/*
* JBoss, Home of Professional Open Source
* Copyright 2008, Red Hat Middleware LLC, and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.infinispan.factories;
import org.infinispan.config.Configuration;
import org.infinispan.container.DataContainer;
import org.infinispan.container.entries.CacheEntry;
import org.infinispan.container.entries.MVCCEntry;
import org.infinispan.container.entries.NullMarkerEntry;
import org.infinispan.container.entries.NullMarkerEntryForRemoval;
import org.infinispan.container.entries.ReadCommittedEntry;
import org.infinispan.container.entries.RepeatableReadEntry;
import org.infinispan.context.Flag;
import org.infinispan.context.InvocationContext;
import org.infinispan.factories.annotations.Inject;
import org.infinispan.factories.annotations.Start;
import org.infinispan.notifications.cachelistener.CacheNotifier;
import org.infinispan.util.Util;
import org.infinispan.util.concurrent.IsolationLevel;
import org.infinispan.util.concurrent.TimeoutException;
import org.infinispan.util.concurrent.locks.LockManager;
import org.infinispan.util.logging.Log;
import org.infinispan.util.logging.LogFactory;
public class EntryFactoryImpl implements EntryFactory {
private boolean useRepeatableRead;
DataContainer container;
boolean writeSkewCheck;
LockManager lockManager;
Configuration configuration;
CacheNotifier notifier;
private static final Log log = LogFactory.getLog(EntryFactoryImpl.class);
private static final boolean trace = log.isTraceEnabled();
@Inject
public void injectDependencies(DataContainer dataContainer, LockManager lockManager, Configuration configuration, CacheNotifier notifier) {
this.container = dataContainer;
this.configuration = configuration;
this.lockManager = lockManager;
this.notifier = notifier;
}
@Start
public void init() {
useRepeatableRead = configuration.getIsolationLevel() == IsolationLevel.REPEATABLE_READ;
writeSkewCheck = configuration.isWriteSkewCheck();
}
private MVCCEntry createWrappedEntry(Object key, Object value, boolean isForInsert, boolean forRemoval, long lifespan) {
if (value == null && !isForInsert) return useRepeatableRead ?
forRemoval ? new NullMarkerEntryForRemoval(key) : NullMarkerEntry.getInstance()
: null;
return useRepeatableRead ? new RepeatableReadEntry(key, value, lifespan) : new ReadCommittedEntry(key, value, lifespan);
}
public final CacheEntry wrapEntryForReading(InvocationContext ctx, Object key) throws InterruptedException {
CacheEntry cacheEntry;
if (ctx.hasFlag(Flag.FORCE_WRITE_LOCK)) {
if (trace) log.trace("Forcing lock on reading");
return wrapEntryForWriting(ctx, key, false, false, false, false);
} else if ((cacheEntry = ctx.lookupEntry(key)) == null) {
if (trace) log.trace("Key {0} is not in context, fetching from container.", key);
// simple implementation. Peek the entry, wrap it, put wrapped entry in the context.
cacheEntry = container.get(key);
// do not bother wrapping though if this is not in a tx. repeatable read etc are all meaningless unless there is a tx.
if (useRepeatableRead && ctx.isInTxScope()) {
MVCCEntry mvccEntry = cacheEntry == null ?
createWrappedEntry(key, null, false, false, -1) :
createWrappedEntry(key, cacheEntry.getValue(), false, false, cacheEntry.getLifespan());
if (mvccEntry != null) ctx.putLookedUpEntry(key, mvccEntry);
return mvccEntry;
}
// if not in transaction and repeatable read, or simply read committed (regardless of whether in TX or not), do not wrap
if (cacheEntry != null) ctx.putLookedUpEntry(key, cacheEntry);
return cacheEntry;
} else {
if (trace) log.trace("Key is already in context");
return cacheEntry;
}
}
public final MVCCEntry wrapEntryForWriting(InvocationContext ctx, Object key, boolean createIfAbsent, boolean forceLockIfAbsent, boolean alreadyLocked, boolean forRemoval) throws InterruptedException {
CacheEntry cacheEntry = ctx.lookupEntry(key);
MVCCEntry mvccEntry = null;
if (createIfAbsent && cacheEntry != null && cacheEntry.isNull()) cacheEntry = null;
if (cacheEntry != null) // exists in context! Just acquire lock if needed, and wrap.
{
if (trace) log.trace("Exists in context.");
// acquire lock if needed
if (alreadyLocked || acquireLock(ctx, key)) {
if (cacheEntry instanceof MVCCEntry && (!forRemoval || !(cacheEntry instanceof NullMarkerEntry))) {
mvccEntry = (MVCCEntry) cacheEntry;
} else {
// this is a read-only entry that needs to be copied to a proper read-write entry!!
mvccEntry = createWrappedEntry(key, cacheEntry.getValue(), false, forRemoval, cacheEntry.getLifespan());
cacheEntry = mvccEntry;
ctx.putLookedUpEntry(key, cacheEntry);
}
// create a copy of the underlying entry
mvccEntry.copyForUpdate(container, writeSkewCheck);
}
if (cacheEntry.isRemoved() && createIfAbsent) {
if (trace) log.trace("Entry is deleted in current scope. Need to un-delete.");
if (mvccEntry != cacheEntry) mvccEntry = (MVCCEntry) cacheEntry;
mvccEntry.setRemoved(false);
mvccEntry.setValid(true);
}
return mvccEntry;
} else {
// else, fetch from dataContainer.
cacheEntry = container.get(key);
if (cacheEntry != null) {
if (trace) log.trace("Retrieved from container.");
// exists in cache! Just acquire lock if needed, and wrap.
// do we need a lock?
boolean needToCopy = alreadyLocked || acquireLock(ctx, key) || ctx.hasFlag(Flag.SKIP_LOCKING); // even if we do not acquire a lock, if skip-locking is enabled we should copy
mvccEntry = createWrappedEntry(key, cacheEntry.getValue(), false, false, cacheEntry.getLifespan());
ctx.putLookedUpEntry(key, mvccEntry);
if (needToCopy) mvccEntry.copyForUpdate(container, writeSkewCheck);
cacheEntry = mvccEntry;
} else if (createIfAbsent) {
// this is the *only* point where new entries can be created!!
if (trace) log.trace("Creating new entry.");
// now to lock and create the entry. Lock first to prevent concurrent creation!
if (!alreadyLocked) acquireLock(ctx, key);
notifier.notifyCacheEntryCreated(key, true, ctx);
mvccEntry = createWrappedEntry(key, null, true, false, -1);
mvccEntry.setCreated(true);
ctx.putLookedUpEntry(key, mvccEntry);
mvccEntry.copyForUpdate(container, writeSkewCheck);
notifier.notifyCacheEntryCreated(key, false, ctx);
cacheEntry = mvccEntry;
}
}
// see if we need to force the lock on nonexistent entries.
if (mvccEntry == null && forceLockIfAbsent) {
// make sure we record this! Null value since this is a forced lock on the key
if (acquireLock(ctx, key)) ctx.putLookedUpEntry(key, null);
}
return mvccEntry;
}
/**
* Attempts to lock an entry if the lock isn't already held in the current scope, and records the lock in the
* context.
*
* @param ctx context
* @param key Key to lock
* @return true if a lock was needed and acquired, false if it didn't need to acquire the lock (i.e., lock was
* already held)
* @throws InterruptedException if interrupted
* @throws org.infinispan.util.concurrent.TimeoutException
* if we are unable to acquire the lock after a specified timeout.
*/
public final boolean acquireLock(InvocationContext ctx, Object key) throws InterruptedException, TimeoutException {
// don't EVER use lockManager.isLocked() since with lock striping it may be the case that we hold the relevant
// lock which may be shared with another key that we have a lock for already.
// nothing wrong, just means that we fail to record the lock. And that is a problem.
// Better to check our records and lock again if necessary.
boolean shouldSkipLocking = ctx.hasFlag(Flag.SKIP_LOCKING);
if (!ctx.hasLockedKey(key) && !shouldSkipLocking) {
if (lockManager.lockAndRecord(key, ctx)) {
// successfully locked!
return true;
} else {
Object owner = lockManager.getOwner(key);
throw new TimeoutException("Unable to acquire lock after [" + Util.prettyPrintTime(getLockAcquisitionTimeout(ctx)) + "] on key [" + key + "] for requestor [" +
ctx.getLockOwner() + "]! Lock held by [" + owner + "]");
}
}
return false;
}
private long getLockAcquisitionTimeout(InvocationContext ctx) {
return ctx.hasFlag(Flag.ZERO_LOCK_ACQUISITION_TIMEOUT) ?
0 : configuration.getLockAcquisitionTimeout();
}
public final void releaseLock(Object key) {
lockManager.unlock(key, lockManager.getOwner(key));
}
}