import java.util.Arrays;
import java.util.Hashtable;
import java.util.Vector;
+import java.lang.Runnable;
import java.util.concurrent.Semaphore;
/**
*
*/
-public abstract class Process extends Thread {
+public abstract class Process implements Runnable {
/**
* This attribute represents a bind between a java process object and
* a native process. Even if this attribute is public you must never
/* process synchronization tools */
- /* give the full path to semaphore to ensure that our own implementation don't get selected */
- protected java.util.concurrent.Semaphore schedBegin, schedEnd;
private boolean nativeStop = false;
/**
* Default constructor (used in ApplicationHandler to initialize it)
*/
protected Process() {
- super();
this.id = nextProcessId++;
this.name = null;
this.bind = 0;
this.args = new Vector<String>();
this.properties = null;
- schedBegin = new java.util.concurrent.Semaphore(0);
- schedEnd = new java.util.concurrent.Semaphore(0);
}
public Process(Host host, String name, String[]args) {
/* This is the constructor called by all others */
this();
-
+ this.host = host;
if (name == null)
throw new NullPointerException("Process name cannot be NULL");
this.name = name;
this.args = new Vector<String>();
if (null != args)
this.args.addAll(Arrays.asList(args));
-
- try {
- create(host.getName());
- } catch (HostNotFoundException e) {
- throw new RuntimeException("The impossible happened (yet again): the host that I have were not found",e);
- }
this.properties = new Hashtable<String,String>();
* Exit the process
*/
public native void exit();
-
+ /**
+ * This method actually creates and run the process.
+ * @throws HostNotFoundException
+ */
+ public void start() throws HostNotFoundException {
+ create(host.getName());
+ }
+
/**
* This method runs the process. Il calls the method function that you must overwrite.
*/
public void run() {
String[] args = null; /* do not fill it before the signal or this.args will be empty */
-
//waitSignal(); /* wait for other people to fill the process in */
-
- try {
- schedBegin.acquire();
- } catch(InterruptedException e) {
- }
-
try {
args = new String[this.args.size()];
if (this.args.size() > 0) {
this.main(args);
exit();
- schedEnd.release();
} catch(MsgException e) {
e.printStackTrace();
Msg.info("Unexpected behavior. Stopping now");
* exception now. This should be ok since we ignore only a very specific exception
* class and not a generic (such as any RuntimeException).
*/
- System.err.println(currentThread().getName()+": I ignore that other exception");
+ //System.err.println(currentThread().getName()+": I ignore that other exception");
}
- Msg.info(" Process " + ((Process) Thread.currentThread()).msgName() + " has been killed.");
- schedEnd.release();
+ //Msg.info(" Process " + ((Process) Thread.currentThread()).msgName() + " has been killed.");
}
else {
pk.printStackTrace();
*/
public abstract void main(String[]args) throws MsgException;
-
- /** @brief Gives the control from the given user thread back to the maestro
- *
- * schedule() and unschedule() are the basis of interactions between the user threads
- * (executing the user code), and the maestro thread (executing the platform models to decide
- * which user thread should get executed when. Once it decided which user thread should be run
- * (because the blocking action it were blocked onto are terminated in the simulated world), the
- * maestro passes the control to this uthread by calling uthread.schedule() in the maestro thread
- * (check its code for the simple semaphore-based synchronization schema).
- *
- * The uthread executes (while the maestro is blocked), until it starts another blocking
- * action, such as a communication or so. In that case, uthread.unschedule() gets called from
- * the user thread.
- *
- * As other complications, these methods are called directly by the C through a JNI upcall in
- * response to the JNI downcalls done by the Java code. For example, you have this (simplified)
- * execution path:
- * - a process calls the Task.send() method in java
- * - this calls Java_org_simgrid_msg_MsgNative_taskSend() in C through JNI
- * - this ends up calling jprocess_unschedule(), still in C
- * - this calls the java method "org/simgrid/msg/Process/unschedule()V" through JNI
- * - that is to say, the unschedule() method that you are reading the documentation of.
- *
- * To understand all this, you must keep in mind that there is no difference between the C thread
- * describing a process, and the Java thread doing the same. Most of the time, they are system
- * threads from the kernel anyway. In the other case (such as when using green java threads when
- * the OS does not provide any thread feature), I'm unsure of what happens: it's a very long time
- * that I didn't see any such OS.
- *
- * The synchronization itself is implemented using simple semaphores in Java, as you can see by
- * checking the code of these functions (and run() above). That's super simple, and thus welcome
- * given the global complexity of the synchronization architecture: getting C and Java cooperate
- * with regard to thread handling in a portable manner is very uneasy. A simple and straightforward
- * implementation of each synchronization point is precious.
- *
- * But this kinda limits the system scalability. It may reveal difficult to simulate dozens of
- * thousands of processes this way, both for memory limitations and for hard limits pushed by the
- * system on the amount of threads and semaphores (we have 2 semaphores per user process).
- *
- * At time of writing, the best source of information on how to simulate large systems within the
- * Java bindings of simgrid is here: http://tomp2p.net/dev/simgrid/
- *
- */
- public void unschedule() {
- /* this function is called from the user thread only */
- try {
-
- /* unlock the maestro before going to sleep */
- schedEnd.release();
- /* Here, the user thread is locked, waiting for the semaphore, and maestro executes instead */
- schedBegin.acquire();
- /* now that the semaphore is acquired, it means that maestro gave us the control back */
-
- /* the user thread is starting again after giving the control to maestro.
- * Let's check if we were asked to die in between */
- if ( (Thread.currentThread() instanceof Process) &&((Process) Thread.currentThread()).getNativeStop()) {
- throw new ProcessKilled();
- }
-
- } catch (InterruptedException e) {
- /* ignore this exception because this is how we get killed on process.kill or end of simulation.
- * I don't like hiding exceptions this way, but fail to see any other solution
- */
- }
-
- }
-
- /** @brief Gives the control from the maestro back to the given user thread
- *
- * Must be called from the maestro thread -- see unschedule() for details.
- *
- */
- public void schedule() {
- try {
- /* unlock the user thread before going to sleep */
- schedBegin.release();
- /* Here, maestro is locked, waiting for the schedEnd semaphore to get signaled by used thread, that executes instead */
- schedEnd.acquire();
- /* Maestro now has the control back and the user thread went to sleep gently */
-
- } catch(InterruptedException e) {
- throw new RuntimeException("The impossible did happend once again: I got interrupted in schedEnd.acquire()",e);
- }
- }
/**
* Class initializer, to initialize various JNI stuff