/*
* Copyright 2012 Red Hat, Inc. and/or its affiliates.
*
* 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 library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
package org.infinispan.transaction;
import org.infinispan.commands.tx.VersionedPrepareCommand;
import org.infinispan.commands.write.WriteCommand;
import org.infinispan.container.DataContainer;
import org.infinispan.container.entries.CacheEntry;
import org.infinispan.container.entries.ClusteredRepeatableReadEntry;
import org.infinispan.container.versioning.EntryVersion;
import org.infinispan.container.versioning.EntryVersionsMap;
import org.infinispan.container.versioning.IncrementableEntryVersion;
import org.infinispan.container.versioning.VersionGenerator;
import org.infinispan.context.impl.TxInvocationContext;
import org.infinispan.remoting.responses.Response;
import org.infinispan.remoting.responses.SuccessfulResponse;
import org.infinispan.transaction.xa.CacheTransaction;
/**
* Encapsulates write skew logic in maintaining version maps, etc.
*
* @author Manik Surtani
* @since 5.1
*/
public class WriteSkewHelper {
public static void setVersionsSeenOnPrepareCommand(VersionedPrepareCommand command, TxInvocationContext context) {
// Build a map of keys to versions as they were seen by the transaction originator's transaction context
EntryVersionsMap vs = new EntryVersionsMap();
for (WriteCommand wc : command.getModifications()) {
for (Object k : wc.getAffectedKeys()) {
CacheEntry entry = context.lookupEntry(k);
// the entry might be null if an attempt to lock the key was done and the actual value for this key is missing from the data container
if (entry != null) {
vs.put(k, (IncrementableEntryVersion) entry.getMetadata().version());
}
}
}
// Make sure this version map is attached to the prepare command so that lock owners can perform write skew checks
command.setVersionsSeen(vs);
}
public static void readVersionsFromResponse(Response r, CacheTransaction ct) {
if (r != null && r.isSuccessful()) {
SuccessfulResponse sr = (SuccessfulResponse) r;
EntryVersionsMap uv = (EntryVersionsMap) sr.getResponseValue();
if (uv != null) ct.setUpdatedEntryVersions(uv.merge(ct.getUpdatedEntryVersions()));
}
}
public static EntryVersionsMap performWriteSkewCheckAndReturnNewVersions(VersionedPrepareCommand prepareCommand,
DataContainer dataContainer,
VersionGenerator versionGenerator,
TxInvocationContext context,
KeySpecificLogic ksl) {
EntryVersionsMap uv = new EntryVersionsMap();
for (WriteCommand c : prepareCommand.getModifications()) {
for (Object k : c.getAffectedKeys()) {
if (ksl.performCheckOnKey(k)) {
ClusteredRepeatableReadEntry entry = (ClusteredRepeatableReadEntry) context.lookupEntry(k);
if (entry == null) {
continue;
}
if (!context.isOriginLocal()) {
// What version did the transaction originator see??
EntryVersion versionSeen = prepareCommand.getVersionsSeen().get(k);
if (versionSeen != null) {
entry.setVersion(versionSeen);
}
}
if (entry.performWriteSkewCheck(dataContainer, context, c.wasPreviousRead())) {
IncrementableEntryVersion newVersion = entry.isCreated()
? versionGenerator.generateNew()
: versionGenerator.increment((IncrementableEntryVersion) entry.getMetadata().version());
uv.put(k, newVersion);
} else {
// Write skew check detected!
throw new WriteSkewException("Write skew detected on key " + k + " for transaction " + context.getTransaction());
}
}
}
}
return uv;
}
public static EntryVersionsMap performTotalOrderWriteSkewCheckAndReturnNewVersions(VersionedPrepareCommand prepareCommand,
DataContainer dataContainer,
TxInvocationContext context,
KeySpecificLogic ksl) {
EntryVersionsMap uv = new EntryVersionsMap();
for (WriteCommand c : prepareCommand.getModifications()) {
for (Object k : c.getAffectedKeys()) {
if (ksl.performCheckOnKey(k)) {
ClusteredRepeatableReadEntry entry = (ClusteredRepeatableReadEntry) context.lookupEntry(k);
if (entry == null) {
continue;
}
// What version did the transaction originator see??
EntryVersion versionSeen = prepareCommand.getVersionsSeen().get(k);
entry.setVersion(versionSeen);
if (entry.performWriteSkewCheck(dataContainer, context, c.wasPreviousRead())) {
//in total order, it does not care about the version returned. It just need the keys validated
uv.put(k, null);
} else {
// Write skew check detected!
throw new WriteSkewException("Write skew detected on key " + k + " for transaction " + context.getTransaction());
}
}
}
}
return uv;
}
public static interface KeySpecificLogic {
boolean performCheckOnKey(Object key);
}
}