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Apache Geode provides a database-like consistency model, reliable transaction processing and a shared-nothing architecture to maintain very low latency performance with high concurrency processing
/*
* Licensed to the Apache Software Foundation (ASF) under one or more contributor license
* agreements. See the NOTICE file distributed with this work for additional information regarding
* copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License. You may obtain a
* copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package org.apache.geode.internal.cache.lru;
import org.apache.geode.StatisticsFactory;
import org.apache.geode.cache.Region;
import org.apache.geode.distributed.internal.DistributionConfig;
import org.apache.geode.internal.cache.*;
import org.apache.geode.internal.cache.versions.RegionVersionVector;
import org.apache.geode.internal.i18n.LocalizedStrings;
import org.apache.geode.internal.logging.LogService;
import org.apache.geode.internal.logging.log4j.LocalizedMessage;
import org.apache.geode.internal.logging.log4j.LogMarker;
import org.apache.logging.log4j.Logger;
/**
* AbstractLRUClockHand holds the lrulist, and the behavior for maintaining the list in a cu-pipe
* and determining the next entry to be removed. Each EntriesMap that supports LRU holds one of
* these.
*/
public class NewLRUClockHand {
private static final Logger logger = LogService.getLogger();
private BucketRegion bucketRegion = null;
/** The last node in the LRU list after which all new nodes are added */
protected LRUClockNode tail = new GuardNode();
/** The starting point in the LRU list for searching for the LRU node */
protected LRUClockNode head = new GuardNode();
/** The object for locking the head of the cu-pipe. */
final protected HeadLock lock;
/** Description of the Field */
final private LRUStatistics stats;
/** Counter for the size of the LRU list */
protected int size = 0;
public static final boolean debug =
Boolean.getBoolean(DistributionConfig.GEMFIRE_PREFIX + "verbose-lru-clock");
static private final int maxEntries;
static {
String squelch = System.getProperty(DistributionConfig.GEMFIRE_PREFIX + "lru.maxSearchEntries");
if (squelch == null)
maxEntries = -1;
else
maxEntries = Integer.parseInt(squelch);
}
/** only used by enhancer */
// protected NewLRUClockHand( ) { }
// private long size = 0;
public NewLRUClockHand(Object region, EnableLRU ccHelper,
InternalRegionArguments internalRegionArgs) {
setBucketRegion(region);
this.lock = new HeadLock();
// behavior relies on a single evicted node in the pipe when the pipe is empty.
initHeadAndTail();
if (this.bucketRegion != null) {
this.stats = internalRegionArgs.getPartitionedRegion() != null
? internalRegionArgs.getPartitionedRegion().getEvictionController().stats : null;
} else {
LRUStatistics tmp = null;
if (region instanceof PlaceHolderDiskRegion) {
tmp = ((PlaceHolderDiskRegion) region).getPRLRUStats();
} else if (region instanceof PartitionedRegion) {
tmp = ((PartitionedRegion) region).getPRLRUStatsDuringInitialization(); // bug 41938
PartitionedRegion pr = (PartitionedRegion) region;
if (tmp != null) {
pr.getEvictionController().stats = tmp;
}
}
if (tmp == null) {
StatisticsFactory sf = GemFireCacheImpl.getExisting("").getDistributedSystem();
tmp = ccHelper.initStats(region, sf);
}
this.stats = tmp;
}
}
public void setBucketRegion(Object r) {
if (r instanceof BucketRegion) {
this.bucketRegion = (BucketRegion) r; // see bug 41388
}
}
public NewLRUClockHand(Region region, EnableLRU ccHelper, NewLRUClockHand oldList) {
setBucketRegion(region);
this.lock = new HeadLock();
// behavior relies on a single evicted node in the pipe when the pipe is empty.
initHeadAndTail();
if (oldList.stats == null) {
// see bug 41388
StatisticsFactory sf = region.getCache().getDistributedSystem();
this.stats = ccHelper.initStats(region, sf);
} else {
this.stats = oldList.stats;
if (this.bucketRegion != null) {
this.stats.decrementCounter(this.bucketRegion.getCounter());
this.bucketRegion.resetCounter();
} else {
this.stats.resetCounter();
}
}
}
/** Description of the Method */
public void close() {
closeStats();
if (bucketRegion != null)
bucketRegion.close();
}
public void closeStats() {
LRUStatistics ls = this.stats;
if (ls != null) {
ls.close();
}
}
/**
* Adds a new lru node for the entry between the current tail and head of the list.
*
* @param aNode Description of the Parameter
*/
public final void appendEntry(final LRUClockNode aNode) {
synchronized (this.lock) {
if (aNode.nextLRUNode() != null || aNode.prevLRUNode() != null) {
return;
}
if (logger.isTraceEnabled(LogMarker.LRU_CLOCK)) {
logger.trace(LogMarker.LRU_CLOCK, LocalizedMessage
.create(LocalizedStrings.NewLRUClockHand_ADDING_ANODE_TO_LRU_LIST, aNode));
}
aNode.setNextLRUNode(this.tail);
this.tail.prevLRUNode().setNextLRUNode(aNode);
aNode.setPrevLRUNode(this.tail.prevLRUNode());
this.tail.setPrevLRUNode(aNode);
this.size++;
}
}
/**
* return the head entry in the list preserving the cupipe requirement of at least one entry left
* in the list
*/
private LRUClockNode getHeadEntry() {
synchronized (lock) {
LRUClockNode aNode = NewLRUClockHand.this.head.nextLRUNode();
if (aNode == this.tail) {
return null;
}
LRUClockNode next = aNode.nextLRUNode();
this.head.setNextLRUNode(next);
next.setPrevLRUNode(this.head);
aNode.setNextLRUNode(null);
aNode.setPrevLRUNode(null);
this.size--;
return aNode;
}
}
/**
* 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
}
public void dumpList() {
final boolean isDebugEnabled = logger.isTraceEnabled(LogMarker.LRU_CLOCK);
if (!isDebugEnabled) {
return;
}
synchronized (lock) {
int idx = 1;
for (LRUClockNode aNode = this.head; aNode != null; aNode = aNode.nextLRUNode()) {
if (isDebugEnabled) {
logger.trace(LogMarker.LRU_CLOCK, " ({}) {}", (idx++), aNode);
}
}
}
}
public long getExpensiveListCount() {
synchronized (lock) {
long count = 0;
for (LRUClockNode aNode = this.head.nextLRUNode(); aNode != this.tail; aNode =
aNode.nextLRUNode()) {
count++;
}
return count;
}
}
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();
}
/** unsynchronized audit...only run after activity has ceased. */
public void audit() {
System.out.println(getAuditReport());
}
/** remove an entry from the pipe... (marks it evicted to be skipped later) */
public boolean unlinkEntry(LRUClockNode entry) {
if (logger.isTraceEnabled(LogMarker.LRU_CLOCK)) {
logger.trace(LogMarker.LRU_CLOCK,
LocalizedMessage.create(LocalizedStrings.NewLRUClockHand_UNLINKENTRY_CALLED, entry));
}
entry.setEvicted();
stats().incDestroys();
synchronized (lock) {
LRUClockNode next = entry.nextLRUNode();
LRUClockNode prev = entry.prevLRUNode();
if (next == null || prev == null) {
// not in the list anymore.
return false;
}
next.setPrevLRUNode(prev);
prev.setNextLRUNode(next);
entry.setNextLRUNode(null);
entry.setPrevLRUNode(null);
this.size--;
}
return true;
}
/**
* Get the modifier for lru based statistics.
*
* @return The LRUStatistics for this Clock hand's region.
*/
public LRUStatistics stats() {
return this.stats;
}
/**
* called when an LRU map is cleared... resets stats and releases prev and next.
*/
public void clear(RegionVersionVector rvv) {
if (rvv != null) {
return; // when concurrency checks are enabled the clear operation removes entries iteratively
}
synchronized (this.lock) {
if (bucketRegion != null) {
this.stats.decrementCounter(bucketRegion.getCounter());
bucketRegion.resetCounter();
} else {
this.stats.resetCounter();
}
initHeadAndTail();
// LRUClockNode node = this.tail;
// node.setEvicted();
//
// // NYI need to walk the list and call unsetInList for each one.
//
// // tail's next should already be null.
// setHead( node );
}
}
private void initHeadAndTail() {
// I'm not sure, but I think it's important that we
// drop the references to the old head and tail on a region clear
// That will prevent any concurrent operations that are messing
// with existing nodes from screwing up the head and tail after
// the clear.
// Dan 9/23/09
this.head = new GuardNode();
this.tail = new GuardNode();
this.head.setNextLRUNode(this.tail);
this.tail.setPrevLRUNode(this.head);
this.size = 0;
}
/**
* Get size of LRU queue
*
* @return size
*/
public int size() {
return size;
}
/** perform work of clear(), after subclass has properly synchronized */
// private void internalClear() {
// stats().resetCounter();
// LRUClockNode node = this.tail;
// node.setEvicted();
//
// // NYI need to walk the list and call unsetInList for each one.
//
// // tail's next should already be null.
// setHead( node );
// }
/** Marker class name to identify the lock more easily in thread dumps */
protected static class HeadLock extends Object {
}
private static final class GuardNode implements LRUClockNode {
private LRUClockNode next;
LRUClockNode prev;
public int getEntrySize() {
return 0;
}
public LRUClockNode nextLRUNode() {
return next;
}
public LRUClockNode prevLRUNode() {
return prev;
}
public void setEvicted() {
}
public void setNextLRUNode(LRUClockNode next) {
this.next = next;
}
public void setPrevLRUNode(LRUClockNode prev) {
this.prev = prev;
}
public void setRecentlyUsed() {}
public boolean testEvicted() {
return false;
}
public boolean testRecentlyUsed() {
return false;
}
public void unsetEvicted() {}
public void unsetRecentlyUsed() {}
public int updateEntrySize(EnableLRU ccHelper) {
return 0;
}
public int updateEntrySize(EnableLRU ccHelper, Object value) {
return 0;
}
}
}