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/*
* ArrayAllocator.java February 2001
*
* Copyright (C) 2001, Niall Gallagher <niallg@users.sf.net>
*
* Licensed 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.simpleframework.common.buffer;
import java.io.IOException;
/**
* The <code>ArrayAllocator</code> object is used to provide a means
* to allocate buffers using a single byte array. This essentially uses
* the heap to allocate all buffers. As a result the performance of the
* resulting buffers is good, however for very large buffers this will
* use quote allot of the usable heap space. For very large buffers a
* mapped region of shared memory of a file should be considered.
*
* @author Niall Gallagher
*/
public class ArrayAllocator implements Allocator {
/**
* This represents the largest portion of memory that is allowed.
*/
private int limit;
/**
* This represents the default capacity of all allocated buffers.
*/
private int size;
/**
* Constructor for the <code>ArrayAllocator</code> object. This is
* used to instantiate the allocator with a default buffer size of
* half a kilobyte. This ensures that it can be used for general
* purpose byte storage and for minor I/O tasks.
*/
public ArrayAllocator() {
this(512);
}
/**
* Constructor for the <code>ArrayAllocator</code> object. This is
* used to instantiate the allocator with a specified buffer size.
* This is typically used when a very specific buffer capacity is
* required, for example a request body with a known length.
*
* @param size the initial capacity of the allocated buffers
*/
public ArrayAllocator(int size) {
this(size, 1048576);
}
/**
* Constructor for the <code>ArrayAllocator</code> object. This is
* used to instantiate the allocator with a specified buffer size.
* This is typically used when a very specific buffer capacity is
* required, for example a request body with a known length.
*
* @param size the initial capacity of the allocated buffers
* @param limit this is the maximum buffer size created by this
*/
public ArrayAllocator(int size, int limit) {
this.limit = Math.max(size, limit);
this.size = size;
}
/**
* This method is used to allocate a default buffer. This will
* allocate a buffer of predetermined size, allowing it to grow
* to an upper limit to accommodate extra data. If the buffer
* requested is larger than the limit an exception is thrown.
*
* @return this returns an allocated buffer with a default size
*/
public Buffer allocate() throws IOException {
return allocate(size);
}
/**
* This method is used to allocate a default buffer. This will
* allocate a buffer of predetermined size, allowing it to grow
* to an upper limit to accommodate extra data. If the buffer
* requested is larger than the limit an exception is thrown.
*
* @param size the initial capacity of the allocated buffer
*
* @return this returns an allocated buffer with a default size
*/
public Buffer allocate(long size) throws IOException {
int required = (int)size;
if(size > limit) {
throw new BufferException("Specified size %s beyond limit", size);
}
return new ArrayBuffer(required, limit);
}
}
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