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#pragma once
#include "Core/Object.h"
namespace storm {
STORM_PKG(core.sync);
/**
* A basic semaphore usable from whitin Storm. If possible, use a plain os::Lock or os::Sema as
* it does not require any separate allocations.
*
* This object slightly breaks the expected semantics of Storm as it does not make sense to copy
* a semaphore. Instead, all copies will refer to the same semaphore.
*/
class Sema : public Object {
STORM_CLASS;
public:
// Create a semaphore initialized to 1.
STORM_CTOR Sema();
// Create a semaphore initialized to `count`.
STORM_CTOR Sema(Nat count);
// Copy.
Sema(const Sema &o);
// Destroy.
~Sema();
// Deep copy.
void STORM_FN deepCopy(CloneEnv *e);
// Increase the value in the semaphore by 1. May wake any waiting threads.
void STORM_FN up();
// Attempt to decrease the value in the semaphore by 1. Will wait in case the value would
// become negative.
void STORM_FN down();
private:
// Separate allocation for the actual lock. Allocated outside of the Gc since we do not
// allow barriers or movement of the memory allocated for the lock.
struct Data {
size_t refs;
os::Sema sema;
Data(Nat count);
};
// Allocation. Not GC:d.
Data *alloc;
};
}
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