/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.frontend;
import com.google.common.base.Preconditions;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import org.waveprotocol.box.common.DeltaSequence;
import org.waveprotocol.wave.model.id.IdFilter;
import org.waveprotocol.wave.model.id.WaveId;
import org.waveprotocol.wave.model.id.WaveletId;
import org.waveprotocol.wave.model.id.WaveletName;
import org.waveprotocol.wave.model.operation.wave.TransformedWaveletDelta;
import org.waveprotocol.wave.model.version.HashedVersion;
import org.waveprotocol.wave.util.logging.Log;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* A client's subscription to a wave view.
*
* @author anorth@google.com (Alex North)
*/
final class WaveViewSubscription {
/**
* State of a wavelet endpoint.
*/
private static final class WaveletChannelState {
/**
* Resulting versions of deltas submitted on this wavelet for which
* the outbound delta has not yet been seen.
*/
public final Collection<Long> submittedEndVersions = Sets.newHashSet();
/**
* Resulting version of the most recent outbound delta.
*/
public HashedVersion lastVersion = null;
/**
* Whether a submit request is awaiting a response.
*/
public boolean hasOutstandingSubmit = false;
/**
* Outbound deltas held back while a submit is in-flight.
*/
public List<TransformedWaveletDelta> heldBackDeltas = Lists.newLinkedList();
}
private static final Log LOG = Log.get(WaveViewSubscription.class);
private final WaveId waveId;
private final IdFilter waveletIdFilter;
private final ClientFrontend.OpenListener openListener;
private final String channelId;
private final LoadingCache<WaveletId, WaveletChannelState> channels =
CacheBuilder.newBuilder().build(new CacheLoader<WaveletId, WaveletChannelState>() {
@Override
public WaveletChannelState load(WaveletId id) {
return new WaveletChannelState();
}
});
public WaveViewSubscription(WaveId waveId, IdFilter waveletIdFilter, String channelId,
ClientFrontend.OpenListener openListener) {
Preconditions.checkNotNull(waveId, "null wave id");
Preconditions.checkNotNull(waveletIdFilter, "null filter");
Preconditions.checkNotNull(openListener, "null listener");
Preconditions.checkNotNull(channelId, "null channel id");
this.waveId = waveId;
this.waveletIdFilter = waveletIdFilter;
this.channelId = channelId;
this.openListener = openListener;
}
public WaveId getWaveId() {
return waveId;
}
public ClientFrontend.OpenListener getOpenListener() {
return openListener;
}
public String getChannelId() {
return channelId;
}
/**
* Checks whether the subscription includes a wavelet.
*/
public boolean includes(WaveletId waveletId) {
return IdFilter.accepts(waveletIdFilter, waveletId);
}
/** This client sent a submit request */
public synchronized void submitRequest(WaveletName waveletName) {
// A given client can only have one outstanding submit per wavelet.
WaveletChannelState state;
try {
state = channels.get(waveletName.waveletId);
} catch (ExecutionException ex) {
throw new RuntimeException(ex);
}
Preconditions.checkState(!state.hasOutstandingSubmit,
"Received overlapping submit requests to subscription %s", this);
LOG.info("Submit oustandinding on channel " + channelId);
state.hasOutstandingSubmit = true;
}
/**
* A submit response for the given wavelet and version has been sent to this
* client.
*/
public synchronized void submitResponse(WaveletName waveletName, HashedVersion version) {
Preconditions.checkNotNull(version, "Null delta application version");
WaveletId waveletId = waveletName.waveletId;
WaveletChannelState state;
try {
state = channels.get(waveletId);
} catch (ExecutionException ex) {
throw new RuntimeException(ex);
}
Preconditions.checkState(state.hasOutstandingSubmit);
state.submittedEndVersions.add(version.getVersion());
state.hasOutstandingSubmit = false;
LOG.info("Submit resolved on channel " + channelId);
// Forward any queued deltas.
List<TransformedWaveletDelta> filteredDeltas = filterOwnDeltas(state.heldBackDeltas, state);
if (!filteredDeltas.isEmpty()) {
sendUpdate(waveletName, filteredDeltas, null);
}
state.heldBackDeltas.clear();
}
/**
* Sends deltas for this subscription (if appropriate).
*
* If the update contains a delta for a wavelet where the delta is actually
* from this client, the delta is dropped. If there's an outstanding submit
* request the delta is queued until the submit finishes.
*/
public synchronized void onUpdate(WaveletName waveletName, DeltaSequence deltas) {
Preconditions.checkArgument(!deltas.isEmpty());
WaveletChannelState state;
try {
state = channels.get(waveletName.waveletId);
} catch (ExecutionException ex) {
throw new RuntimeException(ex);
}
checkUpdateVersion(waveletName, deltas, state);
state.lastVersion = deltas.getEndVersion();
if (state.hasOutstandingSubmit) {
state.heldBackDeltas.addAll(deltas);
} else {
List<TransformedWaveletDelta> filteredDeltas = filterOwnDeltas(deltas, state);
if (!filteredDeltas.isEmpty()) {
sendUpdate(waveletName, filteredDeltas, null);
}
}
}
/**
* Filters any deltas sent by this client from a list of received deltas.
*
* @param deltas received deltas
* @param state channel state
* @return deltas, if none are from this client, or a copy with own client's
* deltas removed
*/
private List<TransformedWaveletDelta> filterOwnDeltas(List<TransformedWaveletDelta> deltas,
WaveletChannelState state) {
List<TransformedWaveletDelta> filteredDeltas = deltas;
if (!state.submittedEndVersions.isEmpty()) {
filteredDeltas = Lists.newArrayList();
for (TransformedWaveletDelta delta : deltas) {
long deltaEndVersion = delta.getResultingVersion().getVersion();
if (!state.submittedEndVersions.remove(deltaEndVersion)) {
filteredDeltas.add(delta);
}
}
}
return filteredDeltas;
}
/**
* Sends a commit notice for this subscription.
*/
public synchronized void onCommit(WaveletName waveletName, HashedVersion committedVersion) {
sendUpdate(waveletName, ImmutableList.<TransformedWaveletDelta>of(), committedVersion);
}
/**
* Sends an update to the client.
*/
private void sendUpdate(WaveletName waveletName, List<TransformedWaveletDelta> deltas,
HashedVersion committedVersion) {
// Channel id needs to be sent with every message until views can be
// closed, see bug 128.
openListener.onUpdate(waveletName, null, deltas, committedVersion, null, channelId);
}
/**
* Checks the update targets the next expected version.
*/
private void checkUpdateVersion(WaveletName waveletName, DeltaSequence deltas,
WaveletChannelState state) {
if (state.lastVersion != null) {
long expectedVersion = state.lastVersion.getVersion();
long targetVersion = deltas.getStartVersion();
Preconditions.checkState(targetVersion == expectedVersion,
"Subscription expected delta for %s targeting %s, was %s", waveletName, expectedVersion,
targetVersion);
}
}
@Override
public String toString() {
return "[WaveViewSubscription wave: " + waveId + ", channel: " + channelId + "]";
}
}