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//
// ========================================================================
// Copyright (c) 1995 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//
package org.eclipse.jetty.io;
import org.eclipse.jetty.util.NanoTime;
/**
* Extension of the {@link ArrayByteBufferPool} whose bucket sizes increase exponentially instead of linearly.
* Each bucket will be double the size of the previous bucket, this decreases the amounts of buckets required
* which can lower total memory usage if buffers are often being acquired of different sizes. However as there are
* fewer buckets this will also increase the contention on each bucket.
*/
public class LogarithmicArrayByteBufferPool extends ArrayByteBufferPool
{
/**
* Creates a new ByteBufferPool with a default configuration.
*/
public LogarithmicArrayByteBufferPool()
{
this(-1, -1, -1);
}
/**
* Creates a new ByteBufferPool with the given configuration.
*
* @param minCapacity the minimum ByteBuffer capacity
* @param maxCapacity the maximum ByteBuffer capacity
*/
public LogarithmicArrayByteBufferPool(int minCapacity, int maxCapacity)
{
this(minCapacity, maxCapacity, -1, -1, -1);
}
/**
* Creates a new ByteBufferPool with the given configuration.
*
* @param minCapacity the minimum ByteBuffer capacity
* @param maxCapacity the maximum ByteBuffer capacity
* @param maxQueueLength the maximum ByteBuffer queue length
*/
public LogarithmicArrayByteBufferPool(int minCapacity, int maxCapacity, int maxQueueLength)
{
this(minCapacity, maxCapacity, maxQueueLength, -1, -1);
}
/**
* Creates a new ByteBufferPool with the given configuration.
*
* @param minCapacity the minimum ByteBuffer capacity
* @param maxCapacity the maximum ByteBuffer capacity
* @param maxQueueLength the maximum ByteBuffer queue length
* @param maxHeapMemory the max heap memory in bytes
* @param maxDirectMemory the max direct memory in bytes
*/
public LogarithmicArrayByteBufferPool(int minCapacity, int maxCapacity, int maxQueueLength, long maxHeapMemory, long maxDirectMemory)
{
this(minCapacity, maxCapacity, maxQueueLength, maxHeapMemory, maxDirectMemory, maxHeapMemory, maxDirectMemory);
}
/**
* Creates a new ByteBufferPool with the given configuration.
*
* @param minCapacity the minimum ByteBuffer capacity
* @param maxCapacity the maximum ByteBuffer capacity
* @param maxQueueLength the maximum ByteBuffer queue length
* @param maxHeapMemory the max heap memory in bytes
* @param maxDirectMemory the max direct memory in bytes
* @param retainedHeapMemory the max heap memory in bytes, -2 for no retained memory, -1 for unlimited retained memory or 0 to use default heuristic
* @param retainedDirectMemory the max direct memory in bytes, -2 for no retained memory, -1 for unlimited retained memory or 0 to use default heuristic
*/
public LogarithmicArrayByteBufferPool(int minCapacity, int maxCapacity, int maxQueueLength, long maxHeapMemory, long maxDirectMemory, long retainedHeapMemory, long retainedDirectMemory)
{
super(minCapacity, -1, maxCapacity, maxQueueLength, maxHeapMemory, maxDirectMemory, retainedHeapMemory, retainedDirectMemory);
}
@Override
protected RetainableByteBufferPool newRetainableByteBufferPool(int factor, int maxCapacity, int maxBucketSize, long retainedHeapMemory, long retainedDirectMemory)
{
return new LogarithmicRetainablePool(0, maxCapacity, maxBucketSize, retainedHeapMemory, retainedDirectMemory);
}
@Override
protected int bucketFor(int capacity)
{
return 32 - Integer.numberOfLeadingZeros(capacity - 1);
}
@Override
protected int capacityFor(int bucket)
{
return 1 << bucket;
}
@Override
protected void releaseMemory(boolean direct)
{
long oldest = Long.MAX_VALUE;
int index = -1;
Bucket[] buckets = bucketsFor(direct);
for (int i = 0; i < buckets.length; ++i)
{
Bucket bucket = buckets[i];
if (bucket.isEmpty())
continue;
long lastUpdateNanoTime = bucket.getLastUpdate();
if (oldest == Long.MAX_VALUE || NanoTime.isBefore(lastUpdateNanoTime, oldest))
{
oldest = lastUpdateNanoTime;
index = i;
}
}
if (index >= 0)
{
Bucket bucket = buckets[index];
// Acquire a buffer but never return it to the pool.
bucket.acquire();
bucket.resetUpdateTime();
}
}
/**
* A variant of the {@link ArrayRetainableByteBufferPool} that
* uses buckets of buffers that increase in size by a power of
* 2 (eg 1k, 2k, 4k, 8k, etc.).
*/
public static class LogarithmicRetainablePool extends ArrayRetainableByteBufferPool
{
public LogarithmicRetainablePool()
{
this(0, -1, Integer.MAX_VALUE);
}
public LogarithmicRetainablePool(int minCapacity, int maxCapacity, int maxBucketSize)
{
this(minCapacity, maxCapacity, maxBucketSize, -1L, -1L);
}
public LogarithmicRetainablePool(int minCapacity, int maxCapacity, int maxBucketSize, long maxHeapMemory, long maxDirectMemory)
{
super(minCapacity,
-1,
maxCapacity,
maxBucketSize,
c -> 32 - Integer.numberOfLeadingZeros(c - 1),
i -> 1 << i,
maxHeapMemory,
maxDirectMemory
);
}
}
}
