org.apache.kafka.common.utils.ChunkedBytesStream Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.kafka.common.utils;
import java.io.BufferedInputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
/**
* ChunkedBytesStream is a copy of {@link BufferedInputStream} with the following differences:
* - Unlike {@link java.io.BufferedInputStream#skip(long)} this class could be configured to not push skip() to
* input stream. We may want to avoid pushing this to input stream because it's implementation maybe inefficient,
* e.g. the case of ZstdInputStream which allocates a new buffer from buffer pool, per skip call.
* - Unlike {@link java.io.BufferedInputStream}, which allocates an intermediate buffer, this uses a buffer supplier to
* create the intermediate buffer.
* - Unlike {@link java.io.BufferedInputStream}, this implementation does not support {@link InputStream#mark(int)} and
* {@link InputStream#markSupported()} will return false.
*
* Note that:
* - this class is not thread safe and shouldn't be used in scenarios where multiple threads access this.
* - the implementation of this class is performance sensitive. Minor changes such as usage of ByteBuffer instead of byte[]
* can significantly impact performance, hence, proceed with caution.
*/
public class ChunkedBytesStream extends FilterInputStream {
/**
* Supplies the ByteBuffer which is used as intermediate buffer to store the chunk of output data.
*/
private final BufferSupplier bufferSupplier;
/**
* Intermediate buffer to store the chunk of output data. The ChunkedBytesStream is considered closed if
* this buffer is null.
*/
private byte[] intermediateBuf;
/**
* The index one greater than the index of the last valid byte in
* the buffer.
* This value is always in the range 0 through intermediateBuf.length;
* elements intermediateBuf[0] through intermediateBuf[count-1]
* contain buffered input data obtained
* from the underlying input stream.
*/
protected int count = 0;
/**
* The current position in the buffer. This is the index of the next
* character to be read from the buf array.
*
* This value is always in the range 0
* through count. If it is less
* than count, then intermediateBuf[pos]
* is the next byte to be supplied as input;
* if it is equal to count, then
* the next read or skip
* operation will require more bytes to be
* read from the contained input stream.
*/
protected int pos = 0;
/**
* Reference for the intermediate buffer. This reference is only kept for releasing the buffer from the
* buffer supplier.
*/
private final ByteBuffer intermediateBufRef;
/**
* If this flag is true, we will delegate the responsibility of skipping to the
* sourceStream. This is an alternative to reading the data from source stream, storing in an intermediate buffer and
* skipping the values using this implementation.
*/
private final boolean delegateSkipToSourceStream;
public ChunkedBytesStream(InputStream in, BufferSupplier bufferSupplier, int intermediateBufSize, boolean delegateSkipToSourceStream) {
super(in);
this.bufferSupplier = bufferSupplier;
intermediateBufRef = bufferSupplier.get(intermediateBufSize);
if (!intermediateBufRef.hasArray() || (intermediateBufRef.arrayOffset() != 0)) {
throw new IllegalArgumentException("provided ByteBuffer lacks array or has non-zero arrayOffset");
}
intermediateBuf = intermediateBufRef.array();
this.delegateSkipToSourceStream = delegateSkipToSourceStream;
}
/**
* Check to make sure that buffer has not been nulled out due to
* close; if not return it;
*/
private byte[] getBufIfOpen() throws IOException {
byte[] buffer = intermediateBuf;
if (buffer == null)
throw new IOException("Stream closed");
return buffer;
}
/**
* See the general contract of the read
* method of InputStream.
*
* @return the next byte of data, or -1 if the end of the
* stream is reached.
* @throws IOException if this input stream has been closed by
* invoking its {@link #close()} method,
* or an I/O error occurs.
* @see BufferedInputStream#read()
*/
@Override
public int read() throws IOException {
if (pos >= count) {
fill();
if (pos >= count)
return -1;
}
return getBufIfOpen()[pos++] & 0xff;
}
/**
* Check to make sure that underlying input stream has not been
* nulled out due to close; if not return it;
*/
InputStream getInIfOpen() throws IOException {
InputStream input = in;
if (input == null)
throw new IOException("Stream closed");
return input;
}
/**
* Fills the intermediate buffer with more data. The amount of new data read is equal to the remaining empty space
* in the buffer. For optimal performance, read as much data as possible in this call.
* This method also assumes that all data has already been read in, hence pos > count.
*/
int fill() throws IOException {
byte[] buffer = getBufIfOpen();
pos = 0;
count = pos;
int n = getInIfOpen().read(buffer, pos, buffer.length - pos);
if (n > 0)
count = n + pos;
return n;
}
@Override
public void close() throws IOException {
byte[] mybuf = intermediateBuf;
intermediateBuf = null;
InputStream input = in;
in = null;
if (mybuf != null)
bufferSupplier.release(intermediateBufRef);
if (input != null)
input.close();
}
/**
* Reads bytes from this byte-input stream into the specified byte array,
* starting at the given offset.
*
*
This method implements the general contract of the corresponding
* {@link InputStream#read(byte[], int, int) read} method of
* the {@link InputStream} class. As an additional
* convenience, it attempts to read as many bytes as possible by repeatedly
* invoking the read method of the underlying stream. This
* iterated read continues until one of the following
* conditions becomes true:
*
* - The specified number of bytes have been read,
*
*
- The
read method of the underlying stream returns
* -1, indicating end-of-file, or
*
* - The
available method of the underlying stream
* returns zero, indicating that further input requests would block.
*
*
If the first read on the underlying stream returns
* -1 to indicate end-of-file then this method returns
* -1. Otherwise this method returns the number of bytes
* actually read.
*
* Subclasses of this class are encouraged, but not required, to
* attempt to read as many bytes as possible in the same fashion.
*
* @param b destination buffer.
* @param off offset at which to start storing bytes.
* @param len maximum number of bytes to read.
* @return the number of bytes read, or -1 if the end of
* the stream has been reached.
* @throws IOException if this input stream has been closed by
* invoking its {@link #close()} method,
* or an I/O error occurs.
* @see BufferedInputStream#read(byte[], int, int)
*/
public int read(byte[] b, int off, int len) throws IOException {
getBufIfOpen(); // Check for closed stream
if ((off | len | (off + len) | (b.length - (off + len))) < 0) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return 0;
}
int n = 0;
for (; ; ) {
int nread = read1(b, off + n, len - n);
if (nread <= 0)
return (n == 0) ? nread : n;
n += nread;
if (n >= len)
return n;
// if not closed but no bytes available, return
InputStream input = in;
if (input != null && input.available() <= 0)
return n;
}
}
/**
* Read characters into a portion of an array, reading from the underlying
* stream at most once if necessary.
*
* Note - Implementation copied from {@link BufferedInputStream}. Slight modification done to remove
* the mark position.
*/
private int read1(byte[] b, int off, int len) throws IOException {
int avail = count - pos;
if (avail <= 0) {
/* If the requested length is at least as large as the buffer, and
if there is no mark/reset activity, do not bother to copy the
bytes into the local buffer. In this way buffered streams will
cascade harmlessly. */
if (len >= getBufIfOpen().length) {
return getInIfOpen().read(b, off, len);
}
fill();
avail = count - pos;
if (avail <= 0) return -1;
}
int cnt = Math.min(avail, len);
System.arraycopy(getBufIfOpen(), pos, b, off, cnt);
pos += cnt;
return cnt;
}
/**
* Skips over and discards exactly {@code n} bytes of data from this input stream.
* If {@code n} is zero, then no bytes are skipped.
* If {@code n} is negative, then no bytes are skipped.
*
* This method blocks until the requested number of bytes has been skipped, end of file is reached, or an
* exception is thrown.
*
If end of stream is reached before the stream is at the desired position, then the bytes skipped till than pointed
* are returned.
*
If an I/O error occurs, then the input stream may be in an inconsistent state. It is strongly recommended that the
* stream be promptly closed if an I/O error occurs.
*
* This method first skips and discards bytes in the intermediate buffer.
* After that, depending on the value of {@link #delegateSkipToSourceStream}, it either delegates the skipping of
* bytes to the sourceStream or it reads the data from input stream in chunks, copies the data into intermediate
* buffer and skips it.
*
* Starting JDK 12, a new method was introduced in InputStream, skipNBytes which has a similar behaviour as
* this method.
*
* @param toSkip the number of bytes to be skipped.
* @return the actual number of bytes skipped which might be zero.
* @throws IOException if this input stream has been closed by invoking its {@link #close()} method,
* {@code in.skip(n)} throws an IOException, or an I/O error occurs.
*/
@Override
public long skip(long toSkip) throws IOException {
getBufIfOpen(); // Check for closed stream
if (toSkip <= 0) {
return 0;
}
long remaining = toSkip;
// Skip bytes stored in intermediate buffer first
int avail = count - pos;
int bytesSkipped = (int) Math.min(avail, remaining);
pos += bytesSkipped;
remaining -= bytesSkipped;
while (remaining > 0) {
if (delegateSkipToSourceStream) {
// Use sourceStream's skip() to skip the rest.
// conversion to int is acceptable because toSkip and remaining are int.
long delegateBytesSkipped = getInIfOpen().skip(remaining);
if (delegateBytesSkipped == 0) {
// read one byte to check for EOS
if (read() == -1) {
break;
}
// one byte read so decrement number to skip
remaining--;
} else if (delegateBytesSkipped > remaining || delegateBytesSkipped < 0) { // skipped negative or too many bytes
throw new IOException("Unable to skip exactly");
}
remaining -= delegateBytesSkipped;
} else {
// skip from intermediate buffer, filling it first (if required)
if (pos >= count) {
fill();
// if we don't have data in intermediate buffer after fill, then stop skipping
if (pos >= count)
break;
}
avail = count - pos;
bytesSkipped = (int) Math.min(avail, remaining);
pos += bytesSkipped;
remaining -= bytesSkipped;
}
}
return toSkip - remaining;
}
// visible for testing
public InputStream sourceStream() {
return in;
}
/**
* Returns an estimate of the number of bytes that can be read (or
* skipped over) from this input stream without blocking by the next
* invocation of a method for this input stream. The next invocation might be
* the same thread or another thread. A single read or skip of this
* many bytes will not block, but may read or skip fewer bytes.
*
* This method returns the sum of the number of bytes remaining to be read in
* the buffer (count - pos) and the result of calling the
* {@link java.io.FilterInputStream#in in}.available().
*
* @return an estimate of the number of bytes that can be read (or skipped
* over) from this input stream without blocking.
* @throws IOException if this input stream has been closed by
* invoking its {@link #close()} method,
* or an I/O error occurs.
* @see BufferedInputStream#available()
*/
@Override
public synchronized int available() throws IOException {
int n = count - pos;
int avail = getInIfOpen().available();
return n > (Integer.MAX_VALUE - avail)
? Integer.MAX_VALUE
: n + avail;
}
}