Modified barrel ctor to optionally allow HashAlgorithm to be specified

src/MonkeyCache.FileStore/Barrel.cs

@@ -14,8 +14,14 @@ public class Barrel : IBarrel
 		ReaderWriterLockSlim indexLocker;
 		readonly JsonSerializerSettings jsonSettings;
 		Lazy<string> baseDirectory;
+		HashAlgorithm hashAlgorithm;
 
-		Barrel(string cacheDirectory = null)
+		/// <summary>
+		/// FileStore Barrel constructor
+		/// </summary>
+		/// <param name="cacheDirectory">Optionally specify directory where cache will live</param>
+		/// <param name="hash">Optionally specify hash algorithm</param>
+		Barrel(string cacheDirectory = null, HashAlgorithm hash = null)
 		{
 			baseDirectory = new Lazy<string>(() =>
 			{
@@ -24,6 +30,10 @@ public class Barrel : IBarrel
 					: cacheDirectory;
 			});
 
+			hashAlgorithm = hash;
+			if (hashAlgorithm == null)
+				hashAlgorithm = MD5.Create();
+
 			indexLocker = new ReaderWriterLockSlim(LockRecursionPolicy.SupportsRecursion);
 
 			jsonSettings = new JsonSerializerSettings
@@ -456,10 +466,9 @@ void LoadIndex()
 			}
 		}
 
-		static string Hash(string input)
+		string Hash(string input)
 		{
-			var md5Hasher = MD5.Create();
-			var data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input));
+			var data = hashAlgorithm.ComputeHash(Encoding.Default.GetBytes(input));
 			return BitConverter.ToString(data);
 		}