/**
*
* 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.slab;
import java.math.BigDecimal;
import java.util.List;
import java.util.Map.Entry;
import java.util.TreeMap;
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 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.util.ClassSize;
import org.apache.hadoop.hbase.util.HasThread;
import org.apache.hadoop.util.StringUtils;
import com.google.common.base.Preconditions;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
/**
* SlabCache is composed of multiple SingleSizeCaches. It uses a TreeMap in
* order to determine where a given element fits. Redirects gets and puts to the
* correct SingleSizeCache.
*
**/
@InterfaceAudience.Private
public class SlabCache implements SlabItemActionWatcher, BlockCache, HeapSize {
private final ConcurrentHashMap<BlockCacheKey, SingleSizeCache> backingStore;
private final TreeMap<Integer, SingleSizeCache> sizer;
static final Log LOG = LogFactory.getLog(SlabCache.class);
static final int STAT_THREAD_PERIOD_SECS = 60 * 5;
private final ScheduledExecutorService scheduleThreadPool = Executors.newScheduledThreadPool(1,
new ThreadFactoryBuilder().setDaemon(true).setNameFormat("Slab Statistics #%d").build());
long size;
private final CacheStats stats;
final SlabStats requestStats;
final SlabStats successfullyCachedStats;
private final long avgBlockSize;
private static final long CACHE_FIXED_OVERHEAD = ClassSize.estimateBase(
SlabCache.class, false);
/**
* Default constructor, creates an empty SlabCache.
*
* @param size Total size allocated to the SlabCache. (Bytes)
* @param avgBlockSize Average size of a block being cached.
**/
public SlabCache(long size, long avgBlockSize) {
this.avgBlockSize = avgBlockSize;
this.size = size;
this.stats = new CacheStats();
this.requestStats = new SlabStats();
this.successfullyCachedStats = new SlabStats();
backingStore = new ConcurrentHashMap<BlockCacheKey, SingleSizeCache>();
sizer = new TreeMap<Integer, SingleSizeCache>();
this.scheduleThreadPool.scheduleAtFixedRate(new StatisticsThread(this),
STAT_THREAD_PERIOD_SECS, STAT_THREAD_PERIOD_SECS, TimeUnit.SECONDS);
}
/**
* A way of allocating the desired amount of Slabs of each particular size.
*
* This reads two lists from conf, hbase.offheap.slab.proportions and
* hbase.offheap.slab.sizes.
*
* The first list is the percentage of our total space we allocate to the
* slabs.
*
* The second list is blocksize of the slabs in bytes. (E.g. the slab holds
* blocks of this size).
*
* @param conf Configuration file.
*/
public void addSlabByConf(Configuration conf) {
// Proportions we allocate to each slab of the total size.
String[] porportions = conf.getStrings(
"hbase.offheapcache.slab.proportions", "0.80", "0.20");
String[] sizes = conf.getStrings("hbase.offheapcache.slab.sizes",
Long.valueOf(avgBlockSize * 11 / 10).toString(),
Long.valueOf(avgBlockSize * 21 / 10).toString());
if (porportions.length != sizes.length) {
throw new IllegalArgumentException(
"SlabCache conf not "
+ "initialized, error in configuration. hbase.offheap.slab.proportions specifies "
+ porportions.length
+ " slabs while hbase.offheap.slab.sizes specifies "
+ sizes.length + " slabs "
+ "offheapslabporportions and offheapslabsizes");
}
/*
* We use BigDecimals instead of floats because float rounding is annoying
*/
BigDecimal[] parsedProportions = stringArrayToBigDecimalArray(porportions);
BigDecimal[] parsedSizes = stringArrayToBigDecimalArray(sizes);
BigDecimal sumProportions = new BigDecimal(0);
for (BigDecimal b : parsedProportions) {
/* Make sure all proportions are greater than 0 */
Preconditions
.checkArgument(b.compareTo(BigDecimal.ZERO) == 1,
"Proportions in hbase.offheap.slab.proportions must be greater than 0!");
sumProportions = sumProportions.add(b);
}
/* If the sum is greater than 1 */
Preconditions
.checkArgument(sumProportions.compareTo(BigDecimal.ONE) != 1,
"Sum of all proportions in hbase.offheap.slab.proportions must be less than 1");
/* If the sum of all proportions is less than 0.99 */
if (sumProportions.compareTo(new BigDecimal("0.99")) == -1) {
LOG.warn("Sum of hbase.offheap.slab.proportions is less than 0.99! Memory is being wasted");
}
for (int i = 0; i < parsedProportions.length; i++) {
int blockSize = parsedSizes[i].intValue();
int numBlocks = new BigDecimal(this.size).multiply(parsedProportions[i])
.divide(parsedSizes[i], BigDecimal.ROUND_DOWN).intValue();
addSlab(blockSize, numBlocks);
}
}
/**
* Gets the size of the slab cache a ByteBuffer of this size would be
* allocated to.
*
* @param size Size of the ByteBuffer we are checking.
*
* @return the Slab that the above bytebuffer would be allocated towards. If
* object is too large, returns null.
*/
Entry<Integer, SingleSizeCache> getHigherBlock(int size) {
return sizer.higherEntry(size - 1);
}
private BigDecimal[] stringArrayToBigDecimalArray(String[] parsee) {
BigDecimal[] parsed = new BigDecimal[parsee.length];
for (int i = 0; i < parsee.length; i++) {
parsed[i] = new BigDecimal(parsee[i].trim());
}
return parsed;
}
private void addSlab(int blockSize, int numBlocks) {
LOG.info("Creating a slab of blockSize " + blockSize + " with " + numBlocks
+ " blocks.");
sizer.put(blockSize, new SingleSizeCache(blockSize, numBlocks, this));
}
/**
* Cache the block with the specified key and buffer. First finds what size
* SingleSlabCache it should fit in. If the block doesn't fit in any, it will
* return without doing anything.
* <p>
* It is assumed this will NEVER be called on an already cached block. If that
* is done, it is assumed that you are reinserting the same exact block due to
* a race condition, and will throw a runtime exception.
*
* @param cacheKey block cache key
* @param cachedItem block buffer
*/
public void cacheBlock(BlockCacheKey cacheKey, Cacheable cachedItem) {
Entry<Integer, SingleSizeCache> scacheEntry = getHigherBlock(cachedItem
.getSerializedLength());
this.requestStats.addin(cachedItem.getSerializedLength());
if (scacheEntry == null) {
return; // we can't cache, something too big.
}
this.successfullyCachedStats.addin(cachedItem.getSerializedLength());
SingleSizeCache scache = scacheEntry.getValue();
/*
* This will throw a runtime exception if we try to cache the same value
* twice
*/
scache.cacheBlock(cacheKey, cachedItem);
}
/**
* We don't care about whether its in memory or not, so we just pass the call
* through.
*/
public void cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean inMemory) {
cacheBlock(cacheKey, buf);
}
public CacheStats getStats() {
return this.stats;
}
/**
* Get the buffer of the block with the specified name.
* @param caching
* @param key
*
* @return buffer of specified block name, or null if not in cache
*/
public Cacheable getBlock(BlockCacheKey key, boolean caching, boolean repeat) {
SingleSizeCache cachedBlock = backingStore.get(key);
if (cachedBlock == null) {
if (!repeat) stats.miss(caching);
return null;
}
Cacheable contentBlock = cachedBlock.getBlock(key, caching, false);
if (contentBlock != null) {
stats.hit(caching);
} else if (!repeat) {
stats.miss(caching);
}
return contentBlock;
}
/**
* Evicts a block from the cache. This is public, and thus contributes to the
* the evict counter.
*/
public boolean evictBlock(BlockCacheKey cacheKey) {
SingleSizeCache cacheEntry = backingStore.get(cacheKey);
if (cacheEntry == null) {
return false;
} else {
cacheEntry.evictBlock(cacheKey);
return true;
}
}
@Override
public void onEviction(BlockCacheKey key, SingleSizeCache notifier) {
stats.evicted();
backingStore.remove(key);
}
@Override
public void onInsertion(BlockCacheKey key, SingleSizeCache notifier) {
backingStore.put(key, notifier);
}
/**
* Sends a shutdown to all SingleSizeCache's contained by this cache.
*
* Also terminates the scheduleThreadPool.
*/
public void shutdown() {
for (SingleSizeCache s : sizer.values()) {
s.shutdown();
}
this.scheduleThreadPool.shutdown();
}
public long heapSize() {
long childCacheSize = 0;
for (SingleSizeCache s : sizer.values()) {
childCacheSize += s.heapSize();
}
return SlabCache.CACHE_FIXED_OVERHEAD + childCacheSize;
}
public long size() {
return this.size;
}
public long getFreeSize() {
return 0; // this cache, by default, allocates all its space.
}
@Override
public long getBlockCount() {
long count = 0;
for (SingleSizeCache cache : backingStore.values()) {
count += cache.getBlockCount();
}
return count;
}
public long getCurrentSize() {
return size;
}
public long getEvictedCount() {
return stats.getEvictedCount();
}
/*
* Statistics thread. Periodically prints the cache statistics to the log.
*/
static class StatisticsThread extends HasThread {
SlabCache ourcache;
public StatisticsThread(SlabCache slabCache) {
super("SlabCache.StatisticsThread");
setDaemon(true);
this.ourcache = slabCache;
}
@Override
public void run() {
for (SingleSizeCache s : ourcache.sizer.values()) {
s.logStats();
}
SlabCache.LOG.info("Current heap size is: "
+ StringUtils.humanReadableInt(ourcache.heapSize()));
LOG.info("Request Stats");
ourcache.requestStats.logStats();
LOG.info("Successfully Cached Stats");
ourcache.successfullyCachedStats.logStats();
}
}
/**
* Just like CacheStats, but more Slab specific. Finely grained profiling of
* sizes we store using logs.
*
*/
static class SlabStats {
// the maximum size somebody will ever try to cache, then we multiply by
// 10
// so we have finer grained stats.
static final int MULTIPLIER = 10;
final int NUMDIVISIONS = (int) (Math.log(Integer.MAX_VALUE) * MULTIPLIER);
private final AtomicLong[] counts = new AtomicLong[NUMDIVISIONS];
public SlabStats() {
for (int i = 0; i < NUMDIVISIONS; i++) {
counts[i] = new AtomicLong();
}
}
public void addin(int size) {
int index = (int) (Math.log(size) * MULTIPLIER);
counts[index].incrementAndGet();
}
public AtomicLong[] getUsage() {
return counts;
}
double getUpperBound(int index) {
return Math.pow(Math.E, ((index + 0.5) / MULTIPLIER));
}
double getLowerBound(int index) {
return Math.pow(Math.E, ((index - 0.5) / MULTIPLIER));
}
public void logStats() {
AtomicLong[] fineGrainedStats = getUsage();
for (int i = 0; i < fineGrainedStats.length; i++) {
if (fineGrainedStats[i].get() > 0) {
SlabCache.LOG.info("From "
+ StringUtils.humanReadableInt((long) getLowerBound(i)) + "- "
+ StringUtils.humanReadableInt((long) getUpperBound(i)) + ": "
+ StringUtils.humanReadableInt(fineGrainedStats[i].get())
+ " requests");
}
}
}
}
public int evictBlocksByHfileName(String hfileName) {
int numEvicted = 0;
for (BlockCacheKey key : backingStore.keySet()) {
if (key.getHfileName().equals(hfileName)) {
if (evictBlock(key))
++numEvicted;
}
}
return numEvicted;
}
/*
* Not implemented. Extremely costly to do this from the off heap cache, you'd
* need to copy every object on heap once
*/
@Override
public List<BlockCacheColumnFamilySummary> getBlockCacheColumnFamilySummaries(
Configuration conf) {
throw new UnsupportedOperationException();
}
}