { 
                var itemValue = GetFromCache<T>(regionName, key); 
                item = new CacheItem<T>(key, (T)itemValue, regionName); 
            } 
                 
 
            return item; 
        } 
 
        // Check if they key is in the S3 bucket 
        public override bool Contains(string key, string regionName) 
        { 
            var resolvedKey = ResolveKey(regionName, key); 
 
            S3FileInfo fileInfo = new S3FileInfo(_client, _bucketName, resolvedKey); 
 
            return fileInfo.Exists; 
        } 
 
        public override bool UpdateCacheItem<T>(CacheItem<T> item) 
        { 
            // Update the item   
 
            if (item == null) 
                throw new ArgumentNullException("item"); 
 
            var resolvedKey = ResolveKey(item.RegionName, item.Key); 
            var exists = Contains(item.Key, item.RegionName); 
            if (exists) 
                AddToCache(item, null); 
            return exists; 
        } 
 
        public override T Remove<T>(string key, string regionName) 
        { 
            // Removed if exists, return old value  
            T existingValue = default(T); 
            var resolvedKey = ResolveKey(regionName, key); 
 
            if(Contains(key, regionName)) 
            { 
 
                existingValue = (T)GetFromCache<T>(regionName, key); 
            } 
 
            DeleteItem(key, regionName); 
            return existingValue; 
        } 
 
        public override void DeleteItem(string key, string regionName) 
        { 
            var resolvedKey = ResolveKey(regionName, key); 
            //Remove if exists 
            _client.DeleteObject(_bucketName, resolvedKey); 
        } 
 
        private static string ResolveKey(string regionName, string key) 
        { 
            // Both must me non-empty strings  
            if (string.IsNullOrEmpty(regionName)) throw new InvalidOperationException("Region name must be a none empty string"); 
            if (string.IsNullOrEmpty(key)) throw new InvalidOperationException("Region key name must be a none empty string"); 
 
            // We are a simple dictionary with no grouping. regionName might not be unique, key might not be unique, but combine them  
            // and we are guaranteed a unique key  
            return regionName + "/" +regionName + "-" + key; 
        } 
 
        private void AddToCache<T>(CacheItem<T> item, CacheItemPolicy policy) 
        { 
            // JSON serialize it  
            var json = JsonConvert.SerializeObject(item.Value); 
 
            // If the sliding expiration is used, make it the absolute value  
            TimeSpan? expiry = null; 
 
            if (policy != null) 
            { 
                var expiryDate = policy.AbsoluteExpiration; 
                if (policy.SlidingExpiration > TimeSpan.Zero) 
                { 
                    expiryDate = DateTime.UtcNow.Add(policy.SlidingExpiration); 
                } 
                var br = expiryDate; 
 
                // Now, we have a date, convert it to time span from now (all UTC)  
                expiry = (TimeSpan)expiryDate.Subtract(DateTime.UtcNow); 
            } 
 
            var resolvedKey = ResolveKey(item.RegionName, item.Key); 
 
            PutObjectRequest request = new PutObjectRequest 
            { 
                BucketName = _bucketName, 
                Key = resolvedKey, 
            }; 
            using(MemoryStream stream = new MemoryStream()) 
            { 
                using(StreamWriter writer = new StreamWriter(stream)) 
                { 
                    writer.Write(json); 
                    writer.Flush(); 
                    stream.Position = 0; 
 
                    request.InputStream = stream; 
                    _client.PutObject(request); 
                } 
            } 
        } 
 
        private object GetFromCache<T>(string regionName, string key) 
        { 
            var typeOfT = typeof(T); 
            object result = null; 
            var resolvedKey = ResolveKey(regionName, key); 
            var response = _client.GetObject(_bucketName, resolvedKey); 
 
            using (var reader = new StreamReader(response.ResponseStream)) 
            { 
                var fileContents = reader.ReadToEnd(); 
                result = JsonConvert.DeserializeObject<T>(fileContents); 
            } 
 
            return result; 
        } 
         
        public override void UpdatePolicy(string key, CacheItemPolicy policy, string regionName) 
        { 
            // Nothing to do  
        } 
 
        //  
        // These members must be over implemented by our class but are never called by the Documents toolkit  
        // So just throw a not supported exception  
        //  
 
        // This is for default region support. We do not have that  
        public override object this[string key] 
        { 
            get 
            { 
                throw new NotSupportedException(); 
            } 
            set 
            { 
                throw new NotSupportedException(); 
            } 
        } 
 
        // Delete a region in one shot. We do not support that  
        // Note: This is only called if we have DefaultCacheCapabilities.CacheRegions. Since we do not, the caller is responsible for  
        // calling DeleteAll passing all the items of the region (which in turn will call DeleteItem for each)  
        public override void DeleteRegion(string regionName) 
        { 
            throw new NotSupportedException(); 
        } 
 
        // Begin adding an external resource. We do not support that  
        // Note: This is only called if we have DefaultCacheCapabilities.ExternalResources  
        public override Uri BeginAddExternalResource(string key, string regionName, bool readWrite) 
        { 
            throw new NotSupportedException(); 
        } 
 
        // End adding an external resource. We do not support that  
        // Note: This is only called if we have DefaultCacheCapabilities.ExternalResources  
        public override void EndAddExternalResource<T>(bool commit, string key, T value, CacheItemPolicy policy, string regionName) 
        { 
            throw new NotSupportedException(); 
        } 
 
        // Get the item external resource. We do not support that  
        // Note: This is only called if we have DefaultCacheCapabilities.ExternalResources  
        public override Uri GetItemExternalResource(string key, string regionName, bool readWrite) 
        { 
            throw new NotSupportedException(); 
        } 
 
        // Remove the item external resource. We do not support that  
        // Note: This is only called if we have DefaultCacheCapabilities.ExternalResources  
        public override void RemoveItemExternalResource(string key, string regionName) 
        { 
            throw new NotSupportedException(); 
        } 
 
        // Get the item virtual directory path. We do not support that  
        // Note: This is only called if we have DefaultCacheCapabilities.VirtualDirectory  
        public override Uri GetItemVirtualDirectoryUrl(string key, string regionName) 
        { 
            throw new NotSupportedException(); 
        } 
 
        // Getting number of items in the cache. We do not support that  
        public override long GetCount(string regionName) 
        { 
            throw new NotSupportedException(); 
        } 
 
        // Statistics. We do not support that  
        public override CacheStatistics GetStatistics() 
        { 
            throw new NotSupportedException(); 
        } 
 
        // Statistics. We do not support that  
        public override CacheStatistics GetStatistics(string key, string regionName) 
        { 
            throw new NotSupportedException(); 
        } 
 
        // Getting all the values. We do not support that  
        public override IDictionary<string, object> GetValues(IEnumerable<string> keys, string regionName) 
        { 
            throw new NotSupportedException(); 
        } 
 
        // Enumeration of the items. We do not support that  
        protected override IEnumerator<KeyValuePair<string, object>> GetEnumerator() 
        { 
            throw new NotSupportedException(); 
        } 
 
 
        // Enumeration of the keys. We do not support that  
        public override void EnumerateKeys(string region, EnumerateCacheEntriesCallback callback) 
        { 
            throw new NotSupportedException(); 
        } 
 
        // Enumeration of regions. We do not support that  
        public override void EnumerateRegions(EnumerateCacheEntriesCallback callback) 
        { 
            throw new NotSupportedException(); 
        } 
    } 
} 

using System; 
using System.Collections.Generic; 
using System.Diagnostics; 
using System.Xml.Linq; 
 
using Amazon; 
using Amazon.S3; 
 
using Leadtools.Caching; 
using Leadtools.Document; 
using Leadtools.Services.Tools.Helpers; 
 
namespace Leadtools.Services.Tools.Cache 
{ 
 
    public class S3CacheManager : ICacheManager 
    { 
        // Our cache 
        private ObjectCache _objectCache; 
        private CacheItemPolicy _cacheItemPolicy; 
        private bool _isInitialized = false; 
        public string WebRootPath { get; set; } 
 
        // Its name 
        public const string CACHE_NAME = "S3BucketCache"; 
 
        public S3CacheManager(string WebRootPath, XElement cacheManagerElement) 
        { 
            if (string.IsNullOrEmpty(WebRootPath)) 
                throw new ArgumentNullException(nameof(WebRootPath)); 
 
            _isInitialized = false; 
            this.WebRootPath = WebRootPath; 
 
            // Get the values from the XML document 
            ParseXml(cacheManagerElement); 
        } 
 
        public void ParseXml(XElement cacheManagerElement) 
        { 
            // Nothing to parse 
        } 
 
        private const string CACHE_MANAGER_NAME = "S3CacheManger"; 
        public string Name 
        { 
            get { return CACHE_MANAGER_NAME; } 
        } 
 
        public string[] GetCacheNames() 
        { 
            return new string[] { CACHE_NAME }; 
        } 
 
        public bool IsInitialized 
        { 
            get { return _isInitialized; } 
        } 
 
        public void Initialize() 
        { 
            Trace.WriteLine("Initializing default cache from configuration"); 
 
            if (_isInitialized) 
                throw new InvalidOperationException("Cache already initialized"); 
 
            _objectCache = InitializeS3BucketCache(); 
            _objectCache.SetName(CACHE_NAME); 
            if (_objectCache.Name != CACHE_NAME) 
                throw new InvalidOperationException($"ObjectCache implementation {_objectCache.GetType().FullName} does not override SetName"); 
 
            DocumentFactory.LoadDocumentFromCache += LoadDocumentFromCacheHandler; 
            _cacheItemPolicy = InitializePolicy(_objectCache); 
            _isInitialized = true; 
        } 
 
        private void LoadDocumentFromCacheHandler(object sender, ResolveDocumentEventArgs e) 
        { 
            // Get the cache for the document if we have it 
            ObjectCache objectCache = GetCacheForDocument(e.LoadFromCacheOptions.DocumentId); 
            if (objectCache != null) 
                e.LoadFromCacheOptions.Cache = objectCache; 
        } 
 
        public void Cleanup() 
        { 
            if (!_isInitialized) 
                return; 
 
            _objectCache = null; 
            _cacheItemPolicy = null; 
            _isInitialized = false; 
        } 
 
        private ObjectCache InitializeS3BucketCache() 
        { 
            // Called by InitializeService the first time the service is run 
            // Initialize the global Cache object 
 
            string cacheConfigFile = ServiceHelper.GetSettingValue(ServiceHelper.Key_Cache_ConfigFile); 
            cacheConfigFile = ServiceHelper.GetAbsolutePath(cacheConfigFile); 
            if (string.IsNullOrEmpty(cacheConfigFile)) 
                throw new InvalidOperationException($"The cache configuration file location in '{ServiceHelper.Key_Cache_ConfigFile}' in the configuration file is empty"); 
 
            ObjectCache objectCache = null; 
 
            // Set the base directory of the cache (for resolving any relative paths) to this project's path 
            var additional = new Dictionary<string, string>(); 
            additional.Add(ObjectCache.BASE_DIRECTORY_KEY, WebRootPath); 
 
            try 
            { 
                //TODO Setup Connections  
                string awsAccessKeyId = "AWS_ACCESS_KEY"; //Update with Access Key 
                string awsSecretAccessKey = "AWS_SECRET_ACCESS_KEY"; //Update with Secret Access Key 
                RegionEndpoint region = RegionEndpoint.USEast1; //Update to match a region where your S3 buckets are accessible. 
                AmazonS3Client client = new AmazonS3Client(awsAccessKeyId, awsSecretAccessKey, region); 
                string bucketName = "leadtoolstestbucket"; 
                     
                objectCache = new S3BucketCache(client, bucketName); 
            } 
            catch (Exception ex) 
            { 
                throw new InvalidOperationException($"Cannot load cache configuration from '{cacheConfigFile}'", ex); 
            } 
 
            return objectCache; 
        } 
 
        public static CacheItemPolicy InitializePolicy(ObjectCache objectCache) 
        { 
            var policy = new CacheItemPolicy(); 
            return policy; 
        } 
 
        private static void VerifyCacheName(string cacheName, bool allowNull) 
        { 
            if (cacheName == null && allowNull) 
                return; 
 
            if (CACHE_NAME != cacheName) 
                throw new ArgumentException($"Invalid cache name: {cacheName}", nameof(cacheName)); 
        } 
 
        public void CheckCacheAccess(string cacheName) 
        { 
            Console.WriteLine("Made it to check!"); 
            CacheItemPolicy policy = null; 
        } 
 
        public CacheItemPolicy CreatePolicy(string cacheName) 
        { 
            VerifyCacheName(cacheName, false); 
 
            return _cacheItemPolicy.Clone(); 
        } 
 
        public CacheItemPolicy CreatePolicy(ObjectCache objectCache) 
        { 
            // Get the name of this cache 
            string cacheName = GetCacheName(objectCache); 
            if (cacheName == null) 
                throw new InvalidOperationException("Invalid object cache"); 
 
            return CreatePolicy(cacheName); 
        } 
 
        public CacheStatistics GetCacheStatistics(string cacheName) 
        { 
            return null; 
        } 
 
        public void RemoveExpiredItems(string cacheName) 
        { 
            VerifyCacheName(cacheName, true); 
 
            // Only supported by FileCache 
            FileCache fileCache = _objectCache as FileCache; 
            if (fileCache != null) 
            { 
                fileCache.CheckPolicies(); 
            } 
        } 
 
        public ObjectCache DefaultCache 
        { 
            get { return _objectCache; } 
        } 
 
        public ObjectCache GetCacheByName(string cacheName) 
        { 
            VerifyCacheName(cacheName, false); 
            return _objectCache; 
        } 
 
        public string GetCacheName(ObjectCache objectCache) 
        { 
            if (objectCache == null) 
                throw new ArgumentNullException(nameof(objectCache)); 
 
            if (objectCache == _objectCache) 
                return CACHE_NAME; 
 
            return null; 
        } 
 
        public ObjectCache GetCacheForDocument(string documentId) 
        { 
            if (documentId == null) 
                throw new ArgumentNullException(nameof(documentId)); 
 
            return _objectCache; 
        } 
 
        public ObjectCache GetCacheForDocumentOrDefault(string documentId) 
        { 
            ObjectCache objectCache = null; 
 
            if (!string.IsNullOrEmpty(documentId)) 
            { 
                objectCache = GetCacheForDocument(documentId); 
            } 
 
            if (objectCache == null) 
                objectCache = DefaultCache; 
 
            return objectCache; 
        } 
 
        public ObjectCache GetCacheForDocument(Uri documentUri) 
        { 
            if (documentUri == null) 
                throw new ArgumentNullException(nameof(documentUri)); 
 
            // Get the document ID from the URI and call the other version of this function 
            if (!DocumentFactory.IsUploadDocumentUri(documentUri)) 
                throw new ArgumentException($"{documentUri.ToString()} is not a valid LEAD document URI", nameof(documentUri)); 
 
            string documentId = DocumentFactory.GetLeadCacheData(documentUri); 
            return GetCacheForDocument(documentId); 
        } 
 
        public ObjectCache GetCacheForDocumentOrDefault(Uri documentUri) 
        { 
            ObjectCache objectCache = null; 
 
            if (documentUri != null) 
            { 
                objectCache = GetCacheForDocument(documentUri); 
            } 
 
                if (objectCache == null) 
                    objectCache = DefaultCache; 
 
            return objectCache; 
        } 
 
        public ObjectCache GetCacheForLoadFromUri(Uri uri, LoadDocumentOptions loadDocumentOptions) 
        { 
            return _objectCache; 
        } 
 
        public ObjectCache GetCacheForBeginUpload(UploadDocumentOptions uploadDocumentOptions) 
        { 
            return _objectCache; 
        } 
 
        public ObjectCache GetCacheForCreate(CreateDocumentOptions createDocumentOptions) 
        { 
            return _objectCache; 
        } 
    } 
} 

private ObjectCache InitializeS3BucketCache() 
{ 
    // Called by InitializeService the first time the service is run 
    // Initialize the global Cache object 
 
    string cacheConfigFile = ServiceHelper.GetSettingValue(ServiceHelper.Key_Cache_ConfigFile); 
    cacheConfigFile = ServiceHelper.GetAbsolutePath(cacheConfigFile); 
    if (string.IsNullOrEmpty(cacheConfigFile)) 
        throw new InvalidOperationException($"The cache configuration file location in '{ServiceHelper.Key_Cache_ConfigFile}' in the configuration file is empty"); 
 
    ObjectCache objectCache = null; 
 
    // Set the base directory of the cache (for resolving any relative paths) to this project's path 
    var additional = new Dictionary<string, string>(); 
    additional.Add(ObjectCache.BASE_DIRECTORY_KEY, WebRootPath); 
 
    try 
    { 
        //TODO Setup Connections  
        string awsAccessKeyId = "AWS_ACCESS_KEY"; //Update with Access Key 
        string awsSecretAccessKey = "AWS_SECRET_ACCESS_KEY"; //Update with Secret Access Key 
        RegionEndpoint region = RegionEndpoint.USEast1; //Update to match a region where your S3 buckets are accessible. 
        AmazonS3Client client = new AmazonS3Client(awsAccessKeyId, awsSecretAccessKey, region); 
        string bucketName = "leadtoolstestbucket"; 
         
        objectCache = new S3BucketCache(client, bucketName); 
    } 
    catch (Exception ex) 
    { 
        throw new InvalidOperationException($"Cannot load cache configuration from '{cacheConfigFile}'", ex); 
    } 
 
    return objectCache; 
} 

public static void CreateCache() 
{ 
   // Called by InitializeService the first time the service is run 
   // Initialize the global ICacheManager object 
   //ICacheManager cacheManager = null; 
   S3BucketCacheManager cacheManager = new S3BucketCacheManager(WebRootPath, null); 
   // See if we have a CacheManager configuration file 
   /*string cacheManagerConfigFile = GetSettingValue(Key_Cache_CacheManagerConfigFile); 
   cacheManagerConfigFile = GetAbsolutePath(cacheManagerConfigFile); 
   if (!string.IsNullOrEmpty(cacheManagerConfigFile)) 
   { 
      using (var stream = File.OpenRead(cacheManagerConfigFile)) 
      cacheManager = CacheManagerFactory.CreateFromConfiguration(stream, WebRootPath); 
   } 
   else 
   { 
      // Try to create the default ICacheManager directly (backward compatibility) 
      cacheManager = new DefaultCacheManager(WebRootPath, null); 
   } 
   */ 
   if (cacheManager == null) 
      throw new InvalidOperationException("Could not find a valid LEADTOOLS cache system configuration."); 
   cacheManager.Initialize(); 
   _cacheManager = cacheManager; 
}