A flat fee, also referred to as a flat rate or a linear rate, refers to a pricing structure that charges a single fixed fee for a service, regardless of usage.[1] Less commonly, the term may refer to a rate that does not vary with usage or time of use.
Synchronous: interrupt occurs as a result of current process, otherwise asynchronous. User requested: interrupt occurs because of direct result by user task, otherwise coerced. Maskable: if desired the interrupt can be disabled by a user task, otherwise unmasked.
Otherwise, it does not lock the semaphore. Upon successful return, the state of the semaphore is locked and remains locked until the sem_post() function is executed and returns successfully. The sem_wait() function is interruptible by the delivery of a signal. The sem_wait() and sem_trywait() functions return zero if the calling process successfully performed the semaphore lock operation on the semaphore designated by sem.