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// Copyright 2014 Google Inc. All rights reserved.
//
// 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 com.google.devtools.build.lib.util.io;
import java.io.IOException;
import java.io.OutputStream;
/**
* This stream maintains a buffer, which it flushes upon encountering bytes
* that might be new line characters. This stream implements {@link #close()}
* as {@link #flush()}.
*/
abstract class LineFlushingOutputStream extends OutputStream {
static final int BUFFER_LENGTH = 8192;
protected static byte NEWLINE = '\n';
/**
* The buffer containing the characters that have not been flushed yet.
*/
protected final byte[] buffer = new byte[BUFFER_LENGTH];
/**
* The length of the buffer that's actually used.
*/
protected int len = 0;
@Override
public synchronized void write(byte[] b, int off, int inlen)
throws IOException {
if (len == BUFFER_LENGTH) {
flush();
}
int charsInLine = 0;
while(inlen > charsInLine) {
boolean sawNewline = (b[off + charsInLine] == NEWLINE);
charsInLine++;
if (sawNewline || len + charsInLine == BUFFER_LENGTH) {
System.arraycopy(b, off, buffer, len, charsInLine);
len += charsInLine;
off += charsInLine;
inlen -= charsInLine;
flush();
charsInLine = 0;
}
}
System.arraycopy(b, off, buffer, len, charsInLine);
len += charsInLine;
}
@Override
public void write(int byteAsInt) throws IOException {
byte b = (byte) byteAsInt; // make sure we work with bytes in comparisons
write(new byte[] {b}, 0, 1);
}
/**
* Close is implemented as {@link #flush()}. Client code must close the
* underlying output stream itself in case that's desired.
*/
@Override
public synchronized void close() throws IOException {
flush();
}
@Override
public final synchronized void flush() throws IOException {
flushingHook(); // The point of using a hook is to make it synchronized.
}
/**
* The implementing class must define this method, which must at least flush
* the bytes in {@code buffer[0] - buffer[len - 1]}, and reset {@code len=0}.
*
* Don't forget to synchronized the implementation of this method on whatever
* underlying object it writes to!
*/
protected abstract void flushingHook() throws IOException;
}
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