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Switch to LRU for caching sha3 hashes

This commit is contained in:
nicksavers 2014-08-02 04:34:29 +02:00
parent cfe42aec5b
commit be0f70575b
2 changed files with 32 additions and 7 deletions
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15
ethereumj-core/src/main/java/org/ethereum/crypto/HashUtil.java
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@ -5,8 +5,6 @@ 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;
@ -14,9 +12,12 @@ import org.ethereum.util.RLP;
import org.ethereum.util.Utils;
import org.spongycastle.util.encoders.Hex;
import org.ethereum.util.LRUMap;
public class HashUtil {
public static Map<ByteArrayWrapper, byte[]> hashes = new HashMap<>();
private static final int MAX_ENTRIES = 1000; // Should contain most commonly hashed values
private static LRUMap<ByteArrayWrapper, byte[]> sha3Cache = new LRUMap<>(0, MAX_ENTRIES);
public static final byte[] EMPTY_DATA_HASH = HashUtil.sha3(new byte[0]);
private static final MessageDigest sha256digest;
@ -34,11 +35,11 @@ public class HashUtil {
}
public static byte[] sha3(byte[] input) {
ByteArrayWrapper byteArray = new ByteArrayWrapper(input);
if(hashes.keySet().contains(byteArray))
return hashes.get(byteArray);
ByteArrayWrapper inputByteArray = new ByteArrayWrapper(input);
if(sha3Cache.keySet().contains(inputByteArray))
return sha3Cache.get(inputByteArray);
byte[] result = SHA3Helper.sha3(input);
hashes.put(byteArray, result);
sha3Cache.put(inputByteArray, result);
return result;
}

24
ethereumj-core/src/main/java/org/ethereum/util/LRUMap.java Normal file
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@ -0,0 +1,24 @@
package org.ethereum.util;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* Simple LRU map used for reusing lookup values.
*/
public class LRUMap<K,V> extends LinkedHashMap<K,V> {
private static final long serialVersionUID = 1L;
protected final int maxEntries;
public LRUMap(int initialEntries, int maxEntries) {
super(initialEntries, 0.8f, true);
this.maxEntries = maxEntries;
}
@Override
protected boolean removeEldestEntry(Map.Entry<K,V> eldest) {
return size() > maxEntries;
}
}