ost::conditional(3)

NAME

ost::Conditional - A conditional variable synchcronization object for
one to one and one to many signal and control events between processes.

SYNOPSIS

#include <thread.h>
Inherited by ost::Buffer.
Public Member Functions
Conditional (const char *id=NULL)
    Create an instance of a conditional.
virtual ~Conditional ()
    Destroy the conditional.
void signal (bool broadcast)
    Signal a conditional object and a waiting threads.
bool wait (timeout_t timer=0, bool locked=false)
    Wait to be signaled from another thread.
void enterMutex (void)
    Locks the conditional's mutex for this thread.
void lock (void)
    In the future we will use lock in place of enterMutex since the
    conditional composite is not a recursive mutex, and hence using
    enterMutex may cause confusion in expectation with the behavior of
    the Mutex class.
bool tryEnterMutex (void)
    Tries to lock the conditional for the current thread.
bool test (void)
void leaveMutex (void)
    Leaving a mutex frees that mutex for use by another thread.
void unlock (void)

Detailed Description

A conditional variable synchcronization object for one to one and one
to many signal and control events between processes.

Conditional variables may wait for and receive signals to notify when to resume or perform operations. Multiple waiting threads may be woken with a broadcast signal.

Warning:

While this class inherits from Mutex, the methods of the class Conditional just handle the system conditional variable, so the user is responsible for calling enterMutex and leaveMutex so as to avoid race conditions. Another thing to note is that if you have
several threads waiting on one condition, not uncommon in thread
pools, each thread must take care to manually unlock the mutex if
cancellation occurs. Otherwise the first thread cancelled will
deadlock the rest of the thread.

Author:

David Sugar conditional.

Constructor & Destructor Documentation

ost::Conditional::Conditional (const char * id = NULL)

Create an instance of a conditional.

Parameters:

id name of conditional, optional for deadlock testing.

virtual ost::Conditional::~Conditional () [virtual]

Destroy the conditional.

Member Function Documentation

void ost::Conditional::signal (bool broadcast)

Signal a conditional object and a waiting threads.

Parameters:

broadcast this signal to all waiting threads if true.

bool ost::Conditional::wait (timeout_t timer = 0, bool locked = false)

Wait to be signaled from another thread.

Parameters:

timer time period to wait.
locked flag if already locked the mutex.

void ost::Conditional::enterMutex (void)

Locks the conditional's mutex for this thread.

Remember that Conditional's mutex is NOT a recursive mutex!

See also:

leaveMutex

void ost::Conditional::lock (void) [inline]

In the future we will use lock in place of enterMutex since the
conditional composite is not a recursive mutex, and hence using
enterMutex may cause confusion in expectation with the behavior of the Mutex class.

See also:

enterMutex

bool ost::Conditional::tryEnterMutex (void)

Tries to lock the conditional for the current thread.

Behaves like enterMutex , except that it doesn't block the calling thread.

Returns:

true if locking the mutex was succesful otherwise false

See also:

enterMutex

leaveMutex

bool ost::Conditional::test (void) [inline] void ost::Conditional::leaveMutex (void)

Leaving a mutex frees that mutex for use by another thread.

See also:

enterMutex

void ost::Conditional::unlock (void) [inline]

Author

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GNU CommonC++ 25 Aug 2008 ost::Conditional(3)