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package com.fasterxml.jackson.core.util;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicReferenceArray;
/**
* This is a small utility class, whose main functionality is to allow
* simple reuse of raw byte/char buffers. It is usually allocated through
* {@link RecyclerPool} (starting with 2.16): multiple pool
* implementations exists.
* The default pool implementation uses
* {@code ThreadLocal} combined with {@code SoftReference}.
* The end result is a low-overhead GC-cleanable recycling: hopefully
* ideal for use by stream readers.
*
* Rewritten in 2.10 to be thread-safe (see [jackson-core#479] for details),
* to not rely on {@code ThreadLocal} access.
* Rewritten in 2.16 to work with {@link RecyclerPool} abstraction.
*/
public class BufferRecycler
implements RecyclerPool.WithPool
{
/**
* Tag-on interface to allow various other types to expose {@link BufferRecycler}
* they are constructed with.
*
* @since 2.17
*/
public interface Gettable {
/**
* @return Buffer recycler instance object is configured with, if any;
* whether this can be {@code null} depends on type of object
*/
public BufferRecycler bufferRecycler();
}
/**
* Buffer used for reading byte-based input.
*/
public final static int BYTE_READ_IO_BUFFER = 0;
/**
* Buffer used for temporarily storing encoded content; used
* for example by UTF-8 encoding writer
*/
public final static int BYTE_WRITE_ENCODING_BUFFER = 1;
/**
* Buffer used for temporarily concatenating output; used for
* example when requesting output as byte array.
*/
public final static int BYTE_WRITE_CONCAT_BUFFER = 2;
/**
* Buffer used for concatenating binary data that is either being
* encoded as base64 output, or decoded from base64 input.
*
* @since 2.1
*/
public final static int BYTE_BASE64_CODEC_BUFFER = 3;
/**
* Buffer used as input buffer for tokenization for character-based parsers.
*/
public final static int CHAR_TOKEN_BUFFER = 0;
/**
* Buffer used by generators; for byte-backed generators for buffering of
* {@link String} values to output (before encoding into UTF-8),
* and for char-backed generators as actual concatenation buffer.
*/
public final static int CHAR_CONCAT_BUFFER = 1;
/**
* Used through {@link TextBuffer}: directly by parsers (to concatenate
* String values)
* and indirectly via
* {@link com.fasterxml.jackson.core.io.SegmentedStringWriter}
* when serializing (databind level {@code ObjectMapper} and
* {@code ObjectWriter}). In both cases used as segments (and not for whole value),
* but may result in retention of larger chunks for big content
* (long text values during parsing; bigger output documents for generation).
*/
public final static int CHAR_TEXT_BUFFER = 2;
/**
* For parsers, temporary buffer into which {@code char[]} for names is copied
* when requested as such; for {@code WriterBasedGenerator} used for buffering
* during {@code writeString(Reader)} operation (not commonly used).
*/
public final static int CHAR_NAME_COPY_BUFFER = 3;
// Buffer lengths
private final static int[] BYTE_BUFFER_LENGTHS = new int[] { 8000, 8000, 2000, 2000 };
private final static int[] CHAR_BUFFER_LENGTHS = new int[] { 4000, 4000, 200, 200 };
// Note: changed from simple array in 2.10:
protected final AtomicReferenceArray _byteBuffers;
// Note: changed from simple array in 2.10:
protected final AtomicReferenceArray _charBuffers;
private RecyclerPool _pool;
/*
/**********************************************************
/* Life-cycle
/**********************************************************
*/
/**
* Default constructor used for creating instances of this default
* implementation.
*/
public BufferRecycler() {
this(4, 4);
}
/**
* Alternate constructor to be used by sub-classes, to allow customization
* of number of low-level buffers in use.
*
* @param bbCount Number of {@code byte[]} buffers to allocate
* @param cbCount Number of {@code char[]} buffers to allocate
*
* @since 2.4
*/
protected BufferRecycler(int bbCount, int cbCount) {
_byteBuffers = new AtomicReferenceArray<>(bbCount);
_charBuffers = new AtomicReferenceArray<>(cbCount);
}
/**
* @return True if this recycler is linked to pool and may be released
* with {@link #releaseToPool()}; false if no linkage exists.
*
* @since 2.17
*/
public boolean isLinkedWithPool() {
return _pool != null;
}
/*
/**********************************************************
/* Public API, byte buffers
/**********************************************************
*/
/**
* @param ix One of READ_IO_BUFFER constants.
*
* @return Buffer allocated (possibly recycled)
*/
public final byte[] allocByteBuffer(int ix) {
return allocByteBuffer(ix, 0);
}
public byte[] allocByteBuffer(int ix, int minSize) {
final int DEF_SIZE = byteBufferLength(ix);
if (minSize < DEF_SIZE) {
minSize = DEF_SIZE;
}
byte[] buffer = _byteBuffers.getAndSet(ix, null);
if (buffer == null || buffer.length < minSize) {
buffer = balloc(minSize);
}
return buffer;
}
public void releaseByteBuffer(int ix, byte[] buffer) {
// 13-Jan-2024, tatu: [core#1186] Replace only if beneficial:
byte[] oldBuffer = _byteBuffers.get(ix);
if ((oldBuffer == null) || buffer.length > oldBuffer.length) {
// Could use CAS, but should not really matter
_byteBuffers.set(ix, buffer);
}
}
/*
/**********************************************************
/* Public API, char buffers
/**********************************************************
*/
public final char[] allocCharBuffer(int ix) {
return allocCharBuffer(ix, 0);
}
public char[] allocCharBuffer(int ix, int minSize) {
final int DEF_SIZE = charBufferLength(ix);
if (minSize < DEF_SIZE) {
minSize = DEF_SIZE;
}
char[] buffer = _charBuffers.getAndSet(ix, null);
if (buffer == null || buffer.length < minSize) {
buffer = calloc(minSize);
}
return buffer;
}
public void releaseCharBuffer(int ix, char[] buffer) {
// 13-Jan-2024, tatu: [core#1186] Replace only if beneficial:
char[] oldBuffer = _charBuffers.get(ix);
if ((oldBuffer == null) || buffer.length > oldBuffer.length) {
// Could use CAS, but should not really matter
_charBuffers.set(ix, buffer);
}
}
/*
/**********************************************************
/* Overridable helper methods
/**********************************************************
*/
protected int byteBufferLength(int ix) {
return BYTE_BUFFER_LENGTHS[ix];
}
protected int charBufferLength(int ix) {
return CHAR_BUFFER_LENGTHS[ix];
}
/*
/**********************************************************
/* Actual allocations separated for easier debugging/profiling
/**********************************************************
*/
protected byte[] balloc(int size) { return new byte[size]; }
protected char[] calloc(int size) { return new char[size]; }
/*
/**********************************************************
/* WithPool implementation
/**********************************************************
*/
/**
* Method called by owner of this recycler instance, to provide reference to
* {@link RecyclerPool} into which instance is to be released (if any)
*
* @since 2.16
*/
@Override
public BufferRecycler withPool(RecyclerPool pool) {
if (_pool != null) {
throw new IllegalStateException("BufferRecycler already linked to pool: "+pool);
}
// assign to pool to which this BufferRecycler belongs in order to release it
// to the same pool when the work will be completed
_pool = Objects.requireNonNull(pool);
return this;
}
/**
* Method called when owner of this recycler no longer wishes use it; this should
* return it to pool passed via {@code withPool()} (if any).
*
* @since 2.16
*/
@Override
public void releaseToPool() {
if (_pool != null) {
RecyclerPool tmpPool = _pool;
// nullify the reference to the pool in order to avoid the risk of releasing
// the same BufferRecycler more than once, thus compromising the pool integrity
_pool = null;
tmpPool.releasePooled(this);
}
}
}