vpr::MutexPosix Class Reference

Mutex wrapper for POSIX-compliant systems using pthreads mutex variables for the implementation. More...

#include <vpr/Sync/Mutex.h>

List of all members.

Public Member Functions
	MutexPosix ()
	Constructor for vpr::MutexPosix class.
	~MutexPosix ()
	Destructor for vpr::MutexPosix class.
vpr::ReturnStatus	acquire ()
	Locks this mutex.
vpr::ReturnStatus	acquireRead ()
	Acquires a read lock on this mutex.
vpr::ReturnStatus	acquireWrite ()
	Acquires a write lock on this mutex.
vpr::ReturnStatus	tryAcquire ()
	Tries to acquire a lock on this mutex variable (does not block).
vpr::ReturnStatus	tryAcquireRead ()
	Tries to acquire a read lock on this mutex (does not block).
vpr::ReturnStatus	tryAcquireWrite ()
	Tries to acquire a write lock on this mutex (does not block).
vpr::ReturnStatus	release ()
	Releases this mutex.
int	test () const
	Tests the current lock status.
Protected Member Functions
void	operator= (const MutexPosix &)
	MutexPosix (const MutexPosix &)
Protected Attributes
pthread_mutex_t	mMutex
	Mutex variable for the class.
Friends
class	CondVarPosix

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Detailed Description

Mutex wrapper for POSIX-compliant systems using pthreads mutex variables for the implementation.

This is typedef'd to vpr::Mutex.

Definition at line 70 of file MutexPosix.h.

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Constructor & Destructor Documentation

vpr::MutexPosix::MutexPosix

(

)

Constructor for vpr::MutexPosix class.

Postcondition:

The mutex variable is initialized for use. It must be initialized before any other member functions can do anything with it.

Definition at line 49 of file MutexPosix.cpp.

References mMutex.

{
   // Initialize the mutex.
#ifndef _DEBUG
   pthread_mutex_init(&mMutex, NULL);
#else
#ifdef VPR_OS_Linux
   // If Linux and debug, then use error checking mutex
   pthread_mutexattr_t mutex_attr;
   pthread_mutexattr_init(&mutex_attr);
   pthread_mutexattr_settype(&mutex_attr, PTHREAD_MUTEX_ERRORCHECK_NP);
   pthread_mutex_init(&mMutex, &mutex_attr);
   pthread_mutexattr_destroy(&mutex_attr);
#else
   pthread_mutex_init(&mMutex, NULL);
#endif
#endif
}

vpr::MutexPosix::~MutexPosix

(

)

[inline]

Destructor for vpr::MutexPosix class.

Precondition:

The mutex variable should be unlocked before being destroyed, but if it is not, this routine will unlock it and then destroy it.

Postcondition:

The mutex variable is destroyed and unlocked if necessary.

Definition at line 90 of file MutexPosix.h.

References mMutex.

   {
      // Destroy the mutex.
      if ( pthread_mutex_destroy(&mMutex) == -1 )
      {
         pthread_mutex_unlock(&mMutex);
         pthread_mutex_destroy(&mMutex);
      }
   }

vpr::MutexPosix::MutexPosix

(

const MutexPosix &

)

[inline, protected]

Definition at line 277 of file MutexPosix.h.

{;}

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Member Function Documentation

vpr::ReturnStatus vpr::MutexPosix::acquire

(

)

[inline]

Locks this mutex.

Postcondition:

A lock on the mutex variable is acquired by the caller. If a lock has already been acquired by another process/thread, the caller blocks until the mutex has been freed.

Returns:

vpr::ReturnStatus::Succeed is returned if the lock is acquired.

vpr::ReturnStatus::Fail is returned if an error occurred.

Definition at line 110 of file MutexPosix.h.

References vpr::ReturnStatus::Fail, and mMutex.

Referenced by vpr::SocketStreamImplSIM::accept(), vpr::CondVarPosix::acquire(), acquireRead(), acquireWrite(), vpr::SocketStreamImplSIM::addConnector(), vpr::sim::SocketManager::connect(), vpr::Debug::getStream(), vpr::ThreadPool::getThread(), vpr::sim::SocketManager::isListening(), vpr::sim::SocketManager::listen(), vpr::operator<<(), vpr::SocketImplSIM::read_i(), vpr::ThreadPool::threadLoop(), vpr::ThreadPool::threadSleep(), vpr::ThreadPool::wait(), and vpr::CondVarGeneric::wait().

   {
      int retval = pthread_mutex_lock(&mMutex);

      // Locking succeeded.
      if ( retval == 0 )
      {
         return vpr::ReturnStatus();
      }
#ifdef _DEBUG
      // This thread tried to lock the mutex twice and a deadlock condition
      // was reported.
      else if ( retval == EDEADLK )
      {
         perror("Tried to lock mutex twice");
         assert(false && "Mutex deadlock detected");
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
#endif
      // Some other error occurred.
      else
      {
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
   }

vpr::ReturnStatus vpr::MutexPosix::acquireRead

(

)

[inline]

Acquires a read lock on this mutex.

Postcondition:

A lock on the mutex variable is acquired by the caller. If a lock has already been acquired by another process/thread, the caller blocks until the mutex has been freed.

Returns:

vpr::ReturnStatus::Succeed is returned if the lock is acquired.

vpr::ReturnStatus::Fail is returned if an error occurred.

Note:

No special read lock has been defined for now.

Definition at line 148 of file MutexPosix.h.

References acquire().

   {
      return this->acquire();
   }

vpr::ReturnStatus vpr::MutexPosix::acquireWrite

(

)

[inline]

Acquires a write lock on this mutex.

Postcondition:

A lock on the mutex variable is acquired by the caller. If a lock has already been acquired by another process/thread, the caller blocks until the mutex has been freed.

Returns:

vpr::ReturnStatus::Succeed is returned if the lock is acquired.

vpr::ReturnStatus::Fail is returned if an error occurred.

Note:

No special write lock has been defined for now.

Definition at line 165 of file MutexPosix.h.

References acquire().

   {
      return this->acquire();
   }

vpr::ReturnStatus vpr::MutexPosix::tryAcquire

(

)

[inline]

Tries to acquire a lock on this mutex variable (does not block).

Postcondition:

A lock on the mutex variable is acquired by the caller. If a lock has already been acquired by another process/thread, the caller returns does not wait for it to be unlocked.

Returns:

vpr::ReturnStatus::Succeed is returned if the lock is acquired.

vpr::ReturnStatus::Fail is returned if the mutex is already locked.

Definition at line 181 of file MutexPosix.h.

References vpr::ReturnStatus::Fail, and mMutex.

Referenced by vpr::CondVarPosix::tryAcquire(), tryAcquireRead(), and tryAcquireWrite().

   {
      if ( pthread_mutex_trylock(&mMutex) == 0 )
      {
         return vpr::ReturnStatus();
      }
      else
      {
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
   }

vpr::ReturnStatus vpr::MutexPosix::tryAcquireRead

(

)

[inline]

Tries to acquire a read lock on this mutex (does not block).

Postcondition:

A lock on the mutex variable is acquired by the caller. If a lock has already been acquired by another process/thread, the caller returns does not wait for it to be unlocked.

Returns:

vpr::ReturnStatus::Succeed is returned if the read lock is acquired.

vpr::ReturnStatus::Fail is returned if the mutex is already locked.

Definition at line 205 of file MutexPosix.h.

References tryAcquire().

   {
      return this->tryAcquire();
   }

vpr::ReturnStatus vpr::MutexPosix::tryAcquireWrite

(

)

[inline]

Tries to acquire a write lock on this mutex (does not block).

Postcondition:

A lock on the mutex variable is acquired by the caller. If a lock has already been acquired by another process/thread, the caller returns does not wait for it to be unlocked.

Returns:

vpr::ReturnStatus::Succeed is returned if the write lock is acquired.

vpr::ReturnStatus::Fail is returned if the mutex is already locked.

Definition at line 222 of file MutexPosix.h.

References tryAcquire().

   {
      return this->tryAcquire();
   }

vpr::ReturnStatus vpr::MutexPosix::release

(

)

[inline]

Releases this mutex.

Precondition:

The mutex variable must be locked.

Postcondition:

The mutex variable is unlocked.

Returns:

vpr::ReturnStatus::Succeed is returned if the lock is released successfully.

vpr::ReturnStatus::Fail is returned otherwise.

Definition at line 237 of file MutexPosix.h.

References vpr::ReturnStatus::Fail, and mMutex.

Referenced by vpr::SocketStreamImplSIM::accept(), vpr::SocketStreamImplSIM::addConnector(), vpr::sim::SocketManager::connect(), vpr::ThreadPool::getThread(), vpr::sim::SocketManager::isListening(), vpr::sim::SocketManager::listen(), vpr::operator<<(), vpr::SocketImplSIM::read_i(), vpr::CondVarPosix::release(), vpr::CondVarPosix::setMutex(), vpr::CondVarGeneric::setMutex(), vpr::ThreadPool::threadLoop(), vpr::ThreadPool::ThreadPool(), vpr::ThreadPool::threadSleep(), vpr::ThreadPool::wait(), and vpr::CondVarGeneric::wait().

   {
      int retval = pthread_mutex_unlock(&mMutex);

      if (0 == retval )
      {
         return vpr::ReturnStatus();
      }
      else if(EPERM == retval)
      {
         perror("Tried to release a mutex we do not own");
         assert(false && "Mutex release by non-owning thread.");
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
      else
      {
         return vpr::ReturnStatus(vpr::ReturnStatus::Fail);
      }
   }

int vpr::MutexPosix::test

(

)

const

Tests the current lock status.

Postcondition:

The state of the mutex variable is returned.

Returns:

0 is returned if this mutex is not currently locked.

1 is returned if this mutex is locked.

Definition at line 69 of file MutexPosix.cpp.

References mMutex.

Referenced by vpr::ThreadManager::addThread(), vpr::CondVarPosix::broadcast(), vpr::ThreadManager::removeThread(), vpr::CondVarPosix::test(), vpr::CondVarGeneric::test(), vpr::CondVarPosix::wait(), and vpr::CondVarGeneric::wait().

{
   int ret_val;

   ret_val = pthread_mutex_trylock(const_cast<pthread_mutex_t*>(&mMutex));

   // If the return value from pthread_mutex_trylock() is 0, then this
   // process now has a lock on mutex.  Therefore, no other process could
   // have held a lock on it, so unlock the mutex and return 0.
   if ( ret_val == 0 )
   {
      pthread_mutex_unlock(const_cast<pthread_mutex_t*>(&mMutex));
      ret_val = 0;
   }
   // The mutex is currently locked by some thread if ret_val is non-zero.
   else
   {
      ret_val = 1;
   }

   return ret_val;
}

void vpr::MutexPosix::operator=

(

const MutexPosix &

)

[inline, protected]

Definition at line 276 of file MutexPosix.h.

{;}

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Friends And Related Function Documentation

friend class CondVarPosix [friend]

Definition at line 270 of file MutexPosix.h.

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Member Data Documentation

pthread_mutex_t vpr::MutexPosix::mMutex [protected]

Mutex variable for the class.

Definition at line 273 of file MutexPosix.h.

Referenced by acquire(), MutexPosix(), release(), test(), tryAcquire(), vpr::CondVarPosix::wait(), and ~MutexPosix().

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The documentation for this class was generated from the following files:

• MutexPosix.h
• MutexPosix.cpp

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