376 lines
12 KiB
Java
376 lines
12 KiB
Java
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package io.netty.buffer.api.pool;
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import static io.netty.buffer.api.pool.PoolArena.SizeClass.*;
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import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;
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import io.netty.buffer.api.Buffer;
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import io.netty.buffer.api.pool.PoolArena.SizeClass;
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import io.netty.util.internal.MathUtil;
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import io.netty.util.internal.ObjectPool;
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import io.netty.util.internal.ObjectPool.Handle;
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import io.netty.util.internal.PlatformDependent;
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import io.netty.util.internal.logging.InternalLogger;
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import io.netty.util.internal.logging.InternalLoggerFactory;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Queue;
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/**
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* Acts a Thread cache for allocations. This implementation is modelled after
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* <a href="https://people.freebsd.org/~jasone/jemalloc/bsdcan2006/jemalloc.pdf">jemalloc</a> and the described
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* techniques of
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* <a href="https://www.facebook.com/notes/facebook-engineering/scalable-memory-allocation-using-jemalloc/480222803919">
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* Scalable memory allocation using jemalloc</a>.
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*/
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final class PoolThreadCache {
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private static final InternalLogger logger = InternalLoggerFactory.getInstance(PoolThreadCache.class);
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private static final int INTEGER_SIZE_MINUS_ONE = Integer.SIZE - 1;
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final PoolArena arena;
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// Hold the caches for the different size classes, which are tiny, small and normal.
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private final MemoryRegionCache[] smallSubPageCaches;
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private final MemoryRegionCache[] normalCaches;
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private final int freeSweepAllocationThreshold;
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private int allocations;
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PoolThreadCache(PoolArena arena,
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int smallCacheSize, int normalCacheSize, int maxCachedBufferCapacity,
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int freeSweepAllocationThreshold) {
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checkPositiveOrZero(maxCachedBufferCapacity, "maxCachedBufferCapacity");
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this.freeSweepAllocationThreshold = freeSweepAllocationThreshold;
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this.arena = arena;
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if (arena != null) {
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// Create the caches for the heap allocations
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smallSubPageCaches = createSubPageCaches(
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smallCacheSize, arena.numSmallSubpagePools);
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normalCaches = createNormalCaches(
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normalCacheSize, maxCachedBufferCapacity, arena);
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arena.numThreadCaches.getAndIncrement();
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} else {
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// No heapArea is configured so just null out all caches
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smallSubPageCaches = null;
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normalCaches = null;
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}
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// Only check if there are caches in use.
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if ((smallSubPageCaches != null || normalCaches != null)
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&& freeSweepAllocationThreshold < 1) {
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throw new IllegalArgumentException("freeSweepAllocationThreshold: "
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+ freeSweepAllocationThreshold + " (expected: > 0)");
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}
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}
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private static MemoryRegionCache[] createSubPageCaches(
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int cacheSize, int numCaches) {
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if (cacheSize > 0 && numCaches > 0) {
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MemoryRegionCache[] cache = new MemoryRegionCache[numCaches];
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for (int i = 0; i < cache.length; i++) {
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// TODO: maybe use cacheSize / cache.length
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cache[i] = new SubPageMemoryRegionCache(cacheSize);
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}
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return cache;
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} else {
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return null;
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}
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}
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private static MemoryRegionCache[] createNormalCaches(
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int cacheSize, int maxCachedBufferCapacity, PoolArena area) {
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if (cacheSize > 0 && maxCachedBufferCapacity > 0) {
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int max = Math.min(area.chunkSize, maxCachedBufferCapacity);
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// Create as many normal caches as we support based on how many sizeIdx we have and what the upper
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// bound is that we want to cache in general.
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List<MemoryRegionCache> cache = new ArrayList<>() ;
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for (int idx = area.numSmallSubpagePools; idx < area.nSizes && area.sizeIdx2size(idx) <= max ; idx++) {
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cache.add(new NormalMemoryRegionCache(cacheSize));
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}
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return cache.toArray(MemoryRegionCache[]::new);
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} else {
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return null;
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}
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}
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// val > 0
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static int log2(int val) {
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return INTEGER_SIZE_MINUS_ONE - Integer.numberOfLeadingZeros(val);
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}
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/**
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* Try to allocate a small buffer out of the cache. Returns {@code true} if successful {@code false} otherwise
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*/
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Buffer allocateSmall(int size, int sizeIdx) {
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return allocate(cacheForSmall(sizeIdx), size);
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}
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/**
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* Try to allocate a normal buffer out of the cache. Returns {@code true} if successful {@code false} otherwise
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*/
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Buffer allocateNormal(PoolArena area, int size, int sizeIdx) {
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return allocate(cacheForNormal(area, sizeIdx), size);
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}
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private Buffer allocate(MemoryRegionCache cache, int size) {
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if (cache == null) {
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// no cache found so just return false here
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return null;
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}
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Buffer allocated = cache.allocate(size, this);
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if (++ allocations >= freeSweepAllocationThreshold) {
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allocations = 0;
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trim();
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}
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return allocated;
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}
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/**
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* Add {@link PoolChunk} and {@code handle} to the cache if there is enough room.
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* Returns {@code true} if it fit into the cache {@code false} otherwise.
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*/
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boolean add(PoolArena area, PoolChunk chunk,
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long handle, int normCapacity, SizeClass sizeClass) {
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int sizeIdx = area.size2SizeIdx(normCapacity);
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MemoryRegionCache cache = cache(area, sizeIdx, sizeClass);
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if (cache == null) {
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return false;
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}
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return cache.add(chunk, handle, normCapacity);
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}
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private MemoryRegionCache cache(PoolArena area, int sizeIdx, SizeClass sizeClass) {
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switch (sizeClass) {
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case Normal:
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return cacheForNormal(area, sizeIdx);
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case Small:
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return cacheForSmall(sizeIdx);
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default:
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throw new Error();
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}
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}
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/**
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* Should be called if the Thread that uses this cache is about to exist to release resources out of the cache
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*/
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void free() {
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int numFreed = free(smallSubPageCaches) + free(normalCaches);
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if (numFreed > 0 && logger.isDebugEnabled()) {
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logger.debug("Freed {} thread-local buffer(s) from thread: {}", numFreed,
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Thread.currentThread().getName());
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}
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if (arena != null) {
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arena.numThreadCaches.getAndDecrement();
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}
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}
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private static int free(MemoryRegionCache[] caches) {
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if (caches == null) {
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return 0;
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}
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int numFreed = 0;
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for (MemoryRegionCache c: caches) {
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numFreed += free(c);
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}
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return numFreed;
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}
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private static int free(MemoryRegionCache cache) {
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if (cache == null) {
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return 0;
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}
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return cache.free();
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}
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void trim() {
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trim(smallSubPageCaches);
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trim(normalCaches);
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}
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private static void trim(MemoryRegionCache[] caches) {
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if (caches == null) {
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return;
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}
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for (MemoryRegionCache c: caches) {
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trim(c);
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}
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}
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private static void trim(MemoryRegionCache cache) {
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if (cache == null) {
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return;
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}
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cache.trim();
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}
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private MemoryRegionCache cacheForSmall(int sizeIdx) {
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return cache(smallSubPageCaches, sizeIdx);
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}
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private MemoryRegionCache cacheForNormal(PoolArena area, int sizeIdx) {
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// We need to substract area.numSmallSubpagePools as sizeIdx is the overall index for all sizes.
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int idx = sizeIdx - area.numSmallSubpagePools;
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return cache(normalCaches, idx);
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}
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private static MemoryRegionCache cache(MemoryRegionCache[] cache, int sizeIdx) {
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if (cache == null || sizeIdx > cache.length - 1) {
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return null;
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}
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return cache[sizeIdx];
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}
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/**
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* Cache used for buffers which are backed by SMALL size.
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*/
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private static final class SubPageMemoryRegionCache extends MemoryRegionCache {
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SubPageMemoryRegionCache(int size) {
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super(size, Small);
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}
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@Override
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protected Buffer allocBuf(PoolChunk chunk, long handle, int size, PoolThreadCache threadCache) {
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return chunk.allocateBufferWithSubpage(handle, size, threadCache);
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}
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}
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/**
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* Cache used for buffers which are backed by NORMAL size.
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*/
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private static final class NormalMemoryRegionCache extends MemoryRegionCache {
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NormalMemoryRegionCache(int size) {
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super(size, Normal);
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}
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@Override
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protected Buffer allocBuf(PoolChunk chunk, long handle, int size, PoolThreadCache threadCache) {
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return chunk.allocateBuffer(handle, size, threadCache);
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}
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}
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private abstract static class MemoryRegionCache {
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private final int size;
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private final Queue<Entry> queue;
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private final SizeClass sizeClass;
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private int allocations;
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MemoryRegionCache(int size, SizeClass sizeClass) {
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this.size = MathUtil.safeFindNextPositivePowerOfTwo(size);
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queue = PlatformDependent.newFixedMpscQueue(this.size);
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this.sizeClass = sizeClass;
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}
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/**
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* Allocate a new {@link Buffer} using the provided chunk and handle with the capacity restrictions.
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*/
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protected abstract Buffer allocBuf(PoolChunk chunk, long handle, int size, PoolThreadCache threadCache);
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/**
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* Add to cache if not already full.
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*/
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public final boolean add(PoolChunk chunk, long handle, int normCapacity) {
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Entry entry = newEntry(chunk, handle, normCapacity);
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boolean queued = queue.offer(entry);
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if (!queued) {
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// If it was not possible to cache the chunk, immediately recycle the entry
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entry.recycle();
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}
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return queued;
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}
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/**
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* Allocate something out of the cache if possible and remove the entry from the cache.
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*/
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public final Buffer allocate(int size, PoolThreadCache threadCache) {
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Entry entry = queue.poll();
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if (entry == null) {
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return null;
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}
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Buffer buffer = allocBuf(entry.chunk, entry.handle, size, threadCache);
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entry.recycle();
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// allocations are not thread-safe which is fine as this is only called from the same thread all time.
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allocations++;
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return buffer;
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}
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/**
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* Clear out this cache and free up all previous cached {@link PoolChunk}s and {@code handle}s.
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*/
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public final int free() {
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return free(Integer.MAX_VALUE);
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}
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private int free(int max) {
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int numFreed = 0;
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for (; numFreed < max; numFreed++) {
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Entry entry = queue.poll();
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if (entry != null) {
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freeEntry(entry);
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} else {
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// all cleared
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return numFreed;
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}
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}
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return numFreed;
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}
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/**
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* Free up cached {@link PoolChunk}s if not allocated frequently enough.
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*/
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public final void trim() {
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int free = size - allocations;
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allocations = 0;
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// We not even allocated all the number that are
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if (free > 0) {
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free(free);
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}
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}
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private void freeEntry(Entry entry) {
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PoolChunk chunk = entry.chunk;
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long handle = entry.handle;
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entry.recycle();
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chunk.arena.freeChunk(chunk, handle, entry.normCapacity, sizeClass);
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}
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static final class Entry {
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final Handle<Entry> recyclerHandle;
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PoolChunk chunk;
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long handle = -1;
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int normCapacity;
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Entry(Handle<Entry> recyclerHandle) {
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this.recyclerHandle = recyclerHandle;
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}
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void recycle() {
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chunk = null;
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handle = -1;
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recyclerHandle.recycle(this);
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}
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}
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private static Entry newEntry(PoolChunk chunk, long handle, int normCapacity) {
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Entry entry = RECYCLER.get();
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entry.chunk = chunk;
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entry.handle = handle;
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entry.normCapacity = normCapacity;
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return entry;
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}
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private static final ObjectPool<Entry> RECYCLER = ObjectPool.newPool(handle -> new Entry(handle));
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}
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}
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