org.waveprotocol.box.server.waveserver.Wave.java Source code

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Here is the source code for org.waveprotocol.box.server.waveserver.Wave.java

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/**
 * 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.waveserver;

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.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Iterators;
import com.google.common.util.concurrent.ListenableFuture;

import org.waveprotocol.box.server.persistence.PersistenceException;
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.util.logging.Log;

import java.util.Iterator;
import java.util.concurrent.ExecutionException;

/**
 * The wavelets in a wave.
 *
 * @author soren@google.com (Soren Lassen)
 */
final class Wave implements Iterable<WaveletContainer> {
    private static final Log LOG = Log.get(Wave.class);

    private class WaveletCreator<T extends WaveletContainer> extends CacheLoader<WaveletId, T> {
        private final WaveletContainer.Factory<T> factory;

        private final String waveDomain;

        public WaveletCreator(WaveletContainer.Factory<T> factory, String waveDomain) {
            this.factory = factory;
            this.waveDomain = waveDomain;
        }

        @Override
        public T load(WaveletId waveletId) {
            return factory.create(notifiee, WaveletName.of(waveId, waveletId), waveDomain);
        }
    }

    private final WaveId waveId;
    /** Future providing already-existing wavelets in storage. */
    private final ListenableFuture<ImmutableSet<WaveletId>> lookedupWavelets;
    private final LoadingCache<WaveletId, LocalWaveletContainer> localWavelets;
    private final LoadingCache<WaveletId, RemoteWaveletContainer> remoteWavelets;
    private final WaveletNotificationSubscriber notifiee;

    /**
     * Creates a wave. The {@code lookupWavelets} future is examined only when a
     * query is first made.
     */
    public Wave(WaveId waveId, ListenableFuture<ImmutableSet<WaveletId>> lookedupWavelets,
            WaveletNotificationSubscriber notifiee, LocalWaveletContainer.Factory localFactory,
            RemoteWaveletContainer.Factory remoteFactory, String waveDomain) {
        this.waveId = waveId;
        this.lookedupWavelets = lookedupWavelets;
        this.notifiee = notifiee;

        this.localWavelets = CacheBuilder.newBuilder()
                .build(new WaveletCreator<LocalWaveletContainer>(localFactory, waveDomain));
        this.remoteWavelets = CacheBuilder.newBuilder()
                .build(new WaveletCreator<RemoteWaveletContainer>(remoteFactory, waveDomain));
    }

    @Override
    public Iterator<WaveletContainer> iterator() {
        return Iterators.unmodifiableIterator(
                Iterables.concat(localWavelets.asMap().values(), remoteWavelets.asMap().values()).iterator());
    }

    LocalWaveletContainer getLocalWavelet(WaveletId waveletId) throws WaveletStateException {
        return getWavelet(waveletId, localWavelets);
    }

    RemoteWaveletContainer getRemoteWavelet(WaveletId waveletId) throws WaveletStateException {
        return getWavelet(waveletId, remoteWavelets);
    }

    LocalWaveletContainer getOrCreateLocalWavelet(WaveletId waveletId) {
        try {
            return localWavelets.get(waveletId);
        } catch (ExecutionException ex) {
            throw new RuntimeException(ex);
        }
    }

    RemoteWaveletContainer getOrCreateRemoteWavelet(WaveletId waveletId) {
        try {
            return remoteWavelets.get(waveletId);
        } catch (ExecutionException ex) {
            throw new RuntimeException(ex);
        }
    }

    private <T extends WaveletContainer> T getWavelet(WaveletId waveletId, LoadingCache<WaveletId, T> waveletsMap)
            throws WaveletStateException {
        ImmutableSet<WaveletId> storedWavelets;
        try {
            storedWavelets = FutureUtil.getResultOrPropagateException(lookedupWavelets, PersistenceException.class);
        } catch (PersistenceException e) {
            throw new WaveletStateException("Failed to lookup wavelet " + WaveletName.of(waveId, waveletId), e);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            throw new WaveletStateException("Interrupted looking up wavelet " + WaveletName.of(waveId, waveletId),
                    e);
        }

        if (LOG.isFineLoggable()) {
            if (storedWavelets != null) {
                if (storedWavelets.contains(waveletId)) {
                    LOG.fine("Wavelet is in storedWavelets");
                }
                if (waveletsMap.getIfPresent(waveletId) != null) {
                    LOG.fine("Wavelet is in wavletsMap");
                }
            }
        }

        // Since waveletsMap is a computing map, we must call getIfPresent(waveletId)
        // to tell if waveletId is mapped, we cannot test if get(waveletId) returns null.
        if (storedWavelets != null && !storedWavelets.contains(waveletId)
                && waveletsMap.getIfPresent(waveletId) == null) {
            return null;
        } else {
            try {
                T wavelet = waveletsMap.get(waveletId);
                return wavelet;
            } catch (CacheLoader.InvalidCacheLoadException ex) {
                return null;
            } catch (ExecutionException ex) {
                throw new RuntimeException(ex);
            }
        }
    }

    ListenableFuture<ImmutableSet<WaveletId>> getLookedupWavelets() {
        return lookedupWavelets;
    }
}