Spinlock Method Design Pattern

A spinlock is a synchronization mechanism commonly used in embedded systems and other low-level programming scenarios to protect shared resources from concurrent access.

Unlike traditional locks that may put a thread to sleep when it cannot acquire the lock, a spinlock repeatedly checks the lock’s availability in a loop until it becomes available.

Let’s see a simple example of a spinlock in C for an embedded system:

C

#include <stdint.h>
#include <stdbool.h>
 
typedef struct {
    volatile bool locked;
} Spinlock;
 
void spinlock_init(Spinlock* lock) {
    lock->locked = false;
}
 
void spinlock_acquire(Spinlock* lock) {
    // Spin until the lock is acquired
    while (__sync_lock_test_and_set(&lock->locked, true)) {
        // Optionally insert a delay here to reduce CPU usage
        // (Note: This might not be the best practice, as it depends on the specific platform and requirements)
    }
}
 
void spinlock_release(Spinlock* lock) {
    // Release the lock
    __sync_lock_release(&lock->locked);
}
 
// Example usage
int shared_resource = 0;
Spinlock resource_lock;
 
int main() {
    // Initialize the spinlock
    spinlock_init(&resource_lock);
 
    // Acquire the lock before accessing the shared resource
    spinlock_acquire(&resource_lock);
 
    // Access the shared resource
    shared_resource += 10;
 
    // Release the lock after accessing the shared resource
    spinlock_release(&resource_lock);
 
    return 0;
}

Explanation of the above Code:

In this example,

The Spinlock structure contains a locked flag that indicates whether the lock is currently held or not.
The spinlock_acquire function uses the __sync_lock_test_and_set built-in function to atomically set the locked flag to true and return the previous value.
If the previous value was already true, indicating that the lock was held, the function enters a spin loop until the lock becomes available. The spinlock_release function simply sets the locked flag back to false to release the lock.

Design Patterns for Embedded Systems in C

When working with embedded systems in C, there are so many design patterns that are particularly very useful. Many design patterns can be applied to embedded systems development in C. In this article, we will discuss design patterns for Embedded Systems in C, let’s see all of them one by one with the help of examples.

Important Topics for Design Patterns for Embedded Systems in C

What is a Design Pattern?
Creational Design Patterns for Embedded Systems in C
- Factory Method Design Pattern
- Object Method Design Pattern
- Opaque Method Design Pattern
- Singleton Method Design Pattern
Structural Design Patterns for Embedded Systems in C
- Callback Method Design Patterns
- Inheritance Method Design Pattern
- Virtual API Method Design Pattern
Other Design Patterns for Embedded System in C
- Bridge Method Design Pattern
- Concurrency Method Design Pattern
- Spinlock Method Design Pattern
- Mutex Method Design Pattern
- Conditional Method Design Pattern
- Behavioral Method Design Pattern

Spinlock Method Design Pattern

C

Design Patterns for Embedded Systems in C

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