mirror of
https://github.com/openjdk/jdk.git
synced 2025-08-27 06:45:07 +02:00
260 lines
8.3 KiB
Java
260 lines
8.3 KiB
Java
/*
|
|
* Copyright (c) 1994, 2024, Oracle and/or its affiliates. All rights reserved.
|
|
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
|
|
*
|
|
* This code is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License version 2 only, as
|
|
* published by the Free Software Foundation. Oracle designates this
|
|
* particular file as subject to the "Classpath" exception as provided
|
|
* by Oracle in the LICENSE file that accompanied this code.
|
|
*
|
|
* This code is distributed in the hope that it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
* version 2 for more details (a copy is included in the LICENSE file that
|
|
* accompanied this code).
|
|
*
|
|
* You should have received a copy of the GNU General Public License version
|
|
* 2 along with this work; if not, write to the Free Software Foundation,
|
|
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
*
|
|
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
|
|
* or visit www.oracle.com if you need additional information or have any
|
|
* questions.
|
|
*/
|
|
|
|
package java.io;
|
|
|
|
import java.util.Arrays;
|
|
import jdk.internal.misc.InternalLock;
|
|
import jdk.internal.misc.VM;
|
|
|
|
/**
|
|
* The class implements a buffered output stream. By setting up such
|
|
* an output stream, an application can write bytes to the underlying
|
|
* output stream without necessarily causing a call to the underlying
|
|
* system for each byte written.
|
|
*
|
|
* @apiNote
|
|
* Once wrapped in a {@code BufferedOutputStream}, the underlying
|
|
* {@code OutputStream} should not be used directly nor wrapped with
|
|
* another stream.
|
|
*
|
|
* @author Arthur van Hoff
|
|
* @since 1.0
|
|
*/
|
|
public class BufferedOutputStream extends FilterOutputStream {
|
|
private static final int DEFAULT_INITIAL_BUFFER_SIZE = 512;
|
|
private static final int DEFAULT_MAX_BUFFER_SIZE = 8192;
|
|
|
|
// initialized to null when BufferedOutputStream is sub-classed
|
|
private final InternalLock lock;
|
|
|
|
/**
|
|
* The internal buffer where data is stored.
|
|
*/
|
|
protected byte[] buf;
|
|
|
|
/**
|
|
* The number of valid bytes in the buffer. This value is always
|
|
* in the range {@code 0} through {@code buf.length}; elements
|
|
* {@code buf[0]} through {@code buf[count-1]} contain valid
|
|
* byte data.
|
|
*/
|
|
protected int count;
|
|
|
|
/**
|
|
* Max size of the internal buffer.
|
|
*/
|
|
private final int maxBufSize;
|
|
|
|
/**
|
|
* Returns the buffer size to use when no output buffer size specified.
|
|
*/
|
|
private static int initialBufferSize() {
|
|
if (VM.isBooted() && Thread.currentThread().isVirtual()) {
|
|
return DEFAULT_INITIAL_BUFFER_SIZE;
|
|
} else {
|
|
return DEFAULT_MAX_BUFFER_SIZE;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Creates a new buffered output stream.
|
|
*/
|
|
private BufferedOutputStream(OutputStream out, int initialSize, int maxSize) {
|
|
super(out);
|
|
|
|
if (initialSize <= 0) {
|
|
throw new IllegalArgumentException("Buffer size <= 0");
|
|
}
|
|
|
|
if (getClass() == BufferedOutputStream.class) {
|
|
// use InternalLock and resizable buffer when not sub-classed
|
|
this.lock = InternalLock.newLockOrNull();
|
|
this.buf = new byte[initialSize]; // resizable
|
|
} else {
|
|
// use monitors and no resizing when sub-classed
|
|
this.lock = null;
|
|
this.buf = new byte[maxSize];
|
|
}
|
|
this.maxBufSize = maxSize;
|
|
}
|
|
|
|
/**
|
|
* Creates a new buffered output stream to write data to the
|
|
* specified underlying output stream.
|
|
*
|
|
* @param out the underlying output stream.
|
|
*/
|
|
public BufferedOutputStream(OutputStream out) {
|
|
this(out, initialBufferSize(), DEFAULT_MAX_BUFFER_SIZE);
|
|
}
|
|
|
|
/**
|
|
* Creates a new buffered output stream to write data to the
|
|
* specified underlying output stream with the specified buffer
|
|
* size.
|
|
*
|
|
* @param out the underlying output stream.
|
|
* @param size the buffer size.
|
|
* @throws IllegalArgumentException if size <= 0.
|
|
*/
|
|
public BufferedOutputStream(OutputStream out, int size) {
|
|
this(out, size, size);
|
|
}
|
|
|
|
/** Flush the internal buffer */
|
|
private void flushBuffer() throws IOException {
|
|
if (count > 0) {
|
|
out.write(buf, 0, count);
|
|
count = 0;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Grow buf to fit an additional len bytes if needed.
|
|
* If possible, it grows by len+1 to avoid flushing when len bytes
|
|
* are added. A no-op if the buffer is not resizable.
|
|
*
|
|
* This method should only be called while holding the lock.
|
|
*/
|
|
private void growIfNeeded(int len) {
|
|
int neededSize = count + len + 1;
|
|
if (neededSize < 0)
|
|
neededSize = Integer.MAX_VALUE;
|
|
int bufSize = buf.length;
|
|
if (neededSize > bufSize && bufSize < maxBufSize) {
|
|
int newSize = Math.min(neededSize, maxBufSize);
|
|
buf = Arrays.copyOf(buf, newSize);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Writes the specified byte to this buffered output stream.
|
|
*
|
|
* @param b the byte to be written.
|
|
* @throws IOException if an I/O error occurs.
|
|
*/
|
|
@Override
|
|
public void write(int b) throws IOException {
|
|
if (lock != null) {
|
|
lock.lock();
|
|
try {
|
|
implWrite(b);
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
} else {
|
|
synchronized (this) {
|
|
implWrite(b);
|
|
}
|
|
}
|
|
}
|
|
|
|
private void implWrite(int b) throws IOException {
|
|
growIfNeeded(1);
|
|
if (count >= buf.length) {
|
|
flushBuffer();
|
|
}
|
|
buf[count++] = (byte)b;
|
|
}
|
|
|
|
/**
|
|
* Writes {@code len} bytes from the specified byte array
|
|
* starting at offset {@code off} to this buffered output stream.
|
|
*
|
|
* <p> Ordinarily this method stores bytes from the given array into this
|
|
* stream's buffer, flushing the buffer to the underlying output stream as
|
|
* needed. If the requested length is at least as large as this stream's
|
|
* buffer, however, then this method will flush the buffer and write the
|
|
* bytes directly to the underlying output stream. Thus redundant
|
|
* {@code BufferedOutputStream}s will not copy data unnecessarily.
|
|
*
|
|
* @param b the data.
|
|
* @param off the start offset in the data.
|
|
* @param len the number of bytes to write.
|
|
* @throws IOException if an I/O error occurs.
|
|
* @throws IndexOutOfBoundsException {@inheritDoc}
|
|
*/
|
|
@Override
|
|
public void write(byte[] b, int off, int len) throws IOException {
|
|
if (lock != null) {
|
|
lock.lock();
|
|
try {
|
|
implWrite(b, off, len);
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
} else {
|
|
synchronized (this) {
|
|
implWrite(b, off, len);
|
|
}
|
|
}
|
|
}
|
|
|
|
private void implWrite(byte[] b, int off, int len) throws IOException {
|
|
if (len >= maxBufSize) {
|
|
/* If the request length exceeds the max size of the output buffer,
|
|
flush the output buffer and then write the data directly.
|
|
In this way buffered streams will cascade harmlessly. */
|
|
flushBuffer();
|
|
out.write(b, off, len);
|
|
return;
|
|
}
|
|
growIfNeeded(len);
|
|
if (len > buf.length - count) {
|
|
flushBuffer();
|
|
}
|
|
System.arraycopy(b, off, buf, count, len);
|
|
count += len;
|
|
}
|
|
|
|
/**
|
|
* Flushes this buffered output stream. This forces any buffered
|
|
* output bytes to be written out to the underlying output stream.
|
|
*
|
|
* @throws IOException if an I/O error occurs.
|
|
* @see java.io.FilterOutputStream#out
|
|
*/
|
|
@Override
|
|
public void flush() throws IOException {
|
|
if (lock != null) {
|
|
lock.lock();
|
|
try {
|
|
implFlush();
|
|
} finally {
|
|
lock.unlock();
|
|
}
|
|
} else {
|
|
synchronized (this) {
|
|
implFlush();
|
|
}
|
|
}
|
|
}
|
|
|
|
private void implFlush() throws IOException {
|
|
flushBuffer();
|
|
out.flush();
|
|
}
|
|
}
|