com.google.gerrit.server.index.IndexCollection.java Source code

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Here is the source code for com.google.gerrit.server.index.IndexCollection.java

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// Copyright (C) 2013 The Android Open Source Project
//
// 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 com.google.gerrit.server.index;

import com.google.common.collect.Lists;
import com.google.gerrit.extensions.events.LifecycleListener;
import java.util.Collection;
import java.util.Collections;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicReference;

/** Dynamic pointers to the index versions used for searching and writing. */
public abstract class IndexCollection<K, V, I extends Index<K, V>> implements LifecycleListener {
    private final CopyOnWriteArrayList<I> writeIndexes;
    private final AtomicReference<I> searchIndex;

    protected IndexCollection() {
        this.writeIndexes = Lists.newCopyOnWriteArrayList();
        this.searchIndex = new AtomicReference<>();
    }

    /** @return the current search index version. */
    public I getSearchIndex() {
        return searchIndex.get();
    }

    public void setSearchIndex(I index) {
        I old = searchIndex.getAndSet(index);
        if (old != null && old != index && !writeIndexes.contains(old)) {
            old.close();
        }
    }

    public Collection<I> getWriteIndexes() {
        return Collections.unmodifiableCollection(writeIndexes);
    }

    public synchronized I addWriteIndex(I index) {
        int version = index.getSchema().getVersion();
        for (int i = 0; i < writeIndexes.size(); i++) {
            if (writeIndexes.get(i).getSchema().getVersion() == version) {
                return writeIndexes.set(i, index);
            }
        }
        writeIndexes.add(index);
        return null;
    }

    public synchronized void removeWriteIndex(int version) {
        int removeIndex = -1;
        for (int i = 0; i < writeIndexes.size(); i++) {
            if (writeIndexes.get(i).getSchema().getVersion() == version) {
                removeIndex = i;
                break;
            }
        }
        if (removeIndex >= 0) {
            try {
                writeIndexes.get(removeIndex).close();
            } finally {
                writeIndexes.remove(removeIndex);
            }
        }
    }

    public I getWriteIndex(int version) {
        for (I i : writeIndexes) {
            if (i.getSchema().getVersion() == version) {
                return i;
            }
        }
        return null;
    }

    @Override
    public void start() {
    }

    @Override
    public void stop() {
        I read = searchIndex.get();
        if (read != null) {
            read.close();
        }
        for (I write : writeIndexes) {
            if (write != read) {
                write.stop();
                write.close();
            }
        }
    }
}