Deallocate devices on TERM signal (experimental feature)

closes #10
sarxos · Jan 7, 2013 · 9c8acf3 · 9c8acf3
1 parent 064efa2
commit 9c8acf3
Show file tree

Hide file tree

Showing 8 changed files with 225 additions and 56 deletions.
diff --git a/.project b/.project
@@ -1,17 +1,17 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<projectDescription>
-	<name>webcam-capture</name>
-	<comment></comment>
-	<projects>
-	</projects>
-	<buildSpec>
-		<buildCommand>
-			<name>org.eclipse.m2e.core.maven2Builder</name>
-			<arguments>
-			</arguments>
-		</buildCommand>
-	</buildSpec>
-	<natures>
-		<nature>org.eclipse.m2e.core.maven2Nature</nature>
-	</natures>
-</projectDescription>
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>webcam-capture-parent</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.m2e.core.maven2Builder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.m2e.core.maven2Nature</nature>
+	</natures>
+</projectDescription>
diff --git a/webcam-capture-examples/webcam-capture-manycams/.classpath b/webcam-capture-examples/webcam-capture-manycams/.classpath
@@ -1,31 +1,26 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<classpath>
-	<classpathentry kind="src" output="target/classes" path="src/main/java">
-		<attributes>
-			<attribute name="optional" value="true"/>
-			<attribute name="maven.pomderived" value="true"/>
-		</attributes>
-	</classpathentry>
-	<classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources">
-		<attributes>
-			<attribute name="maven.pomderived" value="true"/>
-		</attributes>
-	</classpathentry>
-	<classpathentry kind="src" output="target/test-classes" path="src/test/java">
-		<attributes>
-			<attribute name="optional" value="true"/>
-			<attribute name="maven.pomderived" value="true"/>
-		</attributes>
-	</classpathentry>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6">
-		<attributes>
-			<attribute name="maven.pomderived" value="true"/>
-		</attributes>
-	</classpathentry>
-	<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
-		<attributes>
-			<attribute name="maven.pomderived" value="true"/>
-		</attributes>
-	</classpathentry>
-	<classpathentry kind="output" path="target/classes"/>
-</classpath>
+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="src" output="target/classes" path="src/main/java">
+		<attributes>
+			<attribute name="optional" value="true"/>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="src" output="target/test-classes" path="src/test/java">
+		<attributes>
+			<attribute name="optional" value="true"/>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6">
+		<attributes>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
+		<attributes>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="output" path="target/classes"/>
+</classpath>
diff --git a/webcam-capture/src/main/java/com/github/sarxos/webcam/Webcam.java b/webcam-capture/src/main/java/com/github/sarxos/webcam/Webcam.java
@@ -23,13 +23,13 @@ public class Webcam {
 
 	private static final Logger LOG = LoggerFactory.getLogger(Webcam.class);
 
-	//@formatter:off
+	// @formatter:off
 	private static final String[] DRIVERS_DEFAULT = new String[] {
 		"com.github.sarxos.webcam.ds.openimaj.OpenImajDriver",
 		"com.github.sarxos.webcam.ds.civil.LtiCivilDriver",
 		"com.github.sarxos.webcam.ds.jmf.JmfDriver",
 	};
-	//@formatter:on
+	// @formatter:on
 
 	private static final List<String> DRIVERS_LIST = new ArrayList<String>(Arrays.asList(DRIVERS_DEFAULT));
 	private static final List<Class<?>> DRIVERS_CLASS_LIST = new ArrayList<Class<?>>();
@@ -54,6 +54,11 @@ public void run() {
 	private static WebcamDriver driver = null;
 	private static List<Webcam> webcams = null;
 
+	/**
+	 * Is automated deallocation on TERM signal enabled.
+	 */
+	private static volatile boolean deallocOnTermSignal = false;
+
 	/**
 	 * Webcam listeners.
 	 */
@@ -144,7 +149,7 @@ public synchronized void close() {
 	}
 
 	/**
-	 * Close webcam.
+	 * Close webcam (internal impl).
 	 */
 	private void close0() {
 
@@ -285,7 +290,14 @@ public static List<Webcam> getWebcams() {
 				driver = new WebcamDefaultDriver();
 			}
 
-			for (WebcamDevice device : driver.getDevices()) {
+			List<WebcamDevice> devices = driver.getDevices();
+
+			if (deallocOnTermSignal) {
+				LOG.warn("Automated deallocation on TERM signal is enabled!");
+				WebcamDeallocator.store(devices.toArray(new WebcamDevice[devices.size()]));
+			}
+
+			for (WebcamDevice device : devices) {
 				webcams.add(new Webcam(device));
 			}
 
@@ -462,4 +474,19 @@ protected void dispose() {
 		device.close();
 		device.dispose();
 	}
+
+	/**
+	 * <b>CAUTION!!!</b><br>
+	 * <br>
+	 * This is experimental feature to be used mostly in in development phase.
+	 * After you set handle term signal to true, and fetch capture devices,
+	 * Webcam Capture API will listen for TERM signal and try to close all
+	 * devices after it has been received. <b>This feature can be unstable on
+	 * some systems!</b>
+	 * 
+	 * @param on
+	 */
+	public static void handleTermSignal(boolean on) {
+		deallocOnTermSignal = on;
+	}
 }
diff --git a/webcam-capture/src/main/java/com/github/sarxos/webcam/WebcamDeallocator.java b/webcam-capture/src/main/java/com/github/sarxos/webcam/WebcamDeallocator.java
@@ -0,0 +1,68 @@
+package com.github.sarxos.webcam;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.PrintStream;
+import java.util.Observable;
+import java.util.Observer;
+
+
+
+/**
+ * Deallocator which goal is to release all devices resources when SIGTERM
+ * signal is detected.
+ * 
+ * @author Bartosz Firyn (SarXos)
+ */
+class WebcamDeallocator implements Observer {
+
+	private WebcamDevice[] devices = null;
+	private WebcamSignalHandler handler = new WebcamSignalHandler();
+
+	/**
+	 * This constructor is used internally to create new deallocator for the
+	 * given devices array.
+	 * 
+	 * @param devices the devices to be stored in deallocator
+	 */
+	private WebcamDeallocator(WebcamDevice[] devices) {
+		if (devices != null && devices.length > 0) {
+			this.devices = devices;
+			this.handler.listen("TERM", this);
+		}
+	}
+
+	/**
+	 * Store devices to be deallocated when TERM signal has been received.
+	 * 
+	 * @param devices the devices array to be stored by deallocator
+	 */
+	protected static final void store(WebcamDevice[] devices) {
+		new WebcamDeallocator(devices);
+	}
+
+	@Override
+	public void update(Observable observable, Object object) {
+		for (WebcamDevice device : devices) {
+			try {
+				device.close();
+			} catch (Throwable t) {
+				caugh(t);
+			}
+		}
+	}
+
+	public void caugh(Throwable e) {
+		File f = new File(String.format("webcam-capture-hs-%s", System.currentTimeMillis()));
+		PrintStream ps = null;
+		try {
+			e.printStackTrace(ps = new PrintStream(f));
+		} catch (FileNotFoundException e2) {
+			// ignore, stdout is not working, cannot do anything more
+		} finally {
+			if (ps != null) {
+				ps.close();
+			}
+		}
+	}
+}
diff --git a/webcam-capture/src/main/java/com/github/sarxos/webcam/WebcamSignalHandler.java b/webcam-capture/src/main/java/com/github/sarxos/webcam/WebcamSignalHandler.java
@@ -0,0 +1,42 @@
+package com.github.sarxos.webcam;
+
+import java.util.Observable;
+import java.util.Observer;
+
+import sun.misc.Signal;
+import sun.misc.SignalHandler;
+
+
+/**
+ * Primitive signal handler. This class is using undocumented classes from
+ * sun.misc.* and therefore should be used with caution.
+ * 
+ * @author Bartosz Firyn (SarXos)
+ */
+@SuppressWarnings("restriction")
+class WebcamSignalHandler extends Observable implements SignalHandler {
+
+	private SignalHandler handler = null;
+
+	public void listen(String signal, Observer observer) throws IllegalArgumentException {
+		addObserver(observer);
+		handler = Signal.handle(new Signal(signal), this);
+	}
+
+	@Override
+	public void handle(final sun.misc.Signal signal) {
+
+		// do nothing on "signal default" or "signal ignore"
+		if (handler == SIG_DFL || handler == SIG_IGN) {
+			return;
+		}
+
+		setChanged();
+
+		try {
+			notifyObservers(signal);
+		} finally {
+			handler.handle(signal);
+		}
+	}
+}
diff --git a/webcam-capture/src/main/java/com/github/sarxos/webcam/ds/buildin/WebcamDefaultDevice.java b/webcam-capture/src/main/java/com/github/sarxos/webcam/ds/buildin/WebcamDefaultDevice.java
@@ -50,7 +50,7 @@ public class WebcamDefaultDevice implements WebcamDevice {
 	 * Artificial view sizes. I'm really not sure if will fit into other webcams
 	 * but hope that OpenIMAJ can handle this.
 	 */
-	//@formatter:off
+	// @formatter:off
 	private final static Dimension[] DIMENSIONS = new Dimension[] {
 		SIZE_QQVGA,
 		SIZE_QVGA,
@@ -59,7 +59,7 @@ public class WebcamDefaultDevice implements WebcamDevice {
 		SIZE_VGA,
 		SIZE_XGA,
 	};
-	//@formatter:on
+	// @formatter:on
 
 	/**
 	 * RGB offsets.

diff --git a/webcam-capture/src/main/java/com/github/sarxos/webcam/ds/buildin/WebcamGrabberTask.java b/webcam-capture/src/main/java/com/github/sarxos/webcam/ds/buildin/WebcamGrabberTask.java
@@ -3,17 +3,38 @@
 import com.github.sarxos.webcam.ds.buildin.natives.OpenIMAJGrabber;
 
 
+/**
+ * Abstract webcam processor class.
+ * 
+ * @author Bartosz Firyn (SarXos)
+ */
 public abstract class WebcamGrabberTask {
 
+	/**
+	 * Native grabber.
+	 */
 	protected volatile OpenIMAJGrabber grabber = null;
 
-	protected void process(WebcamGrabberProcessor grabber) {
-		grabber.process(this);
+	/**
+	 * Process task by processor thread.
+	 * 
+	 * @param processor the processor to be used to process this task
+	 */
+	protected void process(WebcamGrabberProcessor processor) {
+		processor.process(this);
 	}
 
+	/**
+	 * Set grabber connected with specific device.
+	 * 
+	 * @param grabber the grabber to be set
+	 */
 	public void setGrabber(OpenIMAJGrabber grabber) {
 		this.grabber = grabber;
 	}
 
+	/**
+	 * Method to be called from inside of the processor thread.
+	 */
 	protected abstract void handle();
 }
diff --git a/webcam-capture/src/main/java/com/github/sarxos/webcam/ds/buildin/cgt/CloseSessionTask.java b/webcam-capture/src/main/java/com/github/sarxos/webcam/ds/buildin/cgt/CloseSessionTask.java
@@ -4,14 +4,30 @@
 import com.github.sarxos.webcam.ds.buildin.WebcamGrabberTask;
 
 
+/**
+ * This task is to close grabber session.
+ * 
+ * @author Bartosz Firyn (SarXos)
+ */
 public class CloseSessionTask extends WebcamGrabberTask {
 
+	/**
+	 * Grabber processor.
+	 */
 	private WebcamGrabberProcessor processor = null;
 
+	/**
+	 * Create task closing session of grabber connected with specific device.
+	 * 
+	 * @param processor
+	 */
 	public CloseSessionTask(WebcamGrabberProcessor processor) {
 		this.processor = processor;
 	}
 
+	/**
+	 * Method to be called from outside of the processor thread.
+	 */
 	public void closeSession() {
 		process(processor);
 	}