Added support for caching GET requests

CryptoExchange.Net/Objects/CallResult.cs

@@ -331,6 +331,11 @@ namespace CryptoExchange.Net.Objects
         /// </summary>
         public TimeSpan? ResponseTime { get; set; }
 
+        /// <summary>
+        /// The data source of this result
+        /// </summary>
+        public ResultDataSource DataSource { get; set; } = ResultDataSource.Server;
+
         /// <summary>
         /// Create a new result
         /// </summary>
@@ -417,6 +422,17 @@ namespace CryptoExchange.Net.Objects
             return new WebCallResult<K>(ResponseStatusCode, ResponseHeaders, ResponseTime, ResponseLength, OriginalData, RequestId, RequestUrl, RequestBody, RequestMethod, RequestHeaders, default, error);
         }
 
+        /// <summary>
+        /// Return a copy of this result with data source set to cache
+        /// </summary>
+        /// <returns></returns>
+        internal WebCallResult<T> Cached()
+        {
+            var result = new WebCallResult<T>(ResponseStatusCode, ResponseHeaders, ResponseTime, ResponseLength, OriginalData, RequestId, RequestUrl, RequestBody, RequestMethod, RequestHeaders, default, Error);
+            result.DataSource = ResultDataSource.Cache;
+            return result;
+        }
+
         /// <inheritdoc />
         public override string ToString()
         {

CryptoExchange.Net/Objects/Enums.cs

@@ -188,4 +188,19 @@
         /// </summary>
         ExponentialBackoff
     }
+
+    /// <summary>
+    /// The data source of the result
+    /// </summary>
+    public enum ResultDataSource
+    {
+        /// <summary>
+        /// From server
+        /// </summary>
+        Server,
+        /// <summary>
+        /// From cache
+        /// </summary>
+        Cache
+    }
 }

CryptoExchange.Net/Objects/Options/RestExchangeOptions.cs

@@ -18,6 +18,16 @@ namespace CryptoExchange.Net.Objects.Options
         /// </summary>
         public TimeSpan TimestampRecalculationInterval { get; set; } = TimeSpan.FromHours(1);
 
+        /// <summary>
+        /// Whether caching is enabled. Caching will only be applied to GET http requests. The lifetime of cached results can be determined by the `CachingMaxAge` option
+        /// </summary>
+        public bool CachingEnabled { get; set; } = false;
+
+        /// <summary>
+        /// The max age of a cached entry, only used when the `CachingEnabled` options is set to true. When a cached entry is older than the max age it will be discarded and a new server request will be done
+        /// </summary>
+        public TimeSpan CachingMaxAge { get; set; } = TimeSpan.FromSeconds(5);
+
         /// <summary>
         /// Create a copy of this options
         /// </summary>
@@ -34,7 +44,9 @@ namespace CryptoExchange.Net.Objects.Options
                 Proxy = Proxy,
                 RequestTimeout = RequestTimeout,
                 RateLimiterEnabled = RateLimiterEnabled,
-                RateLimitingBehaviour = RateLimitingBehaviour
+                RateLimitingBehaviour = RateLimitingBehaviour,
+                CachingEnabled = CachingEnabled,
+                CachingMaxAge = CachingMaxAge,
             };
         }
     }

CryptoExchange.Net/Objects/RequestDefinition.cs

@@ -61,6 +61,12 @@ namespace CryptoExchange.Net.Objects
         /// </summary>
         public TimeSpan? EndpointLimitPeriod { get; set; }
 
+
+        /// <summary>
+        /// Whether this request should never be cached
+        /// </summary>
+        public bool PreventCaching { get; set; }
+
         /// <summary>
         /// ctor
         /// </summary>

CryptoExchange.Net/Objects/RequestDefinitionCache.cs

@@ -48,6 +48,7 @@ namespace CryptoExchange.Net.Objects
         /// <param name="requestBodyFormat">Request body format</param>
         /// <param name="parameterPosition">Parameter position</param>
         /// <param name="arraySerialization">Array serialization type</param>
+        /// <param name="preventCaching">Prevent request caching</param>
         /// <returns></returns>
         public RequestDefinition GetOrCreate(
             HttpMethod method,
@@ -59,7 +60,8 @@ namespace CryptoExchange.Net.Objects
             TimeSpan? endpointLimitPeriod = null,
             RequestBodyFormat? requestBodyFormat = null,
             HttpMethodParameterPosition? parameterPosition = null,
-            ArrayParametersSerialization? arraySerialization = null)
+            ArrayParametersSerialization? arraySerialization = null,
+            bool? preventCaching = null)
         {
 
             if (!_definitions.TryGetValue(method + path, out var def))
@@ -74,6 +76,7 @@ namespace CryptoExchange.Net.Objects
                     ArraySerialization = arraySerialization,
                     RequestBodyFormat = requestBodyFormat,
                     ParameterPosition = parameterPosition,
+                    PreventCaching = preventCaching ?? false
                 };
                 _definitions.TryAdd(method + path, def);
             }