FileLogReader.java

/*
 * Copyright © 2014 Cask Data, 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 co.cask.cdap.logging.read;

import co.cask.cdap.common.conf.CConfiguration;
import co.cask.cdap.common.logging.LoggingContext;
import co.cask.cdap.logging.LoggingConfiguration;
import co.cask.cdap.logging.context.LoggingContextHelper;
import co.cask.cdap.logging.filter.AndFilter;
import co.cask.cdap.logging.filter.Filter;
import co.cask.cdap.logging.serialize.LogSchema;
import co.cask.cdap.logging.write.FileMetaDataManager;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.inject.Inject;
import org.apache.avro.Schema;
import org.apache.twill.filesystem.Location;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Collection;
import java.util.List;
import java.util.NavigableMap;

/**
 * Reads log events from a file.
 */
public class FileLogReader implements LogReader {
  private static final Logger LOG = LoggerFactory.getLogger(FileLogReader.class);

  private final FileMetaDataManager fileMetaDataManager;
  private final Schema schema;

  @Inject
  public FileLogReader(CConfiguration cConf, FileMetaDataManager fileMetaDataManager) {
    String baseDir = cConf.get(LoggingConfiguration.LOG_BASE_DIR);
    Preconditions.checkNotNull(baseDir, "Log base dir cannot be null");

    try {
      this.schema = new LogSchema().getAvroSchema();
      this.fileMetaDataManager = fileMetaDataManager;

    } catch (Exception e) {
      LOG.error("Got exception", e);
      throw Throwables.propagate(e);
    }
  }

  @Override
  public void getLogNext(final LoggingContext loggingContext, final ReadRange readRange, final int maxEvents,
                              final Filter filter, final Callback callback) {
    if (readRange == ReadRange.LATEST) {
      getLogPrev(loggingContext, readRange, maxEvents, filter, callback);
      return;
    }

    callback.init();

    try {
      Filter logFilter = new AndFilter(ImmutableList.of(LoggingContextHelper.createFilter(loggingContext),
                                                        filter));
      long fromTimeMs = readRange.getFromMillis() + 1;

      LOG.trace("Using fromTimeMs={}, readRange={}", fromTimeMs, readRange);
      NavigableMap<Long, Location> sortedFiles = fileMetaDataManager.listFiles(loggingContext);
      if (sortedFiles.isEmpty()) {
        return;
      }

      List<Location> filesInRange = getFilesInRange(sortedFiles, readRange.getFromMillis(), readRange.getToMillis());
      AvroFileReader logReader = new AvroFileReader(schema);
      for (Location file : filesInRange) {
        LOG.trace("Reading file {}", file);
        logReader.readLog(file, logFilter, fromTimeMs, Long.MAX_VALUE, maxEvents - callback.getCount(), callback);
        if (callback.getCount() >= maxEvents) {
          break;
        }
      }
    } catch (Throwable e) {
      LOG.error("Got exception: ", e);
      throw  Throwables.propagate(e);
    }
  }

  @Override
  public void getLogPrev(final LoggingContext loggingContext, final ReadRange readRange, final int maxEvents,
                              final Filter filter, final Callback callback) {
    callback.init();
    try {
      Filter logFilter = new AndFilter(ImmutableList.of(LoggingContextHelper.createFilter(loggingContext),
                                                        filter));

      NavigableMap<Long, Location> sortedFiles = fileMetaDataManager.listFiles(loggingContext);
      if (sortedFiles.isEmpty()) {
        return;
      }

      long fromTimeMs = readRange.getToMillis() - 1;

      LOG.trace("Using fromTimeMs={}, readRange={}", fromTimeMs, readRange);
      List<Location> filesInRange = getFilesInRange(sortedFiles, readRange.getFromMillis(), readRange.getToMillis());
      List<Collection<LogEvent>> logSegments = Lists.newLinkedList();
      AvroFileReader logReader = new AvroFileReader(schema);
      int count = 0;
      for (Location file : Lists.reverse(filesInRange)) {
        LOG.trace("Reading file {}", file);
        Collection<LogEvent> events = logReader.readLogPrev(file, logFilter, fromTimeMs, maxEvents - count);
        logSegments.add(events);
        count += events.size();
        if (count >= maxEvents) {
          break;
        }
      }

      for (LogEvent event : Iterables.concat(Lists.reverse(logSegments))) {
        callback.handle(event);
      }
    } catch (Throwable e) {
      LOG.error("Got exception: ", e);
      throw  Throwables.propagate(e);
    }
  }

  @Override
  public void getLog(final LoggingContext loggingContext, final long fromTimeMs, final long toTimeMs,
                          final Filter filter, final Callback callback) {
    callback.init();
    try {
      Filter logFilter = new AndFilter(ImmutableList.of(LoggingContextHelper.createFilter(loggingContext),
                                                        filter));

      LOG.trace("Using fromTimeMs={}, toTimeMs={}", fromTimeMs, toTimeMs);
      NavigableMap<Long, Location> sortedFiles = fileMetaDataManager.listFiles(loggingContext);
      if (sortedFiles.isEmpty()) {
        return;
      }

      List<Location> filesInRange = getFilesInRange(sortedFiles, fromTimeMs, toTimeMs);
      AvroFileReader avroFileReader = new AvroFileReader(schema);
      for (Location file : filesInRange) {
        LOG.trace("Reading file {}", file);
        avroFileReader.readLog(file, logFilter, fromTimeMs, toTimeMs, Integer.MAX_VALUE, callback);
      }
    } catch (Throwable e) {
      LOG.error("Got exception: ", e);
      throw  Throwables.propagate(e);
    }
  }

  @VisibleForTesting
  static List<Location> getFilesInRange(NavigableMap<Long, Location> sortedFiles, long fromTimeMs, long toTimeMs) {
    // Get a list of files to read based on fromMillis and toMillis.
    // Each file is associated with the time of the first log message in it.
    // Let c be the file with the largest timestamp smaller than readRange.getFromMillis().
    // We need to select all the files within the range [c, readRange.toMillis()).
    Long start = sortedFiles.floorKey(fromTimeMs);
    if (start == null) {
      start = sortedFiles.firstKey();

      // It is possible that the log files for the requested range are already
      // deleted, in case of old program runs. For such requests both the start and toTimeMs
      // will fall outside the range sortedFiles. In that case return empty list.
      if (start > toTimeMs) {
        return ImmutableList.of();
      }
    }
    return ImmutableList.copyOf(sortedFiles.subMap(start, toTimeMs).values());
  }
}