jenkins/war/src/main/java/executable/LogFileOutputStream.java

124 lines
3.6 KiB
Java

/*
* The MIT License
*
* Copyright (c) 2008, Sun Microsystems, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package executable;
import edu.umd.cs.findbugs.annotations.NonNull;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UncheckedIOException;
import sun.misc.Signal;
/**
* {@link OutputStream} that writes to a log file.
*
* <p>
* Unlike the plain {@link FileOutputStream}, this implementation
* listens to SIGALRM and reopens the log file. This behavior is
* necessary for allowing log rotations to happen smoothly.
*
* <p>
* Because the reopen operation needs to happen atomically,
* write operations are synchronized.
*
* @author Kohsuke Kawaguchi
*/
final class LogFileOutputStream extends FilterOutputStream {
/**
* This is where we are writing.
*/
private final File file;
LogFileOutputStream(File file) throws FileNotFoundException {
super(null);
this.file = file;
out = new FileOutputStream(file, true);
if (File.pathSeparatorChar == ':') {
Signal.handle(new Signal("ALRM"), signal -> {
try {
reopen();
} catch (IOException e) {
throw new UncheckedIOException(e); // failed to reopen
}
});
}
}
public synchronized void reopen() throws IOException {
out.close();
out = NULL; // in case reopen fails, initialize with NULL first
out = new FileOutputStream(file, true);
}
@Override
public synchronized void write(@NonNull byte[] b) throws IOException {
out.write(b);
}
@Override
public synchronized void write(@NonNull byte[] b, int off, int len) throws IOException {
out.write(b, off, len);
}
@Override
public synchronized void flush() throws IOException {
out.flush();
}
@Override
public synchronized void close() throws IOException {
out.close();
}
@Override
public synchronized void write(int b) throws IOException {
out.write(b);
}
@Override
public String toString() {
return getClass().getName() + " -> " + file;
}
/**
* /dev/null
*/
private static final OutputStream NULL = new OutputStream() {
@Override
public void write(int b) {
// noop
}
@Override
public void write(@NonNull byte[] b, int off, int len) {
// noop
}
};
}