public String getAuditReport() {
LRUClockNode h = this.head;
int totalNodes = 0;
int evictedNodes = 0;
int usedNodes = 0;
while (h != null) {
totalNodes++;
if (h.testEvicted()) evictedNodes++;
if (h.testRecentlyUsed()) usedNodes++;
h = h.nextLRUNode();
}
StringBuffer result = new StringBuffer(128);
result
.append("LRUList Audit: listEntries = ")
.append(totalNodes)
.append(" evicted = ")
.append(evictedNodes)
.append(" used = ")
.append(usedNodes);
return result.toString();
}
/**
* return the Entry that is considered least recently used. The entry will no longer be in the
* pipe (unless it is the last empty marker).
*/
public LRUClockNode getLRUEntry() {
long numEvals = 0;
for (; ; ) {
LRUClockNode aNode = null;
aNode = getHeadEntry();
if (logger.isTraceEnabled(LogMarker.LRU_CLOCK)) {
logger.trace(LogMarker.LRU_CLOCK, "lru considering {}", aNode);
}
if (aNode == null) { // hit the end of the list
this.stats.incEvaluations(numEvals);
return aNode;
} // hit the end of the list
numEvals++;
// If this Entry is part of a transaction, skip it since
// eviction should not cause commit conflicts
synchronized (aNode) {
if (aNode instanceof AbstractRegionEntry) {
if (((AbstractRegionEntry) aNode).isInUseByTransaction()) {
if (logger.isTraceEnabled(LogMarker.LRU_CLOCK)) {
logger.trace(
LogMarker.LRU_CLOCK,
LocalizedMessage.create(
LocalizedStrings
.NewLRUClockHand_REMOVING_TRANSACTIONAL_ENTRY_FROM_CONSIDERATION));
}
continue;
}
}
if (aNode.testEvicted()) {
if (logger.isTraceEnabled(LogMarker.LRU_CLOCK)) {
logger.trace(
LogMarker.LRU_CLOCK,
LocalizedMessage.create(LocalizedStrings.NewLRUClockHand_DISCARDING_EVICTED_ENTRY));
}
continue;
}
// At this point we have any acceptable entry. Now
// use various criteria to determine if it's good enough
// to return, or if we need to add it back to the list.
if (maxEntries > 0 && numEvals > maxEntries) {
if (logger.isTraceEnabled(LogMarker.LRU_CLOCK)) {
logger.trace(
LogMarker.LRU_CLOCK,
LocalizedMessage.create(
LocalizedStrings.NewLRUClockHand_GREEDILY_PICKING_AN_AVAILABLE_ENTRY));
}
this.stats.incGreedyReturns(1);
// fall through, return this node
} else if (aNode.testRecentlyUsed()) {
// Throw it back, it's in the working set
aNode.unsetRecentlyUsed();
// aNode.setInList();
if (logger.isTraceEnabled(LogMarker.LRU_CLOCK)) {
logger.trace(
LogMarker.LRU_CLOCK,
LocalizedMessage.create(
LocalizedStrings.NewLRUClockHand_SKIPPING_RECENTLY_USED_ENTRY, aNode));
}
appendEntry(aNode);
continue; // keep looking
} else {
if (logger.isTraceEnabled(LogMarker.LRU_CLOCK)) {
logger.trace(
LogMarker.LRU_CLOCK,
LocalizedMessage.create(
LocalizedStrings.NewLRUClockHand_RETURNING_UNUSED_ENTRY, aNode));
}
// fall through, return this node
}
// Return the current node.
this.stats.incEvaluations(numEvals);
return aNode;
} // synchronized
} // for
}
