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SOLR-667 -- Thread safety fixes 

git-svn-id: https://svn.apache.org/repos/asf/lucene/solr/trunk@709188 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Shalin Shekhar Mangar 2008-10-30 16:06:38 +00:00
parent e26e274933
commit 451f519e49
1 changed files with 22 additions and 15 deletions
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37
src/java/org/apache/solr/common/util/ConcurrentLRUCache.java
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@ -22,10 +22,11 @@ import java.util.concurrent.locks.ReentrantLock;
*/
public class ConcurrentLRUCache {
private Map<Object, CacheEntry> map;
private final ConcurrentHashMap<Object, CacheEntry> map;
private final int upperWaterMark, lowerWaterMark;
private boolean stop = false;
private volatile boolean stop = false;
private final ReentrantLock markAndSweepLock = new ReentrantLock(true);
private volatile boolean isCleaning = false;
private final boolean newThreadForCleanup;
private volatile boolean islive = true;
private final Stats stats = new Stats();
@ -82,21 +83,29 @@ public class ConcurrentLRUCache {
if (val == null) return null;
CacheEntry e = new CacheEntry(key, val, stats.accessCounter.incrementAndGet());
CacheEntry oldCacheEntry = map.put(key, e);
stats.size.incrementAndGet();
if (oldCacheEntry != null) {
stats.size.incrementAndGet();
}
if (islive) {
stats.putCounter.incrementAndGet();
} else {
stats.nonLivePutCounter.incrementAndGet();
}
if (stats.size.get() > upperWaterMark) {
// Check if we need to clear out old entries from the cache.
// isCleaning variable is checked instead of markAndSweepLock.isLocked()
// for performance because every put invokation will check until
// the size is back to an acceptable level.
//
// There is a race between the check and the call to markAndSweep, but
// it's unimportant because markAndSweep actually aquires the lock or returns if it can't.
if (stats.size.get() > upperWaterMark && !isCleaning) {
if (newThreadForCleanup) {
if (!markAndSweepLock.isLocked()) {
new Thread() {
public void run() {
markAndSweep();
}
}.start();
}
new Thread() {
public void run() {
markAndSweep();
}
}.start();
} else {
markAndSweep();
}
@ -118,6 +127,7 @@ public class ConcurrentLRUCache {
public void markAndSweep() {
if (!markAndSweepLock.tryLock()) return;
try {
isCleaning = true;
int size = stats.size.get();
long currentLatestAccessed = stats.accessCounter.get();
int itemsToBeRemoved = size - lowerWaterMark;
@ -164,6 +174,7 @@ public class ConcurrentLRUCache {
for (CacheEntry sortCacheEntry : tree)
evictEntry(sortCacheEntry.key);
} finally {
isCleaning = false;
markAndSweepLock.unlock();
}
}
@ -252,10 +263,6 @@ public class ConcurrentLRUCache {
public void destroy() {
stop = true;
if (map != null) {
map.clear();
map = null;
}
}
public Stats getStats() {