51 lines
2.5 KiB
C++
51 lines
2.5 KiB
C++
#pragma once
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#include "CappedSemaphore.h"
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namespace baselib
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{
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BASELIB_CPP_INTERFACE
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{
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// In computer science, a semaphore is a variable or abstract data type used to control access to a common resource by multiple processes in a concurrent
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// system such as a multitasking operating system. A semaphore is simply a variable. This variable is used to solve critical section problems and to achieve
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// process synchronization in the multi processing environment. A trivial semaphore is a plain variable that is changed (for example, incremented or
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// decremented, or toggled) depending on programmer-defined conditions.
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//
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// A useful way to think of a semaphore as used in the real-world system is as a record of how many units of a particular resource are available, coupled with
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// operations to adjust that record safely (i.e. to avoid race conditions) as units are required or become free, and, if necessary, wait until a unit of the
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// resource becomes available.
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//
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// "Semaphore (programming)", Wikipedia: The Free Encyclopedia
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// https://en.wikipedia.org/w/index.php?title=Semaphore_(programming)&oldid=872408126
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//
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// For optimal performance, baselib::BinarySemaphore should be stored at a cache aligned memory location.
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class BinarySemaphore : private CappedSemaphore
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{
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public:
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// Creates a binary semaphore synchronization primitive.
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// Binary means the semaphore can at any given time have at most one token available for consummation.
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//
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// This is just an API facade for CappedSemaphore(1)
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//
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// If there are not enough system resources to create a semaphore, process abort is triggered.
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BinarySemaphore() : CappedSemaphore(1) {}
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using CappedSemaphore::Acquire;
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using CappedSemaphore::TryAcquire;
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using CappedSemaphore::TryTimedAcquire;
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// Submit token to the semaphore.
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// If threads are waiting the token is consumed before this function return.
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//
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// When successful this function is guaranteed to emit a release barrier.
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//
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// \returns true if a token was submitted, false otherwise (meaning the BinarySemaphore already has a token)
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inline bool Release()
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{
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return CappedSemaphore::Release(1) == 1;
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}
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};
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}
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}
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