/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2002-2006
* Sleepycat Software. All rights reserved.
*
* $Id: INCompressor.java,v 1.1 2006/05/06 09:02:11 ckaestne Exp $
*/
package com.sleepycat.je.incomp;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.EnvironmentStats;
import com.sleepycat.je.StatsConfig;
import com.sleepycat.je.cleaner.TrackedFileSummary;
import com.sleepycat.je.cleaner.UtilizationTracker;
import com.sleepycat.je.config.EnvironmentParams;
import com.sleepycat.je.dbi.DatabaseImpl;
import com.sleepycat.je.dbi.DbTree;
import com.sleepycat.je.dbi.EnvironmentImpl;
import com.sleepycat.je.latch.LatchSupport;
import com.sleepycat.je.tree.BIN;
import com.sleepycat.je.tree.BINReference;
import com.sleepycat.je.tree.CursorsExistException;
import com.sleepycat.je.tree.DBIN;
import com.sleepycat.je.tree.DIN;
import com.sleepycat.je.tree.IN;
import com.sleepycat.je.tree.Key;
import com.sleepycat.je.tree.Node;
import com.sleepycat.je.tree.NodeNotEmptyException;
import com.sleepycat.je.tree.Tree;
import com.sleepycat.je.tree.Tree.SearchType;
import com.sleepycat.je.utilint.DaemonThread;
import com.sleepycat.je.utilint.PropUtil;
import com.sleepycat.je.utilint.Tracer;
/**
* The IN Compressor. JE compression consist of removing delete entries from
* BINs, and pruning empty IN/BINs from the tree. Compression is carried out by
* either a daemon thread or lazily by operations (namely checkpointing and
* eviction) that are writing INS.
*/
public class INCompressor extends DaemonThread {
private static final String TRACE_COMPRESS = "INCompress:";
private static final boolean DEBUG = false;
private EnvironmentImpl env;
private long lockTimeout;
/* stats */
private int splitBins = 0;
private int dbClosedBins = 0;
private int cursorsBins = 0;
private int nonEmptyBins = 0;
private int processedBins = 0;
/* per-run stats */
private int splitBinsThisRun = 0;
private int dbClosedBinsThisRun = 0;
private int cursorsBinsThisRun = 0;
private int nonEmptyBinsThisRun = 0;
private int processedBinsThisRun = 0;
/*
* The following stats are not kept per run, because they're set by
* multiple threads doing lazy compression. They are debugging aids; it
* didn't seem like a good idea to add synchronization to the general path.
*/
private int lazyProcessed = 0;
private int lazyEmpty = 0;
private int lazySplit = 0;
private int wokenUp = 0;
/*
* Store logical references to BINs that have deleted entries and are
* candidates for compaction.
*/
private Map binRefQueue;
private Object binRefQueueSync;
public INCompressor(EnvironmentImpl env, long waitTime, String name)
throws DatabaseException {
super(waitTime, name, env);
this.env = env;
lockTimeout = PropUtil.microsToMillis(
env.getConfigManager().getLong
(EnvironmentParams.COMPRESSOR_LOCK_TIMEOUT));
binRefQueue = new HashMap();
binRefQueueSync = new Object();
}
public String toString() {
StringBuffer sb = new StringBuffer();
sb.append("<INCompressor name=\"").append(name).append("\"/>");
return sb.toString();
}
synchronized public void clearEnv() {
env = null;
}
public synchronized void verifyCursors()
throws DatabaseException {
/*
* Environment may have been closed. If so, then our job here is done.
*/
if (env.isClosed()) {
return;
}
/*
* Use a snapshot to verify the cursors. This way we don't have to
* hold a latch while verify takes locks.
*/
List queueSnapshot = null;
synchronized (binRefQueueSync) {
queueSnapshot = new ArrayList(binRefQueue.values());
}
/* Use local caching to reduce DbTree.getDb overhead. */
Map dbCache = new HashMap();
Iterator it = queueSnapshot.iterator();
while (it.hasNext()) {
BINReference binRef = (BINReference) it.next();
DatabaseImpl db = env.getDbMapTree().getDb
(binRef.getDatabaseId(), lockTimeout, dbCache);
BIN bin = searchForBIN(db, binRef);
if (bin != null) {
bin.verifyCursors();
bin.releaseLatch();
}
}
}
/**
* The default daemon work queue is not used because we need a map, not a
* set.
*/
public void addToQueue(Object o)
throws DatabaseException {
throw new DatabaseException
("INCompressor.addToQueue should never be called.");
}
public int getBinRefQueueSize()
throws DatabaseException {
int size = 0;
synchronized (binRefQueueSync) {
size = binRefQueue.size();
}
return size;
}
/*
* There are multiple flavors of the addBin*ToQueue methods. All allow
* the caller to specify whether the daemon should be notified. Currently
* no callers proactively notify, and we rely on lazy compression and
* the daemon timebased wakeup to process the queue.
*/
/**
* Adds the BIN and deleted Key to the queue if the BIN is not already in
* the queue, or adds the deleted key to an existing entry if one exists.
*/
public void addBinKeyToQueue(BIN bin, Key deletedKey, boolean doWakeup)
throws DatabaseException {
synchronized (binRefQueueSync) {
addBinKeyToQueueAlreadyLatched(bin, deletedKey);
}
if (doWakeup) {
wakeup();
}
}
/**
* Adds the BINReference to the queue if the BIN is not already in the
* queue, or adds the deleted keys to an existing entry if one exists.
*/
public void addBinRefToQueue(BINReference binRef, boolean doWakeup)
throws DatabaseException {
synchronized (binRefQueueSync) {
addBinRefToQueueAlreadyLatched(binRef);
}
if (doWakeup) {
wakeup();
}
}
/**
* Adds an entire collection of BINReferences to the queue at once. Use
* this to avoid latching for each add.
*/
public void addMultipleBinRefsToQueue(Collection binRefs,
boolean doWakeup)
throws DatabaseException {
synchronized (binRefQueueSync) {
Iterator it = binRefs.iterator();
while (it.hasNext()) {
BINReference binRef = (BINReference) it.next();
addBinRefToQueueAlreadyLatched(binRef);
}
}
if (doWakeup) {
wakeup();
}
}
/**
* Adds the BINReference with the latch held.
*/
private void addBinRefToQueueAlreadyLatched(BINReference binRef) {
Long node = new Long(binRef.getNodeId());
BINReference existingRef = (BINReference) binRefQueue.get(node);
if (existingRef != null) {
existingRef.addDeletedKeys(binRef);
} else {
binRefQueue.put(node, binRef);
}
}
/**
* Adds the BIN and deleted Key with the latch held.
*/
private void addBinKeyToQueueAlreadyLatched(BIN bin, Key deletedKey) {
Long node = new Long(bin.getNodeId());
BINReference existingRef = (BINReference) binRefQueue.get(node);
if (existingRef != null) {
if (deletedKey != null) {
existingRef.addDeletedKey(deletedKey);
}
} else {
BINReference binRef = bin.createReference();
if (deletedKey != null) {
binRef.addDeletedKey(deletedKey);
}
binRefQueue.put(node, binRef);
}
}
public boolean exists(long nodeId) {
Long node = new Long(nodeId);
synchronized (binRefQueueSync) {
return (binRefQueue.get(node) != null);
}
}
/*
* Return a bin reference for this node if it exists and has a set of
* deletable keys.
*/
private BINReference removeCompressibleBinReference(long nodeId) {
Long node = new Long(nodeId);
BINReference foundRef = null;
synchronized (binRefQueueSync) {
BINReference target = (BINReference) binRefQueue.remove(node);
if (target != null) {
if (target.deletedKeysExist()) {
foundRef = target;
} else {
/*
* This is an entry that needs to be pruned. Put it back
* to be dealt with by the daemon.
*/
binRefQueue.put(node, target);
}
}
}
return foundRef;
}
/**
* Return stats
*/
public void loadStats(StatsConfig config, EnvironmentStats stat)
throws DatabaseException {
stat.setSplitBins(splitBins);
stat.setDbClosedBins(dbClosedBins);
stat.setCursorsBins(cursorsBins);
stat.setNonEmptyBins(nonEmptyBins);
stat.setProcessedBins(processedBins);
stat.setInCompQueueSize(getBinRefQueueSize());
if (DEBUG) {
System.out.println("lazyProcessed = " + lazyProcessed);
System.out.println("lazyEmpty = " + lazyEmpty);
System.out.println("lazySplit = " + lazySplit);
System.out.println("wokenUp=" + wokenUp);
}
if (config.getClear()) {
splitBins = 0;
dbClosedBins = 0;
cursorsBins = 0;
nonEmptyBins = 0;
processedBins = 0;
lazyProcessed = 0;
lazyEmpty = 0;
lazySplit = 0;
wokenUp = 0;
}
}
/**
* Return the number of retries when a deadlock exception occurs.
*/
protected int nDeadlockRetries()
throws DatabaseException {
return env.getConfigManager().getInt
(EnvironmentParams.COMPRESSOR_RETRY);
}
public synchronized void onWakeup()
throws DatabaseException {
if (env.isClosed()) {
return;
}
wokenUp++;
doCompress();
}
/**
* The real work to doing a compress. This may be called by the compressor
* thread or programatically.
*/
public synchronized void doCompress()
throws DatabaseException {
if (!isRunnable()) {
return;
}
/*
* Make a snapshot of the current work queue so the compressor thread
* can safely iterate over the queue. Note that this impacts lazy
* compression, because it lazy compressors will not see BINReferences
* that have been moved to the snapshot.
*/
Map queueSnapshot = null;
int binQueueSize = 0;
synchronized (binRefQueueSync) {
binQueueSize = binRefQueue.size();
if (binQueueSize > 0) {
queueSnapshot = binRefQueue;
binRefQueue = new HashMap();
}
}
/* There is work to be done. */
if (binQueueSize > 0) {
resetPerRunCounters();
Tracer.trace(Level.FINE, env,
"InCompress.doCompress called, queue size: " +
binQueueSize);
assert LatchSupport.countLatchesHeld() == 0;
/*
* Compressed entries must be counted as obsoleted. A separate
* tracker is used to accumulate tracked obsolete info so it can be
* added in a single call under the log write latch. We log the
* info for deleted subtrees immediately because we don't process
* deleted IN entries during recovery; this reduces the chance of
* lost info.
*/
UtilizationTracker tracker = new UtilizationTracker(env);
/* Use local caching to reduce DbTree.getDb overhead. */
Map dbCache = new HashMap();
DbTree dbTree = env.getDbMapTree();
BINSearch binSearch = new BINSearch();
try {
Iterator it = queueSnapshot.values().iterator();
while (it.hasNext()) {
if (env.isClosed()) {
return;
}
BINReference binRef = (BINReference) it.next();
if (!findDBAndBIN(binSearch, binRef, dbTree, dbCache)) {
/*
* Either the db is closed, or the BIN doesn't
* exist. Don't process this BINReference.
*/
continue;
}
if (binRef.deletedKeysExist()) {
/* Compress deleted slots. */
boolean requeued = compressBin
(binSearch.db, binSearch.bin, binRef, tracker);
if (!requeued) {
/*
* This BINReference was fully processed, but there
* may still be deleted slots. If there are still
* deleted keys in the binref, they were relocated
* by a split.
*/
checkForRelocatedSlots
(binSearch.db, binRef, tracker);
}
} else {
/*
* An empty BINReference on the queue was put there by
* a lazy compressor to indicate that we should try to
* prune an empty BIN.
*/
BIN foundBin = binSearch.bin;
byte[] idKey = foundBin.getIdentifierKey();
boolean isDBIN = foundBin.containsDuplicates();
byte[] dupKey = null;
if (isDBIN) {
dupKey = ((DBIN) foundBin).getDupKey();
}
/*
* Release the bin latch taken by the initial
* search. Pruning starts from the top of the tree
* and requires that no latches are held.
*/
foundBin.releaseLatch();
pruneBIN(binSearch.db, binRef, idKey, isDBIN,
dupKey, tracker);
}
}
/*
* Count obsolete nodes and write out modified file summaries
* for recovery. All latches must have been released.
*/
TrackedFileSummary[] summaries = tracker.getTrackedFiles();
if (summaries.length > 0) {
env.getUtilizationProfile().countAndLogSummaries
(summaries);
}
} finally {
assert LatchSupport.countLatchesHeld() == 0;
accumulatePerRunCounters();
}
}
}
/**
* Compresses a single BIN and then deletes the BIN if it is empty.
* @param bin is latched when this method is called, and unlatched when it
* returns.
* @return true if the BINReference was requeued by this method.
*/
private boolean compressBin(DatabaseImpl db,
BIN bin,
BINReference binRef,
UtilizationTracker tracker)
throws DatabaseException {
/* Safe to get identifier keys; bin is latched. */
boolean empty = false;
boolean requeued = false;
byte[] idKey = bin.getIdentifierKey();
byte[] dupKey = null;
boolean isDBIN = bin.containsDuplicates();
try {
int nCursors = bin.nCursors();
if (nCursors > 0) {
/*
* There are cursors pointing to the BIN, so try again later.
*/
addBinRefToQueue(binRef, false);
requeued = true;
cursorsBinsThisRun++;
} else {
requeued = bin.compress(binRef, true /* canFetch */);
if (!requeued) {
/*
* Only check for emptiness if this BINRef is in play and
* not on the queue.
*/
empty = (bin.getNEntries() == 0);
if (empty) {
/*
* While we have the BIN latched, prepare a dup key if
* needed for navigating the tree while pruning.
*/
if (isDBIN) {
dupKey = ((DBIN) bin).getDupKey();
}
}
}
}
} finally {
bin.releaseLatch();
}
/* Prune if the bin is empty and there has been no requeuing. */
if (empty) {
requeued = pruneBIN(db, binRef, idKey, isDBIN, dupKey, tracker);
}
return requeued;
}
/**
* If the target BIN is empty, attempt to remove the empty branch of the
* tree.
* @return true if the pruning was unable to proceed and the BINReference
* was requeued.
*/
private boolean pruneBIN(DatabaseImpl dbImpl,
BINReference binRef,
byte[] idKey,
boolean containsDups,
byte[] dupKey,
UtilizationTracker tracker)
throws DatabaseException {
boolean requeued = false;
try {
Tree tree = dbImpl.getTree();
if (containsDups) {
tree.deleteDup(idKey, dupKey, tracker);
} else {
tree.delete(idKey, tracker);
}
processedBinsThisRun++;
} catch (NodeNotEmptyException NNEE) {
/*
* Something was added to the node since the point when the
* deletion occurred; we can't prune, and we can throw away this
* BINReference.
*/
nonEmptyBinsThisRun++;
} catch (CursorsExistException e) {
/*
* If there are cursors in the way of the delete, retry later.
* For example, When we delete a BIN or DBIN, we're guaranteed that
* there are no cursors at that node. (otherwise, we wouldn't be
* able to remove all the entries. However, there's the possibility
* that the BIN that is the parent of the duplicate tree has
* resident cursors, and in that case, we would not be able to
* remove the whole duplicate tree and DIN root. In that case, we'd
* requeue.
*/
addBinRefToQueue(binRef, false);
cursorsBinsThisRun++;
requeued = true;
}
return requeued;
}
/*
* When we do not requeue the BINRef but there are deleted keys remaining,
* those keys were not found in the BIN and therefore must have been moved
* to another BIN during a split.
*/
private void checkForRelocatedSlots(DatabaseImpl db,
BINReference binRef,
UtilizationTracker tracker)
throws DatabaseException {
Iterator iter = binRef.getDeletedKeyIterator();
if (iter != null) {
/* mainKey is only used for dups. */
byte[] mainKey = binRef.getKey();
boolean isDup = (binRef.getData() != null);
while (iter.hasNext()) {
Key key = (Key) iter.next();
/*
* Lookup the BIN for each deleted key, and compress that BIN
* separately.
*/
BIN splitBin = isDup ?
searchForBIN(db, mainKey, key.getKey()) :
searchForBIN(db, key.getKey(), null);
if (splitBin != null) {
BINReference splitBinRef = splitBin.createReference();
splitBinRef.addDeletedKey(key);
compressBin(db, splitBin, splitBinRef, tracker);
}
}
}
}
private boolean isRunnable()
throws DatabaseException {
return true;
}
/**
* Search the tree for the BIN or DBIN that corresponds to this
* BINReference.
*
* @param binRef the BINReference that indicates the bin we want.
* @return the BIN or DBIN that corresponds to this BINReference. The
* node is latched upon return. Returns null if the BIN can't be found.
*/
public BIN searchForBIN(DatabaseImpl db, BINReference binRef)
throws DatabaseException {
return searchForBIN(db, binRef.getKey(), binRef.getData());
}
private BIN searchForBIN(DatabaseImpl db, byte[] mainKey, byte[] dupKey)
throws DatabaseException {
/* Search for this IN */
Tree tree = db.getTree();
IN in = tree.search
(mainKey, SearchType.NORMAL, -1, null, false /*updateGeneration*/);
/* Couldn't find a bin, return null */
if (in == null) {
return null;
}
/* This is not a duplicate, we're done. */
if (dupKey == null) {
return (BIN) in;
}
/* We need to descend down into a duplicate tree. */
DIN duplicateRoot = null;
DBIN duplicateBin = null;
BIN bin = (BIN) in;
try {
int index = bin.findEntry(mainKey, false, true);
if (index >= 0) {
Node node = null;
if (!bin.isEntryKnownDeleted(index)) {
/* If fetchTarget returns null, a deleted LN was cleaned. */
node = bin.fetchTarget(index);
}
if (node == null) {
bin.releaseLatch();
return null;
}
if (node.containsDuplicates()) {
/* It's a duplicate tree. */
duplicateRoot = (DIN) node;
duplicateRoot.latch();
bin.releaseLatch();
duplicateBin = (DBIN) tree.searchSubTree
(duplicateRoot, dupKey, SearchType.NORMAL, -1, null,
false /*updateGeneration*/);
return duplicateBin;
} else {
/* We haven't migrated to a duplicate tree yet.
* XXX, isn't this taken care of above? */
return bin;
}
} else {
bin.releaseLatch();
return null;
}
} catch (DatabaseException DBE) {
if (bin != null) {
bin.releaseLatchIfOwner();
}
if (duplicateRoot != null) {
duplicateRoot.releaseLatchIfOwner();
}
/*
* FindBugs whines about Redundent comparison to null below, but
* for stylistic purposes we'll leave it in.
*/
if (duplicateBin != null) {
duplicateBin.releaseLatchIfOwner();
}
throw DBE;
}
}
/**
* Reset per-run counters.
*/
private void resetPerRunCounters() {
splitBinsThisRun = 0;
dbClosedBinsThisRun = 0;
cursorsBinsThisRun = 0;
nonEmptyBinsThisRun = 0;
processedBinsThisRun = 0;
}
private void accumulatePerRunCounters() {
splitBins += splitBinsThisRun;
dbClosedBins += dbClosedBinsThisRun;
cursorsBins += cursorsBinsThisRun;
nonEmptyBins += nonEmptyBinsThisRun;
processedBins += processedBinsThisRun;
}
/**
* Lazily compress a single BIN. Do not do any pruning. The target IN
* should be latched when we enter, and it will be remain latched.
*/
public void lazyCompress(IN in)
throws DatabaseException {
if (!in.isCompressible()) {
return;
}
assert in.isLatchOwner();
/* BIN is latched. */
BIN bin = (BIN) in;
int nCursors = bin.nCursors();
if (nCursors > 0) {
/* Cursor prohibit compression. */
return;
} else {
BINReference binRef =
removeCompressibleBinReference(bin.getNodeId());
if ((binRef == null) || (!binRef.deletedKeysExist())) {
return;
} else {
boolean requeued = bin.compress(binRef, false /* canFetch */);
lazyProcessed++;
/*
* If this wasn't requeued, but there were deleted keys
* remaining, requeue, so the daemon can handle this. Either
* we must have shuffled some items because of a split, or a
* child was not resident and we couldn't process that entry.
*/
if (!requeued && binRef.deletedKeysExist()) {
addBinRefToQueue(binRef, false);
lazySplit++;
} else {
if (bin.getNEntries() == 0) {
addBinRefToQueue(binRef, false);
lazyEmpty++;
}
}
}
}
}
/*
* Find the db and bin for a BINReference.
* @return true if the db is open and the target bin is found.
*/
private boolean findDBAndBIN(BINSearch binSearch,
BINReference binRef,
DbTree dbTree,
Map dbCache)
throws DatabaseException {
/* Find the database. */
binSearch.db = dbTree.getDb
(binRef.getDatabaseId(), lockTimeout, dbCache);
if ((binSearch.db == null) ||(binSearch.db.isDeleted())) {
/* The db was deleted. Ignore this BIN Ref. */
dbClosedBinsThisRun++;
return false;
}
/* Perform eviction before each operation. */
env.getEvictor().doCriticalEviction();
/* Find the BIN. */
binSearch.bin = searchForBIN(binSearch.db, binRef);
if ((binSearch.bin == null) ||
binSearch.bin.getNodeId() != binRef.getNodeId()) {
/* The BIN may have been split. */
if (binSearch.bin != null) {
binSearch.bin.releaseLatch();
}
splitBinsThisRun++;
return false;
}
return true;
}
/* Struct to return multiple values from findDBAndBIN. */
private static class BINSearch {
public DatabaseImpl db;
public BIN bin;
}
}