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/**
* 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.HashSet;
import java.util.Iterator;
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.ConcurrentMap;
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 java.util.concurrent.locks.ReentrantReadWriteLock;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.io.HeapSize;
import org.apache.hadoop.hbase.io.hfile.BlockCache;
import org.apache.hadoop.hbase.io.hfile.BlockCacheKey;
import org.apache.hadoop.hbase.io.hfile.BlockCacheUtil;
import org.apache.hadoop.hbase.io.hfile.BlockPriority;
import org.apache.hadoop.hbase.io.hfile.BlockType;
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.CachedBlock;
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.IdReadWriteLock;
import org.apache.hadoop.util.StringUtils;
import com.google.common.annotations.VisibleForTesting;
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.
*
* Eviction is via a similar algorithm as used in
* {@link org.apache.hadoop.hbase.io.hfile.LruBlockCache}
*
*
BucketCache can be used as mainly a block cache (see
* {@link org.apache.hadoop.hbase.io.hfile.CombinedBlockCache}),
* combined with LruBlockCache to decrease CMS GC and heap fragmentation.
*
*
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 {
private 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;
// Number of blocks to clear for each of the bucket size that is full
private static final int DEFAULT_FREE_ENTIRE_BLOCK_FACTOR = 2;
/** Statistics thread */
private static final int statThreadPeriod = 5 * 60;
final static int DEFAULT_WRITER_THREADS = 3;
final static int DEFAULT_WRITER_QUEUE_ITEMS = 64;
// Store/read block data
final IOEngine ioEngine;
// Store the block in this map before writing it to cache
@VisibleForTesting
final ConcurrentMap ramCache;
// In this map, store the block's meta data like offset, length
@VisibleForTesting
ConcurrentMap 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;
/**
* A list of writer queues. We have a queue per {@link WriterThread} we have running.
* In other words, the work adding blocks to the BucketCache is divided up amongst the
* running WriterThreads. Its done by taking hash of the cache key modulo queue count.
* WriterThread when it runs takes whatever has been recently added and 'drains' the entries
* to the BucketCache. It then updates the ramCache and backingMap accordingly.
*/
@VisibleForTesting
final ArrayList> writerQueues =
new ArrayList>();
@VisibleForTesting
final WriterThread[] writerThreads;
/** Volatile boolean to track if free space is in process or not */
private volatile boolean freeInProgress = false;
private final Lock freeSpaceLock = new ReentrantLock();
private UniqueIndexMap deserialiserMap = new UniqueIndexMap();
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);
/** Cache access count (sequential ID) */
private final AtomicLong accessCount = new AtomicLong(0);
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 final BucketCacheStats cacheStats = new BucketCacheStats();
private final String persistencePath;
private final 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 ReentrantReadWriteLock to lock on a particular block identified by offset.
* The purpose of this is to avoid freeing the block which is being read.
*/
@VisibleForTesting
final IdReadWriteLock offsetLock = new IdReadWriteLock();
private final ConcurrentIndex blocksByHFile =
new ConcurrentIndex(new Comparator() {
@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("BucketCacheStatsExecutor").setDaemon(true).build());
// Allocate or free space for the block
private BucketAllocator bucketAllocator;
public BucketCache(String ioEngineName, long capacity, int blockSize, int[] bucketSizes,
int writerThreadNum, int writerQLen, String persistencePath) throws FileNotFoundException,
IOException {
this(ioEngineName, capacity, blockSize, bucketSizes, writerThreadNum, writerQLen,
persistencePath, DEFAULT_ERROR_TOLERATION_DURATION);
}
public BucketCache(String ioEngineName, long capacity, int blockSize, int[] bucketSizes,
int writerThreadNum, int writerQLen, String persistencePath, int ioErrorsTolerationDuration)
throws FileNotFoundException, IOException {
this.ioEngine = getIOEngineFromName(ioEngineName, capacity);
this.writerThreads = new WriterThread[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, bucketSizes);
for (int i = 0; i < writerThreads.length; ++i) {
writerQueues.add(new ArrayBlockingQueue(writerQLen));
}
assert writerQueues.size() == writerThreads.length;
this.ramCache = new ConcurrentHashMap();
this.backingMap = new ConcurrentHashMap((int) blockNumCapacity);
if (ioEngine.isPersistent() && persistencePath != null) {
try {
retrieveFromFile(bucketSizes);
} 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));
writerThreads[i].setName(threadName + "-BucketCacheWriter-" + i);
writerThreads[i].setDaemon(true);
}
startWriterThreads();
// Run the statistics thread periodically to print the cache statistics log
// TODO: Add means of turning this off. Bit obnoxious running thread just to make a log
// every five minutes.
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 + ", bucketAllocator=" + this.bucketAllocator.getClass().getName());
}
/**
* Called by the constructor to start the writer threads. Used by tests that need to override
* starting the threads.
*/
@VisibleForTesting
protected void startWriterThreads() {
for (WriterThread thread : writerThreads) {
thread.start();
}
}
@VisibleForTesting
boolean isCacheEnabled() {
return this.cacheEnabled;
}
public long getMaxSize() {
return this.cacheCapacity;
}
public String getIoEngine() {
return ioEngine.toString();
}
/**
* 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, 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
* @param cacheDataInL1
*/
@Override
public void cacheBlock(BlockCacheKey cacheKey, Cacheable cachedItem, boolean inMemory,
final boolean cacheDataInL1) {
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)) {
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);
if (ramCache.putIfAbsent(cacheKey, re) != null) {
return;
}
int queueNum = (cacheKey.hashCode() & 0x7FFFFFFF) % writerQueues.size();
BlockingQueue bq = writerQueues.get(queueNum);
boolean successfulAddition = false;
if (wait) {
try {
successfulAddition = bq.offer(re, DEFAULT_CACHE_WAIT_TIME, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
} else {
successfulAddition = bq.offer(re);
}
if (!successfulAddition) {
ramCache.remove(cacheKey);
cacheStats.failInsert();
} 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, key.isPrimary());
}
re.access(accessCount.incrementAndGet());
return re.getData();
}
BucketEntry bucketEntry = backingMap.get(key);
if (bucketEntry != null) {
long start = System.nanoTime();
ReentrantReadWriteLock lock = offsetLock.getLock(bucketEntry.offset());
try {
lock.readLock().lock();
// We can not read here even if backingMap does contain the given key because its offset
// maybe changed. If we lock BlockCacheKey instead of offset, then we can only check
// existence here.
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");
}
CacheableDeserializer deserializer =
bucketEntry.deserializerReference(this.deserialiserMap);
Cacheable cachedBlock = deserializer.deserialize(bb, true);
long timeTaken = System.nanoTime() - start;
if (updateCacheMetrics) {
cacheStats.hit(caching, key.isPrimary());
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 {
lock.readLock().unlock();
}
}
if (!repeat && updateCacheMetrics) {
cacheStats.miss(caching, key.isPrimary());
}
return null;
}
@VisibleForTesting
void blockEvicted(BlockCacheKey cacheKey, BucketEntry bucketEntry, boolean decrementBlockNumber) {
bucketAllocator.freeBlock(bucketEntry.offset());
realCacheSize.addAndGet(-1 * bucketEntry.getLength());
blocksByHFile.remove(cacheKey.getHfileName(), cacheKey);
if (decrementBlockNumber) {
this.blockNumber.decrementAndGet();
}
}
@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) {
if (removedBlock != null) {
cacheStats.evicted(0, cacheKey.isPrimary());
return true;
} else {
return false;
}
}
ReentrantReadWriteLock lock = offsetLock.getLock(bucketEntry.offset());
try {
lock.writeLock().lock();
if (backingMap.remove(cacheKey, bucketEntry)) {
blockEvicted(cacheKey, bucketEntry, removedBlock == null);
} else {
return false;
}
} finally {
lock.writeLock().unlock();
}
cacheStats.evicted(bucketEntry.getCachedTime(), cacheKey.isPrimary());
return true;
}
/*
* Statistics thread. Periodically output cache statistics to the log.
*/
private static class StatisticsThread extends Thread {
private final BucketCache bucketCache;
public StatisticsThread(BucketCache bucketCache) {
super("BucketCacheStatsThread");
setDaemon(true);
this.bucketCache = bucketCache;
}
@Override
public void run() {
bucketCache.logStats();
}
}
public void logStats() {
long totalSize = bucketAllocator.getTotalSize();
long usedSize = bucketAllocator.getUsedSize();
long freeSize = totalSize - usedSize;
long cacheSize = getRealCacheSize();
LOG.info("failedBlockAdditions=" + cacheStats.getFailedInserts() + ", " +
"totalSize=" + StringUtils.byteDesc(totalSize) + ", " +
"freeSize=" + 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();
}
public long getRealCacheSize() {
return this.realCacheSize.get();
}
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);
}
/**
* Return the count of bucketSizeinfos still needf ree space
*/
private int bucketSizesAboveThresholdCount(float minFactor) {
BucketAllocator.IndexStatistics[] stats = bucketAllocator.getIndexStatistics();
int fullCount = 0;
for (int i = 0; i < stats.length; i++) {
long freeGoal = (long) Math.floor(stats[i].totalCount() * (1 - minFactor));
freeGoal = Math.max(freeGoal, 1);
if (stats[i].freeCount() < freeGoal) {
fullCount++;
}
}
return fullCount;
}
/**
* This method will find the buckets that are minimally occupied
* and are not reference counted and will free them completely
* without any constraint on the access times of the elements,
* and as a process will completely free at most the number of buckets
* passed, sometimes it might not due to changing refCounts
*
* @param completelyFreeBucketsNeeded number of buckets to free
**/
private void freeEntireBuckets(int completelyFreeBucketsNeeded) {
if (completelyFreeBucketsNeeded != 0) {
// First we will build a set where the offsets are reference counted, usually
// this set is small around O(Handler Count) unless something else is wrong
Set inUseBuckets = new HashSet();
for (BucketEntry entry : backingMap.values()) {
inUseBuckets.add(bucketAllocator.getBucketIndex(entry.offset()));
}
Set candidateBuckets = bucketAllocator.getLeastFilledBuckets(
inUseBuckets, completelyFreeBucketsNeeded);
for (Map.Entry entry : backingMap.entrySet()) {
if (candidateBuckets.contains(bucketAllocator
.getBucketIndex(entry.getValue().offset()))) {
evictBlock(entry.getKey());
}
}
}
}
/**
* 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
* @param why Why we are being called
*/
private void freeSpace(final String why) {
// 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 = LOG.isDebugEnabled()? new StringBuffer(): null;
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];
if (msgBuffer != null) {
msgBuffer.append("Free for bucketSize(" + stats[i].itemSize() + ")="
+ StringUtils.byteDesc(bytesToFreeForBucket[i]) + ", ");
}
}
}
if (msgBuffer != null) {
msgBuffer.append("Free for total=" + StringUtils.byteDesc(bytesToFreeWithoutExtra) + ", ");
}
if (bytesToFreeWithoutExtra <= 0) {
return;
}
long currentSize = bucketAllocator.getUsedSize();
long totalSize=bucketAllocator.getTotalSize();
if (LOG.isDebugEnabled() && msgBuffer != null) {
LOG.debug("Free started because \"" + why + "\"; " + 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 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 bucketQueue = new PriorityQueue(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 and free if there are buckets that still need freeing of space
if (bucketSizesAboveThresholdCount(DEFAULT_MIN_FACTOR) > 0) {
bucketQueue.clear();
remainingBuckets = 3;
bucketQueue.add(bucketSingle);
bucketQueue.add(bucketMulti);
bucketQueue.add(bucketMemory);
while ((bucketGroup = bucketQueue.poll()) != null) {
long bucketBytesToFree = (bytesToFreeWithExtra - bytesFreed) / remainingBuckets;
bytesFreed += bucketGroup.free(bucketBytesToFree);
remainingBuckets--;
}
}
// Even after the above free we might still need freeing because of the
// De-fragmentation of the buckets (also called Slab Calcification problem), i.e
// there might be some buckets where the occupancy is very sparse and thus are not
// yielding the free for the other bucket sizes, the fix for this to evict some
// of the buckets, we do this by evicting the buckets that are least fulled
freeEntireBuckets(DEFAULT_FREE_ENTIRE_BLOCK_FACTOR *
bucketSizesAboveThresholdCount(1.0f));
if (LOG.isDebugEnabled()) {
long single = bucketSingle.totalSize();
long multi = bucketMulti.totalSize();
long memory = bucketMemory.totalSize();
if (LOG.isDebugEnabled()) {
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));
}
}
} catch (Throwable t) {
LOG.warn("Failed freeing space", t);
} finally {
cacheStats.evict();
freeInProgress = false;
freeSpaceLock.unlock();
}
}
// This handles flushing the RAM cache to IOEngine.
@VisibleForTesting
class WriterThread extends HasThread {
private final BlockingQueue inputQueue;
private volatile boolean writerEnabled = true;
WriterThread(BlockingQueue queue) {
super("BucketCacheWriterThread");
this.inputQueue = queue;
}
// Used for test
@VisibleForTesting
void disableWriter() {
this.writerEnabled = false;
}
public void run() {
List entries = new ArrayList();
try {
while (cacheEnabled && writerEnabled) {
try {
try {
// Blocks
entries = getRAMQueueEntries(inputQueue, entries);
} catch (InterruptedException ie) {
if (!cacheEnabled) break;
}
doDrain(entries);
} catch (Exception ioe) {
LOG.error("WriterThread encountered error", ioe);
}
}
} 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.
* Process all that are passed in even if failure being sure to remove from ramCache else we'll
* never undo the references and we'll OOME.
* @param entries Presumes list passed in here will be processed by this invocation only. No
* interference expected.
* @throws InterruptedException
*/
@VisibleForTesting
void doDrain(final List entries) throws InterruptedException {
if (entries.isEmpty()) {
return;
}
// This method is a little hard to follow. We run through the passed in entries and for each
// successful add, we add a non-null BucketEntry to the below bucketEntries. Later we must
// do cleanup making sure we've cleared ramCache of all entries regardless of whether we
// successfully added the item to the bucketcache; if we don't do the cleanup, we'll OOME by
// filling ramCache. We do the clean up by again running through the passed in entries
// doing extra work when we find a non-null bucketEntries corresponding entry.
final int size = entries.size();
BucketEntry[] bucketEntries = new BucketEntry[size];
// Index updated inside loop if success or if we can't succeed. We retry if cache is full
// when we go to add an entry by going around the loop again without upping the index.
int index = 0;
while (cacheEnabled && index < size) {
RAMQueueEntry re = null;
try {
re = entries.get(index);
if (re == null) {
LOG.warn("Couldn't get entry or changed on us; who else is messing with it?");
index++;
continue;
}
BucketEntry bucketEntry =
re.writeToCache(ioEngine, bucketAllocator, deserialiserMap, realCacheSize);
// Successfully added. Up index and add bucketEntry. Clear io exceptions.
bucketEntries[index] = bucketEntry;
if (ioErrorStartTime > 0) {
ioErrorStartTime = -1;
}
index++;
} catch (BucketAllocatorException fle) {
LOG.warn("Failed allocation for " + (re == null ? "" : re.getKey()) + "; " + fle);
// Presume can't add. Too big? Move index on. Entry will be cleared from ramCache below.
bucketEntries[index] = null;
index++;
} catch (CacheFullException cfe) {
// Cache full when we tried to add. Try freeing space and then retrying (don't up index)
if (!freeInProgress) {
freeSpace("Full!");
} else {
Thread.sleep(50);
}
} catch (IOException ioex) {
// Hopefully transient. Retry. checkIOErrorIsTolerated disables cache if problem.
LOG.error("Failed writing to bucket cache", ioex);
checkIOErrorIsTolerated();
}
}
// Make sure data pages are written are on media before we update maps.
try {
ioEngine.sync();
} catch (IOException ioex) {
LOG.error("Failed syncing IO engine", ioex);
checkIOErrorIsTolerated();
// Since we failed sync, free the blocks in bucket allocator
for (int i = 0; i < entries.size(); ++i) {
if (bucketEntries[i] != null) {
bucketAllocator.freeBlock(bucketEntries[i].offset());
bucketEntries[i] = null;
}
}
}
// Now add to backingMap if successfully added to bucket cache. Remove from ramCache if
// success or error.
for (int i = 0; i < size; ++i) {
BlockCacheKey key = entries.get(i).getKey();
// Only add if non-null entry.
if (bucketEntries[i] != null) {
backingMap.put(key, bucketEntries[i]);
}
// Always remove from ramCache even if we failed adding it to the block cache above.
RAMQueueEntry ramCacheEntry = ramCache.remove(key);
if (ramCacheEntry != null) {
heapSize.addAndGet(-1 * entries.get(i).getData().heapSize());
} else if (bucketEntries[i] != null){
// Block should have already been evicted. Remove it and free space.
ReentrantReadWriteLock lock = offsetLock.getLock(bucketEntries[i].offset());
try {
lock.writeLock().lock();
if (backingMap.remove(key, bucketEntries[i])) {
blockEvicted(key, bucketEntries[i], false);
}
} finally {
lock.writeLock().unlock();
}
}
}
long used = bucketAllocator.getUsedSize();
if (used > acceptableSize()) {
freeSpace("Used=" + used + " > acceptable=" + acceptableSize());
}
return;
}
}
/**
* Blocks until elements available in q then tries to grab as many as possible
* before returning.
* @param recepticle Where to stash the elements taken from queue. We clear before we use it
* just in case.
* @param q The queue to take from.
* @return receptical laden with elements taken from the queue or empty if none found.
*/
@VisibleForTesting
static List getRAMQueueEntries(final BlockingQueue q,
final List receptical)
throws InterruptedException {
// Clear sets all entries to null and sets size to 0. We retain allocations. Presume it
// ok even if list grew to accommodate thousands.
receptical.clear();
receptical.add(q.take());
q.drainTo(receptical);
return receptical;
}
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(int[] bucketSizes) 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 deserMap = (UniqueIndexMap) ois
.readObject();
ConcurrentHashMap backingMapFromFile =
(ConcurrentHashMap) ois.readObject();
BucketAllocator allocator = new BucketAllocator(cacheCapacity, bucketSizes,
backingMapFromFile, realCacheSize);
bucketAllocator = allocator;
deserialiserMap = deserMap;
backingMap = backingMapFromFile;
} 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.currentTime();
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;
}
public 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();
}
/**
* Evicts all blocks for a specific HFile.
*
* 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 keySet = blocksByHFile.values(hfileName);
if (keySet == null) {
return 0;
}
int numEvicted = 0;
List keysForHFile = ImmutableList.copyOf(keySet);
for (BlockCacheKey key : keysForHFile) {
if (evictBlock(key)) {
++numEvicted;
}
}
return numEvicted;
}
/**
* 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 {
private static final long serialVersionUID = -6741504807982257534L;
// access counter comparator, descending order
static final Comparator COMPARATOR = new Comparator() {
@Override
public int compare(BucketEntry o1, BucketEntry o2) {
return Long.compare(o2.accessCounter, o1.accessCounter);
}
};
private int offsetBase;
private int length;
private byte offset1;
byte deserialiserIndex;
private volatile long accessCounter;
private BlockPriority priority;
/**
* Time this block was cached. Presumes we are created just before we are added to the cache.
*/
private final long cachedTime = System.nanoTime();
BucketEntry(long offset, int length, long accessCounter, boolean inMemory) {
setOffset(offset);
this.length = length;
this.accessCounter = accessCounter;
if (inMemory) {
this.priority = BlockPriority.MEMORY;
} else {
this.priority = BlockPriority.SINGLE;
}
}
long offset() { // Java has no unsigned numbers
long o = ((long) offsetBase) & 0xFFFFFFFFL; //This needs the L cast otherwise it will be sign extended as a negative number.
o += (((long) (offset1)) & 0xFF) << 32; //The 0xFF here does not need the L cast because it is treated as a positive int.
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 deserializerReference(
UniqueIndexMap deserialiserMap) {
return CacheableDeserializerIdManager.getDeserializer(deserialiserMap
.unmap(deserialiserIndex));
}
protected void setDeserialiserReference(
CacheableDeserializer deserializer,
UniqueIndexMap deserialiserMap) {
this.deserialiserIndex = ((byte) deserialiserMap.map(deserializer
.getDeserialiserIdentifier()));
}
/**
* Block has been accessed. Update its local access counter.
*/
public void access(long accessCounter) {
this.accessCounter = accessCounter;
if (this.priority == BlockPriority.SINGLE) {
this.priority = BlockPriority.MULTI;
}
}
public BlockPriority getPriority() {
return this.priority;
}
public long getCachedTime() {
return cachedTime;
}
}
/**
* 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 {
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 block) {
totalSize += block.getValue().getLength();
queue.add(block);
}
public long free(long toFree) {
Map.Entry 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) {
return Long.compare(this.overflow(), that.overflow());
}
@Override
public boolean equals(Object that) {
return this == that;
}
}
/**
* Block Entry stored in the memory with key,data and so on
*/
@VisibleForTesting
static class RAMQueueEntry {
private BlockCacheKey key;
private Cacheable data;
private long accessCounter;
private boolean inMemory;
public RAMQueueEntry(BlockCacheKey bck, Cacheable data, long accessCounter,
boolean inMemory) {
this.key = bck;
this.data = data;
this.accessCounter = accessCounter;
this.inMemory = inMemory;
}
public Cacheable getData() {
return data;
}
public BlockCacheKey getKey() {
return key;
}
public void access(long accessCounter) {
this.accessCounter = accessCounter;
}
public BucketEntry writeToCache(final IOEngine ioEngine,
final BucketAllocator bucketAllocator,
final UniqueIndexMap 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, accessCounter, inMemory);
bucketEntry.setDeserialiserReference(data.getDeserializer(), deserialiserMap);
try {
if (data instanceof HFileBlock) {
HFileBlock block = (HFileBlock) data;
ByteBuffer sliceBuf = block.getBufferReadOnlyWithHeader();
sliceBuf.rewind();
assert len == sliceBuf.limit() + HFileBlock.EXTRA_SERIALIZATION_SPACE ||
len == sliceBuf.limit() + block.headerSize() + HFileBlock.EXTRA_SERIALIZATION_SPACE;
ByteBuffer extraInfoBuffer = ByteBuffer.allocate(HFileBlock.EXTRA_SERIALIZATION_SPACE);
block.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();
}
}
@Override
public Iterator iterator() {
// Don't bother with ramcache since stuff is in here only a little while.
final Iterator> i =
this.backingMap.entrySet().iterator();
return new Iterator() {
private final long now = System.nanoTime();
@Override
public boolean hasNext() {
return i.hasNext();
}
@Override
public CachedBlock next() {
final Map.Entry e = i.next();
return new CachedBlock() {
@Override
public String toString() {
return BlockCacheUtil.toString(this, now);
}
@Override
public BlockPriority getBlockPriority() {
return e.getValue().getPriority();
}
@Override
public BlockType getBlockType() {
// Not held by BucketEntry. Could add it if wanted on BucketEntry creation.
return null;
}
@Override
public long getOffset() {
return e.getKey().getOffset();
}
@Override
public long getSize() {
return e.getValue().getLength();
}
@Override
public long getCachedTime() {
return e.getValue().getCachedTime();
}
@Override
public String getFilename() {
return e.getKey().getHfileName();
}
@Override
public int compareTo(CachedBlock other) {
int diff = this.getFilename().compareTo(other.getFilename());
if (diff != 0) return diff;
diff = Long.compare(this.getOffset(), other.getOffset());
if (diff != 0) return diff;
if (other.getCachedTime() < 0 || this.getCachedTime() < 0) {
throw new IllegalStateException("" + this.getCachedTime() + ", " +
other.getCachedTime());
}
return Long.compare(other.getCachedTime(), this.getCachedTime());
}
@Override
public int hashCode() {
return e.getKey().hashCode();
}
@Override
public boolean equals(Object obj) {
if (obj instanceof CachedBlock) {
CachedBlock cb = (CachedBlock)obj;
return compareTo(cb) == 0;
} else {
return false;
}
}
};
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
};
}
@Override
public BlockCache[] getBlockCaches() {
return null;
}
}