4 * Copyright 2006,2007 Martin Quinson, Malek Cherier
7 * This program is free software; you can redistribute
8 * it and/or modify it under the terms of the license
9 *(GNU LGPL) which comes with this package.
12 package org.simgrid.msg;
14 import java.util.Arrays;
15 import java.util.Hashtable;
16 import java.util.Vector;
19 * A process may be defined as a code, with some private data, executing
20 * in a location (host). All the process used by your simulation must be
21 * declared in the deployment file (XML format).
22 * To create your own process you must inherit your own process from this
23 * class and override the method "main()". For example if you want to use
24 * a process named Slave proceed as it :
26 * (1) import the class Process of the package simgrid.msg
27 * import simgrid.msg.Process;
29 * public class Slave extends simgrid.msg.Process {
31 * (2) Override the method function
34 * public void main(String[] args) {
35 * System.out.println("Hello MSG");
39 * The name of your process must be declared in the deployment file of your simulation.
40 * For the example, for the previous process Slave this file must contains a line :
41 * <process host="Maxims" function="Slave"/>, where Maxims is the host of the process
42 * Slave. All the process of your simulation are automatically launched and managed by Msg.
43 * A process use tasks to simulate communications or computations with another process.
44 * For more information see Task. For more information on host concept
49 public abstract class Process extends Thread {
51 * This attribute represents a bind between a java process object and
52 * a native process. Even if this attribute is public you must never
53 * access to it. It is set automatically during the build of the object.
58 * Even if this attribute is public you must never access to it.
59 * It is used to compute the id of an MSG process.
61 public static long nextProcessId = 0;
64 * Even if this attribute is public you must never access to it.
65 * It is compute automatically during the creation of the object.
66 * The native functions use this identifier to synchronize the process.
73 public Hashtable<String,String> properties;
76 * The name of the process.
78 protected String name;
80 * The PID of the process
82 protected int pid = -1;
84 * The PPID of the process
86 protected int ppid = -1;
88 * The host of the process
90 protected Host host = null;
95 public String msgName() {
98 /** The arguments of the method function of the process. */
99 public Vector<String> args;
101 /* process synchronization tools */
108 protected Sem schedBegin, schedEnd;
109 private boolean nativeStop = false;
112 * Default constructor (used in ApplicationHandler to initialize it)
114 protected Process() {
116 this.id = nextProcessId++;
119 this.args = new Vector<String>();
120 this.properties = null;
121 schedBegin = new Sem(0);
122 schedEnd = new Sem(0);
127 * Constructs a new process from the name of a host and his name. The method
128 * function of the process doesn't have argument.
130 * @param hostname The name of the host of the process to create.
131 * @param name The name of the process.
133 * @exception HostNotFoundException if no host with this name exists.
137 public Process(String hostname, String name) throws HostNotFoundException {
138 this(Host.getByName(hostname), name, null);
141 * Constructs a new process from the name of a host and his name. The arguments
142 * of the method function of the process are specified by the parameter args.
144 * @param hostname The name of the host of the process to create.
145 * @param name The name of the process.
146 * @param args The arguments of the main function of the process.
148 * @exception HostNotFoundException if no host with this name exists.
150 * @throws NativeException
153 public Process(String hostname, String name, String args[]) throws HostNotFoundException, NativeException {
154 this(Host.getByName(hostname), name, args);
157 * Constructs a new process from a host and his name. The method function of the
158 * process doesn't have argument.
160 * @param host The host of the process to create.
161 * @param name The name of the process.
164 public Process(Host host, String name) {
165 this(host, name, null);
168 * Constructs a new process from a host and his name, the arguments of here method function are
169 * specified by the parameter args.
171 * @param host The host of the process to create.
172 * @param name The name of the process.
173 * @param args The arguments of main method of the process.
176 public Process(Host host, String name, String[]args) {
177 /* This is the constructor called by all others */
181 throw new NullPointerException("Process name cannot be NULL");
184 this.args = new Vector<String>();
186 this.args.addAll(Arrays.asList(args));
188 MsgNative.processCreate(this, host);
194 * This method kills all running process of the simulation.
196 * @param resetPID Should we reset the PID numbers. A negative number means no reset
197 * and a positive number will be used to set the PID of the next newly
200 * @return The function returns the PID of the next created process.
203 public static int killAll(int resetPID) {
204 return MsgNative.processKillAll(resetPID);
208 * This method sets a flag to indicate that this thread must be killed. End user must use static method kill
213 public void nativeStop()
218 * getter for the flag that indicates that this thread must be killed
223 public boolean getNativeStop()
228 * checks if the flag that indicates that this thread must be killed is set to true; if true, starts to kill it. End users should not have to deal with it
229 * If you develop a new MSG native call, please include a call to interruptedStop() at the beginning of your method code, so as the process can be killed if he call
236 public static void ifInterruptedStop() {
237 /* This function does nothing anymore and will get removed very soon */
242 * This method kill a process.
243 * @param process the process to be killed.
248 Msg.info("Process " + msgName() + " will be killed.");
253 * Suspends the process by suspending the task on which it was
254 * waiting for the completion.
257 public void pause() {
258 Process.ifInterruptedStop();
259 MsgNative.processSuspend(this);
262 * Resumes a suspended process by resuming the task on which it was
263 * waiting for the completion.
267 public void restart() {
268 Process.ifInterruptedStop();
269 MsgNative.processResume(this);
272 * Tests if a process is suspended.
274 * @return The method returns true if the process is suspended.
275 * Otherwise the method returns false.
277 public boolean isSuspended() {
278 Process.ifInterruptedStop();
279 return MsgNative.processIsSuspended(this);
282 * Returns the host of a process.
284 * @return The host instance of the process.
288 public Host getHost() {
289 Process.ifInterruptedStop();
290 if (this.host == null) {
291 this.host = MsgNative.processGetHost(this);
296 * This static method gets a process from a PID.
298 * @param PID The process identifier of the process to get.
300 * @return The process with the specified PID.
302 * @exception NativeException on error in the native SimGrid code
304 public static Process fromPID(int PID) throws NativeException {
305 Process.ifInterruptedStop();
306 return MsgNative.processFromPID(PID);
309 * This method returns the PID of the process.
311 * @return The PID of the process.
314 public int getPID() {
315 Process.ifInterruptedStop();
317 pid = MsgNative.processGetPID(this);
322 * This method returns the PID of the parent of a process.
324 * @return The PID of the parent of the process.
327 public int getPPID() {
328 Process.ifInterruptedStop();
330 ppid = MsgNative.processGetPPID(this);
335 * This static method returns the currently running process.
337 * @return The current process.
340 public static Process currentProcess() {
341 Process.ifInterruptedStop();
342 return MsgNative.processSelf();
345 * Migrates a process to another host.
347 * @param process The process to migrate.
348 * @param host The host where to migrate the process.
351 public static void migrate(Process process, Host host) {
352 Process.ifInterruptedStop();
353 MsgNative.processMigrate(process, host);
357 * Makes the current process sleep until time seconds have elapsed.
359 * @param seconds The time the current process must sleep.
361 * @exception HostFailureException on error in the native SimGrid code
363 public static void waitFor(double seconds) throws HostFailureException {
364 Process.ifInterruptedStop();
365 MsgNative.processWaitFor(seconds);
370 public void showArgs() {
371 Process.ifInterruptedStop();
372 Msg.info("[" + this.name + "/" + this.getHost().getName() + "] argc=" +
374 for (int i = 0; i < this.args.size(); i++)
375 Msg.info("[" + this.msgName() + "/" + this.getHost().getName() +
376 "] args[" + i + "]=" + (String) (this.args.get(i)));
379 * Let the simulated process sleep for the given amount of millisecond in the simulated world.
381 * You don't want to use sleep instead, because it would freeze your simulation
382 * run without any impact on the simulated world.
385 public native void simulatedSleep(double seconds);
388 * This method runs the process. Il calls the method function that you must overwrite.
392 String[]args = null; /* do not fill it before the signal or this.args will be empty */
394 //waitSignal(); /* wait for other people to fill the process in */
398 schedBegin.acquire();
399 } catch(InterruptedException e) {
403 args = new String[this.args.size()];
404 if (this.args.size() > 0) {
405 this.args.toArray(args);
409 MsgNative.processExit(this);
411 } catch(MsgException e) {
413 Msg.info("Unexpected behavior. Stopping now");
416 catch(ProcessKilled pk) {
419 MsgNative.processExit(this);
420 } catch (ProcessKilled pk2) {
421 /* Ignore that other exception that *will* occur all the time.
422 * This is because the C mechanic gives the control to the now-killed process
423 * so that it does some garbage collecting on its own. When it does so here,
424 * the Java thread checks when starting if it's supposed to be killed (to inform
425 * the C world). To avoid the infinite loop or anything similar, we ignore that
426 * exception now. This should be ok since we ignore only a very specific exception
427 * class and not a generic (such as any RuntimeException).
429 System.err.println(currentThread().getName()+": I ignore that other exception");
431 Msg.info(" Process " + ((Process) Thread.currentThread()).msgName() + " has been killed.");
435 pk.printStackTrace();
436 Msg.info("Unexpected behavior. Stopping now");
443 * The main function of the process (to implement).
446 * @throws MsgException
448 public abstract void main(String[]args) throws MsgException;
451 /** @brief Gives the control from the given user thread back to the maestro
453 * schedule() and unschedule() are the basis of interactions between the user threads
454 * (executing the user code), and the maestro thread (executing the platform models to decide
455 * which user thread should get executed when. Once it decided which user thread should be run
456 * (because the blocking action it were blocked onto are terminated in the simulated world), the
457 * maestro passes the control to this uthread by calling uthread.schedule() in the maestro thread
458 * (check its code for the simple semaphore-based synchronization schema).
460 * The uthread executes (while the maestro is blocked), until it starts another blocking
461 * action, such as a communication or so. In that case, uthread.unschedule() gets called from
464 * As other complications, these methods are called directly by the C through a JNI upcall in
465 * response to the JNI downcalls done by the Java code. For example, you have this (simplified)
467 * - a process calls the Task.send() method in java
468 * - this calls Java_org_simgrid_msg_MsgNative_taskSend() in C through JNI
469 * - this ends up calling jprocess_unschedule(), still in C
470 * - this calls the java method "org/simgrid/msg/Process/unschedule()V" through JNI
471 * - that is to say, the unschedule() method that you are reading the documentation of.
473 * To understand all this, you must keep in mind that there is no difference between the C thread
474 * describing a process, and the Java thread doing the same. Most of the time, they are system
475 * threads from the kernel anyway. In the other case (such as when using green java threads when
476 * the OS does not provide any thread feature), I'm unsure of what happens: it's a very long time
477 * that I didn't see any such OS.
479 * The synchronization itself is implemented using simple semaphores in Java, as you can see by
480 * checking the code of these functions (and run() above). That's super simple, and thus welcome
481 * given the global complexity of the synchronization architecture: getting C and Java cooperate
482 * with regard to thread handling in a portable manner is very uneasy. A simple and straightforward
483 * implementation of each synchronization point is precious.
485 * But this kinda limits the system scalability. It may reveal difficult to simulate dozens of
486 * thousands of processes this way, both for memory limitations and for hard limits pushed by the
487 * system on the amount of threads and semaphores (we have 2 semaphores per user process).
489 * At time of writing, the best source of information on how to simulate large systems within the
490 * Java bindings of simgrid is here: http://tomp2p.net/dev/simgrid/
493 public void unschedule() {
494 /* this function is called from the user thread only */
497 /* unlock the maestro before going to sleep */
499 /* Here, the user thread is locked, waiting for the semaphore, and maestro executes instead */
500 schedBegin.acquire();
501 /* now that the semaphore is acquired, it means that maestro gave us the control back */
503 /* the user thread is starting again after giving the control to maestro.
504 * Let's check if we were asked to die in between */
505 if ( (Thread.currentThread() instanceof Process) &&((Process) Thread.currentThread()).getNativeStop()) {
506 throw new ProcessKilled();
509 } catch (InterruptedException e) {
510 /* ignore this exception because this is how we get killed on process.kill or end of simulation.
511 * I don't like hiding exceptions this way, but fail to see any other solution
517 /** @brief Gives the control from the maestro back to the given user thread
519 * Must be called from the maestro thread -- see unschedule() for details.
522 public void schedule() {
524 /* unlock the user thread before going to sleep */
525 schedBegin.release();
526 /* Here, maestro is locked, waiting for the schedEnd semaphore to get signaled by used thread, that executes instead */
528 /* Maestro now has the control back and the user thread went to sleep gently */
530 } catch(InterruptedException e) {
531 throw new RuntimeException("The impossible did happend once again: I got interrupted in schedEnd.acquire()",e);
535 /** Send the given task in the mailbox associated with the specified alias (waiting at most given time)
539 * @throws TimeoutException
540 * @throws HostFailureException
541 * @throws TransferFailureException */
542 public void taskSend(String mailbox, Task task, double timeout) throws TransferFailureException, HostFailureException, TimeoutException {
543 Process.ifInterruptedStop();
544 MsgNative.taskSend(mailbox, task, timeout);
547 /** Send the given task in the mailbox associated with the specified alias
550 * @throws TimeoutException
551 * @throws HostFailureException
552 * @throws TransferFailureException */
553 public void taskSend(String mailbox, Task task) throws TransferFailureException, HostFailureException, TimeoutException {
554 Process.ifInterruptedStop();
555 MsgNative.taskSend(mailbox, task, -1);
558 /** Receive a task on mailbox associated with the specified mailbox
561 * @throws TransferFailureException
562 * @throws HostFailureException
563 * @throws TimeoutException
565 public Task taskReceive(String mailbox) throws TransferFailureException, HostFailureException, TimeoutException {
566 Process.ifInterruptedStop();
567 return MsgNative.taskReceive(mailbox, -1.0, null);
570 /** Receive a task on mailbox associated with the specified alias (waiting at most given time)
574 * @throws TransferFailureException
575 * @throws HostFailureException
576 * @throws TimeoutException
578 public Task taskReceive(String mailbox, double timeout) throws TransferFailureException, HostFailureException, TimeoutException {
579 Process.ifInterruptedStop();
580 return MsgNative.taskReceive(mailbox, timeout, null);
583 /** Receive a task on mailbox associated with the specified alias from given sender
588 * @throws TransferFailureException
589 * @throws HostFailureException
590 * @throws TimeoutException
592 public Task taskReceive(String mailbox, double timeout, Host host) throws TransferFailureException, HostFailureException, TimeoutException {
593 Process.ifInterruptedStop();
594 return MsgNative.taskReceive(mailbox, timeout, host);
597 /** Receive a task on mailbox associated with the specified alias from given sender
601 * @throws TransferFailureException
602 * @throws HostFailureException
603 * @throws TimeoutException
605 public Task taskReceive(String mailbox, Host host) throws TransferFailureException, HostFailureException, TimeoutException {
606 Process.ifInterruptedStop();
607 return MsgNative.taskReceive(mailbox, -1.0, host);