Merge pull request #152 from scijava/stdout-stderr

Let the ConsoleService track stdout and stderr messages

Author: ctrueden

src/main/java/org/scijava/console/AbstractConsoleArgument.java

@@ -37,7 +37,7 @@
 
 /**
  * Abstract superclass of {@link ConsoleArgument} implementations.
- * 
+ *
  * @author Curtis Rueden
  */
 public abstract class AbstractConsoleArgument extends

src/main/java/org/scijava/console/ConsoleArgument.java

@@ -46,7 +46,7 @@
  * is encouraged to instead extend {@link AbstractConsoleArgument}, for
  * convenience.
  * </p>
- * 
+ *
  * @author Curtis Rueden
  */
 public interface ConsoleArgument extends HandlerPlugin<LinkedList<String>> {

src/main/java/org/scijava/console/ConsoleService.java

@@ -40,9 +40,10 @@
  * Interface for service that manages interaction with the console.
  * <p>
  * In particular, this is the service that defines how command line arguments
- * are handled.
+ * are handled. It also provides an extension mechanism for {@code stdout} and
+ * {@code stderr} logging.
  * </p>
- * 
+ *
  * @author Curtis Rueden
  */
 public interface ConsoleService extends
@@ -55,4 +56,13 @@ public interface ConsoleService extends
 	 */
 	void processArgs(String... args);
 
+	/** Adds a listener for output sent to {@code stdout} or {@code stderr}. */
+	void addOutputListener(OutputListener l);
+
+	/** Removes a listener for output sent to {@code stdout} or {@code stderr}. */
+	void removeOutputListener(OutputListener l);
+
+	/** Notifies listeners of output sent to {@code stdout} or {@code stderr}. */
+	void notifyListeners(OutputEvent event);
+
 }

src/main/java/org/scijava/console/DefaultConsoleService.java

@@ -31,17 +31,24 @@
 
 package org.scijava.console;
 
+import java.io.OutputStream;
+import java.io.PrintStream;
+import java.util.ArrayList;
 import java.util.LinkedList;
 
+import org.scijava.Context;
+import org.scijava.console.OutputEvent.Source;
 import org.scijava.log.LogService;
 import org.scijava.plugin.AbstractHandlerService;
 import org.scijava.plugin.Parameter;
 import org.scijava.plugin.Plugin;
 import org.scijava.service.Service;
+import org.scijava.thread.ThreadService;
+import org.scijava.thread.ThreadService.ThreadContext;
 
 /**
  * Default service for managing interaction with the console.
- * 
+ *
  * @author Curtis Rueden
  */
 @Plugin(type = Service.class)
@@ -50,9 +57,20 @@ public class DefaultConsoleService extends
 	ConsoleService
 {
 
+	@Parameter
+	private ThreadService threadService;
+
 	@Parameter
 	private LogService log;
 
+	private MultiPrintStream sysout, syserr;
+	private OutputStreamReporter out, err;
+
+	/** List of listeners for {@code stdout} and {@code stderr} output. */
+	private ArrayList<OutputListener> listeners;
+
+	private OutputListener[] cachedListeners;
+
 	// -- ConsoleService methods --
 
 	@Override
@@ -76,6 +94,32 @@ public void processArgs(final String... args) {
 		}
 	}
 
+	@Override
+	public void addOutputListener(final OutputListener l) {
+		if (listeners == null) initListeners();
+		synchronized (listeners) {
+			listeners.add(l);
+			cacheListeners();
+		}
+	}
+
+	@Override
+	public void removeOutputListener(final OutputListener l) {
+		if (listeners == null) initListeners();
+		synchronized (listeners) {
+			listeners.remove(l);
+			cacheListeners();
+		}
+	}
+
+	@Override
+	public void notifyListeners(final OutputEvent event) {
+		if (listeners == null) initListeners();
+		final OutputListener[] toNotify = cachedListeners;
+		for (final OutputListener l : toNotify)
+			l.outputOccurred(event);
+	}
+
 	// -- PTService methods --
 
 	@Override
@@ -91,4 +135,89 @@ public Class<LinkedList<String>> getType() {
 		return (Class) LinkedList.class;
 	}
 
+	// -- Disposable methods --
+
+	@Override
+	public void dispose() {
+		if (out != null) sysout.getParent().removeOutputStream(out);
+		if (err != null) syserr.getParent().removeOutputStream(err);
+	}
+
+	// -- Helper methods - lazy initialization --
+
+	/** Initializes {@link #listeners} and related data structures. */
+	private synchronized void initListeners() {
+		if (listeners != null) return; // already initialized
+
+		sysout = multiPrintStream(System.out);
+		if (System.out != sysout) System.setOut(sysout);
+		out = new OutputStreamReporter(Source.STDOUT);
+		sysout.getParent().addOutputStream(out);
+
+		syserr = multiPrintStream(System.err);
+		if (System.err != syserr) System.setErr(syserr);
+		err = new OutputStreamReporter(Source.STDERR);
+		syserr.getParent().addOutputStream(err);
+
+		listeners = new ArrayList<OutputListener>();
+		cachedListeners = listeners.toArray(new OutputListener[0]);
+	}
+
+	// -- Helper methods --
+
+	private void cacheListeners() {
+		cachedListeners = listeners.toArray(new OutputListener[listeners.size()]);
+	}
+
+	private MultiPrintStream multiPrintStream(final PrintStream ps) {
+		if (ps instanceof MultiPrintStream) return (MultiPrintStream) ps;
+		return new MultiPrintStream(ps);
+	}
+
+	// -- Helper classes --
+
+	/**
+	 * An output stream that publishes its output to the {@link OutputListener}s
+	 * of its associated {@link ConsoleService}.
+	 */
+	private class OutputStreamReporter extends OutputStream {
+
+		/** Source of the output stream; i.e., {@code stdout} or {@code stderr}. */
+		private final Source source;
+
+		public OutputStreamReporter(final Source source) {
+			this.source = source;
+		}
+
+		// -- OutputStream methods --
+
+		@Override
+		public void write(final int b) {
+			final ThreadContext relevance = getRelevance();
+			if (relevance == ThreadContext.OTHER) return; // different context
+			publish(relevance, "" + b);
+		}
+
+		@Override
+		public void write(final byte[] buf, final int off, final int len) {
+			final ThreadContext relevance = getRelevance();
+			if (relevance == ThreadContext.OTHER) return; // different context
+			publish(relevance, new String(buf, off, len));
+		}
+
+		// -- Helper methods --
+
+		private ThreadContext getRelevance() {
+			return threadService.getThreadContext(Thread.currentThread());
+		}
+
+		private void publish(final ThreadContext relevance, final String output) {
+			final Context context = getContext();
+			final boolean contextual = relevance == ThreadContext.SAME;
+			final OutputEvent event =
+				new OutputEvent(context, source, output, contextual);
+			notifyListeners(event);
+		}
+	}
+
 }

src/main/java/org/scijava/console/MultiOutputStream.java

@@ -0,0 +1,128 @@
+/*
+ * #%L
+ * SciJava Common shared library for SciJava software.
+ * %%
+ * Copyright (C) 2009 - 2015 Board of Regents of the University of
+ * Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
+ * Institute of Molecular Cell Biology and Genetics.
+ * %%
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ * #L%
+ */
+
+package org.scijava.console;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.ArrayList;
+
+/**
+ * A {@code MultiOutputStream} is a collection of constituent
+ * {@link OutputStream} objects, to which all output is forwarded.
+ * <p>
+ * Thanks to Ian F. Darwin for <a href=
+ * "http://www.java2s.com/Code/Java/File-Input-Output/TeePrintStreamteesallPrintStreamoperationsintoafileratherliketheUNIXtee1command.htm"
+ * >his implementation of a similar concept</a>.
+ * </p>
+ *
+ * @author Curtis Rueden
+ */
+public class MultiOutputStream extends OutputStream {
+
+	private final ArrayList<OutputStream> streams;
+
+	private OutputStream[] cachedStreams;
+
+	/**
+	 * Forwards output to a list of output streams.
+	 *
+	 * @param os Output streams which will receive this stream's output.
+	 */
+	public MultiOutputStream(final OutputStream... os) {
+		streams = new ArrayList<OutputStream>(os.length);
+		for (int i = 0; i < os.length; i++) {
+			streams.add(os[i]);
+		}
+		cacheStreams();
+	}
+
+	// -- MultiOutputStream methods --
+
+	/** Adds an output stream to those receiving this stream's output. */
+	public void addOutputStream(final OutputStream os) {
+		synchronized (streams) {
+			streams.add(os);
+			cacheStreams();
+		}
+	}
+
+	/** Removes an output stream from those receiving this stream's output. */
+	public void removeOutputStream(final OutputStream os) {
+		synchronized (streams) {
+			streams.remove(os);
+			cacheStreams();
+		}
+	}
+
+	// -- OutputStream methods --
+
+	@Override
+	public void write(final int b) throws IOException {
+		final OutputStream[] toWrite = cachedStreams;
+		for (final OutputStream stream : toWrite)
+			stream.write(b);
+	}
+
+	@Override
+	public void write(final byte[] buf, final int off, final int len)
+		throws IOException
+	{
+		final OutputStream[] toWrite = cachedStreams;
+		for (final OutputStream stream : toWrite)
+			stream.write(buf, off, len);
+	}
+
+	// -- Closeable methods --
+
+	@Override
+	public void close() throws IOException {
+		final OutputStream[] toClose = cachedStreams;
+		for (final OutputStream stream : toClose)
+			stream.close();
+	}
+
+	// -- Flushable methods --
+
+	@Override
+	public void flush() throws IOException {
+		final OutputStream[] toFlush = cachedStreams;
+		for (final OutputStream stream : toFlush)
+			stream.flush();
+	}
+
+	// -- Helper methods --
+
+	private void cacheStreams() {
+		cachedStreams = streams.toArray(new OutputStream[streams.size()]);
+	}
+
+}