Author: kwsutter
Date: Wed Nov 8 11:10:56 2006
New Revision: 472597
URL: http://svn.apache.org/viewvc?view=rev&rev=472597
Log:
Replace the UUIDGenerator with an implementation based on the Apache Commons Id
implementation. This change removes the LGPL implication from the original
implementation.
Added:
incubator/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/Bytes.java
Modified:
incubator/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/UUIDGenerator.java
incubator/openjpa/trunk/openjpa-lib/src/test/java/org/apache/openjpa/lib/util/TestUUIDGenerator.java
Added:
incubator/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/Bytes.java
URL:
http://svn.apache.org/viewvc/incubator/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/Bytes.java?view=auto&rev=472597
==============================================================================
---
incubator/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/Bytes.java
(added)
+++
incubator/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/Bytes.java
Wed Nov 8 11:10:56 2006
@@ -0,0 +1,164 @@
+/*
+ * Copyright 2003-2006 The Apache Software Foundation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.openjpa.lib.util;
+
+/**
+ * This class came from the Apache Commons Id sandbox project in support
+ * of the UUIDGenerator implementation.
+ *
+ * <p>Static methods for managing byte arrays (all methods follow Big
+ * Endian order where most significant bits are in front).</p>
+ *
+ */
+public final class Bytes {
+
+ /**
+ * <p>Hide constructor in utility class.</p>
+ */
+ private Bytes() {
+ }
+
+ /**
+ * Appends two bytes array into one.
+ *
+ * @param a A byte[].
+ * @param b A byte[].
+ * @return A byte[].
+ */
+ public static byte[] append(byte[] a, byte[] b) {
+ byte[] z = new byte[a.length + b.length];
+ System.arraycopy(a, 0, z, 0, a.length);
+ System.arraycopy(b, 0, z, a.length, b.length);
+ return z;
+ }
+
+ /**
+ * Returns a 8-byte array built from a long.
+ *
+ * @param n The number to convert.
+ * @return A byte[].
+ */
+ public static byte[] toBytes(long n) {
+ return toBytes(n, new byte[8]);
+ }
+
+ /**
+ * Build a 8-byte array from a long. No check is performed on the
+ * array length.
+ *
+ * @param n The number to convert.
+ * @param b The array to fill.
+ * @return A byte[].
+ */
+ public static byte[] toBytes(long n, byte[] b) {
+ b[7] = (byte) (n);
+ n >>>= 8;
+ b[6] = (byte) (n);
+ n >>>= 8;
+ b[5] = (byte) (n);
+ n >>>= 8;
+ b[4] = (byte) (n);
+ n >>>= 8;
+ b[3] = (byte) (n);
+ n >>>= 8;
+ b[2] = (byte) (n);
+ n >>>= 8;
+ b[1] = (byte) (n);
+ n >>>= 8;
+ b[0] = (byte) (n);
+
+ return b;
+ }
+
+ /**
+ * Build a long from first 8 bytes of the array.
+ *
+ * @param b The byte[] to convert.
+ * @return A long.
+ */
+ public static long toLong(byte[] b) {
+ return ((((long) b[7]) & 0xFF)
+ + ((((long) b[6]) & 0xFF) << 8)
+ + ((((long) b[5]) & 0xFF) << 16)
+ + ((((long) b[4]) & 0xFF) << 24)
+ + ((((long) b[3]) & 0xFF) << 32)
+ + ((((long) b[2]) & 0xFF) << 40)
+ + ((((long) b[1]) & 0xFF) << 48)
+ + ((((long) b[0]) & 0xFF) << 56));
+ }
+
+ /**
+ * Compares two byte arrays for equality.
+ *
+ * @param a A byte[].
+ * @param b A byte[].
+ * @return True if the arrays have identical contents.
+ */
+ public static boolean areEqual(byte[] a, byte[] b) {
+ int aLength = a.length;
+ if (aLength != b.length) {
+ return false;
+ }
+
+ for (int i = 0; i < aLength; i++) {
+ if (a[i] != b[i]) {
+ return false;
+ }
+ }
+ return true;
+ }
+
+ /**
+ * <p>Compares two byte arrays as specified by <code>Comparable</code>.
+ *
+ * @param lhs - left hand value in the comparison operation.
+ * @param rhs - right hand value in the comparison operation.
+ * @return a negative integer, zero, or a positive integer as
<code>lhs</code>
+ * is less than, equal to, or greater than <code>rhs</code>.
+ */
+ public static int compareTo(byte[] lhs, byte[] rhs) {
+ if (lhs == rhs) {
+ return 0;
+ }
+ if (lhs == null) {
+ return -1;
+ }
+ if (rhs == null) {
+ return +1;
+ }
+ if (lhs.length != rhs.length) {
+ return ((lhs.length < rhs.length) ? -1 : +1);
+ }
+ for (int i = 0; i < lhs.length; i++) {
+ if (lhs[i] < rhs[i]) {
+ return -1;
+ } else if (lhs[i] > rhs[i]) {
+ return 1;
+ }
+ }
+ return 0;
+ }
+
+ /**
+ * Build a short from first 2 bytes of the array.
+ *
+ * @param b The byte[] to convert.
+ * @return A short.
+ */
+ public static short toShort(byte[] b) {
+ return (short) ((b[1] & 0xFF) + ((b[0] & 0xFF) << 8));
+ }
+}
Modified:
incubator/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/UUIDGenerator.java
URL:
http://svn.apache.org/viewvc/incubator/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/UUIDGenerator.java?view=diff&rev=472597&r1=472596&r2=472597
==============================================================================
---
incubator/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/UUIDGenerator.java
(original)
+++
incubator/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/UUIDGenerator.java
Wed Nov 8 11:10:56 2006
@@ -23,18 +23,18 @@
import org.apache.commons.lang.exception.NestableRuntimeException;
/**
- * UUID value generator. Based on the time-based generator in the LGPL
- * project:<br />
- * http://www.doomdark.org/doomdark/proj/jug/<br />
+ * UUID value generator. Based on the time-based generator in the Apache
+ * Commons Id project: http://jakarta.apache.org/commons/sandbox/id/uuid.html
+ *
* The code has been vastly simplified and modified to replace the ethernet
* address of the host machine with the IP, since we do not want to require
* native libs and Java cannot access the MAC address directly.
- * Aside from the above modification, implements the IETF UUID draft
- * specification, found here:<br />
+ *
+ * In spirit, implements the IETF UUID draft specification, found here:<br />
* http://www1.ics.uci.edu/~ejw/authoring/uuid-guid/draft-leach-uuids-guids-01
* .txt
*
- * @author Abe White
+ * @author Abe White, Kevin Sutter
* @nojavadoc
* @since 0.3.3
*/
@@ -48,13 +48,21 @@
private static final byte IDX_TIME_SEQ = 8;
private static final byte IDX_VARIATION = 8; // multiplexed
+ // indexes and lengths within the timestamp for certain boundaries
+ private static final byte TS_TIME_LO_IDX = 4;
+ private static final byte TS_TIME_LO_LEN = 4;
+ private static final byte TS_TIME_MID_IDX = 2;
+ private static final byte TS_TIME_MID_LEN = 2;
+ private static final byte TS_TIME_HI_IDX = 0;
+ private static final byte TS_TIME_HI_LEN = 2;
+
// offset to move from 1/1/1970, which is 0-time for Java, to gregorian
// 0-time 10/15/1582, and multiplier to go from 100nsec to msec units
private static final long GREG_OFFSET = 0x01b21dd213814000L;
private static final long MILLI_MULT = 10000L;
- // type of UUID; is this part of the spec?
- private final static byte TYPE_TIME_BASED = 1;
+ // type of UUID -- time based
+ private final static byte TYPE_TIME_BASED = 0x10;
// random number generator used to reduce conflicts with other JVMs, and
// hasher for strings. note that secure random is very slow the first time
@@ -65,18 +73,23 @@
// the MAC address is usually 6 bytes
private static final byte[] IP;
- // counter is initialized not to 0 but to a random 8-bit number, and each
- // time clock changes, lowest 8-bits of counter are preserved. the purpose
- // is to reduce chances of multi-JVM collisions without reducing perf
- // awhite: I don't really understand this precaution, but it was in the
- // original algo
+ // counter is initialized to 0 and is incremented for each uuid request
+ // within the same timestamp window.
private static int _counter;
- // last used millis time, and a randomized sequence that gets reset
- // whenever the time is reset
- private static long _last = 0L;
- private static byte[] _seq = new byte[2];
+ // current timestamp (used to detect multiple uuid requests within same
+ // timestamp)
+ private static long _currentMillis;
+
+ // last used millis time, and a semi-random sequence that gets reset
+ // when it overflows
+ private static long _lastMillis = 0L;
+ private static final int MAX_14BIT = 0x3FFF;
+ private static short _seq = (short)RANDOM.nextInt(MAX_14BIT);
+ /*
+ * Static initializer to get the IP address of the host machine.
+ */
static {
byte[] ip = null;
try {
@@ -88,8 +101,6 @@
IP = new byte[6];
RANDOM.nextBytes(IP);
System.arraycopy(ip, 0, IP, 2, ip.length);
-
- resetTime();
}
/**
@@ -100,54 +111,35 @@
byte[] uuid = new byte[16];
System.arraycopy(IP, 0, uuid, 10, IP.length);
- // set time info
- long now = System.currentTimeMillis();
+ // Set time info. Have to do this processing within a synchronized
+ // block because of the statics...
+ long now = 0;
synchronized (UUIDGenerator.class) {
- // if time moves backwards somehow, spec says to reset
randomization
- if (now < _last)
- resetTime();
- else if (now == _last && _counter == MILLI_MULT) {
- // if we run out of slots in this milli, increment
- now++;
- _last = now;
- _counter &= 0xFF; // rest counter?
- } else if (now > _last) {
- _last = now;
- _counter &= 0xFF; // rest counter?
- }
-
- // translate timestamp to 100ns slot since beginning of gregorian
- now *= MILLI_MULT;
- now += GREG_OFFSET;
-
- // add nano slot
- now += _counter;
- _counter++; // increment counter
-
- // set random info
- for (int i = 0; i < _seq.length; i++)
- uuid[IDX_TIME_SEQ + i] = _seq[i];
+ // Get the time to use for this uuid. This method has the side
+ // effect of modifying the clock sequence, as well.
+ now = getTime();
+
+ // Insert the resulting clock sequence into the uuid
+ uuid[IDX_TIME_SEQ] = (byte) ((_seq & 0x3F00) >>> 8);
+ uuid[IDX_VARIATION] |= 0x80;
+ uuid[IDX_TIME_SEQ+1] = (byte) (_seq & 0xFF);
+
}
// have to break up time because bytes are spread through uuid
- int timeHi = (int) (now >>> 32);
- int timeLo = (int) now;
+ byte[] timeBytes = Bytes.toBytes(now);
- uuid[IDX_TIME_HI] = (byte) (timeHi >>> 24);
- uuid[IDX_TIME_HI + 1] = (byte) (timeHi >>> 16);
- uuid[IDX_TIME_MID] = (byte) (timeHi >>> 8);
- uuid[IDX_TIME_MID + 1] = (byte) timeHi;
-
- uuid[IDX_TIME_LO] = (byte) (timeLo >>> 24);
- uuid[IDX_TIME_LO + 1] = (byte) (timeLo >>> 16);
- uuid[IDX_TIME_LO + 2] = (byte) (timeLo >>> 8);
- uuid[IDX_TIME_LO + 3] = (byte) timeLo;
-
- // set type info
- uuid[IDX_TYPE] &= (byte) 0x0F;
- uuid[IDX_TYPE] |= (byte) (TYPE_TIME_BASED << 4);
- uuid[IDX_VARIATION] &= 0x3F;
- uuid[IDX_VARIATION] |= 0x80;
+ // Copy time low
+ System.arraycopy(timeBytes, TS_TIME_LO_IDX, uuid, IDX_TIME_LO,
+ TS_TIME_LO_LEN);
+ // Copy time mid
+ System.arraycopy(timeBytes, TS_TIME_MID_IDX, uuid, IDX_TIME_MID,
+ TS_TIME_MID_LEN);
+ // Copy time hi
+ System.arraycopy(timeBytes, TS_TIME_HI_IDX, uuid, IDX_TIME_HI,
+ TS_TIME_HI_LEN);
+ //Set version (time-based)
+ uuid[IDX_TYPE] |= TYPE_TIME_BASED; // 0001 0000
return uuid;
}
@@ -172,16 +164,58 @@
}
/**
- * Reset the random time sequence and counter. Must be called from
- * synchronized code.
+ * Get the timestamp to be used for this uuid. Must be called from
+ * a synchronized block.
+ *
+ * @return long timestamp
*/
- private static void resetTime() {
- _last = 0L;
- RANDOM.nextBytes(_seq);
-
- // awhite: I don't understand this; copied from original algo
- byte[] tmp = new byte[1];
- RANDOM.nextBytes(tmp);
- _counter = tmp[0] & 0xFF;
+ private static long getTime() {
+ long newTime = getUUIDTime();
+ if (newTime <= _lastMillis) {
+ incrementSequence();
+ }
+ _lastMillis = newTime;
+ return newTime;
}
+
+ /**
+ * Gets the appropriately modified timestamep for the UUID. Must be called
+ * from a synchronized block.
+ *
+ * @return long timestamp in 100ns intervals since the Gregorian change
+ * offset
+ */
+ private static long getUUIDTime() {
+ if (_currentMillis != System.currentTimeMillis()) {
+ _currentMillis = System.currentTimeMillis();
+ _counter = 0; // reset counter
+ }
+
+ // check to see if we have created too many uuid's for this timestamp
+ if (_counter + 1 >= MILLI_MULT) {
+ // Original algorithm threw exception. Seemed like overkill.
+ // Let's just increment the timestamp instead and start over...
+ _currentMillis++;
+ _counter = 0;
+ }
+
+ // calculate time as current millis plus offset times 100 ns ticks
+ long currentTime = (_currentMillis + GREG_OFFSET) * MILLI_MULT;
+
+ // return the uuid time plus the artificial tick counter incremented
+ return currentTime + _counter++;
+ }
+
+ /**
+ * Increments the clock sequence for this uuid. Must be called from a
+ * synchronized block.
+ */
+ private static void incrementSequence() {
+ // increment, but if it's greater than its 14-bits, reset it
+ if (++_seq > MAX_14BIT) {
+ _seq = (short)RANDOM.nextInt(MAX_14BIT); // semi-random
+ }
+ }
+
+
}
Modified:
incubator/openjpa/trunk/openjpa-lib/src/test/java/org/apache/openjpa/lib/util/TestUUIDGenerator.java
URL:
http://svn.apache.org/viewvc/incubator/openjpa/trunk/openjpa-lib/src/test/java/org/apache/openjpa/lib/util/TestUUIDGenerator.java?view=diff&rev=472597&r1=472596&r2=472597
==============================================================================
---
incubator/openjpa/trunk/openjpa-lib/src/test/java/org/apache/openjpa/lib/util/TestUUIDGenerator.java
(original)
+++
incubator/openjpa/trunk/openjpa-lib/src/test/java/org/apache/openjpa/lib/util/TestUUIDGenerator.java
Wed Nov 8 11:10:56 2006
@@ -26,13 +26,13 @@
public void testUniqueString() {
Set seen = new HashSet();
- for (int i = 0; i < 1000; i++)
+ for (int i = 0; i < 10000; i++)
assertTrue(seen.add(UUIDGenerator.nextString()));
}
public void testUniqueHex() {
Set seen = new HashSet();
- for (int i = 0; i < 1000; i++)
+ for (int i = 0; i < 10000; i++)
assertTrue(seen.add(UUIDGenerator.nextHex()));
}
}
