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Version 1.5 - Add support for efficient pause()ing, whileEqual and whileLessThan with limited busy waiting.
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‎README‎

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[ Version History ]
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Version 1.5 - Add support for efficient pause()ing, whileEqual and whileLessThan with limited busy waiting.
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Version 1.4.1 - Add an AffinityThreadFactory to support ExecutorService
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Version 1.4 - Support binding of a whole core for hyper-threaded systems. AffinityLock.acquireCore()

‎pom.xml‎

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<groupId>vanilla.java</groupId>
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<artifactId>affinity</artifactId>
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<version>1.4.1</version>
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<version>1.5</version>
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<packaging>jar</packaging>
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<licenses>
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</plugin>
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<plugin>
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<artifactId>maven-javadoc-plugin</artifactId>
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<version>2.5</version>
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<executions>
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<execution>
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<phase>package</phase>
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<plugin>
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<groupId>org.apache.felix</groupId>
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<artifactId>maven-bundle-plugin</artifactId>
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<version>2.3.6</version>
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<extensions>true</extensions>
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<configuration>
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<instructions>

‎src/main/c/Makefile‎

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all: $(TARGET)
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$(TARGET): vanilla_java_affinity_impl_NativeAffinity.c $(WORKING_DIR)/vanilla_java_affinity_impl_NativeAffinity.h
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$(TARGET): vanilla_java_affinity_impl_NativeAffinity.c $(WORKING_DIR)/vanilla_java_affinity_impl_NativeAffinity.h $(WORKING_DIR)/vanilla_java_clock_impl_JNIClock.h $(WORKING_DIR)/vanilla_java_busywaiting_impl_BusyWaiting.h
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gcc -O2 -shared -fPIC -L$(JVM_SHARED_LIB) -ljvm -lrt $(INCLUDES) vanilla_java_affinity_impl_NativeAffinity.c -o $(TARGET)
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$(WORKING_DIR)/vanilla_java_affinity_impl_NativeAffinity.h: $(TARGET_DIR)/vanilla/java/affinity/impl/NativeAffinity.class
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mkdir -p $(TARGET_DIR)/jni
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javah -force -classpath $(JAVAH_CLASSPATH) -d $(WORKING_DIR) vanilla.java.affinity.impl.NativeAffinity
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$(WORKING_DIR)/vanilla_java_clock_impl_JNIClock.h: $(TARGET_DIR)/vanilla/java/clock/impl/JNIClock.class
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mkdir -p $(TARGET_DIR)/jni
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javah -force -classpath $(JAVAH_CLASSPATH) -d $(WORKING_DIR) vanilla.java.clock.impl.JNIClock
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$(WORKING_DIR)/vanilla_java_busywaiting_impl_BusyWaiting.h: $(TARGET_DIR)/vanilla/java/busywaiting/impl/JNIBusyWaiting.class
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mkdir -p $(TARGET_DIR)/jni
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javah -force -classpath $(JAVAH_CLASSPATH) -d $(WORKING_DIR) vanilla.java.busywaiting.impl.JNIBusyWaiting

‎src/main/c/vanilla_java_affinity_impl_NativeAffinity.c‎

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#include <jni.h>
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#include <sched.h>
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#include "vanilla_java_affinity_impl_NativeAffinity.h"
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#include "vanilla_java_busywaiting_impl_JNIBusyWaiting.h"
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#include "vanilla_java_clock_impl_JNIClock.h"
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/*
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* Class: vanilla_java_affinity_impl_NativeAffinity
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* Method: getAffinity0
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(JNIEnv *env, jclass c) {
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return (jlong) rdtsc();
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}
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// From http://locklessinc.com/articles/locks/
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/* Compile read-write barrier */
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#define barrier() asm volatile("": : :"memory")
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/* Pause instruction to prevent excess processor bus usage */
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#define cpu_relax() asm volatile("pause\n": : :"memory")
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/*
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* Class: vanilla_java_busywaiting_impl_JNIBusyWaiting
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* Method: pause0
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* Signature: ()V
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*/
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JNIEXPORT void JNICALL Java_vanilla_java_busywaiting_impl_JNIBusyWaiting_pause0
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(JNIEnv *env, jclass c) {
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cpu_relax();
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}
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/*
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* Class: vanilla_java_busywaiting_impl_JNIBusyWaiting
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* Method: whileEqual0
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* Signature: (JIJ)J
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*/
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JNIEXPORT jlong JNICALL Java_vanilla_java_busywaiting_impl_JNIBusyWaiting_whileEqual0
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(JNIEnv *env, jclass c, jlong address0, jint iterations, jlong value) {
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volatile jlong * address = (volatile jlong *) address0;
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barrier();
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jlong value2 = *address;
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while(value2 == value && iterations-- > 0) {
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cpu_relax();
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barrier();
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value2 = *address;
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}
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return value2;
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}
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/*
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* Class: vanilla_java_busywaiting_impl_JNIBusyWaiting
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* Method: whileLessThan0
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* Signature: (JIJ)J
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*/
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JNIEXPORT jlong JNICALL Java_vanilla_java_busywaiting_impl_JNIBusyWaiting_whileLessThan0
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(JNIEnv *env, jclass c, jlong address0, jint iterations, jlong value) {
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volatile jlong * address = (volatile jlong *) address0;
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barrier();
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jlong value2 = *address;
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while(value2 < value && iterations-- > 0) {
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cpu_relax();
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barrier();
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value2 = *address;
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}
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return value2;
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}

‎src/main/java/vanilla/java/busywaiting/BusyWaiter.java‎

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/*
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* Copyright 2011 Peter Lawrey
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package vanilla.java.busywaiting;
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import vanilla.java.busywaiting.impl.JNIBusyWaiting;
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import vanilla.java.busywaiting.impl.JavaBusyWaiting;
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/**
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* @author peter.lawrey
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*/
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public class BusyWaiter {
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private static final IBusyWaiter BUSY_WAITER;
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static {
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if (JNIBusyWaiting.LOADED)
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BUSY_WAITER = JNIBusyWaiting.INSTANCE;
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else
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BUSY_WAITER = JavaBusyWaiting.INSTANCE;
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}
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/**
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* Pause in the most efficient way available.
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*/
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public static void pause() {
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BUSY_WAITER.pause();
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}
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/**
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* poll a long value until it changes (or the iterations have been reached)
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*
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* @param obj Object to examine or null for raw address space.
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* @param address offset in the Object or address pointer
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* @param iterations number of times to try before giving up.
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* @param value value to test for, return as soon a the value changes.
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* @return the value value found.
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*/
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public static long whileEqual(Object obj, long address, int iterations, long value) {
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return BUSY_WAITER.whileEqual(obj, address, iterations, value);
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}
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/**
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* poll a long value while it is less than a value (or the iterations have been reached)
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*
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* @param obj Object to examine or null for raw address space.
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* @param address offset in the Object or address pointer
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* @param iterations number of times to try before giving up.
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* @param value value to test for, return as soon a the value is equal or more than.
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* @return the value value found.
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*/
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public static long whileLessThan(Object obj, long address, int iterations, long value) {
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return BUSY_WAITER.whileLessThan(obj, address, iterations, value);
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}
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}

‎src/main/java/vanilla/java/busywaiting/IBusyWaiter.java‎

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/*
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* Copyright 2011 Peter Lawrey
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package vanilla.java.busywaiting;
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/**
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* @author peter.lawrey
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*/
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public interface IBusyWaiter {
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public void pause();
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public long whileEqual(Object obj, long address, int iterations, long value);
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public long whileLessThan(Object obj, long address, int iterations, long value);
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}

‎src/main/java/vanilla/java/busywaiting/impl/JNIBusyWaiting.java‎

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/*
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* Copyright 2011 Peter Lawrey
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package vanilla.java.busywaiting.impl;
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import vanilla.java.busywaiting.IBusyWaiter;
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/**
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* @author peter.lawrey
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*/
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public enum JNIBusyWaiting implements IBusyWaiter {
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INSTANCE;
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public static final boolean LOADED;
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static {
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boolean loaded;
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try {
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System.loadLibrary("affinity");
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loaded = true;
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} catch (UnsatisfiedLinkError ule) {
35+
loaded = false;
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}
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LOADED = loaded;
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}
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public static native void pause0();
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public static native long whileEqual0(long address, int iterations, long value);
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public static native long whileLessThan0(long address, int iterations, long value);
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@Override
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public void pause() {
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pause0();
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}
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@Override
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public long whileEqual(Object obj, long address, int iterations, long value) {
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if (obj == null)
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return whileEqual0(address, iterations, value);
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return whileEqual0(obj, address, iterations, value);
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}
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private static long whileEqual0(Object obj, long address, int iterations, long value) {
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long value2 = JavaBusyWaiting.UNSAFE.getLongVolatile(null, address);
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while (value2 == value && iterations-- > 0) {
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pause0();
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value2 = JavaBusyWaiting.UNSAFE.getLongVolatile(obj, address);
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}
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return value2;
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}
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@Override
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public long whileLessThan(Object obj, long address, int iterations, long value) {
70+
if (obj == null)
71+
return whileLessThan0(address, iterations, value);
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return whileLessThan0(obj, address, iterations, value);
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}
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private static long whileLessThan0(Object obj, long address, int iterations, long value) {
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long value2 = JavaBusyWaiting.UNSAFE.getLongVolatile(null, address);
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while (value2 < value && iterations-- > 0) {
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pause0();
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value2 = JavaBusyWaiting.UNSAFE.getLongVolatile(obj, address);
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}
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return value2;
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}
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}

‎src/main/java/vanilla/java/busywaiting/impl/JavaBusyWaiting.java‎

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/*
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* Copyright 2011 Peter Lawrey
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
6+
* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package vanilla.java.busywaiting.impl;
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import sun.misc.Unsafe;
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import vanilla.java.busywaiting.IBusyWaiter;
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import java.lang.reflect.Field;
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/**
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* @author peter.lawrey
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*/
27+
public enum JavaBusyWaiting implements IBusyWaiter {
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INSTANCE;
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static final Unsafe UNSAFE;
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@Override
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public void pause() {
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Thread.yield();
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}
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@Override
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public long whileEqual(Object obj, long address, int iterations, long value) {
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long value2 = UNSAFE.getLongVolatile(null, address);
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while (value2 == value && iterations-- > 0) {
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pause();
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value2 = UNSAFE.getLongVolatile(obj, address);
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}
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return value2;
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}
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@Override
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public long whileLessThan(Object obj, long address, int iterations, long value) {
50+
long value2 = UNSAFE.getLongVolatile(null, address);
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while (value2 < value && iterations-- > 0) {
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pause();
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value2 = UNSAFE.getLongVolatile(obj, address);
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}
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return value2;
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}
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static {
59+
try {
60+
Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
61+
theUnsafe.setAccessible(true);
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UNSAFE = (Unsafe) theUnsafe.get(null);
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} catch (Exception e) {
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throw new AssertionError(e);
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}
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}
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}

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