com.github.jeluard.stone.storage.memory.MemoryStorage.java Source code

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Here is the source code for com.github.jeluard.stone.storage.memory.MemoryStorage.java

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/**
 * Copyright 2012 Julien Eluard
 * This project includes software developed by Julien Eluard: https://github.com/jeluard/
 *
 * 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.github.jeluard.stone.storage.memory;

import com.github.jeluard.guayaba.base.Pair;
import com.github.jeluard.stone.spi.Storage;
import com.google.common.primitives.Longs;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicLongArray;
import java.util.concurrent.atomic.AtomicReferenceArray;

/**
 * An in-memory {@link Storage} implementation.
 */
public final class MemoryStorage extends Storage {

    private final AtomicLong index = new AtomicLong(0);
    private final AtomicLongArray timestamps;
    private final AtomicReferenceArray<int[]> values;

    public MemoryStorage(final int maximumSize) {
        super(maximumSize);

        this.timestamps = new AtomicLongArray(getMaximumSize());
        this.values = new AtomicReferenceArray<int[]>(getMaximumSize());
    }

    @Override
    public Iterable<Pair<Long, int[]>> all() throws IOException {
        final int maxSize = getMaximumSize();
        final List<Pair<Long, int[]>> all = new ArrayList<Pair<Long, int[]>>(maxSize);
        for (int i = 0; i < maxSize; i++) {
            final long timestamp = this.timestamps.get(i);
            if (timestamp == 0L) {
                break;
            }

            all.add(new Pair<Long, int[]>(timestamp, this.values.get(i)));
        }
        Collections.sort(all, new Comparator<Pair<Long, int[]>>() {
            @Override
            public int compare(final Pair<Long, int[]> pair1, Pair<Long, int[]> pair2) {
                return Longs.compare(pair1.first, pair2.first);
            }
        });
        return all;
    }

    private int index() {
        return (int) (this.index.getAndIncrement() % getMaximumSize());
    }

    @Override
    public void append(final long timestamp, final int[] values) {
        final int currentIndex = index();
        this.timestamps.set(currentIndex, timestamp);
        this.values.set(currentIndex, values.clone());
    }

}