/**
* 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.regionserver.StoreFile;
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 block, and use
* {@link BucketCache#ramCache} and {@link BucketCache#backingMap} in order to
* determine whether a given element hit. It could uses memory
* {@link ByteBufferIOEngine} or file {@link FileIOEngine}to store/read the
* block data.
*
* Eviction is using similar algorithm as
* {@link org.apache.hadoop.hbase.io.hfile.LruBlockCache}
*
* BucketCache could be used as mainly a block cache(see
* {@link CombinedBlockCache}), combined with LruBlockCache to decrease CMS and
* fragment by GC.
*
* Also could be used as a secondary cache(e.g. using Fusionio to store block)
* to enlarge cache space by
* {@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 ConcurrentHashMap<BlockCacheKey, RAMQueueEntry> ramCache;
// In this map, store the block's meta data like offset, length
private ConcurrentHashMap<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");
}
/**
* 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
* @return buffer of specified cache key, or null if not in cache
*/
@Override
public Cacheable getBlock(BlockCacheKey key, boolean caching, boolean repeat) {
if (!cacheEnabled)
return null;
RAMQueueEntry re = ramCache.get(key);
if (re != null) {
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);
ioEngine.read(bb, bucketEntry.offset());
Cacheable cachedBlock = bucketEntry.deserializerReference(
deserialiserMap).deserialize(bb, true);
long timeTaken = System.nanoTime() - start;
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)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 prints the cache statistics to the log.
*/
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 minSize() {
return (long) Math.floor(bucketAllocator.getTotalSize() * DEFAULT_MIN_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();
}
}
}