vsync / spinlock / rec_spinlock.h

Recursive spinlock implementation using recursive.h.

Groups: Reentrant

see caslock.h

Example:

#include <vsync/spinlock/rec_spinlock.h>
#include <vsync/common/assert.h>
#include <pthread.h>
#include <stdio.h>

#define N            12
#define EXPECTED_VAL N

rec_spinlock_t g_lock = REC_SPINLOCK_INIT();
vuint32_t g_x         = 0;
vuint32_t g_y         = 0;

void *
run(void *args)
{
    vuint32_t tid = (vuint32_t)(vsize_t)args;
    // can be acquired multiple times without causing dead-lock
    rec_spinlock_acquire(&g_lock, tid);
    rec_spinlock_acquire(&g_lock, tid);
    g_x++;
    g_y++;
    rec_spinlock_release(&g_lock);
    rec_spinlock_release(&g_lock);

    (void)args;
    return NULL;
}

int
main(void)
{
    pthread_t threads[N];

    for (vsize_t i = 0; i < N; i++) {
        pthread_create(&threads[i], NULL, run, (void *)i);
    }

    for (vsize_t i = 0; i < N; i++) {
        pthread_join(threads[i], NULL);
    }

    ASSERT(g_x == EXPECTED_VAL);
    ASSERT(g_x == g_y);
    printf("Final value %u\n", g_x);
    return 0;
}

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Macros

Macro	Description
REC_SPINLOCK_INIT	Initializer of rec_spinlock.

Macro REC_SPINLOCK_INIT

REC_SPINLOCK_INIT()

Initializer of rec_spinlock.

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Functions

Function	Description
rec_spinlock_init	Initializes the recursive spinlock.
rec_spinlock_tryacquire	Tries to acquire the recursive spinlock.
rec_spinlock_acquire	Acquires the recursive spinlock.
rec_spinlock_release	Releases the recursive spinlock.

Function rec_spinlock_init

static void rec_spinlock_init(struct rec_spinlock_s *l)

Initializes the recursive spinlock.

Parameters:

• l: address of rec_spinlock_t object.

Note: alternatively use REC_SPINLOCK_INIT.

Function rec_spinlock_tryacquire

static vbool_t rec_spinlock_tryacquire(struct rec_spinlock_s *l, vuint32_t id)

Tries to acquire the recursive spinlock.

Parameters:

• l: address of rec_spinlock_t object.
• id: thread ID or core ID.

Returns: true, if lock is acquired successfully.

Returns: false, if failed to acquire the lock.

Function rec_spinlock_acquire

static void rec_spinlock_acquire(struct rec_spinlock_s *l, vuint32_t id)

Acquires the recursive spinlock.

Parameters:

• l: address of recursive spinlock lock object
• id: thread ID or core ID.

Function rec_spinlock_release

static void rec_spinlock_release(struct rec_spinlock_s *l)

Releases the recursive spinlock.

Parameters:

• l: address of rec_spinlock_t object.

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