java/lang/natThread.cc

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

/* Copyright (C) 1998, 1999, 2000, 2001, 2002  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 <jni.h>

#ifdef ENABLE_JVMPI
#include <jvmpi.h>
#endif


// 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 it only ever gets notified when the thread
  // exits.
  _Jv_Mutex_t join_mutex;
  _Jv_ConditionVariable_t join_cond;

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

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

static void finalize_native (jobject ptr);

// This is called from the constructor to initialize the native side
// of the Thread.
void
java::lang::Thread::initialize_native (void)
{
  natThread *nt = (natThread *) _Jv_AllocBytes (sizeof (natThread));

  // The native thread data is kept in a Object field, not a RawData, so that
  // the GC allocator can be used and a finalizer run after the thread becomes
  // unreachable. Note that this relies on the GC's ability to finalize
  // non-Java objects. FIXME?
  data = reinterpret_cast<jobject> (nt);

  // Register a finalizer to clean up the native thread resources.
  _Jv_RegisterFinalizer (data, finalize_native);

  _Jv_MutexInit (&nt->join_mutex);
  _Jv_CondInit (&nt->join_cond);
  nt->thread = _Jv_ThreadInitData (this);
  // FIXME: if JNI_ENV is set we will want to free it.  It is
  // malloc()d.
  nt->jni_env = NULL;
}

static void
finalize_native (jobject ptr)
{
  natThread *nt = (natThread *) ptr;
  _Jv_ThreadDestroyData (nt->thread);
}

jint
java::lang::Thread::countStackFrames (void)
{
  // NOTE: This is deprecated in JDK 1.2.
  throw new UnsupportedOperationException
    (JvNewStringLatin1 ("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.
  throw new UnsupportedOperationException
    (JvNewStringLatin1 ("Thread.destroy unimplemented"));
}

jboolean
java::lang::Thread::holdsLock (jobject obj)
{
  if (!obj)
    throw new NullPointerException;
  return !_Jv_ObjectCheckMonitor (obj);
}

void
java::lang::Thread::interrupt (void)
{
  natThread *nt = (natThread *) data;
  _Jv_ThreadInterrupt (nt->thread);
}

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

  Thread *current = currentThread ();

  // Here `NT' is the native structure for the thread we are trying to join.
  natThread *nt = (natThread *) data;

  // Now wait for: (1) an interrupt, (2) the thread to exit, or (3)
  // the timeout to occur.
  _Jv_MutexLock (&nt->join_mutex);
  if (! isAlive ())
    {
      _Jv_MutexUnlock (&nt->join_mutex);
      return;
    }
  _Jv_CondWait (&nt->join_cond, &nt->join_mutex, millis, nanos);
  _Jv_MutexUnlock (&nt->join_mutex);

  if (current->isInterrupted (true))
    throw new InterruptedException;
}

void
java::lang::Thread::resume (void)
{
  checkAccess ();
  throw new UnsupportedOperationException
    (JvNewStringLatin1 ("Thread.resume unimplemented"));
}

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

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

  Thread *current = currentThread ();

  // We use a condition variable to implement sleeping so that an
  // interrupt can wake us up.
  natThread *nt = (natThread *) current->data;
  _Jv_MutexLock (&nt->join_mutex);
  _Jv_CondWait (&nt->join_cond, &nt->join_mutex, millis, nanos);
  _Jv_MutexUnlock (&nt->join_mutex);

  if (current->isInterrupted (true))
    throw new InterruptedException;
}

void
java::lang::Thread::finish_ ()
{
  natThread *nt = (natThread *) data;

  group->removeThread (this);

#ifdef ENABLE_JVMPI
  if (_Jv_JVMPI_Notify_THREAD_END)
    {
      JVMPI_Event event;

      event.event_type = JVMPI_EVENT_THREAD_END;
      event.env_id = _Jv_GetCurrentJNIEnv ();

      _Jv_DisableGC ();
      (*_Jv_JVMPI_Notify_THREAD_END) (&event);
      _Jv_EnableGC ();
    }
#endif

  group = NULL;

  // Signal any threads that are waiting to join() us.
  _Jv_MutexLock (&nt->join_mutex);
  alive_flag = false;
  _Jv_CondNotifyAll (&nt->join_cond, &nt->join_mutex);
  _Jv_MutexUnlock (&nt->join_mutex);
}

// Run once at thread startup, either when thread is attached or when
// _Jv_ThreadRun is called.
static void
_Jv_NotifyThreadStart (java::lang::Thread* thread)
{
#ifdef ENABLE_JVMPI
      if (_Jv_JVMPI_Notify_THREAD_START)
	{
	  JVMPI_Event event;

	  jstring thread_name = thread->getName ();
	  jstring group_name = NULL, parent_name = NULL;
	  java::lang::ThreadGroup *group = thread->getThreadGroup ();

	  if (group)
	    {
	      group_name = group->getName ();
	      group = group->getParent ();

	      if (group)
		parent_name = group->getName ();
	    }

	  int thread_len = thread_name ? JvGetStringUTFLength (thread_name) : 0;
	  int group_len = group_name ? JvGetStringUTFLength (group_name) : 0;
	  int parent_len = parent_name ? JvGetStringUTFLength (parent_name) : 0;

	  char thread_chars[thread_len + 1];
	  char group_chars[group_len + 1];
	  char parent_chars[parent_len + 1];

	  if (thread_name)
	    JvGetStringUTFRegion (thread_name, 0,
				  thread_name->length(), thread_chars);
	  if (group_name)
	    JvGetStringUTFRegion (group_name, 0,
				  group_name->length(), group_chars);
	  if (parent_name)
	    JvGetStringUTFRegion (parent_name, 0,
				  parent_name->length(), parent_chars);

	  thread_chars[thread_len] = '\0';
	  group_chars[group_len] = '\0';
	  parent_chars[parent_len] = '\0';

	  event.event_type = JVMPI_EVENT_THREAD_START;
	  event.env_id = NULL;
	  event.u.thread_start.thread_name = thread_chars;
	  event.u.thread_start.group_name = group_chars;
	  event.u.thread_start.parent_name = parent_chars;
	  event.u.thread_start.thread_id = (jobjectID) thread;
	  event.u.thread_start.thread_env_id = _Jv_GetCurrentJNIEnv ();

	  _Jv_DisableGC ();
	  (*_Jv_JVMPI_Notify_THREAD_START) (&event);
	  _Jv_EnableGC ();
	}
#endif
}

void
_Jv_ThreadRun (java::lang::Thread* thread)
{
  try
    {
      _Jv_NotifyThreadStart (thread);
      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);

  // Its illegal to re-start() a thread, even if its dead.
  if (!startable_flag)
    throw new IllegalThreadStateException;

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

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

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

static int nextThreadNumber = 0;

jstring
java::lang::Thread::gen_name (void)
{
  jint i;
  jclass sync = &java::lang::Thread::class$;
  {
    JvSynchronize dummy(sync);
    i = ++nextThreadNumber;
  }

  // Use an array large enough for "-2147483648"; i.e. 11 chars, + "Thread-".
  jchar buffer[7+11];
  jchar *bufend = (jchar *) ((char *) buffer + sizeof(buffer));
  i = _Jv_FormatInt (bufend, i);
  jchar *ptr = bufend - i;
  // Prepend "Thread-".
  *--ptr = '-';
  *--ptr = 'd';
  *--ptr = 'a';
  *--ptr = 'e';
  *--ptr = 'r';
  *--ptr = 'h';
  *--ptr = 'T';
  return JvNewString (ptr, bufend - ptr);
}

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;
}

// Attach the current native thread to an existing (but unstarted) Thread
// object. Returns -1 on failure, 0 upon success.
jint
_Jv_AttachCurrentThread(java::lang::Thread* thread)
{
  if (thread == NULL || thread->startable_flag == false)
    return -1;
  thread->startable_flag = false;
  thread->alive_flag = true;
  natThread *nt = (natThread *) thread->data;
  _Jv_ThreadRegister (nt->thread);
  return 0;
}

java::lang::Thread*
_Jv_AttachCurrentThread(jstring name, java::lang::ThreadGroup* group)
{
  java::lang::Thread *thread = _Jv_ThreadCurrent ();
  if (thread != NULL)
    return thread;
  if (name == NULL)
    name = java::lang::Thread::gen_name ();
  thread = new java::lang::Thread (NULL, group, NULL, name);
  _Jv_AttachCurrentThread (thread);
  _Jv_NotifyThreadStart (thread);
  return thread;
}

java::lang::Thread*
_Jv_AttachCurrentThreadAsDaemon(jstring name, java::lang::ThreadGroup* group)
{
  java::lang::Thread *thread = _Jv_ThreadCurrent ();
  if (thread != NULL)
    return thread;
  if (name == NULL)
    name = java::lang::Thread::gen_name ();
  thread = new java::lang::Thread (NULL, group, NULL, name);
  thread->setDaemon (true);
  _Jv_AttachCurrentThread (thread);
  _Jv_NotifyThreadStart (thread);
  return thread;
}

jint
_Jv_DetachCurrentThread (void)
{
  java::lang::Thread *t = _Jv_ThreadCurrent ();
  if (t == NULL)
    return -1;

  _Jv_ThreadUnRegister ();
  // Release the monitors.
  t->finish_ ();

  return 0;
}