vsync / spinlock / ttaslock.h

Test, Test and Set lock.

Example:

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

#define N            12
#define EXPECTED_VAL N

ttaslock_t g_lock = TTASLOCK_INIT();
vuint32_t g_x     = 0;
vuint32_t g_y     = 0;

void *
run(void *args)
{
    ttaslock_acquire(&g_lock);
    g_x++;
    g_y++;
    ttaslock_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;
}

References:

Maurice Herlihy, Nir Shavit - The Art of Multiprocessor Programming 7.3

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Macros

Macro	Description
TTASLOCK_INIT	Initializer of ttaslock_t.

Macro TTASLOCK_INIT

TTASLOCK_INIT()

Initializer of ttaslock_t.

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Functions

Function	Description
ttaslock_init	Initializes the TTAS lock.
ttaslock_acquire	Acquires the TAS lock.
ttaslock_tryacquire	Tries to acquire the TTAS lock.
ttaslock_release	Releases the TTAS lock.

Function ttaslock_init

static void ttaslock_init(ttaslock_t *l)

Initializes the TTAS lock.

Parameters:

• l: address of ttaslock_t object.

Note: alternatively use TTASLOCK_INIT.

Function ttaslock_acquire

static void ttaslock_acquire(ttaslock_t *l)

Acquires the TAS lock.

Parameters:

• l: address of ttaslock_t object.

Function ttaslock_tryacquire

static vbool_t ttaslock_tryacquire(ttaslock_t *l)

Tries to acquire the TTAS lock.

Parameters:

• l: address of ttaslock_t object.

Returns: true, if lock is acquired successfully.

Returns: false, if failed to acquire the lock.

Function ttaslock_release

static void ttaslock_release(ttaslock_t *l)

Releases the TTAS lock.

Parameters:

• l: address of ttaslock_t object.

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