/*
* 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.tomcat.util.log;
import java.io.IOException;
import java.io.PrintStream;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.NoSuchElementException;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
/**
* This helper class may be used to do sophisticated redirection of System.out and System.err on a per Thread basis. A
* stack is implemented per Thread so that nested startCapture and stopCapture can be used.
*/
public class SystemLogHandler extends PrintStream {
// ----------------------------------------------------------- Constructors
/**
* Construct the handler to capture the output of the given steam.
*
* @param wrapped The stream to capture
*/
public SystemLogHandler(PrintStream wrapped) {
super(wrapped);
out = wrapped;
}
// ----------------------------------------------------- Instance Variables
/**
* Wrapped PrintStream.
*/
private final PrintStream out;
/**
* Thread <-> CaptureLog associations.
*/
private static final ThreadLocal<Deque<CaptureLog>> logs = new ThreadLocal<>();
/**
* Spare CaptureLog ready for reuse.
*/
private static final Queue<CaptureLog> reuse = new ConcurrentLinkedQueue<>();
// --------------------------------------------------------- Public Methods
/**
* Start capturing thread's output.
*/
public static void startCapture() {
CaptureLog log;
if (!reuse.isEmpty()) {
try {
log = reuse.remove();
} catch (NoSuchElementException e) {
log = new CaptureLog();
}
} else {
log = new CaptureLog();
}
Deque<CaptureLog> stack = logs.get();
if (stack == null) {
stack = new ArrayDeque<>();
logs.set(stack);
}
stack.addFirst(log);
}
/**
* Stop capturing thread's output.
*
* @return The captured data
*/
public static String stopCapture() {
Queue<CaptureLog> stack = logs.get();
if (stack == null || stack.isEmpty()) {
return null;
}
CaptureLog log = stack.remove();
if (log == null) {
return null;
}
String capture = log.getCapture();
log.reset();
reuse.add(log);
return capture;
}
// ------------------------------------------------------ Protected Methods
/**
* Find PrintStream to which the output must be written to.
*
* @return the print stream
*/
protected PrintStream findStream() {
Queue<CaptureLog> stack = logs.get();
if (stack != null && !stack.isEmpty()) {
CaptureLog log = stack.peek();
if (log != null) {
PrintStream ps = log.getStream();
if (ps != null) {
return ps;
}
}
}
return out;
}
// ---------------------------------------------------- PrintStream Methods
@Override
public void flush() {
findStream().flush();
}
@Override
public void close() {
findStream().close();
}
@Override
public boolean checkError() {
return findStream().checkError();
}
@Override
protected void setError() {
// findStream().setError();
}
@Override
public void write(int b) {
findStream().write(b);
}
@Override
public void write(byte[] b) throws IOException {
findStream().write(b);
}
@Override
public void write(byte[] buf, int off, int len) {
findStream().write(buf, off, len);
}
@Override
public void print(boolean b) {
findStream().print(b);
}
@Override
public void print(char c) {
findStream().print(c);
}
@Override
public void print(int i) {
findStream().print(i);
}
@Override
public void print(long l) {
findStream().print(l);
}
@Override
public void print(float f) {
findStream().print(f);
}
@Override
public void print(double d) {
findStream().print(d);
}
@Override
public void print(char[] s) {
findStream().print(s);
}
@Override
public void print(String s) {
findStream().print(s);
}
@Override
public void print(Object obj) {
findStream().print(obj);
}
@Override
public void println() {
findStream().println();
}
@Override
public void println(boolean x) {
findStream().println(x);
}
@Override
public void println(char x) {
findStream().println(x);
}
@Override
public void println(int x) {
findStream().println(x);
}
@Override
public void println(long x) {
findStream().println(x);
}
@Override
public void println(float x) {
findStream().println(x);
}
@Override
public void println(double x) {
findStream().println(x);
}
@Override
public void println(char[] x) {
findStream().println(x);
}
@Override
public void println(String x) {
findStream().println(x);
}
@Override
public void println(Object x) {
findStream().println(x);
}
}