org.apache.aurora.scheduler.storage.durability.Recovery.java Source code

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Here is the source code for org.apache.aurora.scheduler.storage.durability.Recovery.java

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/**
 * 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.apache.aurora.scheduler.storage.durability;

import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.stream.Stream;

import com.google.common.collect.Lists;

import org.apache.aurora.common.quantity.Amount;
import org.apache.aurora.common.quantity.Time;
import org.apache.aurora.gen.storage.Op;
import org.apache.aurora.scheduler.storage.durability.Persistence.Edit;
import org.apache.aurora.scheduler.storage.durability.Persistence.PersistenceException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Utility class to clone a persistence.
 */
final class Recovery {

    private static final Logger LOG = LoggerFactory.getLogger(Recovery.class);

    private Recovery() {
        // utility class.
    }

    /**
     * Copies all state from one persistence to another, batching into calls to
     * {@link Persistence#persist(Stream)}.
     *
     * @param from Source.
     * @param to Destination.
     * @param batchSize Maximum number of entries to include in any given persist.
     */
    static void copy(Persistence from, Persistence to, int batchSize) {
        requireEmpty(to);

        long start = System.nanoTime();
        AtomicLong count = new AtomicLong();
        AtomicInteger batchNumber = new AtomicInteger();
        List<Op> batch = Lists.newArrayListWithExpectedSize(batchSize);
        Runnable saveBatch = () -> {
            LOG.info("Saving batch " + batchNumber.incrementAndGet());
            try {
                to.persist(batch.stream());
            } catch (PersistenceException e) {
                throw new RuntimeException(e);
            }
            batch.clear();
        };

        AtomicBoolean dataBegin = new AtomicBoolean(false);
        try {
            from.recover().filter(edit -> {
                if (edit.isDeleteAll()) {
                    // Suppress any storage reset instructions.
                    // Persistence implementations may recover with these, but do not support persisting
                    // them.  As a result, we require that the recovery source produces a reset
                    // instruction at the beginning of the stream, if at all.

                    if (dataBegin.get()) {
                        throw new IllegalStateException(
                                "A storage reset instruction arrived after the beginning of data");
                    }
                    return false;
                } else {
                    dataBegin.set(true);
                }
                return true;
            }).forEach(edit -> {
                count.incrementAndGet();
                batch.add(edit.getOp());
                if (batch.size() == batchSize) {
                    saveBatch.run();
                    LOG.info("Fetching batch");
                }
            });
        } catch (PersistenceException e) {
            throw new RuntimeException(e);
        }

        if (!batch.isEmpty()) {
            saveBatch.run();
        }
        long end = System.nanoTime();
        LOG.info("Recovery finished");
        LOG.info("Copied " + count.get() + " ops in "
                + Amount.of(end - start, Time.NANOSECONDS).as(Time.MILLISECONDS) + " ms");
    }

    private static void requireEmpty(Persistence persistence) {
        LOG.info("Ensuring recovery destination is empty");
        try (Stream<Edit> edits = persistence.recover()) {
            if (edits.findFirst().isPresent()) {
                throw new IllegalStateException("Refusing to recover into non-empty persistence");
            }
        } catch (PersistenceException e) {
            throw new RuntimeException(e);
        }
    }
}