| /** |
| * 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.hadoop.hbase.fs.legacy.snapshot; |
| |
| import java.io.FileNotFoundException; |
| import java.io.IOException; |
| import java.util.Collection; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.Timer; |
| import java.util.TimerTask; |
| import java.util.concurrent.locks.ReentrantLock; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import com.google.common.collect.Lists; |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.hadoop.hbase.classification.InterfaceAudience; |
| import org.apache.hadoop.hbase.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.fs.FileStatus; |
| import org.apache.hadoop.fs.FileSystem; |
| import org.apache.hadoop.fs.Path; |
| import org.apache.hadoop.hbase.Stoppable; |
| import org.apache.hadoop.hbase.fs.legacy.LegacyLayout; |
| import org.apache.hadoop.hbase.master.snapshot.SnapshotManager; |
| import org.apache.hadoop.hbase.snapshot.CorruptedSnapshotException; |
| import org.apache.hadoop.hbase.snapshot.SnapshotDescriptionUtils; |
| import org.apache.hadoop.hbase.util.FSUtils; |
| |
| /** |
| * Intelligently keep track of all the files for all the snapshots. |
| * <p> |
| * A cache of files is kept to avoid querying the {@link FileSystem} frequently. If there is a cache |
| * miss the directory modification time is used to ensure that we don't rescan directories that we |
| * already have in cache. We only check the modification times of the snapshot directories |
| * (/hbase/.snapshot/[snapshot_name]) to determine if the files need to be loaded into the cache. |
| * <p> |
| * New snapshots will be added to the cache and deleted snapshots will be removed when we refresh |
| * the cache. If the files underneath a snapshot directory are changed, but not the snapshot itself, |
| * we will ignore updates to that snapshot's files. |
| * <p> |
| * This is sufficient because each snapshot has its own directory and is added via an atomic rename |
| * <i>once</i>, when the snapshot is created. We don't need to worry about the data in the snapshot |
| * being run. |
| * <p> |
| * Further, the cache is periodically refreshed ensure that files in snapshots that were deleted are |
| * also removed from the cache. |
| * <p> |
| * A {@link SnapshotFileCache.SnapshotFileInspector} must be passed when creating <tt>this</tt> to |
| * allow extraction of files under /hbase/.snapshot/[snapshot name] directory, for each snapshot. |
| * This allows you to only cache files under, for instance, all the logs in the .logs directory or |
| * all the files under all the regions. |
| * <p> |
| * <tt>this</tt> also considers all running snapshots (those under /hbase/.snapshot/.tmp) as valid |
| * snapshots and will attempt to cache files from those snapshots as well. |
| * <p> |
| * Queries about a given file are thread-safe with respect to multiple queries and cache refreshes. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Evolving |
| public class SnapshotFileCache implements Stoppable { |
| interface SnapshotFileInspector { |
| /** |
| * Returns a collection of file names needed by the snapshot. |
| * @param snapshotDir {@link Path} to the snapshot directory to scan. |
| * @return the collection of file names needed by the snapshot. |
| */ |
| Collection<String> filesUnderSnapshot(final Path snapshotDir) throws IOException; |
| } |
| |
| private static final Log LOG = LogFactory.getLog(SnapshotFileCache.class); |
| private volatile boolean stop = false; |
| private final FileSystem fs; |
| private final Path rootDir; |
| private final SnapshotFileInspector fileInspector; |
| private final Path snapshotDir; |
| private final Set<String> cache = new HashSet<String>(); |
| /** |
| * This is a helper map of information about the snapshot directories so we don't need to rescan |
| * them if they haven't changed since the last time we looked. |
| */ |
| private final Map<String, SnapshotDirectoryInfo> snapshots = |
| new HashMap<String, SnapshotDirectoryInfo>(); |
| private final Timer refreshTimer; |
| |
| private long lastModifiedTime = Long.MIN_VALUE; |
| |
| /** |
| * Create a snapshot file cache for all snapshots under the specified [root]/.snapshot on the |
| * filesystem. |
| * <p> |
| * Immediately loads the file cache. |
| * @param conf to extract the configured {@link FileSystem} where the snapshots are stored and |
| * hbase root directory |
| * @param cacheRefreshPeriod frequency (ms) with which the cache should be refreshed |
| * @param refreshThreadName name of the cache refresh thread |
| * @param inspectSnapshotFiles Filter to apply to each snapshot to extract the files. |
| * @throws IOException if the {@link FileSystem} or root directory cannot be loaded |
| */ |
| public SnapshotFileCache(Configuration conf, long cacheRefreshPeriod, String refreshThreadName, |
| SnapshotFileInspector inspectSnapshotFiles) throws IOException { |
| this(FSUtils.getCurrentFileSystem(conf), FSUtils.getRootDir(conf), 0, cacheRefreshPeriod, |
| refreshThreadName, inspectSnapshotFiles); |
| } |
| |
| /** |
| * Create a snapshot file cache for all snapshots under the specified [root]/.snapshot on the |
| * filesystem |
| * @param fs {@link FileSystem} where the snapshots are stored |
| * @param rootDir hbase root directory |
| * @param cacheRefreshPeriod period (ms) with which the cache should be refreshed |
| * @param cacheRefreshDelay amount of time to wait for the cache to be refreshed |
| * @param refreshThreadName name of the cache refresh thread |
| * @param inspectSnapshotFiles Filter to apply to each snapshot to extract the files. |
| */ |
| public SnapshotFileCache(FileSystem fs, Path rootDir, long cacheRefreshPeriod, |
| long cacheRefreshDelay, String refreshThreadName, SnapshotFileInspector inspectSnapshotFiles) { |
| this.fs = fs; |
| this.rootDir = rootDir; |
| this.fileInspector = inspectSnapshotFiles; |
| this.snapshotDir = LegacyLayout.getSnapshotDir(rootDir); |
| // periodically refresh the file cache to make sure we aren't superfluously saving files. |
| this.refreshTimer = new Timer(refreshThreadName, true); |
| this.refreshTimer.scheduleAtFixedRate(new RefreshCacheTask(), cacheRefreshDelay, |
| cacheRefreshPeriod); |
| } |
| |
| /** |
| * Trigger a cache refresh, even if its before the next cache refresh. Does not affect pending |
| * cache refreshes. |
| * <p> |
| * Blocks until the cache is refreshed. |
| * <p> |
| * Exposed for TESTING. |
| */ |
| public void triggerCacheRefreshForTesting() { |
| try { |
| SnapshotFileCache.this.refreshCache(); |
| } catch (IOException e) { |
| LOG.warn("Failed to refresh snapshot hfile cache!", e); |
| } |
| LOG.debug("Current cache:" + cache); |
| } |
| |
| /** |
| * Check to see if any of the passed file names is contained in any of the snapshots. |
| * First checks an in-memory cache of the files to keep. If its not in the cache, then the cache |
| * is refreshed and the cache checked again for that file. |
| * This ensures that we never return files that exist. |
| * <p> |
| * Note this may lead to periodic false positives for the file being referenced. Periodically, the |
| * cache is refreshed even if there are no requests to ensure that the false negatives get removed |
| * eventually. For instance, suppose you have a file in the snapshot and it gets loaded into the |
| * cache. Then at some point later that snapshot is deleted. If the cache has not been refreshed |
| * at that point, cache will still think the file system contains that file and return |
| * <tt>true</tt>, even if it is no longer present (false positive). However, if the file never was |
| * on the filesystem, we will never find it and always return <tt>false</tt>. |
| * @param files file to check, NOTE: Relies that files are loaded from hdfs before method |
| * is called (NOT LAZY) |
| * @return <tt>unReferencedFiles</tt> the collection of files that do not have snapshot references |
| * @throws IOException if there is an unexpected error reaching the filesystem. |
| */ |
| // XXX this is inefficient to synchronize on the method, when what we really need to guard against |
| // is an illegal access to the cache. Really we could do a mutex-guarded pointer swap on the |
| // cache, but that seems overkill at the moment and isn't necessarily a bottleneck. |
| public synchronized Iterable<FileStatus> getUnreferencedFiles(Iterable<FileStatus> files, |
| final SnapshotManager snapshotManager) |
| throws IOException { |
| List<FileStatus> unReferencedFiles = Lists.newArrayList(); |
| List<String> snapshotsInProgress = null; |
| boolean refreshed = false; |
| for (FileStatus file : files) { |
| String fileName = file.getPath().getName(); |
| if (!refreshed && !cache.contains(fileName)) { |
| refreshCache(); |
| refreshed = true; |
| } |
| if (cache.contains(fileName)) { |
| continue; |
| } |
| if (snapshotsInProgress == null) { |
| snapshotsInProgress = getSnapshotsInProgress(snapshotManager); |
| } |
| if (snapshotsInProgress.contains(fileName)) { |
| continue; |
| } |
| unReferencedFiles.add(file); |
| } |
| return unReferencedFiles; |
| } |
| |
| private synchronized void refreshCache() throws IOException { |
| long lastTimestamp = Long.MAX_VALUE; |
| boolean hasChanges = false; |
| |
| // get the status of the snapshots directory and check if it is has changes |
| try { |
| FileStatus dirStatus = fs.getFileStatus(snapshotDir); |
| lastTimestamp = dirStatus.getModificationTime(); |
| hasChanges |= (lastTimestamp >= lastModifiedTime); |
| } catch (FileNotFoundException e) { |
| if (this.cache.size() > 0) { |
| LOG.error("Snapshot directory: " + snapshotDir + " doesn't exist"); |
| } |
| return; |
| } |
| |
| // get the status of the snapshots temporary directory and check if it has changes |
| // The top-level directory timestamp is not updated, so we have to check the inner-level. |
| try { |
| Path snapshotTmpDir = LegacyLayout.getWorkingSnapshotDir(rootDir); |
| FileStatus tempDirStatus = fs.getFileStatus(snapshotTmpDir); |
| lastTimestamp = Math.min(lastTimestamp, tempDirStatus.getModificationTime()); |
| hasChanges |= (lastTimestamp >= lastModifiedTime); |
| if (!hasChanges) { |
| FileStatus[] tmpSnapshots = FSUtils.listStatus(fs, snapshotDir); |
| if (tmpSnapshots != null) { |
| for (FileStatus dirStatus: tmpSnapshots) { |
| lastTimestamp = Math.min(lastTimestamp, dirStatus.getModificationTime()); |
| } |
| hasChanges |= (lastTimestamp >= lastModifiedTime); |
| } |
| } |
| } catch (FileNotFoundException e) { |
| // Nothing todo, if the tmp dir is empty |
| } |
| |
| // if the snapshot directory wasn't modified since we last check, we are done |
| if (!hasChanges) { |
| return; |
| } |
| |
| // directory was modified, so we need to reload our cache |
| // there could be a slight race here where we miss the cache, check the directory modification |
| // time, then someone updates the directory, causing us to not scan the directory again. |
| // However, snapshot directories are only created once, so this isn't an issue. |
| |
| // 1. update the modified time |
| this.lastModifiedTime = lastTimestamp; |
| |
| // 2.clear the cache |
| this.cache.clear(); |
| Map<String, SnapshotDirectoryInfo> known = new HashMap<String, SnapshotDirectoryInfo>(); |
| |
| // 3. check each of the snapshot directories |
| FileStatus[] snapshots = FSUtils.listStatus(fs, snapshotDir); |
| if (snapshots == null) { |
| // remove all the remembered snapshots because we don't have any left |
| if (LOG.isDebugEnabled() && this.snapshots.size() > 0) { |
| LOG.debug("No snapshots on-disk, cache empty"); |
| } |
| this.snapshots.clear(); |
| return; |
| } |
| |
| // 3.1 iterate through the on-disk snapshots |
| for (FileStatus snapshot : snapshots) { |
| String name = snapshot.getPath().getName(); |
| // its not the tmp dir, |
| if (!name.equals(LegacyLayout.SNAPSHOT_TMP_DIR_NAME)) { |
| SnapshotDirectoryInfo files = this.snapshots.remove(name); |
| // 3.1.1 if we don't know about the snapshot or its been modified, we need to update the |
| // files the latter could occur where I create a snapshot, then delete it, and then make a |
| // new snapshot with the same name. We will need to update the cache the information from |
| // that new snapshot, even though it has the same name as the files referenced have |
| // probably changed. |
| if (files == null || files.hasBeenModified(snapshot.getModificationTime())) { |
| // get all files for the snapshot and create a new info |
| Collection<String> storedFiles = fileInspector.filesUnderSnapshot(snapshot.getPath()); |
| files = new SnapshotDirectoryInfo(snapshot.getModificationTime(), storedFiles); |
| } |
| // 3.2 add all the files to cache |
| this.cache.addAll(files.getFiles()); |
| known.put(name, files); |
| } |
| } |
| |
| // 4. set the snapshots we are tracking |
| this.snapshots.clear(); |
| this.snapshots.putAll(known); |
| } |
| |
| @VisibleForTesting List<String> getSnapshotsInProgress( |
| final SnapshotManager snapshotManager) throws IOException { |
| List<String> snapshotInProgress = Lists.newArrayList(); |
| // only add those files to the cache, but not to the known snapshots |
| Path snapshotTmpDir = LegacyLayout.getWorkingSnapshotDir(rootDir); |
| // only add those files to the cache, but not to the known snapshots |
| FileStatus[] running = FSUtils.listStatus(fs, snapshotTmpDir); |
| if (running != null) { |
| for (FileStatus run : running) { |
| ReentrantLock lock = null; |
| if (snapshotManager != null) { |
| lock = snapshotManager.getLocks().acquireLock(run.getPath().getName()); |
| } |
| try { |
| snapshotInProgress.addAll(fileInspector.filesUnderSnapshot(run.getPath())); |
| } catch (CorruptedSnapshotException e) { |
| // See HBASE-16464 |
| if (e.getCause() instanceof FileNotFoundException) { |
| // If the snapshot is corrupt, we will delete it |
| fs.delete(run.getPath(), true); |
| LOG.warn("delete the " + run.getPath() + " due to exception:", e.getCause()); |
| } else { |
| throw e; |
| } |
| } finally { |
| if (lock != null) { |
| lock.unlock(); |
| } |
| } |
| } |
| } |
| return snapshotInProgress; |
| } |
| |
| /** |
| * Simple helper task that just periodically attempts to refresh the cache |
| */ |
| public class RefreshCacheTask extends TimerTask { |
| @Override |
| public void run() { |
| try { |
| SnapshotFileCache.this.refreshCache(); |
| } catch (IOException e) { |
| LOG.warn("Failed to refresh snapshot hfile cache!", e); |
| } |
| } |
| } |
| |
| @Override |
| public void stop(String why) { |
| if (!this.stop) { |
| this.stop = true; |
| this.refreshTimer.cancel(); |
| } |
| |
| } |
| |
| @Override |
| public boolean isStopped() { |
| return this.stop; |
| } |
| |
| /** |
| * Information about a snapshot directory |
| */ |
| private static class SnapshotDirectoryInfo { |
| long lastModified; |
| Collection<String> files; |
| |
| public SnapshotDirectoryInfo(long mtime, Collection<String> files) { |
| this.lastModified = mtime; |
| this.files = files; |
| } |
| |
| /** |
| * @return the hfiles in the snapshot when <tt>this</tt> was made. |
| */ |
| public Collection<String> getFiles() { |
| return this.files; |
| } |
| |
| /** |
| * Check if the snapshot directory has been modified |
| * @param mtime current modification time of the directory |
| * @return <tt>true</tt> if it the modification time of the directory is newer time when we |
| * created <tt>this</tt> |
| */ |
| public boolean hasBeenModified(long mtime) { |
| return this.lastModified < mtime; |
| } |
| } |
| } |