gcc/libjava/java/lang/natThread.cc

// natThread.cc - Native part of Thread class.

/* Copyright (C) 1998, 1999, 2000  Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

#include <config.h>

#include <stdlib.h>

#include <gcj/cni.h>
#include <jvm.h>
#include <java-threads.h>

#include <java/lang/Thread.h>
#include <java/lang/ThreadGroup.h>
#include <java/lang/IllegalArgumentException.h>
#include <java/lang/UnsupportedOperationException.h>
#include <java/lang/IllegalThreadStateException.h>
#include <java/lang/InterruptedException.h>
#include <java/lang/NullPointerException.h>
#include <gnu/gcj/RawData.h>

#include <jni.h>



// This structure is used to represent all the data the native side
// needs.  An object of this type is assigned to the `data' member of
// the Thread class.
struct natThread
{
  // These are used to interrupt sleep and join calls.  We can share a
  // condition variable here since this thread can either be sleeping
  // or waiting for a thread exit, but not both.
  _Jv_Mutex_t interrupt_mutex;
  _Jv_ConditionVariable_t interrupt_cond;

  // This is private data for the thread system layer.
  _Jv_Thread_t *thread;

  // Each thread has its own JNI object.
  JNIEnv *jni_env;

  // All threads waiting to join this thread are linked together and
  // waiting on their respective `interrupt' condition variables.
  // When this thread exits, it notifies each such thread by
  // signalling the condition.  In this case the `interrupt_flag' is
  // not set; this is how the waiting thread knows whether the join
  // has failed or whether it should throw an exception.
  struct natThread *joiner;

  // Chain for waiters.
  struct natThread *next;
};

// We use this for its side effects: it lets us lock a mutex directly
// and not lose if an exception is thrown.
class locker
{
private:
  _Jv_Mutex_t *mutex;

public:
  locker (_Jv_Mutex_t *m)
    : mutex (m)
  {
    _Jv_MutexLock (mutex);
  }

  ~locker ()
  {
    _Jv_MutexUnlock (mutex);
  }
};

// This is called from the constructor to initialize the native side
// of the Thread.
void
java::lang::Thread::initialize_native (void)
{
  // FIXME: this must interact with the GC in some logical way.  At
  // the very least we must register a finalizer to clean up.  This
  // isn't easy to do.  If the Thread object resurrects itself in its
  // own finalizer then we will need to reinitialize this structure at
  // any "interesting" point.
  natThread *nt = (natThread *) _Jv_AllocBytes (sizeof (natThread));
  data = reinterpret_cast<gnu::gcj::RawData *> (nt);
  _Jv_MutexInit (&nt->interrupt_mutex);
  _Jv_CondInit (&nt->interrupt_cond);
  _Jv_ThreadInitData (&nt->thread, this);
  // FIXME: if JNI_ENV is set we will want to free it.  It is
  // malloc()d.
  nt->jni_env = NULL;
  nt->joiner = 0;
  nt->next = 0;
}

jint
java::lang::Thread::countStackFrames (void)
{
  // NOTE: This is deprecated in JDK 1.2.
  JvFail ("java::lang::Thread::countStackFrames unimplemented");
  return 0;
}

java::lang::Thread *
java::lang::Thread::currentThread (void)
{
  return _Jv_ThreadCurrent ();
}

void
java::lang::Thread::destroy (void)
{
  // NOTE: This is marked as unimplemented in the JDK 1.2
  // documentation.
  JvFail ("java::lang::Thread::destroy unimplemented");
}

void
java::lang::Thread::interrupt (void)
{
  interrupt_flag = true;

  // Wake up this thread, whether it is sleeping or waiting for
  // another thread to exit.
  natThread *nt = (natThread *) data;
  _Jv_MutexLock (&nt->interrupt_mutex);
  // Notify the interrupt condition to interrupt sleep() and join() calls.
  _Jv_CondNotify (&nt->interrupt_cond, &nt->interrupt_mutex);
  // Send a signal to the target thread to interrupt system calls. On Linux,
  // this will also interrupt the target thread from *any* _Jv_CondWait call,
  // ie wait(). This behaviour is not portable, however.
  _Jv_ThreadInterrupt (nt->thread);
  _Jv_MutexUnlock (&nt->interrupt_mutex);
}

void
java::lang::Thread::join (jlong millis, jint nanos)
{
  // FIXME: what if we are trying to join ourselves with no timeout?

  if (millis < 0 || nanos < 0 || nanos > 999999)
    _Jv_Throw (new IllegalArgumentException);

  Thread *current = currentThread ();
  if (current->isInterrupted_ ())
    _Jv_Throw (new InterruptedException);

  // Update the list of all threads waiting for this thread to exit.
  // We grab a mutex when doing this in order to ensure that the
  // required state changes are atomic.
  _Jv_MonitorEnter (this);
  if (! isAlive ())
    {
      _Jv_MonitorExit (this);
      return;
    }

  // Here `CURR_NT' is the native structure for the currently
  // executing thread, while `NT' is the native structure for the
  // thread we are trying to join.
  natThread *curr_nt = (natThread *) current->data;
  natThread *nt = (natThread *) data;

  JvAssert (curr_nt->next == NULL);
  // Put thread CURR_NT onto NT's list.  When NT exits, it will
  // traverse its list and notify all joiners.
  curr_nt->next = nt->joiner;
  nt->joiner = curr_nt;
  _Jv_MonitorExit (this);


  // Now wait for: (1) an interrupt, (2) the thread to exit, or (3)
  // the timeout to occur.  Use a `locker' object because _Jv_CondWait
  // can throw an exception.
  {
    locker l (&curr_nt->interrupt_mutex);
    _Jv_CondWait (&curr_nt->interrupt_cond,
		  &curr_nt->interrupt_mutex,
		  millis, nanos);
  }

  // Now the join has completed, one way or another.  Update the
  // joiners list to account for this.
  _Jv_MonitorEnter (this);
  JvAssert (nt->joiner != NULL);
  natThread *prev = 0;
  natThread *t;
  for (t = nt->joiner; t != NULL; t = t->next)
    {
      if (t == curr_nt)
	{
	  if (prev)
	    prev->next = t->next;
	  else
	    nt->joiner = t->next;
	  t->next = 0;
	  break;
	}
      prev = t;
    }
  JvAssert (t != NULL);
  _Jv_MonitorExit (this);

  if (current->isInterrupted_ ())
    _Jv_Throw (new InterruptedException);
}

void
java::lang::Thread::resume (void)
{
  checkAccess ();
  JvFail ("java::lang::Thread::resume unimplemented");
}

void
java::lang::Thread::setPriority (jint newPriority)
{
  checkAccess ();
  if (newPriority < MIN_PRIORITY || newPriority > MAX_PRIORITY)
    _Jv_Throw (new IllegalArgumentException);

  jint gmax = group->getMaxPriority();
  if (newPriority > gmax)
    newPriority = gmax;

  priority = newPriority;
  natThread *nt = (natThread *) data;
  _Jv_ThreadSetPriority (nt->thread, priority);
}

void
java::lang::Thread::sleep (jlong millis, jint nanos)
{
  if (millis < 0 || nanos < 0 || nanos > 999999)
    _Jv_Throw (new IllegalArgumentException);

  if (millis == 0 && nanos == 0)
    ++nanos;

  Thread *current = currentThread ();
  if (current->isInterrupted_ ())
    _Jv_Throw (new InterruptedException);

  // We use a condition variable to implement sleeping so that an
  // interrupt can wake us up.
  natThread *nt = (natThread *) current->data;
  {
    // Use a locker because _Jv_CondWait can throw an exception.
    locker l (&nt->interrupt_mutex);
    _Jv_CondWait (&nt->interrupt_cond, &nt->interrupt_mutex,
		  millis, nanos);
  }

  if (current->isInterrupted_ ())
    _Jv_Throw (new InterruptedException);
}

void
java::lang::Thread::finish_ ()
{
  // Notify all threads waiting to join this this.
  _Jv_MonitorEnter (this);
  alive_flag = false;

  // Note that we don't bother cleaning up the joiner list here.  That
  // is taken care of when each thread wakes up again.
  natThread *nt = (natThread *) data;
  for (natThread *t = nt->joiner; t != NULL; t = t->next)
    {
      _Jv_MutexLock (&t->interrupt_mutex);
      _Jv_CondNotify (&t->interrupt_cond, &t->interrupt_mutex);
      _Jv_MutexUnlock (&t->interrupt_mutex);
    }

  group->remove (this);

  _Jv_MonitorExit (this);
}

void
java::lang::Thread::run_ (jobject obj)
{
  java::lang::Thread *thread = (java::lang::Thread *) obj;
  try
    {
      thread->run ();
    }
  catch (java::lang::Throwable *t)
    {
      // Uncaught exceptions are forwarded to the ThreadGroup.  If
      // this results in an uncaught exception, that is ignored.
      try
	{
	  thread->group->uncaughtException (thread, t);
	}
      catch (java::lang::Throwable *f)
	{
	  // Nothing.
	}
    }

  thread->finish_ ();
}

void
java::lang::Thread::start (void)
{
  JvSynchronize sync (this);

  if (alive_flag)
    _Jv_Throw (new IllegalThreadStateException);

  alive_flag = true;
  natThread *nt = (natThread *) data;
  _Jv_ThreadStart (this, nt->thread, (_Jv_ThreadStartFunc *) &run_);
}

void
java::lang::Thread::stop (java::lang::Throwable *)
{
  _Jv_Throw (new UnsupportedOperationException
	     (JvNewStringLatin1 ("java::lang::Thread::stop unimplemented")));
}

void
java::lang::Thread::suspend (void)
{
  checkAccess ();
  _Jv_Throw (new UnsupportedOperationException 
	     (JvNewStringLatin1 ("java::lang::Thread::suspend unimplemented")));
}

void
java::lang::Thread::yield (void)
{
  _Jv_ThreadYield ();
}

JNIEnv *
_Jv_GetCurrentJNIEnv ()
{
  java::lang::Thread *t = _Jv_ThreadCurrent ();
  if (t == NULL)
    return NULL;
  return ((natThread *) t->data)->jni_env;
}

void
_Jv_SetCurrentJNIEnv (JNIEnv *env)
{
  java::lang::Thread *t = _Jv_ThreadCurrent ();
  JvAssert (t != NULL);
  ((natThread *) t->data)->jni_env = env;
}