path: root/ace/Token.cpp

// Token.cpp
// $Id$

#define ACE_BUILD_DLL
#include "ace/Thread.h"
#include "ace/Token.h"

#if defined (ACE_HAS_THREADS)

#if !defined (__ACE_INLINE__)
#include "ace/Token.i"
#endif /* __ACE_INLINE__ */

ACE_ALLOC_HOOK_DEFINE(ACE_Token)

void
ACE_Token::dump (void) const
{
  ACE_TRACE ("ACE_Token::dump");
}

ACE_Token::ACE_Queue_Entry::ACE_Queue_Entry (ACE_Thread_Mutex &m, 
					     ACE_thread_t t_id)
  : next_ (0),
    thread_id_ (t_id),
    cv_ (m),
    runable_ (0)
{
  ACE_TRACE ("ACE_Token::ACE_Queue_Entry::ACE_Queue_Entry");
}

ACE_Token::ACE_Token (LPCTSTR name, void *any)
  : head_ (0), 
    tail_ (0), 
    lock_ (name, any),
    in_use_ (0), 
    waiters_ (0),
    nesting_level_ (0)
{
//  ACE_TRACE ("ACE_Token::ACE_Token");
}

ACE_Token::~ACE_Token (void)
{
  ACE_TRACE ("ACE_Token::~ACE_Token");
}

// Remove an entry from the list.  Must be 
// called with locks held.

void
ACE_Token::remove_entry (ACE_Token::ACE_Queue_Entry *entry)
{
  ACE_TRACE ("ACE_Token::remove_entry");
  ACE_Token::ACE_Queue_Entry *curr = 0;
  ACE_Token::ACE_Queue_Entry *prev = 0;

  if (this->head_ == 0)
    return;

  for (curr = this->head_;
       curr != 0 && curr != entry;
       curr = curr->next_)
    prev = curr;

  if (curr == 0) // Didn't find the entry...
    return; 
  else if (prev == 0) // Delete at the head.
    this->head_ = this->head_->next_;
  else // Delete in the middle.
    prev->next_ = curr->next_;

  // We need to update the tail of the list 
  // if we've deleted the last entry. 

  if (curr->next_ == 0)
    this->tail_ = curr;
}

int 
ACE_Token::shared_acquire (void (*sleep_hook_func)(void *), 
			   void *arg,
			   ACE_Time_Value *timeout)
{
  ACE_TRACE ("ACE_Token::shared_acquire");
  ACE_GUARD_RETURN (ACE_Thread_Mutex, ace_mon, this->lock_, -1);

  ACE_thread_t thr_id = ACE_Thread::self ();

#if defined (DEBUGGING)
  cerr << '(' << ACE_Thread::self () << ')'
       << " acquire: owner_ = " << this->owner_
       << ", owner_ addr = " << &this->owner_
       << ", nesting level = " << this->nesting_level_ << endl;
#endif /* DEBUGGING */

  if (this->in_use_) // Someone already holds the token.
    {	
      if (ACE_OS::thr_equal (thr_id, this->owner_)) // I own it!
	{	
	  this->nesting_level_++;
	  return 0;
	}
      // Do a quick check for "polling" behavior.
      else if (timeout != 0 && timeout->sec () == 0 && timeout->usec () == 0)
	{
	  errno = ETIME;
	  return -1;
	}
      else // We've got to sleep until we get the token.
	{
	  // Allocate q entry on stack.  This works since we don't
	  // exit this method's activation record until we've got the
	  // token.
	  ACE_Token::ACE_Queue_Entry my_entry (this->lock_, thr_id);
	  int ret = 0;

	  if (this->head_ == 0) // I'm first and only waiter in line...
	    {	
	      this->head_ = &my_entry;
	      this->tail_ = &my_entry;
	    }
	  else // I'm queued at the end of the list.
	    {
	      this->tail_->next_ = &my_entry;
	      this->tail_ = &my_entry;
	    } 

	  this->waiters_++;

	  // Execute appropriate <sleep_hook> callback.
	  // (@@ should these methods return a success/failure
	  // status, and if so, what should we do with it?) 

	  if (sleep_hook_func)
	    {
	      (*sleep_hook_func) (arg);
	      ret++;
	    }
	  else // Execute virtual method.
	    {
	      this->sleep_hook ();
	      ret++;
	    }

	  // Sleep until we've got the token (ignore signals).

	  while (my_entry.cv_.wait (timeout) == -1)
	    {
	      // Note, this should obey whatever thread-specific
	      // interrupt policy is currently in place...
	      if (errno == EINTR)
		continue;
#if defined (DEBUGGING)
	      cerr << '(' << ACE_Thread::self () << ')'
		   << " acquire: " 
		   << (errno == ETIME ? "timed out" : "error occurred") 
		   << endl;
#endif /* DEBUGGING */
	      // We come here if a timeout occurs or some serious
	      // ACE_Condition object error.
	      this->remove_entry (&my_entry);
	      return -1;
	    }

	  ACE_ASSERT (my_entry.runable_);
#if defined (DEBUGGING)
	  cerr << '(' << ACE_Thread::self () << ')'
	       << " acquire (UNBLOCKED)" << endl;
#endif /* DEBUGGING */
	  return ret;
	}
    }
  else
    {
      this->in_use_ = 1;
      this->owner_ = thr_id; // Its mine! 
      return 0;
    }
}

// By default this is a no-op.

/* virtual */
void
ACE_Token::sleep_hook (void)
{
  ACE_TRACE ("ACE_Token::sleep_hook");
}

int 
ACE_Token::acquire (ACE_Time_Value *timeout)
{
  ACE_TRACE ("ACE_Token::acquire");
  return this->shared_acquire (0, 0, timeout);
}

// Acquire the token, sleeping until it is obtained or until
// <timeout> expires.

int 
ACE_Token::acquire (void (*sleep_hook_func)(void *), 
		void *arg,
		ACE_Time_Value *timeout)
{
  ACE_TRACE ("ACE_Token::acquire");
  return this->shared_acquire (sleep_hook_func, arg, timeout);
}

// Try to renew the token.

int
ACE_Token::renew (int requeue_position, ACE_Time_Value *timeout)
{
  ACE_TRACE ("ACE_Token::renew");
  ACE_GUARD_RETURN (ACE_Thread_Mutex, ace_mon, this->lock_, -1);

#if defined (DEBUGGING)
  cerr << '(' << ACE_Thread::self () << ')'
       << " renew: owner_ thr = " << this->owner_ 
       << ", owner_ addr = " << &this->owner_ 
       << ", nesting level = " << this->nesting_level_ << endl;
#endif /* DEBUGGING */
  ACE_ASSERT (ACE_OS::thr_equal (ACE_Thread::self (), this->owner_));

  // Check to see if there are any waiters.  If not, we just keep the token.
  if (this->head_ != 0)
    {
      ACE_Token::ACE_Queue_Entry my_entry (this->lock_, this->owner_);
      int save_nesting_level_ = this->nesting_level_;

      this->owner_ = this->head_->thread_id_;
      this->nesting_level_ = 0;

      // Wake up next waiter and make it runable.
      this->head_->cv_.signal ();
      this->head_->runable_ = 1;

      this->head_ = this->head_->next_;

      if (this->head_ == 0) // No other threads - just add me 
	{	
	  this->head_ = &my_entry;
	  this->tail_ = &my_entry;
	} 
      else if (requeue_position == -1) // Insert at the end of the queue.
	{
	  this->tail_->next_ = &my_entry;
	  this->tail_ = &my_entry;
	}
      else if (requeue_position == 0) // Insert at head of queue.
	{
	  my_entry.next_ = this->head_;
	  this->head_ = &my_entry;
	}
      else // Insert in the middle of the queue somewhere.
	{
	  ACE_Token::ACE_Queue_Entry *insert_after = this->head_;

	  // Determine where our thread should go in the queue of
	  // waiters. 

	  while (requeue_position-- && insert_after->next_ != 0)
	    insert_after = insert_after->next_;

	  my_entry.next_ = insert_after->next_;

	  if (my_entry.next_ == 0)
	    this->tail_ = &my_entry;

	  insert_after->next_ = &my_entry;
	}

      // Sleep until we've got the token (ignore signals).

      while (my_entry.cv_.wait (timeout) == -1)
	{
	  // Note, this should obey whatever thread-specific
	  // interrupt policy is currently in place...
	  if (errno == EINTR)
	    continue;
#if defined (DEBUGGING)
	  cerr << '(' << ACE_Thread::self () << ')'
	       << " renew: " 
	       << (errno == ETIME ? "timed out" : "error occurred") << endl;
#endif /* DEBUGGING */
	  // We come here if a timeout occurs or 
	  // some serious ACE_Condition object error.
	  this->remove_entry (&my_entry);
	  return -1;
	}

      ACE_ASSERT (my_entry.runable_);
      this->nesting_level_ = save_nesting_level_;
      this->owner_ = my_entry.thread_id_;
    }
  return 0;
}

// Release the current holder of the token (which had
// better be the caller's thread!).

int
ACE_Token::release (void)
{
  ACE_TRACE ("ACE_Token::release");
  ACE_GUARD_RETURN (ACE_Thread_Mutex, ace_mon, this->lock_, -1);

  ACE_ASSERT (ACE_OS::thr_equal (ACE_Thread::self (), this->owner_));

#if defined (DEBUGGING)
  cerr << '(' << ACE_Thread::self () << ')'
       << " release: owner_ thr = " << this->owner_ 
       << ", owner_ addr = " << &this->owner_ 
       << ", nesting level = " << this->nesting_level_ << endl;
#endif /* DEBUGGING */

  if (this->nesting_level_ > 0)
    --this->nesting_level_;
  else 
    {
      if (this->head_ == 0)
	this->in_use_ = 0; // No more waiters...
      else 
	{
	  this->owner_ = this->head_->thread_id_;
	  --this->waiters_;

	  // Wake up waiter and make it runable.
	  this->head_->cv_.signal ();
	  this->head_->runable_ = 1;

	  this->head_ = this->head_->next_;

	  if (this->head_ == 0)
	    this->tail_ = 0;
	} 
    }
  return 0;
}

#endif /* ACE_HAS_THREADS */

#if defined (ACE_TEMPLATES_REQUIRE_SPECIALIZATION)
#endif /* ACE_TEMPLATES_REQUIRE_SPECIALIZATION */