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;
17 import java.util.concurrent.Semaphore;
20 * A process may be defined as a code, with some private data, executing
21 * in a location (host). All the process used by your simulation must be
22 * declared in the deployment file (XML format).
23 * To create your own process you must inherit your own process from this
24 * class and override the method "main()". For example if you want to use
25 * a process named Slave proceed as it :
27 * (1) import the class Process of the package simgrid.msg
28 * import simgrid.msg.Process;
30 * public class Slave extends simgrid.msg.Process {
32 * (2) Override the method function
35 * public void main(String[] args) {
36 * System.out.println("Hello MSG");
40 * The name of your process must be declared in the deployment file of your simulation.
41 * For the example, for the previous process Slave this file must contains a line :
42 * <process host="Maxims" function="Slave"/>, where Maxims is the host of the process
43 * Slave. All the process of your simulation are automatically launched and managed by Msg.
44 * A process use tasks to simulate communications or computations with another process.
45 * For more information see Task. For more information on host concept
50 public abstract class Process extends Thread {
52 * This attribute represents a bind between a java process object and
53 * a native process. Even if this attribute is public you must never
54 * access to it. It is set automatically during the build of the object.
59 * Even if this attribute is public you must never access to it.
60 * It is used to compute the id of an MSG process.
62 public static long nextProcessId = 0;
65 * Even if this attribute is public you must never access to it.
66 * It is compute automatically during the creation of the object.
67 * The native functions use this identifier to synchronize the process.
74 public Hashtable<String,String> properties;
77 * The name of the process.
79 protected String name;
81 * The PID of the process
83 protected int pid = -1;
85 * The PPID of the process
87 protected int ppid = -1;
89 * The host of the process
91 protected Host host = null;
96 public String msgName() {
99 /** The arguments of the method function of the process. */
100 public Vector<String> args;
102 /* process synchronization tools */
109 protected Semaphore schedBegin, schedEnd;
110 private boolean nativeStop = false;
113 * Default constructor (used in ApplicationHandler to initialize it)
115 protected Process() {
117 this.id = nextProcessId++;
120 this.args = new Vector<String>();
121 this.properties = null;
122 schedBegin = new Semaphore(0);
123 schedEnd = new Semaphore(0);
128 * Constructs a new process from the name of a host and his name. The method
129 * function of the process doesn't have argument.
131 * @param hostname The name of the host of the process to create.
132 * @param name The name of the process.
134 * @exception HostNotFoundException if no host with this name exists.
138 public Process(String hostname, String name) throws HostNotFoundException {
139 this(Host.getByName(hostname), name, null);
142 * Constructs a new process from the name of a host and his name. The arguments
143 * of the method function of the process are specified by the parameter args.
145 * @param hostname The name of the host of the process to create.
146 * @param name The name of the process.
147 * @param args The arguments of the main function of the process.
149 * @exception HostNotFoundException if no host with this name exists.
151 * @throws NativeException
154 public Process(String hostname, String name, String args[]) throws HostNotFoundException, NativeException {
155 this(Host.getByName(hostname), name, args);
158 * Constructs a new process from a host and his name. The method function of the
159 * process doesn't have argument.
161 * @param host The host of the process to create.
162 * @param name The name of the process.
165 public Process(Host host, String name) {
166 this(host, name, null);
169 * Constructs a new process from a host and his name, the arguments of here method function are
170 * specified by the parameter args.
172 * @param host The host of the process to create.
173 * @param name The name of the process.
174 * @param args The arguments of main method of the process.
177 public Process(Host host, String name, String[]args) {
178 /* This is the constructor called by all others */
182 throw new NullPointerException("Process name cannot be NULL");
185 this.args = new Vector<String>();
187 this.args.addAll(Arrays.asList(args));
190 MsgNative.processCreate(this, host.getName());
191 } catch (HostNotFoundException e) {
192 throw new RuntimeException("The impossible happend (yet again): the host that I have were not found",e);
199 * This method kills all running process of the simulation.
201 * @param resetPID Should we reset the PID numbers. A negative number means no reset
202 * and a positive number will be used to set the PID of the next newly
205 * @return The function returns the PID of the next created process.
208 public static int killAll(int resetPID) {
209 return MsgNative.processKillAll(resetPID);
213 * This method sets a flag to indicate that this thread must be killed. End user must use static method kill
218 public void nativeStop()
223 * getter for the flag that indicates that this thread must be killed
228 public boolean getNativeStop()
234 * This method kill a process.
235 * @param process the process to be killed.
240 Msg.info("Process " + msgName() + " will be killed.");
245 * Suspends the process by suspending the task on which it was
246 * waiting for the completion.
249 public void pause() {
250 MsgNative.processSuspend(this);
253 * Resumes a suspended process by resuming the task on which it was
254 * waiting for the completion.
258 public void restart() {
259 MsgNative.processResume(this);
262 * Tests if a process is suspended.
264 * @return The method returns true if the process is suspended.
265 * Otherwise the method returns false.
267 public boolean isSuspended() {
268 return MsgNative.processIsSuspended(this);
271 * Returns the host of a process.
273 * @return The host instance of the process.
277 public Host getHost() {
278 if (this.host == null) {
279 this.host = MsgNative.processGetHost(this);
284 * This static method gets a process from a PID.
286 * @param PID The process identifier of the process to get.
288 * @return The process with the specified PID.
290 * @exception NativeException on error in the native SimGrid code
292 public static Process fromPID(int PID) throws NativeException {
293 return MsgNative.processFromPID(PID);
296 * This method returns the PID of the process.
298 * @return The PID of the process.
301 public int getPID() {
303 pid = MsgNative.processGetPID(this);
308 * This method returns the PID of the parent of a process.
310 * @return The PID of the parent of the process.
313 public int getPPID() {
315 ppid = MsgNative.processGetPPID(this);
320 * This static method returns the currently running process.
322 * @return The current process.
325 public static Process currentProcess() {
326 return MsgNative.processSelf();
329 * Migrates a process to another host.
331 * @param process The process to migrate.
332 * @param host The host where to migrate the process.
335 public static void migrate(Process process, Host host) {
336 MsgNative.processMigrate(process, host);
340 * Makes the current process sleep until time seconds have elapsed.
342 * @param seconds The time the current process must sleep.
344 * @exception HostFailureException on error in the native SimGrid code
346 public static void waitFor(double seconds) throws HostFailureException {
347 MsgNative.processWaitFor(seconds);
352 public void showArgs() {
353 Msg.info("[" + this.name + "/" + this.getHost().getName() + "] argc=" +
355 for (int i = 0; i < this.args.size(); i++)
356 Msg.info("[" + this.msgName() + "/" + this.getHost().getName() +
357 "] args[" + i + "]=" + (String) (this.args.get(i)));
360 * Let the simulated process sleep for the given amount of millisecond in the simulated world.
362 * You don't want to use sleep instead, because it would freeze your simulation
363 * run without any impact on the simulated world.
366 public native void simulatedSleep(double seconds);
369 * This method runs the process. Il calls the method function that you must overwrite.
373 String[]args = null; /* do not fill it before the signal or this.args will be empty */
375 //waitSignal(); /* wait for other people to fill the process in */
379 schedBegin.acquire();
380 } catch(InterruptedException e) {
384 args = new String[this.args.size()];
385 if (this.args.size() > 0) {
386 this.args.toArray(args);
390 MsgNative.processExit(this);
392 } catch(MsgException e) {
394 Msg.info("Unexpected behavior. Stopping now");
397 catch(ProcessKilled pk) {
400 MsgNative.processExit(this);
401 } catch (ProcessKilled pk2) {
402 /* Ignore that other exception that *will* occur all the time.
403 * This is because the C mechanic gives the control to the now-killed process
404 * so that it does some garbage collecting on its own. When it does so here,
405 * the Java thread checks when starting if it's supposed to be killed (to inform
406 * the C world). To avoid the infinite loop or anything similar, we ignore that
407 * exception now. This should be ok since we ignore only a very specific exception
408 * class and not a generic (such as any RuntimeException).
410 System.err.println(currentThread().getName()+": I ignore that other exception");
412 Msg.info(" Process " + ((Process) Thread.currentThread()).msgName() + " has been killed.");
416 pk.printStackTrace();
417 Msg.info("Unexpected behavior. Stopping now");
424 * The main function of the process (to implement).
427 * @throws MsgException
429 public abstract void main(String[]args) throws MsgException;
432 /** @brief Gives the control from the given user thread back to the maestro
434 * schedule() and unschedule() are the basis of interactions between the user threads
435 * (executing the user code), and the maestro thread (executing the platform models to decide
436 * which user thread should get executed when. Once it decided which user thread should be run
437 * (because the blocking action it were blocked onto are terminated in the simulated world), the
438 * maestro passes the control to this uthread by calling uthread.schedule() in the maestro thread
439 * (check its code for the simple semaphore-based synchronization schema).
441 * The uthread executes (while the maestro is blocked), until it starts another blocking
442 * action, such as a communication or so. In that case, uthread.unschedule() gets called from
445 * As other complications, these methods are called directly by the C through a JNI upcall in
446 * response to the JNI downcalls done by the Java code. For example, you have this (simplified)
448 * - a process calls the Task.send() method in java
449 * - this calls Java_org_simgrid_msg_MsgNative_taskSend() in C through JNI
450 * - this ends up calling jprocess_unschedule(), still in C
451 * - this calls the java method "org/simgrid/msg/Process/unschedule()V" through JNI
452 * - that is to say, the unschedule() method that you are reading the documentation of.
454 * To understand all this, you must keep in mind that there is no difference between the C thread
455 * describing a process, and the Java thread doing the same. Most of the time, they are system
456 * threads from the kernel anyway. In the other case (such as when using green java threads when
457 * the OS does not provide any thread feature), I'm unsure of what happens: it's a very long time
458 * that I didn't see any such OS.
460 * The synchronization itself is implemented using simple semaphores in Java, as you can see by
461 * checking the code of these functions (and run() above). That's super simple, and thus welcome
462 * given the global complexity of the synchronization architecture: getting C and Java cooperate
463 * with regard to thread handling in a portable manner is very uneasy. A simple and straightforward
464 * implementation of each synchronization point is precious.
466 * But this kinda limits the system scalability. It may reveal difficult to simulate dozens of
467 * thousands of processes this way, both for memory limitations and for hard limits pushed by the
468 * system on the amount of threads and semaphores (we have 2 semaphores per user process).
470 * At time of writing, the best source of information on how to simulate large systems within the
471 * Java bindings of simgrid is here: http://tomp2p.net/dev/simgrid/
474 public void unschedule() {
475 /* this function is called from the user thread only */
478 /* unlock the maestro before going to sleep */
480 /* Here, the user thread is locked, waiting for the semaphore, and maestro executes instead */
481 schedBegin.acquire();
482 /* now that the semaphore is acquired, it means that maestro gave us the control back */
484 /* the user thread is starting again after giving the control to maestro.
485 * Let's check if we were asked to die in between */
486 if ( (Thread.currentThread() instanceof Process) &&((Process) Thread.currentThread()).getNativeStop()) {
487 throw new ProcessKilled();
490 } catch (InterruptedException e) {
491 /* ignore this exception because this is how we get killed on process.kill or end of simulation.
492 * I don't like hiding exceptions this way, but fail to see any other solution
498 /** @brief Gives the control from the maestro back to the given user thread
500 * Must be called from the maestro thread -- see unschedule() for details.
503 public void schedule() {
505 /* unlock the user thread before going to sleep */
506 schedBegin.release();
507 /* Here, maestro is locked, waiting for the schedEnd semaphore to get signaled by used thread, that executes instead */
509 /* Maestro now has the control back and the user thread went to sleep gently */
511 } catch(InterruptedException e) {
512 throw new RuntimeException("The impossible did happend once again: I got interrupted in schedEnd.acquire()",e);
516 /** Send the given task in the mailbox associated with the specified alias (waiting at most given time)
520 * @throws TimeoutException
521 * @throws HostFailureException
522 * @throws TransferFailureException */
523 public void taskSend(String mailbox, Task task, double timeout) throws TransferFailureException, HostFailureException, TimeoutException {
524 MsgNative.taskSend(mailbox, task, timeout);
527 /** Send the given task in the mailbox associated with the specified alias
530 * @throws TimeoutException
531 * @throws HostFailureException
532 * @throws TransferFailureException */
533 public void taskSend(String mailbox, Task task) throws TransferFailureException, HostFailureException, TimeoutException {
534 MsgNative.taskSend(mailbox, task, -1);
537 /** Receive a task on mailbox associated with the specified mailbox
540 * @throws TransferFailureException
541 * @throws HostFailureException
542 * @throws TimeoutException
544 public Task taskReceive(String mailbox) throws TransferFailureException, HostFailureException, TimeoutException {
545 return MsgNative.taskReceive(mailbox, -1.0, null);
548 /** Receive a task on mailbox associated with the specified alias (waiting at most given time)
552 * @throws TransferFailureException
553 * @throws HostFailureException
554 * @throws TimeoutException
556 public Task taskReceive(String mailbox, double timeout) throws TransferFailureException, HostFailureException, TimeoutException {
557 return MsgNative.taskReceive(mailbox, timeout, null);
560 /** Receive a task on mailbox associated with the specified alias from given sender
565 * @throws TransferFailureException
566 * @throws HostFailureException
567 * @throws TimeoutException
569 public Task taskReceive(String mailbox, double timeout, Host host) throws TransferFailureException, HostFailureException, TimeoutException {
570 return MsgNative.taskReceive(mailbox, timeout, host);
573 /** Receive a task on mailbox associated with the specified alias from given sender
577 * @throws TransferFailureException
578 * @throws HostFailureException
579 * @throws TimeoutException
581 public Task taskReceive(String mailbox, Host host) throws TransferFailureException, HostFailureException, TimeoutException {
582 return MsgNative.taskReceive(mailbox, -1.0, host);