Use sha3 cache for extra performance

ethereumj-core/src/main/java/org/ethereum/core/AccountState.java

@@ -1,6 +1,7 @@
 package org.ethereum.core;
 
-import org.ethereum.crypto.HashUtil;
+import static org.ethereum.util.ByteUtil.EMPTY_BYTE_ARRAY;
+import static org.ethereum.crypto.HashUtil.EMPTY_DATA_HASH;
 import org.ethereum.util.RLP;
 import org.ethereum.util.RLPList;
 
@@ -28,7 +29,7 @@ public class AccountState {
      * I define a convenient equivalence TRIE (σ[a] s ) ≡ σ[a] s . 
      * It shall be understood that σ[a] s is not a ‘physical’ member 
      * of the account and does not contribute to its later serialisation */
-    private byte[] stateRoot = new byte[0];
+    private byte[] stateRoot = EMPTY_BYTE_ARRAY;
     
     /* The hash of the EVM code of this contract—this is the code 
      * that gets executed should this address receive a message call; 
@@ -36,7 +37,7 @@ public class AccountState {
      * after construction. All such code fragments are contained in 
      * the state database under their corresponding hashes for later 
      * retrieval */
-    private byte[] codeHash = HashUtil.sha3(new byte[0]);
+    private byte[] codeHash = EMPTY_DATA_HASH;
 
     public AccountState() {
         this(BigInteger.ZERO, BigInteger.ZERO);

ethereumj-core/src/main/java/org/ethereum/crypto/HashUtil.java

@@ -5,7 +5,10 @@ import static java.util.Arrays.copyOfRange;
 import java.math.BigInteger;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
+import java.util.HashMap;
+import java.util.Map;
 
+import org.ethereum.db.ByteArrayWrapper;
 import org.ethereum.util.ByteUtil;
 import org.ethereum.util.RLP;
 import org.ethereum.util.Utils;
@@ -13,7 +16,8 @@ import org.spongycastle.util.encoders.Hex;
 
 public class HashUtil {
 
-    public static byte[] EMPTY_DATA_HASH = HashUtil.sha3(new byte[0]);
+	public static Map<ByteArrayWrapper, byte[]> hashes = new HashMap<>();
+    public static final byte[] EMPTY_DATA_HASH = HashUtil.sha3(new byte[0]);
 
     private static final MessageDigest sha256digest;
     
@@ -30,11 +34,12 @@ public class HashUtil {
     }
 
 	public static byte[] sha3(byte[] input) {
-		return SHA3Helper.sha3(input);
-	}
-	
-	public static String sha3String(String input) {
-		return SHA3Helper.sha3String(input);
+		ByteArrayWrapper byteArray = new ByteArrayWrapper(input);
+		if(hashes.keySet().contains(byteArray))
+			return hashes.get(byteArray);
+		byte[] result = SHA3Helper.sha3(input);
+		hashes.put(byteArray, result);
+		return result; 
 	}
 	
     /**

ethereumj-core/src/main/java/org/ethereum/crypto/SHA3Helper.java

@@ -7,20 +7,22 @@ import org.spongycastle.util.encoders.Hex;
 
 public class SHA3Helper {
 	
+	private static int DEFAULT_SIZE = 256;
+	
     public static String sha3String(String message) {
-		return sha3String(message, new SHA3Digest(256), true);
+        return sha3String(message, new SHA3Digest(DEFAULT_SIZE), true);
     }
 
     public static String sha3String(byte[] message) {
-		return sha3String(message, new SHA3Digest(256), true);
+        return sha3String(message, new SHA3Digest(DEFAULT_SIZE), true);
     }
 
     public static byte[] sha3(String message) {
-		return sha3(Hex.decode(message), new SHA3Digest(256), true);
+        return sha3(Hex.decode(message), new SHA3Digest(DEFAULT_SIZE), true);
     }
 
     public static byte[] sha3(byte[] message) {
-		return sha3(message, new SHA3Digest(256), true);
+        return sha3(message, new SHA3Digest(DEFAULT_SIZE), true);
     }
 
     protected static String sha3String(String message, Size bitSize) {
@@ -91,4 +93,5 @@ public class SHA3Helper {
             return this.bits;
         }
     }
+            
 }

ethereumj-core/src/main/java/org/ethereum/util/ByteUtil.java

@@ -10,6 +10,8 @@ import org.spongycastle.util.encoders.Hex;
 
 public class ByteUtil {
 
+	public static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
+	
     /**
      * Creates a copy of bytes and appends b to the end of it
      */