com.sun.btrace.ThreadEnteredMap Maven / Gradle / Ivy
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package com.sun.btrace;
import java.io.IOException;
import java.lang.ref.WeakReference;
/**
*
* @author Jaroslav Bachorik
*/
final public class ThreadEnteredMap {
final private static int SECTIONS = 13;
final private static int BUCKETS = 27;
final private static int DEFAULT_BUCKET_SIZE = 4;
final private Object[][][] map = new Object[SECTIONS][BUCKETS][];
final private int[][] mapPtr = new int[SECTIONS][BUCKETS];
private Object nullValue;
public ThreadEnteredMap(Object nullValue) {
this.nullValue = nullValue;
}
public static void main(String[] args) throws IOException {
ThreadEnteredMap instance = new ThreadEnteredMap("null");
long cnt = 0;
long start = System.nanoTime();
for(int i=0;i<4000000;i++) {
cnt += i;
}
long dur = System.nanoTime() - start;
System.err.println("#" + cnt + " in " + dur + "ns");
System.err.println(dur / 4000000);
for(int i=0;i<400000;i++) {
instance.enter("in");
instance.exit();
}
final ThreadEnteredMap tem = new ThreadEnteredMap("null");
cnt = 0;
System.err.println("Ready?");
System.in.read();
Thread[] thrd = new Thread[200];
for(int i=0;i<4;i++) {
final int idx = i;
thrd[i] = new Thread(new Runnable() {
public void run() {
long cnt = 0;
long start = System.nanoTime();
for(int i=0;i<4000000;i++) {
tem.enter("in");
cnt += i;
tem.exit();
}
long dur = System.nanoTime() - start;
System.out.println("Thread #" + idx);
System.err.println("#" + cnt + " in " + dur + "ns");
System.err.println(dur / 4000000);
}
}, "Thread#" + i);
}
for(int i=0;i<4;i++) {
thrd[i].start();
}
}
public Object get() {
Thread thrd = Thread.currentThread();
long thrdId = thrd.getId();
int sectionId = (int)(((thrdId << 1) - (thrdId << 8)) & (SECTIONS - 1));
Object[][] section = map[sectionId];
int[] sectionPtr = mapPtr[sectionId];
int bucketId = (int)(int)(((thrdId << 1) - (thrdId << 8)) & (BUCKETS - 1));
synchronized(section) {
Object[] bucket = section[bucketId];
if (bucket != null && bucket.length > 0) {
int ptr = sectionPtr[bucketId];
for(int i=0;i)bucket[i]).get();
if (bThread == thrd) {
return bucket[i+1] == nullValue ? null : bucket[i+1];
}
}
}
return null;
}
}
public boolean enter(Object rt) {
Thread thrd = Thread.currentThread();
long thrdId = thrd.getId();
int sectionId = (int)(((thrdId << 1) - (thrdId << 8)) & (SECTIONS - 1));
Object[][] section = map[sectionId];
int[] sectionPtr = mapPtr[sectionId];
int bucketId = (int)(int)(((thrdId << 1) - (thrdId << 8)) & (BUCKETS - 1));
synchronized(section) {
Object[] bucket = section[bucketId];
int ptr = sectionPtr[bucketId];
if (bucket != null && bucket.length > 0) {
for(int i=0;i)bucket[i]).get();
if (bThread == null) {
// the previous thread with the same ID has already been GCd
bucket[i] = new WeakReference(thrd);
bucket[i+1] = rt;
return true;
} else if (bThread == thrd) {
if (bucket[i+1] == nullValue) {
bucket[i+1] = rt;
return true;
}
return false;
}
}
}
if (bucket == null || bucket.length == 0) {
bucket = new Object[DEFAULT_BUCKET_SIZE * 2];
section[bucketId] = bucket;
} else {
if (ptr >= bucket.length) {
Object[] newBucket = new Object[bucket.length * 2];
System.arraycopy(bucket, 0, newBucket, 0, bucket.length);
bucket = newBucket;
section[bucketId] = bucket;
}
}
bucket[ptr++] = new WeakReference(thrd);
bucket[ptr++] = rt;
mapPtr[sectionId][bucketId] = ptr;
return true;
}
}
public void exit() {
Thread thrd = Thread.currentThread();
long thrdId = thrd.getId();
int sectionId = (int)(((thrdId << 1) - (thrdId << 8)) & (SECTIONS - 1));
Object[][] section = map[sectionId];
int[] sectionPtr = mapPtr[sectionId];
int bucketId = (int)(int)(((thrdId << 1) - (thrdId << 8)) & (BUCKETS - 1));
synchronized(section) {
Object[] bucket = section[bucketId];
if (bucket != null && bucket.length > 0) {
int ptr = sectionPtr[bucketId];
for(int i=0;i)bucket[i]).get();
if (bThread == thrd) {
bucket[i+1] = nullValue;
}
}
}
}
}
}
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