A wrapper class for a Posix condition variable. More...

#include <ThreadSupport.h>

Public Member Functions
	Cond () throw ()
	Construct a POSIX condition variable, with default attributes.

	Cond (const Cond &x) throw ()
	Copy constructor.

	~Cond ()
	Destruct a Cond.

void	lock ()
	Lock the mutex associated with the condition variable.

void	unlock ()
	Unlock the mutex associated with the condition variable.

void	signal ()
	Unblock at least one thread waiting on the condition variable.

void	broadcast ()
	Restart all threads waiting on the condition variable.

void	wait ()
	Wait on the condition variable.

Private Member Functions
Cond &	operator= (const Cond &)
	No assignment allowed.

Private Attributes
pthread_cond_t	_p_cond

Mutex	_mutex

Detailed Description

A wrapper class for a Posix condition variable.

Constructor & Destructor Documentation

◆ Cond() [1/2]

Cond::Cond	(		)
throw	(	)

Construct a POSIX condition variable, with default attributes.

See man page for pthread_cond_init.

References _p_cond.

◆ Cond() [2/2]

Cond::Cond	(	const Cond &	x	)
throw	(	)

Copy constructor.

Creates new unlocked condition variable and mutex.

◆ ~Cond()

Cond::~Cond ( )

Destruct a Cond.

See man page for pthread_cond_destroy. Cond must not be waited on by any thread, otherwise std::terminate() is called.

References _p_cond, and CLOG.

Member Function Documentation

◆ broadcast()

void nidas::util::Cond::broadcast ( )

inline

Restart all threads waiting on the condition variable.

See also: lock().

References _p_cond.

Referenced by PacketReader::loop(), nidas::core::SampleBuffer::run(), nidas::core::SampleSorter::run(), nidas::util::Multisync::sync(), and nidas::util::Multisync::sync().

◆ lock()

void nidas::util::Cond::lock ( )

inline

Lock the mutex associated with the condition variable.

Here is an example (lifted from the pthread_cond_init man page): of two threads sharing variables x and y. One thread waits for a signal that x is greater than y:

int x,y;
Cond xyCond;
...
xyCond.lock();
while (x <= y) xyCond.wait();
// operate on x and y
xyCond.unlock();

Another thread manipulates x and y and signals when x > y:

xyCond.lock();
// modify x and y
if (x > y) xyCond.signal();
xyCond.unlock();

Exceptions

Exception

References _mutex, and nidas::util::Mutex::lock().

Referenced by nidas::core::SampleOutputRequestThread::addConnectRequest(), nidas::core::SampleOutputRequestThread::addDeleteRequest(), nidas::util::Autolock::Autolock(), nidas::core::SampleOutputRequestThread::clear(), nidas::dynld::raf::SyncRecordReader::endOfStream(), nidas::core::SampleSorter::flush(), nidas::core::SampleBuffer::heapDecrement(), nidas::core::SampleSorter::heapDecrement(), nidas::core::SampleBuffer::interrupt(), nidas::core::SampleOutputRequestThread::interrupt(), nidas::core::SampleSorter::interrupt(), nidas::core::SensorOpener::interrupt(), PacketReader::loop(), nidas::dynld::raf::SyncRecordReader::nextSample(), nidas::core::SensorOpener::openSensor(), nidas::core::SensorOpener::reopenSensor(), WriterThread::run(), nidas::core::SampleBuffer::run(), nidas::core::SampleOutputRequestThread::run(), nidas::core::SampleSorter::run(), nidas::core::SensorOpener::run(), nidas::util::Synchronized::Synchronized(), PacketReader::~PacketReader(), and nidas::dynld::raf::SyncRecordReader::~SyncRecordReader().

◆ operator=()

Cond & nidas::util::Cond::operator= ( const Cond & )

private

No assignment allowed.

◆ signal()

void nidas::util::Cond::signal ( )

inline

Unblock at least one thread waiting on the condition variable.

See also: lock() for an example. According to the man page, it is not safe to call Cond::signal() from an asynchronous signal handler.

Exceptions

Exception

References _p_cond.

Referenced by nidas::core::SampleOutputRequestThread::addConnectRequest(), nidas::core::SampleOutputRequestThread::addDeleteRequest(), nidas::dynld::raf::SyncRecordReader::endOfStream(), nidas::core::SampleSorter::flush(), nidas::core::SampleBuffer::heapDecrement(), nidas::core::SampleSorter::heapDecrement(), nidas::core::SampleBuffer::interrupt(), nidas::core::SampleOutputRequestThread::interrupt(), nidas::core::SampleSorter::interrupt(), nidas::core::SensorOpener::interrupt(), nidas::dynld::raf::SyncRecordReader::nextSample(), nidas::core::SensorOpener::openSensor(), nidas::core::SensorOpener::reopenSensor(), and nidas::core::SampleSorter::run().

◆ unlock()

void nidas::util::Cond::unlock ( )

inline

Unlock the mutex associated with the condition variable.

See also: lock() for an example.

Exceptions

Exception

References _mutex, and nidas::util::Mutex::unlock().

Referenced by nidas::core::SampleOutputRequestThread::addConnectRequest(), nidas::core::SampleOutputRequestThread::addDeleteRequest(), nidas::core::SampleOutputRequestThread::clear(), nidas::dynld::raf::SyncRecordReader::endOfStream(), nidas::core::SampleSorter::flush(), nidas::core::SampleBuffer::heapDecrement(), nidas::core::SampleSorter::heapDecrement(), nidas::core::SampleBuffer::interrupt(), nidas::core::SampleOutputRequestThread::interrupt(), nidas::core::SampleSorter::interrupt(), nidas::core::SensorOpener::interrupt(), PacketReader::loop(), nidas::dynld::raf::SyncRecordReader::nextSample(), nidas::core::SensorOpener::openSensor(), nidas::core::SensorOpener::reopenSensor(), WriterThread::run(), nidas::core::SampleBuffer::run(), nidas::core::SampleOutputRequestThread::run(), nidas::core::SampleSorter::run(), nidas::core::SensorOpener::run(), nidas::util::Autolock::~Autolock(), PacketReader::~PacketReader(), nidas::util::Synchronized::~Synchronized(), and nidas::dynld::raf::SyncRecordReader::~SyncRecordReader().

◆ wait()

void Cond::wait ( )

Wait on the condition variable.

See also

lock() for an example. wait() does several things:

It immediately unlocks the mutex
It blocks until the condition variable is signalled
It locks the mutex again wait() is a cancellation point, which sets up the appropriate cancellation cleanup handlers so that the mutex is unlocked if the thread is cancelled.

Exceptions

Exception

References _mutex, _p_cond, and nidas::util::Mutex::ptr().

Referenced by nidas::core::SampleSorter::flush(), nidas::dynld::raf::SyncRecordReader::nextSample(), WriterThread::run(), nidas::core::SampleBuffer::run(), nidas::core::SampleOutputRequestThread::run(), nidas::core::SampleSorter::run(), nidas::core::SensorOpener::run(), nidas::util::Multisync::sync(), and nidas::util::Multisync::sync().