/**
* Copyright 2009 Google Inc.
*
* Licensed 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.waveprotocol.box.server.waveserver;
import com.google.common.base.Function;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.protobuf.InvalidProtocolBufferException;
import org.waveprotocol.box.common.DeltaSequence;
import org.waveprotocol.box.server.frontend.CommittedWaveletSnapshot;
import org.waveprotocol.box.server.persistence.PersistenceException;
import org.waveprotocol.box.server.util.WaveletDataUtil;
import org.waveprotocol.wave.federation.Proto.ProtocolAppliedWaveletDelta;
import org.waveprotocol.wave.model.id.WaveletName;
import org.waveprotocol.wave.model.operation.OperationException;
import org.waveprotocol.wave.model.operation.OperationPair;
import org.waveprotocol.wave.model.operation.TransformException;
import org.waveprotocol.wave.model.operation.wave.Transform;
import org.waveprotocol.wave.model.operation.wave.TransformedWaveletDelta;
import org.waveprotocol.wave.model.operation.wave.WaveletDelta;
import org.waveprotocol.wave.model.operation.wave.WaveletOperation;
import org.waveprotocol.wave.model.version.HashedVersion;
import org.waveprotocol.wave.model.wave.ParticipantId;
import org.waveprotocol.wave.model.wave.ParticipantIdUtil;
import org.waveprotocol.wave.model.wave.data.ObservableWaveletData;
import org.waveprotocol.wave.model.wave.data.ReadableWaveletData;
import org.waveprotocol.wave.util.logging.Log;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/**
* Contains the history of a wavelet - applied and transformed deltas plus the
* content of the wavelet.
*
* TODO(soren): Unload the wavelet (remove it from WaveMap) if it becomes
* corrupt or fails to load from storage.
*/
abstract class WaveletContainerImpl implements WaveletContainer {
private static final Log LOG = Log.get(WaveletContainerImpl.class);
private static final int AWAIT_LOAD_TIMEOUT_SECONDS = 20;
protected enum State {
/** Everything is working fine. */
OK,
/** Wavelet state is being loaded from storage. */
LOADING,
/** Wavelet has been deleted, the instance will not contain any data. */
DELETED,
/**
* For some reason this instance is broken, e.g. a remote wavelet update
* signature failed.
*/
CORRUPTED
}
// TODO(soren): inject an executor which can be shared with other wavelets
private final Executor storageContinuationExecutor =
Executors.newSingleThreadExecutor();
private final Lock readLock;
private final ReentrantReadWriteLock.WriteLock writeLock;
private final WaveletName waveletName;
private final WaveletNotificationSubscriber notifiee;
private final ParticipantId sharedDomainParticipantId;
/** Is counted down when initial loading from storage completes. */
private final CountDownLatch loadLatch = new CountDownLatch(1);
/** Is set at most once, before loadLatch is counted down. */
private WaveletState waveletState;
private State state = State.LOADING;
/**
* Constructs an empty WaveletContainer for a wavelet.
* WaveletData is not set until a delta has been applied.
*
* @param notifiee the subscriber to notify of wavelet updates and commits.
* @param waveletState the wavelet's delta history and current state.
* @param waveDomain the wave server domain.
*/
public WaveletContainerImpl(WaveletName waveletName, WaveletNotificationSubscriber notifiee,
final ListenableFuture<? extends WaveletState> waveletStateFuture, String waveDomain) {
this.waveletName = waveletName;
this.notifiee = notifiee;
this.sharedDomainParticipantId =
waveDomain != null ? ParticipantIdUtil.makeUnsafeSharedDomainParticipantId(waveDomain)
: null;
ReentrantReadWriteLock readWriteLock = new ReentrantReadWriteLock();
this.readLock = readWriteLock.readLock();
this.writeLock = readWriteLock.writeLock();
waveletStateFuture.addListener(
new Runnable() {
@Override
public void run() {
acquireWriteLock();
try {
Preconditions.checkState(waveletState == null,
"Repeat attempts to set wavelet state");
Preconditions.checkState(state == State.LOADING, "Unexpected state %s", state);
waveletState = FutureUtil.getResultOrPropagateException(
waveletStateFuture, PersistenceException.class);
Preconditions.checkState(waveletState.getWaveletName().equals(getWaveletName()),
"Wrong wavelet state, named %s, expected %s",
waveletState.getWaveletName(), getWaveletName());
state = State.OK;
} catch (PersistenceException e) {
LOG.warning("Failed to load wavelet " + getWaveletName(), e);
state = State.CORRUPTED;
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
LOG.warning("Interrupted loading wavelet " + getWaveletName(), e);
state = State.CORRUPTED;
} catch (RuntimeException e) {
// TODO(soren): would be better to terminate the process in this case
LOG.severe("Unexpected exception loading wavelet " + getWaveletName(), e);
state = State.CORRUPTED;
} finally {
releaseWriteLock();
}
loadLatch.countDown();
}
},
storageContinuationExecutor);
}
protected void acquireReadLock() {
readLock.lock();
}
protected void releaseReadLock() {
readLock.unlock();
}
protected void acquireWriteLock() {
writeLock.lock();
}
protected void releaseWriteLock() {
writeLock.unlock();
}
protected void notifyOfDeltas(ImmutableList<WaveletDeltaRecord> deltas,
ImmutableSet<String> domainsToNotify) {
Preconditions.checkState(writeLock.isHeldByCurrentThread(), "must hold write lock");
Preconditions.checkArgument(!deltas.isEmpty(), "empty deltas");
HashedVersion endVersion = deltas.get(deltas.size() - 1).getResultingVersion();
HashedVersion currentVersion = getCurrentVersion();
Preconditions.checkArgument(endVersion.equals(currentVersion),
"cannot notify of deltas ending in %s != current version %s", endVersion, currentVersion);
notifiee.waveletUpdate(waveletState.getSnapshot(), deltas, domainsToNotify);
}
protected void notifyOfCommit(HashedVersion version, ImmutableSet<String> domainsToNotify) {
Preconditions.checkState(writeLock.isHeldByCurrentThread(), "must hold write lock");
notifiee.waveletCommitted(getWaveletName(), version, domainsToNotify);
}
/**
* Blocks until the initial load of the wavelet state from storage completes.
* Should be called without the read or write lock held.
*
* @throws WaveletStateException if the wavelet fails to load,
* either because of a storage access failure or timeout,
* or because the current thread is interrupted.
*/
protected void awaitLoad() throws WaveletStateException {
Preconditions.checkState(!writeLock.isHeldByCurrentThread(), "should not hold write lock");
try {
if (!loadLatch.await(AWAIT_LOAD_TIMEOUT_SECONDS, TimeUnit.SECONDS)) {
throw new WaveletStateException("Timed out waiting for wavelet to load");
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new WaveletStateException("Interrupted waiting for wavelet to load");
}
}
/**
* Verifies that the wavelet is in an operational state (not loading,
* not corrupt).
*
* Should be preceded by a call to awaitLoad() so that the initial load from
* storage has completed. Should be called with the read or write lock held.
*
* @throws WaveletStateException if the wavelet is loading or marked corrupt.
*/
protected void checkStateOk() throws WaveletStateException {
if (state != State.OK) {
throw new WaveletStateException("The wavelet is in an unusable state: " + state);
}
}
/**
* Flags the wavelet corrupted so future calls to checkStateOk() will fail.
*/
protected void markStateCorrupted() {
Preconditions.checkState(writeLock.isHeldByCurrentThread(), "must hold write lock");
state = State.CORRUPTED;
}
protected void persist(final HashedVersion version, final ImmutableSet<String> domainsToNotify) {
Preconditions.checkState(writeLock.isHeldByCurrentThread(), "must hold write lock");
final ListenableFuture<Void> result = waveletState.persist(version);
result.addListener(
new Runnable() {
@Override
public void run() {
acquireWriteLock();
try {
// waveletState.flush(version); // TODO(soren): implement this
notifyOfCommit(version, domainsToNotify);
} finally {
releaseWriteLock();
}
}
},
storageContinuationExecutor);
}
@Override
public WaveletName getWaveletName() {
return waveletName;
}
@Override
public boolean checkAccessPermission(ParticipantId participantId) throws WaveletStateException {
awaitLoad();
acquireReadLock();
try {
checkStateOk();
// ParticipantId will be null if the user isn't logged in. A user who isn't logged in should
// have access to public waves once they've been implemented.
// If the wavelet is empty, everyone has access (to write the first delta).
// TODO(soren): determine if off-domain participants should be denied access if empty
ReadableWaveletData snapshot = waveletState.getSnapshot();
return WaveletDataUtil.checkAccessPermission(snapshot, participantId, sharedDomainParticipantId);
} finally {
releaseReadLock();
}
}
@Override
public HashedVersion getLastCommittedVersion() throws WaveletStateException {
awaitLoad();
acquireReadLock();
try {
checkStateOk();
return waveletState.getLastPersistedVersion();
} finally {
releaseReadLock();
}
}
@Override
public ObservableWaveletData copyWaveletData() throws WaveletStateException {
awaitLoad();
acquireReadLock();
try {
checkStateOk();
return WaveletDataUtil.copyWavelet(waveletState.getSnapshot());
} finally {
releaseReadLock();
}
}
@Override
public CommittedWaveletSnapshot getSnapshot() throws WaveletStateException {
awaitLoad();
acquireReadLock();
try {
checkStateOk();
return new CommittedWaveletSnapshot(waveletState.getSnapshot(),
waveletState.getLastPersistedVersion());
} finally {
releaseReadLock();
}
}
@Override
public <T> T applyFunction(Function<ReadableWaveletData, T> function)
throws WaveletStateException {
awaitLoad();
acquireReadLock();
try {
checkStateOk();
return function.apply(waveletState.getSnapshot());
} finally {
releaseReadLock();
}
}
/**
* Transform a wavelet delta if it has been submitted against a different head (currentVersion).
* Must be called with write lock held.
*
* @param delta to possibly transform
* @return the transformed delta and the version it was applied at
* (the version is the current version of the wavelet, unless the delta is
* a duplicate in which case it is the version at which it was originally
* applied)
* @throws InvalidHashException if submitting against same version but different hash
* @throws OperationException if transformation fails
*/
protected WaveletDelta maybeTransformSubmittedDelta(WaveletDelta delta)
throws InvalidHashException, OperationException {
HashedVersion targetVersion = delta.getTargetVersion();
HashedVersion currentVersion = getCurrentVersion();
if (targetVersion.equals(currentVersion)) {
// Applied version is the same, we're submitting against head, don't need to do OT
return delta;
} else {
// Not submitting against head, we need to do OT, but check the versions really are different
if (targetVersion.getVersion() == currentVersion.getVersion()) {
LOG.warning("Mismatched hash, expected " + currentVersion + ") but delta targets (" +
targetVersion + ")");
throw new InvalidHashException(currentVersion, targetVersion);
} else {
return transformSubmittedDelta(delta);
}
}
}
/**
* Finds range of server deltas needed to transform against, then transforms all client
* ops against the server ops.
*/
private WaveletDelta transformSubmittedDelta(WaveletDelta submittedDelta)
throws OperationException, InvalidHashException {
HashedVersion targetVersion = submittedDelta.getTargetVersion();
HashedVersion currentVersion = getCurrentVersion();
Preconditions.checkArgument(!targetVersion.equals(currentVersion));
DeltaSequence serverDeltas =
waveletState.getTransformedDeltaHistory(targetVersion, currentVersion);
if (serverDeltas == null) {
LOG.warning("Attempt to apply delta at unknown hashed version " + targetVersion);
throw new InvalidHashException(currentVersion, targetVersion);
}
Preconditions.checkState(!serverDeltas.isEmpty(),
"No deltas between valid versions %s and %s", targetVersion, currentVersion);
ParticipantId clientAuthor = submittedDelta.getAuthor();
// TODO(anorth): remove this copy somehow; currently, it's necessary to
// ensure that clientOps.equals() works correctly below (because
// WaveletDelta breaks the List.equals() contract)
List<WaveletOperation> clientOps = Lists.newArrayList(submittedDelta);
for (TransformedWaveletDelta serverDelta : serverDeltas) {
// If the client delta transforms to nothing before we've traversed all
// the server deltas, return the version at which the delta was
// obliterated (rather than the current version) to ensure that delta
// submission is idempotent.
if (clientOps.isEmpty()) {
return new WaveletDelta(clientAuthor, targetVersion, clientOps);
}
ParticipantId serverAuthor = serverDelta.getAuthor();
if (clientAuthor.equals(serverAuthor) && clientOps.equals(serverDelta)) {
// This is a duplicate of the server delta.
return new WaveletDelta(clientAuthor, targetVersion, clientOps);
}
clientOps = transformOps(clientOps, serverDelta);
targetVersion = serverDelta.getResultingVersion();
}
Preconditions.checkState(targetVersion.equals(currentVersion));
return new WaveletDelta(clientAuthor, targetVersion, clientOps);
}
/**
* Transforms the specified client operations against the specified server operations,
* returning the transformed client operations in a new list.
*
* @param clientOps may be unmodifiable
* @param serverOps may be unmodifiable
* @return transformed client ops
*/
private List<WaveletOperation> transformOps(List<WaveletOperation> clientOps,
List<WaveletOperation> serverOps) throws OperationException {
List<WaveletOperation> transformedClientOps = Lists.newArrayList();
for (WaveletOperation c : clientOps) {
for (WaveletOperation s : serverOps) {
OperationPair<WaveletOperation> pair;
try {
pair = Transform.transform(c, s);
} catch (TransformException e) {
throw new OperationException(e);
}
c = pair.clientOp();
}
transformedClientOps.add(c);
}
return transformedClientOps;
}
/**
* Builds a {@link WaveletDeltaRecord} and applies it to the wavelet container.
* The delta must be non-empty.
*/
protected WaveletDeltaRecord applyDelta(
ByteStringMessage<ProtocolAppliedWaveletDelta> appliedDelta, WaveletDelta transformed)
throws InvalidProtocolBufferException, OperationException {
TransformedWaveletDelta transformedDelta =
AppliedDeltaUtil.buildTransformedDelta(appliedDelta, transformed);
waveletState.appendDelta(transformed.getTargetVersion(), transformedDelta, appliedDelta);
return new WaveletDeltaRecord(transformed.getTargetVersion(), appliedDelta, transformedDelta);
}
/**
* @param versionActuallyAppliedAt the version to look up
* @return the applied delta applied at the specified hashed version
*/
protected ByteStringMessage<ProtocolAppliedWaveletDelta> lookupAppliedDelta(
HashedVersion versionActuallyAppliedAt) {
return waveletState.getAppliedDelta(versionActuallyAppliedAt);
}
/**
* @param endVersion the version to look up
* @return the applied delta with the given resulting version
*/
protected ByteStringMessage<ProtocolAppliedWaveletDelta> lookupAppliedDeltaByEndVersion(
HashedVersion endVersion) {
return waveletState.getAppliedDeltaByEndVersion(endVersion);
}
protected TransformedWaveletDelta lookupTransformedDelta(HashedVersion appliedAtVersion) {
return waveletState.getTransformedDelta(appliedAtVersion);
}
/**
* @throws AccessControlException with the given message if version does not
* match a delta boundary in the wavelet history.
*/
private void checkVersionIsDeltaBoundary(HashedVersion version, String message)
throws AccessControlException {
HashedVersion actual = waveletState.getHashedVersion(version.getVersion());
if (!version.equals(actual)) {
LOG.info("Unrecognized " + message + " at version " + version + ", actual " + actual);
// We omit the hash from the message to avoid leaking it.
throw new AccessControlException(
"Unrecognized " + message + " at version " + version.getVersion());
}
}
@Override
public Collection<ByteStringMessage<ProtocolAppliedWaveletDelta>> requestHistory(
HashedVersion startVersion, HashedVersion endVersion)
throws AccessControlException, WaveletStateException {
acquireReadLock();
try {
checkStateOk();
checkVersionIsDeltaBoundary(startVersion, "start version");
checkVersionIsDeltaBoundary(endVersion, "end version");
return waveletState.getAppliedDeltaHistory(startVersion, endVersion);
} finally {
releaseReadLock();
}
}
@Override
public Collection<TransformedWaveletDelta> requestTransformedHistory(HashedVersion startVersion,
HashedVersion endVersion) throws AccessControlException, WaveletStateException {
awaitLoad();
acquireReadLock();
try {
checkStateOk();
checkVersionIsDeltaBoundary(startVersion, "start version");
checkVersionIsDeltaBoundary(endVersion, "end version");
return waveletState.getTransformedDeltaHistory(startVersion, endVersion);
} finally {
releaseReadLock();
}
}
@Override
public boolean hasParticipant(ParticipantId participant) throws WaveletStateException {
awaitLoad();
acquireReadLock();
try {
checkStateOk();
ReadableWaveletData snapshot = waveletState.getSnapshot();
return snapshot != null && snapshot.getParticipants().contains(participant);
} finally {
releaseReadLock();
}
}
@Override
public ParticipantId getSharedDomainParticipant() {
return sharedDomainParticipantId;
}
@Override
public ParticipantId getCreator() {
ReadableWaveletData snapshot = waveletState.getSnapshot();
return snapshot != null ? snapshot.getCreator() : null;
}
@Override
public boolean isEmpty() throws WaveletStateException {
awaitLoad();
acquireReadLock();
try {
checkStateOk();
return waveletState.getSnapshot() == null;
} finally {
releaseReadLock();
}
}
protected HashedVersion getCurrentVersion() {
return waveletState.getCurrentVersion();
}
protected ReadableWaveletData accessSnapshot() {
return waveletState.getSnapshot();
}
}