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Public Member Functions
Semaphore Class Reference

A classic semaphore synchronization primitive. More...

#include "psemaphore.h"

List of all members.

Public Member Functions

 Semaphore (int initial_count=1)
void acquire ()
 Decrements the internal count.
int get_count () const
 Returns the current semaphore count.
void output (ostream &out) const
int release ()
 Increments the semaphore's internal count.
bool try_acquire ()
 If the semaphore can be acquired without blocking, does so and returns true.

Detailed Description

A classic semaphore synchronization primitive.

A semaphore manages an internal counter which is decremented by each acquire() call and incremented by each release() call. The counter can never go below zero; when acquire() finds that it is zero, it blocks, waiting until some other thread calls release().

Definition at line 33 of file psemaphore.h.


Member Function Documentation

void Semaphore::acquire ( ) [inline]

Decrements the internal count.

If the count was already at zero, blocks until the count is nonzero, then decrements it.

Definition at line 69 of file psemaphore.I.

References ConditionVarDirect::wait().

int Semaphore::get_count ( ) const [inline]

Returns the current semaphore count.

Note that this call is not thread-safe (the count may change at any time).

Definition at line 122 of file psemaphore.I.

int Semaphore::release ( ) [inline]

Increments the semaphore's internal count.

This may wake up another thread blocked on acquire().

Returns the count of the semaphore upon release.

Definition at line 106 of file psemaphore.I.

References ConditionVarDirect::notify().

bool Semaphore::try_acquire ( ) [inline]

If the semaphore can be acquired without blocking, does so and returns true.

Otherwise, returns false.

Definition at line 86 of file psemaphore.I.


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