/**
* 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.hadoop.io;
import java.io.*;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import org.apache.commons.logging.Log;
import org.apache.hadoop.conf.Configuration;
/**
* An utility class for I/O related functionality.
*/
public class IOUtils {
/**
* Copies from one stream to another.
* @param in InputStrem to read from
* @param out OutputStream to write to
* @param buffSize the size of the buffer
* @param close whether or not close the InputStream and
* OutputStream at the end. The streams are closed in the finally clause.
*/
public static void copyBytes(InputStream in, OutputStream out, int buffSize, boolean close)
throws IOException {
try {
copyBytes(in, out, buffSize);
} finally {
if(close) {
out.close();
in.close();
}
}
}
/**
* Copies from one stream to another.
*
* @param in InputStrem to read from
* @param out OutputStream to write to
* @param buffSize the size of the buffer
*/
public static void copyBytes(InputStream in, OutputStream out, int buffSize)
throws IOException {
PrintStream ps = out instanceof PrintStream ? (PrintStream)out : null;
byte buf[] = new byte[buffSize];
int bytesRead = in.read(buf);
while (bytesRead >= 0) {
out.write(buf, 0, bytesRead);
if ((ps != null) && ps.checkError()) {
throw new IOException("Unable to write to output stream.");
}
bytesRead = in.read(buf);
}
}
/**
* Copies from one stream to another. <strong>closes the input and output streams
* at the end</strong>.
* @param in InputStrem to read from
* @param out OutputStream to write to
* @param conf the Configuration object
*/
public static void copyBytes(InputStream in, OutputStream out, Configuration conf)
throws IOException {
copyBytes(in, out, conf.getInt("io.file.buffer.size", 4096), true);
}
/**
* Copies from one stream to another.
* @param in InputStrem to read from
* @param out OutputStream to write to
* @param conf the Configuration object
* @param close whether or not close the InputStream and
* OutputStream at the end. The streams are closed in the finally clause.
*/
public static void copyBytes(InputStream in, OutputStream out, Configuration conf, boolean close)
throws IOException {
copyBytes(in, out, conf.getInt("io.file.buffer.size", 4096), close);
}
/**
* Copies the specified length of bytes from in to out.
*
* @param in InputStream to read from
* @param out OutputStream to write to
* @param length number of bytes to copy
* @param bufferSize the size of the buffer
* @param close whether to close the streams
* @throws IOException if bytes can not be read or written
*/
public static void copyBytes(InputStream in, OutputStream out,
final long length, final int bufferSize, final boolean close
) throws IOException {
final byte buf[] = new byte[bufferSize];
try {
int n = 0;
for(long remaining = length; remaining > 0 && n != -1; remaining -= n) {
final int toRead = remaining < buf.length? (int)remaining : buf.length;
n = in.read(buf, 0, toRead);
if (n > 0) {
out.write(buf, 0, n);
}
}
if (close) {
out.close();
out = null;
in.close();
in = null;
}
} finally {
if (close) {
closeStream(out);
closeStream(in);
}
}
}
/**
* Utility wrapper for reading from {@link InputStream}. It catches any errors
* thrown by the underlying stream (either IO or decompression-related), and
* re-throws as an IOException.
*
* @param is - InputStream to be read from
* @param buf - buffer the data is read into
* @param off - offset within buf
* @param len - amount of data to be read
* @return number of bytes read
*/
public static int wrappedReadForCompressedData(InputStream is, byte[] buf,
int off, int len) throws IOException {
try {
return is.read(buf, off, len);
} catch (IOException ie) {
throw ie;
} catch (Throwable t) {
throw new IOException("Error while reading compressed data", t);
}
}
/** Reads len bytes in a loop.
* @param in The InputStream to read from
* @param buf The buffer to fill
* @param off offset from the buffer
* @param len the length of bytes to read
* @throws IOException if it could not read requested number of bytes
* for any reason (including EOF)
*/
public static void readFully( InputStream in, byte buf[],
int off, int len ) throws IOException {
int toRead = len;
while ( toRead > 0 ) {
int ret = in.read( buf, off, toRead );
if ( ret < 0 ) {
throw new IOException( "Premature EOF from inputStream");
}
toRead -= ret;
off += ret;
}
}
/** Reads len bytes in a loop using the channel of the stream
* @param fileChannel a FileChannel to read len bytes into buf
* @param buf The buffer to fill
* @param off offset from the buffer
* @param len the length of bytes to read
* @throws IOException if it could not read requested number of bytes
* for any reason (including EOF)
*/
public static void readFileChannelFully( FileChannel fileChannel, byte buf[],
int off, int len ) throws IOException {
int toRead = len;
ByteBuffer byteBuffer = ByteBuffer.wrap(buf, off, len);
while ( toRead > 0 ) {
int ret = fileChannel.read(byteBuffer);
if ( ret < 0 ) {
throw new IOException( "Premeture EOF from inputStream");
}
toRead -= ret;
off += ret;
}
}
/** Similar to readFully(). Skips bytes in a loop.
* @param in The InputStream to skip bytes from
* @param len number of bytes to skip.
* @throws IOException if it could not skip requested number of bytes
* for any reason (including EOF)
*/
public static void skipFully( InputStream in, long len ) throws IOException {
while ( len > 0 ) {
long ret = in.skip( len );
if ( ret < 0 ) {
throw new IOException( "Premature EOF from inputStream");
}
len -= ret;
}
}
/**
* Close the Closeable objects and <b>ignore</b> any {@link IOException} or
* null pointers. Must only be used for cleanup in exception handlers.
* @param log the log to record problems to at debug level. Can be null.
* @param closeables the objects to close
*/
public static void cleanup(Log log, java.io.Closeable... closeables) {
for(java.io.Closeable c : closeables) {
if (c != null) {
try {
c.close();
} catch(IOException e) {
if (log != null && log.isDebugEnabled()) {
log.debug("Exception in closing " + c, e);
}
}
}
}
}
/**
* Closes the stream ignoring {@link IOException}.
* Must only be called in cleaning up from exception handlers.
* @param stream the Stream to close
*/
public static void closeStream( java.io.Closeable stream ) {
cleanup(null, stream);
}
/**
* Closes the socket ignoring {@link IOException}
* @param sock the Socket to close
*/
public static void closeSocket( Socket sock ) {
// avoids try { close() } dance
if ( sock != null ) {
try {
sock.close();
} catch ( IOException ignored ) {
}
}
}
/** /dev/null of OutputStreams.
*/
public static class NullOutputStream extends OutputStream {
public void write(byte[] b, int off, int len) throws IOException {
}
public void write(int b) throws IOException {
}
}
}