| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.beam.sdk.util; |
| |
| import static org.apache.beam.vendor.guava.v20_0.com.google.common.base.Preconditions.checkArgument; |
| import static org.apache.beam.vendor.guava.v20_0.com.google.common.base.Preconditions.checkNotNull; |
| |
| import java.io.IOException; |
| import java.io.Reader; |
| import java.nio.channels.Channels; |
| import java.nio.charset.StandardCharsets; |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.List; |
| import java.util.regex.Matcher; |
| import java.util.regex.Pattern; |
| import org.apache.beam.sdk.io.FileSystems; |
| import org.apache.beam.sdk.io.fs.MatchResult.Metadata; |
| import org.apache.beam.vendor.guava.v20_0.com.google.common.annotations.VisibleForTesting; |
| import org.apache.beam.vendor.guava.v20_0.com.google.common.base.Strings; |
| import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.Iterables; |
| import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.Lists; |
| import org.apache.beam.vendor.guava.v20_0.com.google.common.io.CharStreams; |
| import org.joda.time.Duration; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Utility methods for working with sharded files. For internal use only; many parameters are just |
| * hardcoded to allow existing uses to work OK. |
| */ |
| public class NumberedShardedFile implements ShardedFile { |
| |
| private static final Logger LOG = LoggerFactory.getLogger(NumberedShardedFile.class); |
| |
| static final int MAX_READ_RETRIES = 4; |
| static final Duration DEFAULT_SLEEP_DURATION = Duration.standardSeconds(10L); |
| static final FluentBackoff BACK_OFF_FACTORY = |
| FluentBackoff.DEFAULT |
| .withInitialBackoff(DEFAULT_SLEEP_DURATION) |
| .withMaxRetries(MAX_READ_RETRIES); |
| |
| private static final Pattern DEFAULT_SHARD_TEMPLATE = |
| Pattern.compile("(?x) \\S* (?<shardnum> \\d+) -of- (?<numshards> \\d+)"); |
| |
| private final String filePattern; |
| private final Pattern shardTemplate; |
| |
| /** |
| * Constructor that uses default shard template. |
| * |
| * @param filePattern path or glob of files to include |
| */ |
| public NumberedShardedFile(String filePattern) { |
| this(filePattern, DEFAULT_SHARD_TEMPLATE); |
| } |
| |
| /** |
| * Constructor. |
| * |
| * @param filePattern path or glob of files to include |
| * @param shardTemplate template of shard name to parse out the total number of shards which is |
| * used in I/O retry to avoid inconsistency of filesystem. Customized template should assign |
| * name "numshards" to capturing group - total shard number. |
| */ |
| public NumberedShardedFile(String filePattern, Pattern shardTemplate) { |
| checkArgument( |
| !Strings.isNullOrEmpty(filePattern), |
| "Expected valid file path, but received %s", |
| filePattern); |
| checkNotNull( |
| shardTemplate, |
| "Expected non-null shard pattern. " |
| + "Please call the other constructor to use default pattern: %s", |
| DEFAULT_SHARD_TEMPLATE); |
| |
| this.filePattern = filePattern; |
| this.shardTemplate = shardTemplate; |
| } |
| |
| public String getFilePattern() { |
| return filePattern; |
| } |
| |
| /** |
| * Discovers all shards of this file using the provided {@link Sleeper} and {@link BackOff}. |
| * |
| * <p>Because of eventual consistency, reads may discover no files or fewer files than the shard |
| * template implies. In this case, the read is considered to have failed. |
| */ |
| @Override |
| public List<String> readFilesWithRetries(Sleeper sleeper, BackOff backOff) |
| throws IOException, InterruptedException { |
| IOException lastException = null; |
| |
| do { |
| try { |
| // Match inputPath which may contains glob |
| Collection<Metadata> files = |
| Iterables.getOnlyElement(FileSystems.match(Collections.singletonList(filePattern))) |
| .metadata(); |
| |
| LOG.debug("Found {} file(s) by matching the path: {}", files.size(), filePattern); |
| |
| if (files.isEmpty() || !checkTotalNumOfFiles(files)) { |
| continue; |
| } |
| |
| // Read data from file paths |
| return readLines(files); |
| } catch (IOException e) { |
| // Ignore and retry |
| lastException = e; |
| LOG.warn("Error in file reading. Ignore and retry."); |
| } |
| } while (BackOffUtils.next(sleeper, backOff)); |
| // Failed after max retries |
| throw new IOException( |
| String.format("Unable to read file(s) after retrying %d times", MAX_READ_RETRIES), |
| lastException); |
| } |
| |
| /** |
| * Discovers all shards of this file. |
| * |
| * <p>Because of eventual consistency, reads may discover no files or fewer files than the shard |
| * template implies. In this case, the read is considered to have failed. |
| */ |
| public List<String> readFilesWithRetries() throws IOException, InterruptedException { |
| return readFilesWithRetries(Sleeper.DEFAULT, BACK_OFF_FACTORY.backoff()); |
| } |
| |
| @Override |
| public String toString() { |
| return String.format("%s with shard template '%s'", filePattern, shardTemplate); |
| } |
| |
| /** |
| * Reads all the lines of all the files. |
| * |
| * <p>Not suitable for use except in testing of small data, since the data size may be far more |
| * than can be reasonably processed serially, in-memory, by a single thread. |
| */ |
| @VisibleForTesting |
| List<String> readLines(Collection<Metadata> files) throws IOException { |
| List<String> allLines = Lists.newArrayList(); |
| int i = 1; |
| for (Metadata file : files) { |
| try (Reader reader = |
| Channels.newReader(FileSystems.open(file.resourceId()), StandardCharsets.UTF_8.name())) { |
| List<String> lines = CharStreams.readLines(reader); |
| allLines.addAll(lines); |
| LOG.debug("[{} of {}] Read {} lines from file: {}", i, files.size(), lines.size(), file); |
| } |
| i++; |
| } |
| return allLines; |
| } |
| |
| /** |
| * Check if total number of files is correct by comparing with the number that is parsed from |
| * shard name using a name template. If no template is specified, "SSSS-of-NNNN" will be used as |
| * default, and "NNNN" will be the expected total number of files. |
| * |
| * @return {@code true} if at least one shard name matches template and total number of given |
| * files equals the number that is parsed from shard name. |
| */ |
| @VisibleForTesting |
| boolean checkTotalNumOfFiles(Collection<Metadata> files) { |
| for (Metadata fileMedadata : files) { |
| String fileName = fileMedadata.resourceId().getFilename(); |
| |
| if (fileName == null) { |
| // this path has zero elements |
| continue; |
| } |
| Matcher matcher = shardTemplate.matcher(fileName); |
| if (!matcher.matches()) { |
| // shard name doesn't match the pattern, check with the next shard |
| continue; |
| } |
| // once match, extract total number of shards and compare to file list |
| return files.size() == Integer.parseInt(matcher.group("numshards")); |
| } |
| return false; |
| } |
| } |