/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2002-2006
* Sleepycat Software. All rights reserved.
*
* $Id: INList.java,v 1.1 2006/05/06 09:00:23 ckaestne Exp $
*/
package com.sleepycat.je.dbi;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.latch.Latch;
import com.sleepycat.je.latch.LatchSupport;
import com.sleepycat.je.tree.IN;
/**
* The INList is a list of in-memory INs for a given environment.
*/
public class INList {
private static final String DEBUG_NAME = INList.class.getName();
private SortedSet ins = null;
private Set addedINs = null;
private EnvironmentImpl envImpl;
/* If both latches are acquired, major must always be acquired first. */
private Latch majorLatch;
private Latch minorLatch;
private boolean updateMemoryUsage;
INList(EnvironmentImpl envImpl) {
this.envImpl = envImpl;
ins = new TreeSet();
addedINs = new HashSet();
majorLatch =
LatchSupport.makeLatch(DEBUG_NAME + " Major Latch", envImpl);
minorLatch =
LatchSupport.makeLatch(DEBUG_NAME + " Minor Latch", envImpl);
updateMemoryUsage = true;
}
/**
* Used only by tree verifier when validating INList. Must be called with
* orig.majorLatch acquired.
*/
public INList(INList orig, EnvironmentImpl envImpl)
throws DatabaseException {
ins = new TreeSet(orig.getINs());
addedINs = new HashSet();
this.envImpl = envImpl;
majorLatch =
LatchSupport.makeLatch(DEBUG_NAME + " Major Latch", envImpl);
minorLatch =
LatchSupport.makeLatch(DEBUG_NAME + " Minor Latch", envImpl);
updateMemoryUsage = false;
}
/*
* We ignore latching on this method because it's only called from validate
* which ignores latching anyway.
*/
public SortedSet getINs() {
return ins;
}
/*
* Don't require latching, ok to be imprecise.
*/
public int getSize() {
return ins.size();
}
/**
* An IN has just come into memory, add it to the list.
*/
public void add(IN in)
throws DatabaseException {
boolean enteredWithLatchHeld = majorLatch.isOwner();
boolean addToMajor = true;
try {
if (enteredWithLatchHeld) {
/*
* Don't try to acquire the major latch twice, that's not
* supported. If we do hold the latch, don't modify the major
* list, we may be faulting in an IN while iterating over the
* list from the evictor.
*/
addToMajor = false;
} else {
if (!(majorLatch.acquireNoWait())) {
/* We couldn't acquire the latch. */
addToMajor = false;
}
}
if (addToMajor) {
addAndSetMemory(ins, in);
} else {
minorLatch.acquire();
try {
addAndSetMemory(addedINs, in);
} finally {
minorLatch.release();
}
/*
* The holder of the majorLatch may have released it. If so,
* try to put the minor list into the major list so no INs are
* orphaned.
*/
if (!enteredWithLatchHeld) {
if (majorLatch.acquireNoWait()) {
try {
latchMinorAndDumpAddedINs();
} finally {
releaseMajorLatch();
}
}
}
}
} finally {
if (addToMajor) {
releaseMajorLatchIfHeld();
}
}
}
private void addAndSetMemory(Set set, IN in) {
boolean addOk = set.add(in);
assert addOk : "failed adding in " + in.getNodeId();
if (updateMemoryUsage) {
MemoryBudget mb = envImpl.getMemoryBudget();
mb.updateTreeMemoryUsage(in.getInMemorySize());
in.setInListResident(true);
}
}
/**
* An IN is getting evicted or is displaced by recovery. Caller is
* responsible for acquiring the major latch before calling this and
* releasing it when they're done.
*/
public void removeLatchAlreadyHeld(IN in)
throws DatabaseException {
assert majorLatch.isOwner();
boolean removeDone = ins.remove(in);
if (!removeDone) {
/* Look in addedINs set. */
minorLatch.acquire();
try {
removeDone = addedINs.remove(in);
dumpAddedINsIntoMajorSet();
} finally {
minorLatch.release();
}
}
assert removeDone;
if (updateMemoryUsage) {
envImpl.getMemoryBudget().
updateTreeMemoryUsage(in.getAccumulatedDelta() -
in.getInMemorySize());
in.setInListResident(false);
}
}
/**
* An IN is getting swept or is displaced by recovery.
*/
public void remove(IN in)
throws DatabaseException {
assert LatchSupport.countLatchesHeld() == 0;
majorLatch.acquire();
try {
removeLatchAlreadyHeld(in);
} finally {
releaseMajorLatch();
}
}
public SortedSet tailSet(IN in)
throws DatabaseException {
assert majorLatch.isOwner();
return ins.tailSet(in);
}
public IN first()
throws DatabaseException {
assert majorLatch.isOwner();
return (IN) ins.first();
}
/**
* Return an iterator over the main 'ins' set. Returned iterator will not
* show the elements in addedINs.
*
* The major latch should be held before entering. The caller is
* responsible for releasing the major latch when they're finished with the
* iterator.
*
* @return an iterator over the main 'ins' set.
*/
public Iterator iterator() {
assert majorLatch.isOwner();
return ins.iterator();
}
/**
* Clear the entire list during recovery and at shutdown.
*/
public void clear()
throws DatabaseException {
assert LatchSupport.countLatchesHeld() == 0;
majorLatch.acquire();
minorLatch.acquire();
ins.clear();
addedINs.clear();
minorLatch.release();
releaseMajorLatch();
if (updateMemoryUsage) {
envImpl.getMemoryBudget().refreshTreeMemoryUsage(0);
}
}
public void dump() {
System.out.println("size=" + getSize());
Iterator iter = ins.iterator();
while (iter.hasNext()) {
IN theIN = (IN) iter.next();
System.out.println("db=" + theIN.getDatabase().getId() +
" nid=: " + theIN.getNodeId() + "/" +
theIN.getLevel());
}
}
/**
* The locking hierarchy is:
* 1. INList major latch.
* 2. IN latch.
* In other words, the INList major latch must be taken before any IN
* latches to avoid deadlock.
*/
public void latchMajor()
throws DatabaseException {
assert LatchSupport.countLatchesHeld() == 0;
majorLatch.acquire();
}
public void releaseMajorLatchIfHeld()
throws DatabaseException {
if (majorLatch.isOwner()) {
releaseMajorLatch();
}
}
public void releaseMajorLatch()
throws DatabaseException {
/*
* Before we release the major latch, take a look at addedINs and see
* if anything has been added to it while we held the major latch. If
* so, added it to ins.
*/
latchMinorAndDumpAddedINs();
majorLatch.release();
}
private void dumpAddedINsIntoMajorSet() {
if (addedINs.size() > 0) {
ins.addAll(addedINs);
addedINs.clear();
}
}
void latchMinorAndDumpAddedINs()
throws DatabaseException {
latchMinor();
try {
dumpAddedINsIntoMajorSet();
} finally {
releaseMinorLatch();
}
}
private void latchMinor()
throws DatabaseException {
minorLatch.acquire();
}
private void releaseMinorLatch()
throws DatabaseException {
minorLatch.release();
}
}