Table of Contents
What is reentrant function?
A function is said to be reentrant if there is a provision to interrupt the function in the course of execution, service the interrupt service routine and then resume the earlier going on function, without hampering its earlier course of action.
What is re-entrant safe code?
Reentrant (multi-instance) code is a reusable routine that multiple programs can invoke, interrupt, and reinvoke simultaneously. When you want to reuse code, but associate each instance of the shared code with unique, preserved data, use reentrant code.
What is reentrant and non-reentrant function in C?
A function can be non-reentrant if it uses memory that is not on the stack. If a function uses a static variable or a global variable, or a dynamically-allocated object that it finds for itself, then it is non-reentrant and any two calls to the function can interfere.
What is reentrant procedure?
2. A reentrant procedure is one in which a single copy of the program code can be shared by multiple users during the same period of time. Re entrance has two key aspects: The program code cannot modify itself and the local data for each user must be stored separately.
Are all reentrant functions thread-safe?
Hence, a thread-safe function is always reentrant, but a reentrant function is not always thread-safe. The class is thread-safe if its member functions can be called safely from multiple threads, even if all the threads use the same instance of the class.
What is reentrant kernel?
A re-entrant kernel enables processes (or, to be more precise, their corresponding kernel threads) to give away the CPU while in kernel mode. They do not hinder other processes from also entering kernel mode. A typical use case is IO wait. The process wants to read a file.
How do you know if a code is reentrant?
1 Answer. The way to determine if a function is reentrant is to analyse what it does. 2) The code is not self-modifying (fortunately, self-modifying code is relatively rare in standard C or C++).
What is the difference between reentrant and thread safe classes?
By extension, a class is said to be reentrant if its member functions can be called safely from multiple threads, as long as each thread uses a different instance of the class. The class is thread-safe if its member functions can be called safely from multiple threads, even if all the threads use the same instance of the class.
Should not call another non-reentrant function in a thread?
Should not call another non-reentrant function. Reentrancy is distinct from, but closely related to, thread-safety. A function can be thread-safe and still not reentrant.
What makes a class Thread-safe?
The class is thread-safe if its member functions can be called safely from multiple threads, even if all the threads use the same instance of the class. Note: Terminology in the multithreading domain isn’t entirely standardized.
What is the difference between a mutex and a reentrant?
For example, a function could be wrapped all around with a mutex (which avoids problems in multithreading environments), but if that function is used in an interrupt service routine, it could starve waiting for the first execution to release the mutex. The key for avoiding confusion is that reentrant refers to only one thread executing.