PersistentMessageFinder.java

/**
 * Copyright 2016 Yahoo 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 com.yahoo.pulsar.broker.service.persistent;

import com.yahoo.pulsar.common.util.Codec;
import com.yahoo.pulsar.client.impl.MessageImpl;

import org.apache.bookkeeper.mledger.AsyncCallbacks;
import org.apache.bookkeeper.mledger.ManagedCursor;
import org.apache.bookkeeper.mledger.ManagedLedgerException;
import org.apache.bookkeeper.mledger.Position;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;

import static com.google.common.base.Preconditions.checkArgument;

/**
 *
 * given a timestamp find the first message (position) (published) at or before the timestamp
 */
public class PersistentMessageFinder implements AsyncCallbacks.FindEntryCallback {
    private final ManagedCursor cursor;
    private final String subName;
    private final String topicName;
    private long timestamp = 0;

    private static final int FALSE = 0;
    private static final int TRUE = 1;
    @SuppressWarnings("unused")
    private volatile int messageFindInProgress = FALSE;
    private static final AtomicIntegerFieldUpdater<PersistentMessageFinder> messageFindInProgressUpdater = AtomicIntegerFieldUpdater
            .newUpdater(PersistentMessageFinder.class, "messageFindInProgress");

    public PersistentMessageFinder(String topicName, ManagedCursor cursor) {
        this.topicName = topicName;
        this.cursor = cursor;
        this.subName = Codec.decode(cursor.getName());
    }

    public void findMessages(final long timestamp, AsyncCallbacks.FindEntryCallback callback) {
        this.timestamp = timestamp;
        if (messageFindInProgressUpdater.compareAndSet(this, FALSE, TRUE)) {
            if (log.isDebugEnabled()) {
                log.debug("[{}] Starting message position find at timestamp {}", subName, timestamp);
            }

            cursor.asyncFindNewestMatching(ManagedCursor.FindPositionConstraint.SearchAllAvailableEntries, entry -> {
                MessageImpl msg = null;
                try {
                    msg = MessageImpl.deserialize(entry.getDataBuffer());
                    return msg.getPublishTime() <= timestamp;
                } catch (Exception e) {
                    log.error("[{}][{}] Error deserializing message for message position find", topicName, subName, e);
                } finally {
                    entry.release();
                    if (msg != null) {
                        msg.recycle();
                    }
                }
                return false;
            }, this, callback);
        } else {
            if (log.isDebugEnabled()) {
                log.debug("[{}][{}] Ignore message position find scheduled task, last find is still running", topicName,
                        subName);
            }
            callback.findEntryFailed(
                    new ManagedLedgerException.ConcurrentFindCursorPositionException("last find is still running"),
                    null);
        }
    }

    private static final Logger log = LoggerFactory.getLogger(PersistentMessageFinder.class);

    @Override
    public void findEntryComplete(Position position, Object ctx) {
        checkArgument(ctx instanceof AsyncCallbacks.FindEntryCallback);
        AsyncCallbacks.FindEntryCallback callback = (AsyncCallbacks.FindEntryCallback) ctx;
        if (position != null) {
            log.info("[{}][{}] Found position {} closest to provided timestamp {}", topicName, subName, position,
                    timestamp);
        } else {
            if (log.isDebugEnabled()) {
                log.debug("[{}][{}] No position found closest to provided timestamp {}", topicName, subName, timestamp);
            }
        }
        messageFindInProgress = FALSE;
        callback.findEntryComplete(position, null);
    }

    @Override
    public void findEntryFailed(ManagedLedgerException exception, Object ctx) {
        checkArgument(ctx instanceof AsyncCallbacks.FindEntryCallback);
        AsyncCallbacks.FindEntryCallback callback = (AsyncCallbacks.FindEntryCallback) ctx;
        if (log.isDebugEnabled()) {
            log.debug("[{}][{}] message position find operation failed for provided timestamp {}", topicName, subName,
                    timestamp, exception);
        }
        messageFindInProgress = FALSE;
        callback.findEntryFailed(exception, null);
    }
}