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/*
* Copyright 2012 The Netty Project
*
* The Netty Project 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:
*
* https://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 io.netty.buffer;
import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;
import io.netty.buffer.PoolArena.SizeClass;
import io.netty.util.Recycler.EnhancedHandle;
import io.netty.util.internal.MathUtil;
import io.netty.util.internal.ObjectPool;
import io.netty.util.internal.ObjectPool.Handle;
import io.netty.util.internal.ObjectPool.ObjectCreator;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* Acts a Thread cache for allocations. This implementation is moduled after
* jemalloc and the descripted
* technics of
*
* Scalable memory allocation using jemalloc.
*/
final class PoolThreadCache {
private static final InternalLogger logger = InternalLoggerFactory.getInstance(PoolThreadCache.class);
private static final int INTEGER_SIZE_MINUS_ONE = Integer.SIZE - 1;
final PoolArena heapArena;
final PoolArena directArena;
// Hold the caches for the different size classes, which are small and normal.
private final MemoryRegionCache[] smallSubPageHeapCaches;
private final MemoryRegionCache[] smallSubPageDirectCaches;
private final MemoryRegionCache[] normalHeapCaches;
private final MemoryRegionCache[] normalDirectCaches;
private final int freeSweepAllocationThreshold;
private final AtomicBoolean freed = new AtomicBoolean();
@SuppressWarnings("unused") // Field is only here for the finalizer.
private final FreeOnFinalize freeOnFinalize;
private int allocations;
// TODO: Test if adding padding helps under contention
//private long pad0, pad1, pad2, pad3, pad4, pad5, pad6, pad7;
PoolThreadCache(PoolArena heapArena, PoolArena directArena,
int smallCacheSize, int normalCacheSize, int maxCachedBufferCapacity,
int freeSweepAllocationThreshold, boolean useFinalizer) {
checkPositiveOrZero(maxCachedBufferCapacity, "maxCachedBufferCapacity");
this.freeSweepAllocationThreshold = freeSweepAllocationThreshold;
this.heapArena = heapArena;
this.directArena = directArena;
if (directArena != null) {
smallSubPageDirectCaches = createSubPageCaches(smallCacheSize, directArena.sizeClass.nSubpages);
normalDirectCaches = createNormalCaches(normalCacheSize, maxCachedBufferCapacity, directArena);
directArena.numThreadCaches.getAndIncrement();
} else {
// No directArea is configured so just null out all caches
smallSubPageDirectCaches = null;
normalDirectCaches = null;
}
if (heapArena != null) {
// Create the caches for the heap allocations
smallSubPageHeapCaches = createSubPageCaches(smallCacheSize, heapArena.sizeClass.nSubpages);
normalHeapCaches = createNormalCaches(normalCacheSize, maxCachedBufferCapacity, heapArena);
heapArena.numThreadCaches.getAndIncrement();
} else {
// No heapArea is configured so just null out all caches
smallSubPageHeapCaches = null;
normalHeapCaches = null;
}
// Only check if there are caches in use.
if ((smallSubPageDirectCaches != null || normalDirectCaches != null
|| smallSubPageHeapCaches != null || normalHeapCaches != null)
&& freeSweepAllocationThreshold < 1) {
throw new IllegalArgumentException("freeSweepAllocationThreshold: "
+ freeSweepAllocationThreshold + " (expected: > 0)");
}
freeOnFinalize = useFinalizer ? new FreeOnFinalize(this) : null;
}
private static MemoryRegionCache[] createSubPageCaches(
int cacheSize, int numCaches) {
if (cacheSize > 0 && numCaches > 0) {
@SuppressWarnings("unchecked")
MemoryRegionCache[] cache = new MemoryRegionCache[numCaches];
for (int i = 0; i < cache.length; i++) {
// TODO: maybe use cacheSize / cache.length
cache[i] = new SubPageMemoryRegionCache(cacheSize);
}
return cache;
} else {
return null;
}
}
@SuppressWarnings("unchecked")
private static MemoryRegionCache[] createNormalCaches(
int cacheSize, int maxCachedBufferCapacity, PoolArena area) {
if (cacheSize > 0 && maxCachedBufferCapacity > 0) {
int max = Math.min(area.sizeClass.chunkSize, maxCachedBufferCapacity);
// Create as many normal caches as we support based on how many sizeIdx we have and what the upper
// bound is that we want to cache in general.
List> cache = new ArrayList>() ;
for (int idx = area.sizeClass.nSubpages; idx < area.sizeClass.nSizes &&
area.sizeClass.sizeIdx2size(idx) <= max; idx++) {
cache.add(new NormalMemoryRegionCache(cacheSize));
}
return cache.toArray(new MemoryRegionCache[0]);
} else {
return null;
}
}
// val > 0
static int log2(int val) {
return INTEGER_SIZE_MINUS_ONE - Integer.numberOfLeadingZeros(val);
}
/**
* Try to allocate a small buffer out of the cache. Returns {@code true} if successful {@code false} otherwise
*/
boolean allocateSmall(PoolArena area, PooledByteBuf buf, int reqCapacity, int sizeIdx) {
return allocate(cacheForSmall(area, sizeIdx), buf, reqCapacity);
}
/**
* Try to allocate a normal buffer out of the cache. Returns {@code true} if successful {@code false} otherwise
*/
boolean allocateNormal(PoolArena area, PooledByteBuf buf, int reqCapacity, int sizeIdx) {
return allocate(cacheForNormal(area, sizeIdx), buf, reqCapacity);
}
@SuppressWarnings({ "unchecked", "rawtypes" })
private boolean allocate(MemoryRegionCache cache, PooledByteBuf buf, int reqCapacity) {
if (cache == null) {
// no cache found so just return false here
return false;
}
boolean allocated = cache.allocate(buf, reqCapacity, this);
if (++ allocations >= freeSweepAllocationThreshold) {
allocations = 0;
trim();
}
return allocated;
}
/**
* Add {@link PoolChunk} and {@code handle} to the cache if there is enough room.
* Returns {@code true} if it fit into the cache {@code false} otherwise.
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
boolean add(PoolArena area, PoolChunk chunk, ByteBuffer nioBuffer,
long handle, int normCapacity, SizeClass sizeClass) {
int sizeIdx = area.sizeClass.size2SizeIdx(normCapacity);
MemoryRegionCache cache = cache(area, sizeIdx, sizeClass);
if (cache == null) {
return false;
}
if (freed.get()) {
return false;
}
return cache.add(chunk, nioBuffer, handle, normCapacity);
}
private MemoryRegionCache cache(PoolArena area, int sizeIdx, SizeClass sizeClass) {
switch (sizeClass) {
case Normal:
return cacheForNormal(area, sizeIdx);
case Small:
return cacheForSmall(area, sizeIdx);
default:
throw new Error();
}
}
/**
* Should be called if the Thread that uses this cache is about to exit to release resources out of the cache
*/
void free(boolean finalizer) {
// As free() may be called either by the finalizer or by FastThreadLocal.onRemoval(...) we need to ensure
// we only call this one time.
if (freed.compareAndSet(false, true)) {
if (freeOnFinalize != null) {
// Help GC: this can race with a finalizer thread, but will be null out regardless
freeOnFinalize.cache = null;
}
int numFreed = free(smallSubPageDirectCaches, finalizer) +
free(normalDirectCaches, finalizer) +
free(smallSubPageHeapCaches, finalizer) +
free(normalHeapCaches, finalizer);
if (numFreed > 0 && logger.isDebugEnabled()) {
logger.debug("Freed {} thread-local buffer(s) from thread: {}", numFreed,
Thread.currentThread().getName());
}
if (directArena != null) {
directArena.numThreadCaches.getAndDecrement();
}
if (heapArena != null) {
heapArena.numThreadCaches.getAndDecrement();
}
}
}
private static int free(MemoryRegionCache[] caches, boolean finalizer) {
if (caches == null) {
return 0;
}
int numFreed = 0;
for (MemoryRegionCache c: caches) {
numFreed += free(c, finalizer);
}
return numFreed;
}
private static int free(MemoryRegionCache cache, boolean finalizer) {
if (cache == null) {
return 0;
}
return cache.free(finalizer);
}
void trim() {
trim(smallSubPageDirectCaches);
trim(normalDirectCaches);
trim(smallSubPageHeapCaches);
trim(normalHeapCaches);
}
private static void trim(MemoryRegionCache[] caches) {
if (caches == null) {
return;
}
for (MemoryRegionCache c: caches) {
trim(c);
}
}
private static void trim(MemoryRegionCache cache) {
if (cache == null) {
return;
}
cache.trim();
}
private MemoryRegionCache cacheForSmall(PoolArena area, int sizeIdx) {
if (area.isDirect()) {
return cache(smallSubPageDirectCaches, sizeIdx);
}
return cache(smallSubPageHeapCaches, sizeIdx);
}
private MemoryRegionCache cacheForNormal(PoolArena area, int sizeIdx) {
// We need to subtract area.sizeClass.nSubpages as sizeIdx is the overall index for all sizes.
int idx = sizeIdx - area.sizeClass.nSubpages;
if (area.isDirect()) {
return cache(normalDirectCaches, idx);
}
return cache(normalHeapCaches, idx);
}
private static MemoryRegionCache cache(MemoryRegionCache[] cache, int sizeIdx) {
if (cache == null || sizeIdx > cache.length - 1) {
return null;
}
return cache[sizeIdx];
}
/**
* Cache used for buffers which are backed by TINY or SMALL size.
*/
private static final class SubPageMemoryRegionCache extends MemoryRegionCache {
SubPageMemoryRegionCache(int size) {
super(size, SizeClass.Small);
}
@Override
protected void initBuf(
PoolChunk chunk, ByteBuffer nioBuffer, long handle, PooledByteBuf buf, int reqCapacity,
PoolThreadCache threadCache) {
chunk.initBufWithSubpage(buf, nioBuffer, handle, reqCapacity, threadCache);
}
}
/**
* Cache used for buffers which are backed by NORMAL size.
*/
private static final class NormalMemoryRegionCache extends MemoryRegionCache {
NormalMemoryRegionCache(int size) {
super(size, SizeClass.Normal);
}
@Override
protected void initBuf(
PoolChunk chunk, ByteBuffer nioBuffer, long handle, PooledByteBuf buf, int reqCapacity,
PoolThreadCache threadCache) {
chunk.initBuf(buf, nioBuffer, handle, reqCapacity, threadCache);
}
}
private abstract static class MemoryRegionCache {
private final int size;
private final Queue> queue;
private final SizeClass sizeClass;
private int allocations;
MemoryRegionCache(int size, SizeClass sizeClass) {
this.size = MathUtil.safeFindNextPositivePowerOfTwo(size);
queue = PlatformDependent.newFixedMpscUnpaddedQueue(this.size);
this.sizeClass = sizeClass;
}
/**
* Init the {@link PooledByteBuf} using the provided chunk and handle with the capacity restrictions.
*/
protected abstract void initBuf(PoolChunk chunk, ByteBuffer nioBuffer, long handle,
PooledByteBuf buf, int reqCapacity, PoolThreadCache threadCache);
/**
* Add to cache if not already full.
*/
@SuppressWarnings("unchecked")
public final boolean add(PoolChunk chunk, ByteBuffer nioBuffer, long handle, int normCapacity) {
Entry entry = newEntry(chunk, nioBuffer, handle, normCapacity);
boolean queued = queue.offer(entry);
if (!queued) {
// If it was not possible to cache the chunk, immediately recycle the entry
entry.unguardedRecycle();
}
return queued;
}
/**
* Allocate something out of the cache if possible and remove the entry from the cache.
*/
public final boolean allocate(PooledByteBuf buf, int reqCapacity, PoolThreadCache threadCache) {
Entry entry = queue.poll();
if (entry == null) {
return false;
}
initBuf(entry.chunk, entry.nioBuffer, entry.handle, buf, reqCapacity, threadCache);
entry.unguardedRecycle();
// allocations is not thread-safe which is fine as this is only called from the same thread all time.
++ allocations;
return true;
}
/**
* Clear out this cache and free up all previous cached {@link PoolChunk}s and {@code handle}s.
*/
public final int free(boolean finalizer) {
return free(Integer.MAX_VALUE, finalizer);
}
private int free(int max, boolean finalizer) {
int numFreed = 0;
for (; numFreed < max; numFreed++) {
Entry entry = queue.poll();
if (entry != null) {
freeEntry(entry, finalizer);
} else {
// all cleared
return numFreed;
}
}
return numFreed;
}
/**
* Free up cached {@link PoolChunk}s if not allocated frequently enough.
*/
public final void trim() {
int free = size - allocations;
allocations = 0;
// We not even allocated all the number that are
if (free > 0) {
free(free, false);
}
}
@SuppressWarnings({ "unchecked", "rawtypes" })
private void freeEntry(Entry entry, boolean finalizer) {
// Capture entry state before we recycle the entry object.
PoolChunk chunk = entry.chunk;
long handle = entry.handle;
ByteBuffer nioBuffer = entry.nioBuffer;
int normCapacity = entry.normCapacity;
if (!finalizer) {
// recycle now so PoolChunk can be GC'ed. This will only be done if this is not freed because of
// a finalizer.
entry.recycle();
}
chunk.arena.freeChunk(chunk, handle, normCapacity, sizeClass, nioBuffer, finalizer);
}
static final class Entry {
final EnhancedHandle> recyclerHandle;
PoolChunk chunk;
ByteBuffer nioBuffer;
long handle = -1;
int normCapacity;
Entry(Handle> recyclerHandle) {
this.recyclerHandle = (EnhancedHandle>) recyclerHandle;
}
void recycle() {
chunk = null;
nioBuffer = null;
handle = -1;
recyclerHandle.recycle(this);
}
void unguardedRecycle() {
chunk = null;
nioBuffer = null;
handle = -1;
recyclerHandle.unguardedRecycle(this);
}
}
@SuppressWarnings("rawtypes")
private static Entry newEntry(PoolChunk chunk, ByteBuffer nioBuffer, long handle, int normCapacity) {
Entry entry = RECYCLER.get();
entry.chunk = chunk;
entry.nioBuffer = nioBuffer;
entry.handle = handle;
entry.normCapacity = normCapacity;
return entry;
}
@SuppressWarnings("rawtypes")
private static final ObjectPool RECYCLER = ObjectPool.newPool(new ObjectCreator() {
@SuppressWarnings("unchecked")
@Override
public Entry newObject(Handle handle) {
return new Entry(handle);
}
});
}
private static final class FreeOnFinalize {
private volatile PoolThreadCache cache;
private FreeOnFinalize(PoolThreadCache cache) {
this.cache = cache;
}
/// TODO: In the future when we move to Java9+ we should use java.lang.ref.Cleaner.
@SuppressWarnings({"FinalizeDeclaration", "deprecation"})
@Override
protected void finalize() throws Throwable {
try {
super.finalize();
} finally {
PoolThreadCache cache = this.cache;
// this can race with a non-finalizer thread calling free: regardless who wins, the cache will be
// null out
this.cache = null;
if (cache != null) {
cache.free(true);
}
}
}
}
}
