vlink::Semaphore Class Reference

In-process counting semaphore with optional acquire timeout. More...

#include <semaphore.h>

Collaboration diagram for vlink::Semaphore:

Public Member Functions
	Semaphore (size_t count=0) noexcept
	Constructs a Semaphore with an initial counter value.
	~Semaphore () noexcept
	Destructor. Wakes all blocked acquirers before destruction.
bool	acquire (size_t n=1, int timeout_ms=kInfinite) noexcept
	Decrements the semaphore counter by n, blocking until permits are available.
void	release (size_t n=1) noexcept
	Increments the semaphore counter by n, waking blocked acquirers.
void	reset (bool interrupt_waiters=false) noexcept
	Resets the semaphore counter to zero.
size_t	get_count () const noexcept
	Returns the current value of the semaphore counter.

Static Public Attributes
static constexpr int	kInfinite {-1}
	Sentinel value for acquire() meaning "wait indefinitely".

Detailed Description

In-process counting semaphore with optional acquire timeout.

The internal counter is initialised via the constructor and can be atomically decremented (acquire) or incremented (release).

Constructor & Destructor Documentation

Semaphore()

vlink::Semaphore::Semaphore ( size_t count = 0 )

explicitnoexcept

Constructs a Semaphore with an initial counter value.

Parameters

count

Initial number of available permits (default: 0).

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~Semaphore()

vlink::Semaphore::~Semaphore ( )

noexcept

Destructor. Wakes all blocked acquirers before destruction.

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Member Function Documentation

acquire()

bool vlink::Semaphore::acquire ( size_t n = 1, int timeout_ms = kInfinite )

noexcept

Decrements the semaphore counter by n, blocking until permits are available.

If the counter is less than n, the caller is blocked until enough release() calls bring the counter up. A timeout causes the function to return false without decrementing the counter.

Parameters

n	Number of permits to acquire (default: 1).
timeout_ms	Maximum time to wait in milliseconds. Use kInfinite (-1) to wait indefinitely (default).

Returns

true if the permits were acquired, false on timeout or if the semaphore was reset with interrupt_waiters == true.

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get_count()

size_t vlink::Semaphore::get_count ( ) const

nodiscardnoexcept

Returns the current value of the semaphore counter.

The returned value is a snapshot; it may change before the caller can use it. Intended for diagnostic and logging purposes only.

Returns

Current counter value.

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release()

void vlink::Semaphore::release ( size_t n = 1 )

noexcept

Increments the semaphore counter by n, waking blocked acquirers.

If threads are blocked in acquire(), they are notified. The notification is delivered to at most n waiting threads.

Parameters

n	Number of permits to release (default: 1).

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reset()

void vlink::Semaphore::reset ( bool interrupt_waiters = false )

noexcept

Resets the semaphore counter to zero.

If interrupt_waiters is true, all threads blocked in acquire() are woken and their calls return false. Use this during shutdown to unblock consumers cleanly.

Parameters

interrupt_waiters

If true, wake all blocked acquirers (default: false).

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Member Data Documentation

kInfinite

int vlink::Semaphore::kInfinite {-1}

staticconstexpr

Sentinel value for acquire() meaning "wait indefinitely".

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

• include/vlink/base/semaphore.h