From 322e76d2a9364284b70609fe0a75444e86c7ef8b Mon Sep 17 00:00:00 2001
From: zzz <zzz@mail.i2p>
Date: Fri, 21 Jun 2013 15:13:37 +0000
Subject: [PATCH] speed up XORComparators
---
.../src/net/i2p/kademlia/XORComparator.java | 19 +++++++++++++++----
.../networkdb/kademlia/XORComparator.java | 19 +++++++++++--------
2 files changed, 26 insertions(+), 12 deletions(-)
diff --git a/apps/i2psnark/java/src/net/i2p/kademlia/XORComparator.java b/apps/i2psnark/java/src/net/i2p/kademlia/XORComparator.java
index 8d8cb5663a..2ac5017ddf 100644
--- a/apps/i2psnark/java/src/net/i2p/kademlia/XORComparator.java
+++ b/apps/i2psnark/java/src/net/i2p/kademlia/XORComparator.java
@@ -2,7 +2,6 @@ package net.i2p.kademlia;
import java.util.Comparator;
-import net.i2p.data.DataHelper;
import net.i2p.data.SimpleDataStructure;
/**
@@ -21,8 +20,20 @@ class XORComparator<T extends SimpleDataStructure> implements Comparator<T> {
}
public int compare(T lhs, T rhs) {
- byte lhsDelta[] = DataHelper.xor(lhs.getData(), _base);
- byte rhsDelta[] = DataHelper.xor(rhs.getData(), _base);
- return DataHelper.compareTo(lhsDelta, rhsDelta);
+ // same as the following but byte-by-byte for efficiency
+ //byte lhsDelta[] = DataHelper.xor(lhs.getData(), _base);
+ //byte rhsDelta[] = DataHelper.xor(rhs.getData(), _base);
+ //return DataHelper.compareTo(lhsDelta, rhsDelta);
+ byte lhsb[] = lhs.getData();
+ byte rhsb[] = rhs.getData();
+ for (int i = 0; i < _base.length; i++) {
+ int ld = (lhsb[i] ^ _base[i]) & 0xff;
+ int rd = (rhsb[i] ^ _base[i]) & 0xff;
+ if (ld < rd)
+ return -1;
+ if (ld > rd)
+ return 1;
+ }
+ return 0;
}
}
diff --git a/router/java/src/net/i2p/router/networkdb/kademlia/XORComparator.java b/router/java/src/net/i2p/router/networkdb/kademlia/XORComparator.java
index 9242103cd3..cd734b685f 100644
--- a/router/java/src/net/i2p/router/networkdb/kademlia/XORComparator.java
+++ b/router/java/src/net/i2p/router/networkdb/kademlia/XORComparator.java
@@ -2,32 +2,35 @@ package net.i2p.router.networkdb.kademlia;
import java.util.Comparator;
-import net.i2p.data.DataHelper;
import net.i2p.data.Hash;
/**
* Help sort Hashes in relation to a base key using the XOR metric.
- * Warning - not thread safe.
*/
class XORComparator implements Comparator<Hash> {
private final byte[] _base;
- private final byte[] _lx, _rx;
/**
* @param target key to compare distances with
*/
public XORComparator(Hash target) {
_base = target.getData();
- _lx = new byte[Hash.HASH_LENGTH];
- _rx = new byte[Hash.HASH_LENGTH];
}
/**
* getData() of args must be non-null
*/
public int compare(Hash lhs, Hash rhs) {
- DataHelper.xor(lhs.getData(), 0, _base, 0, _lx, 0, Hash.HASH_LENGTH);
- DataHelper.xor(rhs.getData(), 0, _base, 0, _rx, 0, Hash.HASH_LENGTH);
- return DataHelper.compareTo(_lx, _rx);
+ byte lhsb[] = lhs.getData();
+ byte rhsb[] = rhs.getData();
+ for (int i = 0; i < _base.length; i++) {
+ int ld = (lhsb[i] ^ _base[i]) & 0xff;
+ int rd = (rhsb[i] ^ _base[i]) & 0xff;
+ if (ld < rd)
+ return -1;
+ if (ld > rd)
+ return 1;
+ }
+ return 0;
}
}
--
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