HDFS-2421. Improve the concurrency of SerialNumberMap in NameNode. Contributed by Jing Zhao and Weiyan Wang

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1374127 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Tsz-wo Sze 2012-08-17 01:54:16 +00:00
parent 87d87b04e6
commit ffbadbdd36
2 changed files with 28 additions and 14 deletions

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@ -415,6 +415,9 @@ Branch-2 ( Unreleased changes )
HDFS-3697. Enable fadvise readahead by default. (todd)
HDFS-2421. Improve the concurrency of SerialNumberMap in NameNode.
(Jing Zhao and Weiyan Wang via szetszwo)
BUG FIXES
HDFS-3385. The last block of INodeFileUnderConstruction is not

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@ -17,7 +17,10 @@
*/
package org.apache.hadoop.hdfs.server.namenode;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
/** Manage name-to-serial-number maps for users and groups. */
class SerialNumberManager {
@ -40,33 +43,41 @@ private SerialNumberManager() {}
}
private static class SerialNumberMap<T> {
private int max = 0;
private int nextSerialNumber() {return max++;}
private AtomicInteger max = new AtomicInteger(1);
private ConcurrentMap<T, Integer> t2i = new ConcurrentHashMap<T, Integer>();
private ConcurrentMap<Integer, T> i2t = new ConcurrentHashMap<Integer, T>();
private Map<T, Integer> t2i = new HashMap<T, Integer>();
private Map<Integer, T> i2t = new HashMap<Integer, T>();
synchronized int get(T t) {
int get(T t) {
if (t == null) {
return 0;
}
Integer sn = t2i.get(t);
if (sn == null) {
sn = nextSerialNumber();
t2i.put(t, sn);
sn = max.getAndIncrement();
Integer old = t2i.putIfAbsent(t, sn);
if (old != null) {
return old;
}
i2t.put(sn, t);
}
return sn;
}
synchronized T get(int i) {
if (!i2t.containsKey(i)) {
T get(int i) {
if (i == 0) {
return null;
}
T t = i2t.get(i);
if (t == null) {
throw new IllegalStateException("!i2t.containsKey(" + i
+ "), this=" + this);
}
return i2t.get(i);
return t;
}
@Override
/** {@inheritDoc} */
public String toString() {
return "max=" + max + ",\n t2i=" + t2i + ",\n i2t=" + i2t;
}
}
}
}