/**
* 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.waveserver;
import org.waveprotocol.box.server.persistence.PersistenceException;
import org.waveprotocol.wave.model.wave.data.ReadableWaveletData;
import java.io.Closeable;
import java.util.Collection;
/**
* Stores wavelet deltas and snapshots.
*
* @author soren@google.com (Soren Lassen)
*/
public interface DeltaAndSnapshotStore extends WaveletStore<DeltaAndSnapshotStore.WaveletAccess> {
/**
* Accesses the state for a wavelet.
* Permits reading a snapshot of the wavelet state and historical deltas,
* and appending deltas to the history.
*
* Callers must serialize all calls to
* {@link #appendDeltas(Collection,ReadableWaveletData)}.
*/
interface WaveletAccess extends WaveletDeltaRecordReader, Closeable {
/**
* @return Immutable copy of the last known committed state of the wavelet.
*/
ReadableWaveletData getSnapshot();
/**
* Blocking call to append deltas to the end of the delta history.
* If the call returns normally (doesn't throw an exception), then
* the deltas have been successfully and "durably" stored, that is,
* the method forces the data to disk.
*
* @param deltas Contiguous deltas, beginning from the DeltaAccess object's
* end version. It is the caller's responsibility to ensure that
* everything matches up (applied and transformed deltas in the
* records match, that the hashes are correctly computed, etc).
* @param resultingSnapshot A snapshot of the state of the wavelet after
* {@code deltas} are applied.
* @throws PersistenceException if anything goes wrong with the underlying
* storage.
*/
void appendDeltas(Collection<WaveletDeltaRecord> deltas,
ReadableWaveletData resultingSnapshot) throws PersistenceException;
}
}