From 1d4b4bd357be41b31c815faa77a7331f1000ba21 Mon Sep 17 00:00:00 2001
From: "Robert J. Moore" <Robert.J.Moore@allanbank.com>
Date: Wed, 7 Oct 2015 22:02:47 -0400
Subject: [PATCH] [core] Update the AcknowledgedCounterGenerator to use a power
of two size for the window so a mask can be used instead of a modulo
operation. This avoids issues when there is overflow of the id integer values
to negative values.
---
.../AcknowledgedCounterGenerator.java | 36 ++++++++---
.../AcknowledgedCounterGeneratorTest.java | 61 +++++++++++++++++++
2 files changed, 89 insertions(+), 8 deletions(-)
create mode 100644 core/src/test/java/com/yahoo/ycsb/generator/AcknowledgedCounterGeneratorTest.java
diff --git a/core/src/main/java/com/yahoo/ycsb/generator/AcknowledgedCounterGenerator.java b/core/src/main/java/com/yahoo/ycsb/generator/AcknowledgedCounterGenerator.java
index 443b47f5..69884c29 100644
--- a/core/src/main/java/com/yahoo/ycsb/generator/AcknowledgedCounterGenerator.java
+++ b/core/src/main/java/com/yahoo/ycsb/generator/AcknowledgedCounterGenerator.java
@@ -1,3 +1,19 @@
+/**
+ * Copyright (c) 2015 YCSB contributors. All rights reserved.
+ *
+ * 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. See accompanying
+ * LICENSE file.
+ */
package com.yahoo.ycsb.generator;
import java.util.concurrent.locks.ReentrantLock;
@@ -8,7 +24,11 @@ import java.util.concurrent.locks.ReentrantLock;
*/
public class AcknowledgedCounterGenerator extends CounterGenerator
{
- private static final int WINDOW_SIZE = 1000000;
+ /** The size of the window of pending id ack's. 2^20 = {@value} */
+ static final int WINDOW_SIZE = Integer.rotateLeft(1, 20);
+
+ /** The mask to use to turn an id into a slot in {@link #window}. */
+ private static final int WINDOW_MASK = WINDOW_SIZE - 1;
private final ReentrantLock lock;
private final boolean[] window;
@@ -40,22 +60,22 @@ public class AcknowledgedCounterGenerator extends CounterGenerator
*/
public void acknowledge(int value)
{
- if (value > limit + WINDOW_SIZE) {
+ final int currentSlot = (value & WINDOW_MASK);
+ if (window[currentSlot] == true) {
throw new RuntimeException("Too many unacknowledged insertion keys.");
}
- window[value % WINDOW_SIZE] = true;
+ window[currentSlot] = true;
if (lock.tryLock()) {
// move a contiguous sequence from the window
// over to the "limit" variable
-
try {
+ // Only loop through the entire window at most once.
+ int beforeFirstSlot = (limit & WINDOW_MASK);
int index;
-
- for (index = limit + 1; index <= value; ++index) {
- int slot = index % WINDOW_SIZE;
-
+ for (index = limit + 1; index != beforeFirstSlot; ++index) {
+ int slot = (index & WINDOW_MASK);
if (!window[slot]) {
break;
}
diff --git a/core/src/test/java/com/yahoo/ycsb/generator/AcknowledgedCounterGeneratorTest.java b/core/src/test/java/com/yahoo/ycsb/generator/AcknowledgedCounterGeneratorTest.java
new file mode 100644
index 00000000..54e02322
--- /dev/null
+++ b/core/src/test/java/com/yahoo/ycsb/generator/AcknowledgedCounterGeneratorTest.java
@@ -0,0 +1,61 @@
+/**
+ * Copyright (c) 2015 YCSB contributors. All rights reserved.
+ *
+ * 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. See accompanying
+ * LICENSE file.
+ */
+package com.yahoo.ycsb.generator;
+
+import java.util.Random;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+
+import org.testng.annotations.Test;
+
+/**
+ * Tests for the AcknowledgedCounterGenerator class.
+ */
+public class AcknowledgedCounterGeneratorTest {
+
+ /**
+ * Test that advancing past {@link Integer#MAX_VALUE} works.
+ */
+ @Test
+ public void testIncrementPastIntegerMaxValue() {
+ final long toTry = AcknowledgedCounterGenerator.WINDOW_SIZE * 3;
+
+ AcknowledgedCounterGenerator generator =
+ new AcknowledgedCounterGenerator(Integer.MAX_VALUE - 1000);
+
+ Random rand = new Random(System.currentTimeMillis());
+ BlockingQueue<Integer> pending = new ArrayBlockingQueue<Integer>(1000);
+ for (long i = 0; i < toTry; ++i) {
+ int value = generator.nextInt();
+
+ while (!pending.offer(value)) {
+
+ Integer first = pending.poll();
+
+ // Don't always advance by one.
+ if (rand.nextBoolean()) {
+ generator.acknowledge(first);
+ } else {
+ Integer second = pending.poll();
+ pending.add(first);
+ generator.acknowledge(second);
+ }
+ }
+ }
+
+ }
+}
--
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