Threads Namespace Reference

interface to threads that should be portable. More...

Classes
class	Atomic
class	AtomicPointer
	Atomic instantiated with a pointer. The class really only handles the casting from a void* to a T*. More...
class	Barrier
	Waits for a number of threads to reach a certain point (i.e. the call to Barrier::waitForAll). Once everyone has arrived, everyone is released. More...
class	ConditionVar
	Is an object that faciliates many threads to wait for something to happen. More...
class	Lock
	A lock of a type that (hopefully) suits your needs. To use it, you need the Locker class. More...
class	Locker
	Locks the lock, shutting out access from other threads if needed. More...
class	Mutex
	Is a lock that allows a thread to have exlusive rights to something. More...
class	MutexLocker
class	ReadLockLocker
class	ReadWriteLock
	Lock that permits multiple readers to lock the object at the same time, but it will not allow any readers when writelocked, and no writelock is allowed when readlocked. More...
class	SpinLock
	Is an alternative to Mutex. It is a lock which causes a thread trying to acquire it to simply wait in a loop ("spin") while repeatedly checking if the lock is available. Because they avoid overhead from operating system process re-scheduling or context switching, spinlocks are efficient if threads are only likely to be blocked for a short period. More...
class	SpinRWLock
	Is an alternative to ReadWriteLock. It is a lock which causes a thread trying to acquire it to simply wait in a loop ("spin") while repeatedly checking if the lock is available. Because they avoid overhead from operating system process re-scheduling or context switching, spinlocks are efficient if threads are only likely to be blocked for a short period. More...
class	Thread
	Is the base class for all threads. Start it by creating it and give it the function or CallBack to execute. More...
class	Work
	The abstraction of something that can be done. It can be an ordinary CallBack, a static function (must return bool) or a TaskFunction on a CallBackerinheriting class, or a Task. The three examples are shown below. More...
class	WorkManager
	Takes work and puts it on a queue for execution either in parallel, singlethread or manual. More...
class	WriteLockLocker

Typedefs
typedef void *	ThreadID

Functions
bool	atomicSetIfValueIs (volatile int &val, int curval, int newval, int *actualvalptr)
ThreadID	currentThread ()
int	getNrProcessors ()
int	getSystemNrProcessors ()
bool	lockSimpleSpinLock (volatile int &lock, Locker::WaitType)
bool	lockSimpleSpinWaitLock (volatile int &lock)
void	setCurrentThreadProcessorAffinity (int cpu)
void	sleep (double seconds)
void	unlockSimpleSpinLock (volatile int &lock)

Detailed Description

interface to threads that should be portable.

simple interface to thread locking

As usual, other thread systems are available but they are as far as we know simply too big and dependent.

The two ingredients are: The lock itself - commonly a class variable A locker (managing the setting and releasing of the lock)

Typical usage:

class X { ... Threads::Lock datalock_; ... };

void X::doSomething() { Threads::Locker locker( datalock_ ); for ( int i..... }

Typedef Documentation

ThreadID

typedef void* Threads::ThreadID

Function Documentation

atomicSetIfValueIs()

bool Threads::atomicSetIfValueIs	(	volatile int &	val,
		int	curval,
		int	newval,
		int *	actualvalptr
	)

Atomically sets the 'val' only if its value is currently the value of 'curval'. If the value in 'val' is identical to the value of 'curval', function will change 'val' and return true. Otherwise, it will not change 'val', it will return false, and update the value at 'actualvalptr' to the current value of 'val'.

currentThread()

ThreadID Threads::currentThread

(

)

getNrProcessors()

int Threads::getNrProcessors

(

)

getSystemNrProcessors()

int Threads::getSystemNrProcessors

(

)

Fetches number of processors from operating system, unless: DTECT_USE_MULTIPROC is set to 'n' or 'N' The user settings contain a 'Nr Processors' entry.

lockSimpleSpinLock()

bool Threads::lockSimpleSpinLock	(	volatile int &	lock,
		Locker::WaitType
	)

lockSimpleSpinWaitLock()

bool Threads::lockSimpleSpinWaitLock

(

volatile int &

lock

)

Any volatile integer that is initialized to 0 can act as a spinlock using this funciton. If you lock it, you have to unlock it by setting it to 0. Note that parallelStudio will report these as violations of thread-safety. Hence use thes only when standard locks cannot be used (e.g. static locks in functions).

setCurrentThreadProcessorAffinity()

void Threads::setCurrentThreadProcessorAffinity

(

int

cpu

)

Tells the current thread to always run on a certain cpu. Set to -1 to remove binding. Not guaranteed to work on all platforms.

sleep()

void Threads::sleep

(

double

seconds

)

Causes the current thread to sleep

unlockSimpleSpinLock()

void Threads::unlockSimpleSpinLock

(

volatile int &

lock

)