Java tutorial
/** * Copyright The Apache Software Foundation * * 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.io.hfile.bucket; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; import java.nio.ByteBuffer; import java.util.ArrayList; import java.util.Comparator; import java.util.List; import java.util.Map; import java.util.PriorityQueue; import java.util.Set; import java.util.concurrent.ArrayBlockingQueue; import java.util.concurrent.BlockingQueue; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicLong; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.io.HeapSize; import org.apache.hadoop.hbase.io.hfile.BlockCache; import org.apache.hadoop.hbase.io.hfile.BlockCacheColumnFamilySummary; import org.apache.hadoop.hbase.io.hfile.BlockCacheKey; import org.apache.hadoop.hbase.io.hfile.CacheStats; import org.apache.hadoop.hbase.io.hfile.Cacheable; import org.apache.hadoop.hbase.io.hfile.CacheableDeserializer; import org.apache.hadoop.hbase.io.hfile.CacheableDeserializerIdManager; import org.apache.hadoop.hbase.io.hfile.CombinedBlockCache; import org.apache.hadoop.hbase.io.hfile.HFileBlock; import org.apache.hadoop.hbase.util.ConcurrentIndex; import org.apache.hadoop.hbase.util.EnvironmentEdgeManager; import org.apache.hadoop.hbase.util.HasThread; import org.apache.hadoop.hbase.util.IdLock; import org.apache.hadoop.util.StringUtils; import com.google.common.collect.ImmutableList; import com.google.common.util.concurrent.ThreadFactoryBuilder; /** * BucketCache uses {@link BucketAllocator} to allocate/free blocks, and uses * {@link BucketCache#ramCache} and {@link BucketCache#backingMap} in order to * determine if a given element is in the cache. The bucket cache can use on-heap or * off-heap memory {@link ByteBufferIOEngine} or in a file {@link FileIOEngine} to * store/read the block data. * * <p>Eviction is via a similar algorithm as used in * {@link org.apache.hadoop.hbase.io.hfile.LruBlockCache} * * <p>BucketCache can be used as mainly a block cache (see * {@link CombinedBlockCache}), combined with LruBlockCache to decrease CMS GC and * heap fragmentation. * * <p>It also can be used as a secondary cache (e.g. using a file on ssd/fusionio to store * blocks) to enlarge cache space via * {@link org.apache.hadoop.hbase.io.hfile.LruBlockCache#setVictimCache} */ @InterfaceAudience.Private public class BucketCache implements BlockCache, HeapSize { static final Log LOG = LogFactory.getLog(BucketCache.class); /** Priority buckets */ private static final float DEFAULT_SINGLE_FACTOR = 0.25f; private static final float DEFAULT_MULTI_FACTOR = 0.50f; private static final float DEFAULT_MEMORY_FACTOR = 0.25f; private static final float DEFAULT_EXTRA_FREE_FACTOR = 0.10f; private static final float DEFAULT_ACCEPT_FACTOR = 0.95f; private static final float DEFAULT_MIN_FACTOR = 0.85f; /** Statistics thread */ private static final int statThreadPeriod = 3 * 60; final static int DEFAULT_WRITER_THREADS = 3; final static int DEFAULT_WRITER_QUEUE_ITEMS = 64; // Store/read block data IOEngine ioEngine; // Store the block in this map before writing it to cache private Map<BlockCacheKey, RAMQueueEntry> ramCache; // In this map, store the block's meta data like offset, length private Map<BlockCacheKey, BucketEntry> backingMap; /** * Flag if the cache is enabled or not... We shut it off if there are IO * errors for some time, so that Bucket IO exceptions/errors don't bring down * the HBase server. */ private volatile boolean cacheEnabled; private ArrayList<BlockingQueue<RAMQueueEntry>> writerQueues = new ArrayList<BlockingQueue<RAMQueueEntry>>(); WriterThread writerThreads[]; /** Volatile boolean to track if free space is in process or not */ private volatile boolean freeInProgress = false; private Lock freeSpaceLock = new ReentrantLock(); private UniqueIndexMap<Integer> deserialiserMap = new UniqueIndexMap<Integer>(); private final AtomicLong realCacheSize = new AtomicLong(0); private final AtomicLong heapSize = new AtomicLong(0); /** Current number of cached elements */ private final AtomicLong blockNumber = new AtomicLong(0); private final AtomicLong failedBlockAdditions = new AtomicLong(0); /** Cache access count (sequential ID) */ private final AtomicLong accessCount = new AtomicLong(0); private final Object[] cacheWaitSignals; private static final int DEFAULT_CACHE_WAIT_TIME = 50; // Used in test now. If the flag is false and the cache speed is very fast, // bucket cache will skip some blocks when caching. If the flag is true, we // will wait blocks flushed to IOEngine for some time when caching boolean wait_when_cache = false; private BucketCacheStats cacheStats = new BucketCacheStats(); private String persistencePath; private long cacheCapacity; /** Approximate block size */ private final long blockSize; /** Duration of IO errors tolerated before we disable cache, 1 min as default */ private final int ioErrorsTolerationDuration; // 1 min public static final int DEFAULT_ERROR_TOLERATION_DURATION = 60 * 1000; // Start time of first IO error when reading or writing IO Engine, it will be // reset after a successful read/write. private volatile long ioErrorStartTime = -1; /** * A "sparse lock" implementation allowing to lock on a particular block * identified by offset. The purpose of this is to avoid freeing the block * which is being read. * * TODO:We could extend the IdLock to IdReadWriteLock for better. */ private IdLock offsetLock = new IdLock(); private final ConcurrentIndex<String, BlockCacheKey> blocksByHFile = new ConcurrentIndex<String, BlockCacheKey>( new Comparator<BlockCacheKey>() { @Override public int compare(BlockCacheKey a, BlockCacheKey b) { if (a.getOffset() == b.getOffset()) { return 0; } else if (a.getOffset() < b.getOffset()) { return -1; } return 1; } }); /** Statistics thread schedule pool (for heavy debugging, could remove) */ private final ScheduledExecutorService scheduleThreadPool = Executors.newScheduledThreadPool(1, new ThreadFactoryBuilder().setNameFormat("BucketCache Statistics #%d").setDaemon(true).build()); // Allocate or free space for the block private BucketAllocator bucketAllocator; public BucketCache(String ioEngineName, long capacity, int blockSize, int writerThreadNum, int writerQLen, String persistencePath) throws FileNotFoundException, IOException { this(ioEngineName, capacity, blockSize, writerThreadNum, writerQLen, persistencePath, DEFAULT_ERROR_TOLERATION_DURATION); } public BucketCache(String ioEngineName, long capacity, int blockSize, int writerThreadNum, int writerQLen, String persistencePath, int ioErrorsTolerationDuration) throws FileNotFoundException, IOException { this.ioEngine = getIOEngineFromName(ioEngineName, capacity); this.writerThreads = new WriterThread[writerThreadNum]; this.cacheWaitSignals = new Object[writerThreadNum]; long blockNumCapacity = capacity / blockSize; if (blockNumCapacity >= Integer.MAX_VALUE) { // Enough for about 32TB of cache! throw new IllegalArgumentException("Cache capacity is too large, only support 32TB now"); } this.cacheCapacity = capacity; this.persistencePath = persistencePath; this.blockSize = blockSize; this.ioErrorsTolerationDuration = ioErrorsTolerationDuration; bucketAllocator = new BucketAllocator(capacity); for (int i = 0; i < writerThreads.length; ++i) { writerQueues.add(new ArrayBlockingQueue<RAMQueueEntry>(writerQLen)); this.cacheWaitSignals[i] = new Object(); } assert writerQueues.size() == writerThreads.length; this.ramCache = new ConcurrentHashMap<BlockCacheKey, RAMQueueEntry>(); this.backingMap = new ConcurrentHashMap<BlockCacheKey, BucketEntry>((int) blockNumCapacity); if (ioEngine.isPersistent() && persistencePath != null) { try { retrieveFromFile(); } catch (IOException ioex) { LOG.error("Can't restore from file because of", ioex); } catch (ClassNotFoundException cnfe) { LOG.error("Can't restore from file in rebuild because can't deserialise", cnfe); throw new RuntimeException(cnfe); } } final String threadName = Thread.currentThread().getName(); this.cacheEnabled = true; for (int i = 0; i < writerThreads.length; ++i) { writerThreads[i] = new WriterThread(writerQueues.get(i), i); writerThreads[i].setName(threadName + "-BucketCacheWriter-" + i); writerThreads[i].start(); } // Run the statistics thread periodically to print the cache statistics log this.scheduleThreadPool.scheduleAtFixedRate(new StatisticsThread(this), statThreadPeriod, statThreadPeriod, TimeUnit.SECONDS); LOG.info("Started bucket cache; ioengine=" + ioEngineName + ", capacity=" + StringUtils.byteDesc(capacity) + ", blockSize=" + StringUtils.byteDesc(blockSize) + ", writerThreadNum=" + writerThreadNum + ", writerQLen=" + writerQLen + ", persistencePath=" + persistencePath); } /** * Get the IOEngine from the IO engine name * @param ioEngineName * @param capacity * @return the IOEngine * @throws IOException */ private IOEngine getIOEngineFromName(String ioEngineName, long capacity) throws IOException { if (ioEngineName.startsWith("file:")) return new FileIOEngine(ioEngineName.substring(5), capacity); else if (ioEngineName.startsWith("offheap")) return new ByteBufferIOEngine(capacity, true); else if (ioEngineName.startsWith("heap")) return new ByteBufferIOEngine(capacity, false); else throw new IllegalArgumentException( "Don't understand io engine name for cache - prefix with file:, heap or offheap"); } /** * Cache the block with the specified name and buffer. * @param cacheKey block's cache key * @param buf block buffer */ @Override public void cacheBlock(BlockCacheKey cacheKey, Cacheable buf) { cacheBlock(cacheKey, buf, false); } /** * Cache the block with the specified name and buffer. * @param cacheKey block's cache key * @param cachedItem block buffer * @param inMemory if block is in-memory */ @Override public void cacheBlock(BlockCacheKey cacheKey, Cacheable cachedItem, boolean inMemory) { cacheBlockWithWait(cacheKey, cachedItem, inMemory, wait_when_cache); } /** * Cache the block to ramCache * @param cacheKey block's cache key * @param cachedItem block buffer * @param inMemory if block is in-memory * @param wait if true, blocking wait when queue is full */ public void cacheBlockWithWait(BlockCacheKey cacheKey, Cacheable cachedItem, boolean inMemory, boolean wait) { if (!cacheEnabled) return; if (backingMap.containsKey(cacheKey) || ramCache.containsKey(cacheKey)) return; /* * Stuff the entry into the RAM cache so it can get drained to the * persistent store */ RAMQueueEntry re = new RAMQueueEntry(cacheKey, cachedItem, accessCount.incrementAndGet(), inMemory); ramCache.put(cacheKey, re); int queueNum = (cacheKey.hashCode() & 0x7FFFFFFF) % writerQueues.size(); BlockingQueue<RAMQueueEntry> bq = writerQueues.get(queueNum); boolean successfulAddition = bq.offer(re); if (!successfulAddition && wait) { synchronized (cacheWaitSignals[queueNum]) { try { cacheWaitSignals[queueNum].wait(DEFAULT_CACHE_WAIT_TIME); } catch (InterruptedException ie) { Thread.currentThread().interrupt(); } } successfulAddition = bq.offer(re); } if (!successfulAddition) { ramCache.remove(cacheKey); failedBlockAdditions.incrementAndGet(); } else { this.blockNumber.incrementAndGet(); this.heapSize.addAndGet(cachedItem.heapSize()); blocksByHFile.put(cacheKey.getHfileName(), cacheKey); } } /** * Get the buffer of the block with the specified key. * @param key block's cache key * @param caching true if the caller caches blocks on cache misses * @param repeat Whether this is a repeat lookup for the same block * @param updateCacheMetrics Whether we should update cache metrics or not * @return buffer of specified cache key, or null if not in cache */ @Override public Cacheable getBlock(BlockCacheKey key, boolean caching, boolean repeat, boolean updateCacheMetrics) { if (!cacheEnabled) return null; RAMQueueEntry re = ramCache.get(key); if (re != null) { if (updateCacheMetrics) cacheStats.hit(caching); re.access(accessCount.incrementAndGet()); return re.getData(); } BucketEntry bucketEntry = backingMap.get(key); if (bucketEntry != null) { long start = System.nanoTime(); IdLock.Entry lockEntry = null; try { lockEntry = offsetLock.getLockEntry(bucketEntry.offset()); if (bucketEntry.equals(backingMap.get(key))) { int len = bucketEntry.getLength(); ByteBuffer bb = ByteBuffer.allocate(len); int lenRead = ioEngine.read(bb, bucketEntry.offset()); if (lenRead != len) { throw new RuntimeException("Only " + lenRead + " bytes read, " + len + " expected"); } Cacheable cachedBlock = bucketEntry.deserializerReference(deserialiserMap).deserialize(bb, true); long timeTaken = System.nanoTime() - start; if (updateCacheMetrics) { cacheStats.hit(caching); cacheStats.ioHit(timeTaken); } bucketEntry.access(accessCount.incrementAndGet()); if (this.ioErrorStartTime > 0) { ioErrorStartTime = -1; } return cachedBlock; } } catch (IOException ioex) { LOG.error("Failed reading block " + key + " from bucket cache", ioex); checkIOErrorIsTolerated(); } finally { if (lockEntry != null) { offsetLock.releaseLockEntry(lockEntry); } } } if (!repeat && updateCacheMetrics) cacheStats.miss(caching); return null; } @Override public boolean evictBlock(BlockCacheKey cacheKey) { if (!cacheEnabled) return false; RAMQueueEntry removedBlock = ramCache.remove(cacheKey); if (removedBlock != null) { this.blockNumber.decrementAndGet(); this.heapSize.addAndGet(-1 * removedBlock.getData().heapSize()); } BucketEntry bucketEntry = backingMap.get(cacheKey); if (bucketEntry != null) { IdLock.Entry lockEntry = null; try { lockEntry = offsetLock.getLockEntry(bucketEntry.offset()); if (bucketEntry.equals(backingMap.remove(cacheKey))) { bucketAllocator.freeBlock(bucketEntry.offset()); realCacheSize.addAndGet(-1 * bucketEntry.getLength()); blocksByHFile.remove(cacheKey.getHfileName(), cacheKey); if (removedBlock == null) { this.blockNumber.decrementAndGet(); } } else { return false; } } catch (IOException ie) { LOG.warn("Failed evicting block " + cacheKey); return false; } finally { if (lockEntry != null) { offsetLock.releaseLockEntry(lockEntry); } } } cacheStats.evicted(); return true; } /* * Statistics thread. Periodically output cache statistics to the log. */ // TODO: Fix. We run a thread to log at DEBUG. If no DEBUG level, we still run the thread! // A thread just to log is OTT. FIX. private static class StatisticsThread extends Thread { BucketCache bucketCache; public StatisticsThread(BucketCache bucketCache) { super("BucketCache.StatisticsThread"); setDaemon(true); this.bucketCache = bucketCache; } @Override public void run() { bucketCache.logStats(); } } public void logStats() { if (!LOG.isDebugEnabled()) return; // Log size long totalSize = bucketAllocator.getTotalSize(); long usedSize = bucketAllocator.getUsedSize(); long freeSize = totalSize - usedSize; long cacheSize = this.realCacheSize.get(); LOG.debug("BucketCache Stats: " + "failedBlockAdditions=" + this.failedBlockAdditions.get() + ", " + "total=" + StringUtils.byteDesc(totalSize) + ", " + "free=" + StringUtils.byteDesc(freeSize) + ", " + "usedSize=" + StringUtils.byteDesc(usedSize) + ", " + "cacheSize=" + StringUtils.byteDesc(cacheSize) + ", " + "accesses=" + cacheStats.getRequestCount() + ", " + "hits=" + cacheStats.getHitCount() + ", " + "IOhitsPerSecond=" + cacheStats.getIOHitsPerSecond() + ", " + "IOTimePerHit=" + String.format("%.2f", cacheStats.getIOTimePerHit()) + ", " + "hitRatio=" + (cacheStats.getHitCount() == 0 ? "0," : (StringUtils.formatPercent(cacheStats.getHitRatio(), 2) + ", ")) + "cachingAccesses=" + cacheStats.getRequestCachingCount() + ", " + "cachingHits=" + cacheStats.getHitCachingCount() + ", " + "cachingHitsRatio=" + (cacheStats.getHitCachingCount() == 0 ? "0," : (StringUtils.formatPercent(cacheStats.getHitCachingRatio(), 2) + ", ")) + "evictions=" + cacheStats.getEvictionCount() + ", " + "evicted=" + cacheStats.getEvictedCount() + ", " + "evictedPerRun=" + cacheStats.evictedPerEviction()); cacheStats.reset(); } private long acceptableSize() { return (long) Math.floor(bucketAllocator.getTotalSize() * DEFAULT_ACCEPT_FACTOR); } private long singleSize() { return (long) Math.floor(bucketAllocator.getTotalSize() * DEFAULT_SINGLE_FACTOR * DEFAULT_MIN_FACTOR); } private long multiSize() { return (long) Math.floor(bucketAllocator.getTotalSize() * DEFAULT_MULTI_FACTOR * DEFAULT_MIN_FACTOR); } private long memorySize() { return (long) Math.floor(bucketAllocator.getTotalSize() * DEFAULT_MEMORY_FACTOR * DEFAULT_MIN_FACTOR); } /** * Free the space if the used size reaches acceptableSize() or one size block * couldn't be allocated. When freeing the space, we use the LRU algorithm and * ensure there must be some blocks evicted */ private void freeSpace() { // Ensure only one freeSpace progress at a time if (!freeSpaceLock.tryLock()) return; try { freeInProgress = true; long bytesToFreeWithoutExtra = 0; /* * Calculate free byte for each bucketSizeinfo */ StringBuffer msgBuffer = new StringBuffer(); BucketAllocator.IndexStatistics[] stats = bucketAllocator.getIndexStatistics(); long[] bytesToFreeForBucket = new long[stats.length]; for (int i = 0; i < stats.length; i++) { bytesToFreeForBucket[i] = 0; long freeGoal = (long) Math.floor(stats[i].totalCount() * (1 - DEFAULT_MIN_FACTOR)); freeGoal = Math.max(freeGoal, 1); if (stats[i].freeCount() < freeGoal) { bytesToFreeForBucket[i] = stats[i].itemSize() * (freeGoal - stats[i].freeCount()); bytesToFreeWithoutExtra += bytesToFreeForBucket[i]; msgBuffer.append("Free for bucketSize(" + stats[i].itemSize() + ")=" + StringUtils.byteDesc(bytesToFreeForBucket[i]) + ", "); } } msgBuffer.append("Free for total=" + StringUtils.byteDesc(bytesToFreeWithoutExtra) + ", "); if (bytesToFreeWithoutExtra <= 0) { return; } long currentSize = bucketAllocator.getUsedSize(); long totalSize = bucketAllocator.getTotalSize(); LOG.debug("Bucket cache free space started; Attempting to " + msgBuffer.toString() + " of current used=" + StringUtils.byteDesc(currentSize) + ",actual cacheSize=" + StringUtils.byteDesc(realCacheSize.get()) + ",total=" + StringUtils.byteDesc(totalSize)); long bytesToFreeWithExtra = (long) Math .floor(bytesToFreeWithoutExtra * (1 + DEFAULT_EXTRA_FREE_FACTOR)); // Instantiate priority buckets BucketEntryGroup bucketSingle = new BucketEntryGroup(bytesToFreeWithExtra, blockSize, singleSize()); BucketEntryGroup bucketMulti = new BucketEntryGroup(bytesToFreeWithExtra, blockSize, multiSize()); BucketEntryGroup bucketMemory = new BucketEntryGroup(bytesToFreeWithExtra, blockSize, memorySize()); // Scan entire map putting bucket entry into appropriate bucket entry // group for (Map.Entry<BlockCacheKey, BucketEntry> bucketEntryWithKey : backingMap.entrySet()) { switch (bucketEntryWithKey.getValue().getPriority()) { case SINGLE: { bucketSingle.add(bucketEntryWithKey); break; } case MULTI: { bucketMulti.add(bucketEntryWithKey); break; } case MEMORY: { bucketMemory.add(bucketEntryWithKey); break; } } } PriorityQueue<BucketEntryGroup> bucketQueue = new PriorityQueue<BucketEntryGroup>(3); bucketQueue.add(bucketSingle); bucketQueue.add(bucketMulti); bucketQueue.add(bucketMemory); int remainingBuckets = 3; long bytesFreed = 0; BucketEntryGroup bucketGroup; while ((bucketGroup = bucketQueue.poll()) != null) { long overflow = bucketGroup.overflow(); if (overflow > 0) { long bucketBytesToFree = Math.min(overflow, (bytesToFreeWithoutExtra - bytesFreed) / remainingBuckets); bytesFreed += bucketGroup.free(bucketBytesToFree); } remainingBuckets--; } /** * Check whether need extra free because some bucketSizeinfo still needs * free space */ stats = bucketAllocator.getIndexStatistics(); boolean needFreeForExtra = false; for (int i = 0; i < stats.length; i++) { long freeGoal = (long) Math.floor(stats[i].totalCount() * (1 - DEFAULT_MIN_FACTOR)); freeGoal = Math.max(freeGoal, 1); if (stats[i].freeCount() < freeGoal) { needFreeForExtra = true; break; } } if (needFreeForExtra) { bucketQueue.clear(); remainingBuckets = 2; bucketQueue.add(bucketSingle); bucketQueue.add(bucketMulti); while ((bucketGroup = bucketQueue.poll()) != null) { long bucketBytesToFree = (bytesToFreeWithExtra - bytesFreed) / remainingBuckets; bytesFreed += bucketGroup.free(bucketBytesToFree); remainingBuckets--; } } if (LOG.isDebugEnabled()) { long single = bucketSingle.totalSize(); long multi = bucketMulti.totalSize(); long memory = bucketMemory.totalSize(); LOG.debug("Bucket cache free space completed; " + "freed=" + StringUtils.byteDesc(bytesFreed) + ", " + "total=" + StringUtils.byteDesc(totalSize) + ", " + "single=" + StringUtils.byteDesc(single) + ", " + "multi=" + StringUtils.byteDesc(multi) + ", " + "memory=" + StringUtils.byteDesc(memory)); } } finally { cacheStats.evict(); freeInProgress = false; freeSpaceLock.unlock(); } } // This handles flushing the RAM cache to IOEngine. private class WriterThread extends HasThread { BlockingQueue<RAMQueueEntry> inputQueue; final int threadNO; boolean writerEnabled = true; WriterThread(BlockingQueue<RAMQueueEntry> queue, int threadNO) { super(); this.inputQueue = queue; this.threadNO = threadNO; setDaemon(true); } // Used for test void disableWriter() { this.writerEnabled = false; } public void run() { List<RAMQueueEntry> entries = new ArrayList<RAMQueueEntry>(); try { while (cacheEnabled && writerEnabled) { try { // Blocks entries.add(inputQueue.take()); inputQueue.drainTo(entries); synchronized (cacheWaitSignals[threadNO]) { cacheWaitSignals[threadNO].notifyAll(); } } catch (InterruptedException ie) { if (!cacheEnabled) break; } doDrain(entries); } } catch (Throwable t) { LOG.warn("Failed doing drain", t); } LOG.info(this.getName() + " exiting, cacheEnabled=" + cacheEnabled); } /** * Flush the entries in ramCache to IOEngine and add bucket entry to * backingMap * @param entries * @throws InterruptedException */ private void doDrain(List<RAMQueueEntry> entries) throws InterruptedException { BucketEntry[] bucketEntries = new BucketEntry[entries.size()]; RAMQueueEntry[] ramEntries = new RAMQueueEntry[entries.size()]; int done = 0; while (entries.size() > 0 && cacheEnabled) { // Keep going in case we throw... RAMQueueEntry ramEntry = null; try { ramEntry = entries.remove(entries.size() - 1); if (ramEntry == null) { LOG.warn("Couldn't get the entry from RAM queue, who steals it?"); continue; } BucketEntry bucketEntry = ramEntry.writeToCache(ioEngine, bucketAllocator, deserialiserMap, realCacheSize); ramEntries[done] = ramEntry; bucketEntries[done++] = bucketEntry; if (ioErrorStartTime > 0) { ioErrorStartTime = -1; } } catch (BucketAllocatorException fle) { LOG.warn("Failed allocating for block " + (ramEntry == null ? "" : ramEntry.getKey()), fle); } catch (CacheFullException cfe) { if (!freeInProgress) { freeSpace(); } else { Thread.sleep(50); } } catch (IOException ioex) { LOG.error("Failed writing to bucket cache", ioex); checkIOErrorIsTolerated(); } } // Make sure that the data pages we have written are on the media before // we update the map. try { ioEngine.sync(); } catch (IOException ioex) { LOG.error("Faild syncing IO engine", ioex); checkIOErrorIsTolerated(); // Since we failed sync, free the blocks in bucket allocator for (int i = 0; i < done; ++i) { if (bucketEntries[i] != null) { bucketAllocator.freeBlock(bucketEntries[i].offset()); } } done = 0; } for (int i = 0; i < done; ++i) { if (bucketEntries[i] != null) { backingMap.put(ramEntries[i].getKey(), bucketEntries[i]); } RAMQueueEntry ramCacheEntry = ramCache.remove(ramEntries[i].getKey()); if (ramCacheEntry != null) { heapSize.addAndGet(-1 * ramEntries[i].getData().heapSize()); } } if (bucketAllocator.getUsedSize() > acceptableSize()) { freeSpace(); } } } private void persistToFile() throws IOException { assert !cacheEnabled; FileOutputStream fos = null; ObjectOutputStream oos = null; try { if (!ioEngine.isPersistent()) throw new IOException("Attempt to persist non-persistent cache mappings!"); fos = new FileOutputStream(persistencePath, false); oos = new ObjectOutputStream(fos); oos.writeLong(cacheCapacity); oos.writeUTF(ioEngine.getClass().getName()); oos.writeUTF(backingMap.getClass().getName()); oos.writeObject(deserialiserMap); oos.writeObject(backingMap); } finally { if (oos != null) oos.close(); if (fos != null) fos.close(); } } @SuppressWarnings("unchecked") private void retrieveFromFile() throws IOException, BucketAllocatorException, ClassNotFoundException { File persistenceFile = new File(persistencePath); if (!persistenceFile.exists()) { return; } assert !cacheEnabled; FileInputStream fis = null; ObjectInputStream ois = null; try { if (!ioEngine.isPersistent()) throw new IOException("Attempt to restore non-persistent cache mappings!"); fis = new FileInputStream(persistencePath); ois = new ObjectInputStream(fis); long capacitySize = ois.readLong(); if (capacitySize != cacheCapacity) throw new IOException("Mismatched cache capacity:" + StringUtils.byteDesc(capacitySize) + ", expected: " + StringUtils.byteDesc(cacheCapacity)); String ioclass = ois.readUTF(); String mapclass = ois.readUTF(); if (!ioEngine.getClass().getName().equals(ioclass)) throw new IOException("Class name for IO engine mismatch: " + ioclass + ", expected:" + ioEngine.getClass().getName()); if (!backingMap.getClass().getName().equals(mapclass)) throw new IOException("Class name for cache map mismatch: " + mapclass + ", expected:" + backingMap.getClass().getName()); UniqueIndexMap<Integer> deserMap = (UniqueIndexMap<Integer>) ois.readObject(); BucketAllocator allocator = new BucketAllocator(cacheCapacity, backingMap, this.realCacheSize); backingMap = (ConcurrentHashMap<BlockCacheKey, BucketEntry>) ois.readObject(); bucketAllocator = allocator; deserialiserMap = deserMap; } finally { if (ois != null) ois.close(); if (fis != null) fis.close(); if (!persistenceFile.delete()) { throw new IOException("Failed deleting persistence file " + persistenceFile.getAbsolutePath()); } } } /** * Check whether we tolerate IO error this time. If the duration of IOEngine * throwing errors exceeds ioErrorsDurationTimeTolerated, we will disable the * cache */ private void checkIOErrorIsTolerated() { long now = EnvironmentEdgeManager.currentTimeMillis(); if (this.ioErrorStartTime > 0) { if (cacheEnabled && (now - ioErrorStartTime) > this.ioErrorsTolerationDuration) { LOG.error("IO errors duration time has exceeded " + ioErrorsTolerationDuration + "ms, disabing cache, please check your IOEngine"); disableCache(); } } else { this.ioErrorStartTime = now; } } /** * Used to shut down the cache -or- turn it off in the case of something * broken. */ private void disableCache() { if (!cacheEnabled) return; cacheEnabled = false; ioEngine.shutdown(); this.scheduleThreadPool.shutdown(); for (int i = 0; i < writerThreads.length; ++i) writerThreads[i].interrupt(); this.ramCache.clear(); if (!ioEngine.isPersistent() || persistencePath == null) { this.backingMap.clear(); } } private void join() throws InterruptedException { for (int i = 0; i < writerThreads.length; ++i) writerThreads[i].join(); } @Override public void shutdown() { disableCache(); LOG.info("Shutdown bucket cache: IO persistent=" + ioEngine.isPersistent() + "; path to write=" + persistencePath); if (ioEngine.isPersistent() && persistencePath != null) { try { join(); persistToFile(); } catch (IOException ex) { LOG.error("Unable to persist data on exit: " + ex.toString(), ex); } catch (InterruptedException e) { LOG.warn("Failed to persist data on exit", e); } } } @Override public CacheStats getStats() { return cacheStats; } BucketAllocator getAllocator() { return this.bucketAllocator; } @Override public long heapSize() { return this.heapSize.get(); } @Override public long size() { return this.realCacheSize.get(); } @Override public long getFreeSize() { return this.bucketAllocator.getFreeSize(); } @Override public long getBlockCount() { return this.blockNumber.get(); } @Override public long getCurrentSize() { return this.bucketAllocator.getUsedSize(); } @Override public long getEvictedCount() { return cacheStats.getEvictedCount(); } /** * Evicts all blocks for a specific HFile. * <p> * This is used for evict-on-close to remove all blocks of a specific HFile. * * @return the number of blocks evicted */ @Override public int evictBlocksByHfileName(String hfileName) { // Copy the list to avoid ConcurrentModificationException // as evictBlockKey removes the key from the index Set<BlockCacheKey> keySet = blocksByHFile.values(hfileName); if (keySet == null) { return 0; } int numEvicted = 0; List<BlockCacheKey> keysForHFile = ImmutableList.copyOf(keySet); for (BlockCacheKey key : keysForHFile) { if (evictBlock(key)) { ++numEvicted; } } return numEvicted; } @Override public List<BlockCacheColumnFamilySummary> getBlockCacheColumnFamilySummaries(Configuration conf) { throw new UnsupportedOperationException(); } static enum BlockPriority { /** * Accessed a single time (used for scan-resistance) */ SINGLE, /** * Accessed multiple times */ MULTI, /** * Block from in-memory store */ MEMORY }; /** * Item in cache. We expect this to be where most memory goes. Java uses 8 * bytes just for object headers; after this, we want to use as little as * possible - so we only use 8 bytes, but in order to do so we end up messing * around with all this Java casting stuff. Offset stored as 5 bytes that make * up the long. Doubt we'll see devices this big for ages. Offsets are divided * by 256. So 5 bytes gives us 256TB or so. */ static class BucketEntry implements Serializable, Comparable<BucketEntry> { private static final long serialVersionUID = -6741504807982257534L; private int offsetBase; private int length; private byte offset1; byte deserialiserIndex; private volatile long accessTime; private BlockPriority priority; BucketEntry(long offset, int length, long accessTime, boolean inMemory) { setOffset(offset); this.length = length; this.accessTime = accessTime; if (inMemory) { this.priority = BlockPriority.MEMORY; } else { this.priority = BlockPriority.SINGLE; } } long offset() { // Java has no unsigned numbers long o = ((long) offsetBase) & 0xFFFFFFFF; o += (((long) (offset1)) & 0xFF) << 32; return o << 8; } private void setOffset(long value) { assert (value & 0xFF) == 0; value >>= 8; offsetBase = (int) value; offset1 = (byte) (value >> 32); } public int getLength() { return length; } protected CacheableDeserializer<Cacheable> deserializerReference(UniqueIndexMap<Integer> deserialiserMap) { return CacheableDeserializerIdManager.getDeserializer(deserialiserMap.unmap(deserialiserIndex)); } protected void setDeserialiserReference(CacheableDeserializer<Cacheable> deserializer, UniqueIndexMap<Integer> deserialiserMap) { this.deserialiserIndex = ((byte) deserialiserMap.map(deserializer.getDeserialiserIdentifier())); } /** * Block has been accessed. Update its local access time. */ public void access(long accessTime) { this.accessTime = accessTime; if (this.priority == BlockPriority.SINGLE) { this.priority = BlockPriority.MULTI; } } public BlockPriority getPriority() { return this.priority; } @Override public int compareTo(BucketEntry that) { if (this.accessTime == that.accessTime) return 0; return this.accessTime < that.accessTime ? 1 : -1; } @Override public boolean equals(Object that) { return this == that; } } /** * Used to group bucket entries into priority buckets. There will be a * BucketEntryGroup for each priority (single, multi, memory). Once bucketed, * the eviction algorithm takes the appropriate number of elements out of each * according to configuration parameters and their relative sizes. */ private class BucketEntryGroup implements Comparable<BucketEntryGroup> { private CachedEntryQueue queue; private long totalSize = 0; private long bucketSize; public BucketEntryGroup(long bytesToFree, long blockSize, long bucketSize) { this.bucketSize = bucketSize; queue = new CachedEntryQueue(bytesToFree, blockSize); totalSize = 0; } public void add(Map.Entry<BlockCacheKey, BucketEntry> block) { totalSize += block.getValue().getLength(); queue.add(block); } public long free(long toFree) { Map.Entry<BlockCacheKey, BucketEntry> entry; long freedBytes = 0; while ((entry = queue.pollLast()) != null) { evictBlock(entry.getKey()); freedBytes += entry.getValue().getLength(); if (freedBytes >= toFree) { return freedBytes; } } return freedBytes; } public long overflow() { return totalSize - bucketSize; } public long totalSize() { return totalSize; } @Override public int compareTo(BucketEntryGroup that) { if (this.overflow() == that.overflow()) return 0; return this.overflow() > that.overflow() ? 1 : -1; } @Override public boolean equals(Object that) { return this == that; } } /** * Block Entry stored in the memory with key,data and so on */ private static class RAMQueueEntry { private BlockCacheKey key; private Cacheable data; private long accessTime; private boolean inMemory; public RAMQueueEntry(BlockCacheKey bck, Cacheable data, long accessTime, boolean inMemory) { this.key = bck; this.data = data; this.accessTime = accessTime; this.inMemory = inMemory; } public Cacheable getData() { return data; } public BlockCacheKey getKey() { return key; } public void access(long accessTime) { this.accessTime = accessTime; } public BucketEntry writeToCache(final IOEngine ioEngine, final BucketAllocator bucketAllocator, final UniqueIndexMap<Integer> deserialiserMap, final AtomicLong realCacheSize) throws CacheFullException, IOException, BucketAllocatorException { int len = data.getSerializedLength(); // This cacheable thing can't be serialized... if (len == 0) return null; long offset = bucketAllocator.allocateBlock(len); BucketEntry bucketEntry = new BucketEntry(offset, len, accessTime, inMemory); bucketEntry.setDeserialiserReference(data.getDeserializer(), deserialiserMap); try { if (data instanceof HFileBlock) { ByteBuffer sliceBuf = ((HFileBlock) data).getBufferReadOnlyWithHeader(); sliceBuf.rewind(); assert len == sliceBuf.limit() + HFileBlock.EXTRA_SERIALIZATION_SPACE; ByteBuffer extraInfoBuffer = ByteBuffer.allocate(HFileBlock.EXTRA_SERIALIZATION_SPACE); ((HFileBlock) data).serializeExtraInfo(extraInfoBuffer); ioEngine.write(sliceBuf, offset); ioEngine.write(extraInfoBuffer, offset + len - HFileBlock.EXTRA_SERIALIZATION_SPACE); } else { ByteBuffer bb = ByteBuffer.allocate(len); data.serialize(bb); ioEngine.write(bb, offset); } } catch (IOException ioe) { // free it in bucket allocator bucketAllocator.freeBlock(offset); throw ioe; } realCacheSize.addAndGet(len); return bucketEntry; } } /** * Only used in test * @throws InterruptedException */ void stopWriterThreads() throws InterruptedException { for (WriterThread writerThread : writerThreads) { writerThread.disableWriter(); writerThread.interrupt(); writerThread.join(); } } }