1 files changed, 114 insertions, 0 deletions
diff --git a/src/java/com/cycling74/max/MaxQelem.java b/src/java/com/cycling74/max/MaxQelem.java
new file mode 100644
index 0000000..100f671
--- /dev/null
+++ b/src/java/com/cycling74/max/MaxQelem.java
@@ -0,0 +1,114 @@
+package com.cycling74.max;
+
+/**
+ * Background job utility class. This is used to execute code in the 
+ * background that might take time to execute. Calling <code>set</code>
+ * will trigger/execute the "job". If <code>set</code> is called while 
+ * the "job" is running, the "job" won't be called again.
+ * <p>On PDJ, a Qelem is simply a Java thread that wait to be triggered.
+ * </p> 
+ */
+public class MaxQelem {
+    Thread job;
+	Executable exec;
+	boolean incall;
+	static int nbQelem = 0;
+	boolean stopThread = true;
+	
+    /**
+     * Constructs a Qelem that is bound the overriden class with method
+     * name qfn.
+     */
+	public MaxQelem() {
+		exec = new Callback(this, "qfn");
+		do_init();
+	}
+
+    /**
+     * Constructs a Qelem that is bound to an executable.
+     * @param exec the executable to run
+     */
+	public MaxQelem(Executable exec) {
+		this.exec = exec;
+		do_init();
+	}
+	
+    /**
+     * Constructs a Qelem that is bound to a class with method name.
+     * @param src the object that contains the method
+     * @param method the method to execute
+     */
+	public MaxQelem(Object src, String method) {
+		exec = new Callback(src, method);
+		do_init();
+	}
+	
+	private void do_init() {
+	    job = new Thread(new Dispatcher(), "MaxQelem#" + (++nbQelem));
+	    job.setPriority(Thread.MIN_PRIORITY);
+	}
+	
+	/**
+	 * Puts thread in front execution. <b>Does nothing on PDJ</b>
+	 */
+	public void front() {
+	}
+
+	/**
+	 * The callback method, otherwise it calls the 'executable' method 
+	 * provided in constructor.
+	 */
+	public void qfn() {	
+	}
+	
+	/** 
+	 * Ask qfn to execute. If it is already set, the qfn won't be called
+	 * twice.
+	 */
+	public synchronized void set() {
+	    if ( !incall ) {
+	        job.notify();
+	    }
+	}
+	
+	/**
+	 * Cancels execution of qelem. Use with caution since it will throw
+	 * an InterruptedException on PDJ.
+	 */
+	public synchronized void unset() {
+	    job.interrupt();
+	}
+	
+	
+    /**
+     * Releases current Qelem and cancel the running thread.
+     */
+	public void release() {
+		unset();
+		stopThread = true;
+	}
+
+    /**
+     * Returns the executable object.
+     * @return the executble object that is bound to this Qelem
+     */
+	public Executable getExecutable() {
+		return exec;
+	}
+	
+	class Dispatcher implements Runnable {
+	    public void run() {
+	        while( !stopThread ) {
+	            try {
+	                incall = false;
+	                job.wait();
+	                incall = true;
+	                exec.execute();
+	            } catch (InterruptedException e) {
+                   // TODO Auto-generated catch block
+	                e.printStackTrace();
+                }
+		    }
+	    }
+	}
+}