/**
* Copyright 2010 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.persistence.memory;
import com.google.common.collect.ImmutableSet;
import org.waveprotocol.box.common.ExceptionalIterator;
import org.waveprotocol.box.server.persistence.FileNotFoundPersistenceException;
import org.waveprotocol.box.server.persistence.PersistenceException;
import org.waveprotocol.box.server.waveserver.DeltaStore;
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.util.CollectionUtils;
import java.util.Map;
/**
* A simple in-memory implementation of DeltaStore.
*
* @author josephg@google.com (Joseph Gentle)
*/
public class MemoryDeltaStore implements DeltaStore {
/**
* The actual data.
* Note: We don't remove map entries in the top-level map when all wavelets in a wave are deleted.
* This is a very small memory leak that won't cause problems in practice.
*/
private final Map<WaveId, Map<WaveletId, MemoryDeltaCollection>> data =
CollectionUtils.newHashMap();
private Map<WaveletId, MemoryDeltaCollection> getOrCreateWaveData(WaveId waveId) {
Map<WaveletId, MemoryDeltaCollection> waveData = data.get(waveId);
if (waveData == null) {
waveData = CollectionUtils.newHashMap();
data.put(waveId, waveData);
}
return waveData;
}
@Override
public void delete(WaveletName waveletName) throws PersistenceException {
Map<WaveletId, MemoryDeltaCollection> waveData = data.get(waveletName.waveId);
if (waveData == null) {
throw new FileNotFoundPersistenceException("WaveletData unknown");
} else {
if (waveData.remove(waveletName.waveletId) == null) {
// Nothing was removed.
throw new FileNotFoundPersistenceException("Nothing was removed");
}
}
}
@Override
public ImmutableSet<WaveletId> lookup(WaveId waveId) {
Map<WaveletId, MemoryDeltaCollection> waveData = data.get(waveId);
if (waveData == null) {
return ImmutableSet.of();
} else {
ImmutableSet.Builder<WaveletId> builder = ImmutableSet.builder();
for (MemoryDeltaCollection collection : waveData.values()) {
if (!collection.isEmpty()) {
builder.add(collection.getWaveletName().waveletId);
}
}
return builder.build();
}
}
@Override
public DeltasAccess open(WaveletName waveletName) {
Map<WaveletId, MemoryDeltaCollection> waveData = getOrCreateWaveData(waveletName.waveId);
MemoryDeltaCollection collection = waveData.get(waveletName.waveletId);
if (collection == null) {
collection = new MemoryDeltaCollection(waveletName);
waveData.put(waveletName.waveletId, collection);
}
return collection;
}
@Override
public ExceptionalIterator<WaveId, PersistenceException> getWaveIdIterator() {
ImmutableSet.Builder<WaveId> builder = ImmutableSet.builder();
// Filter out empty waves
for (Map.Entry<WaveId, Map<WaveletId, MemoryDeltaCollection>> e : data.entrySet()) {
if (!e.getValue().isEmpty()) {
for (MemoryDeltaCollection collection : e.getValue().values()) {
if (!collection.isEmpty()) {
builder.add(e.getKey());
break;
}
}
}
}
return ExceptionalIterator.FromIterator.create(builder.build().iterator());
}
}