callbackq.h

#ifndef UCS_CALLBACKQ_H
#define UCS_CALLBACKQ_H

#include <ucs/datastruct/list.h>
#include <ucs/sys/compiler_def.h>
#include <ucs/type/status.h>
#include <stddef.h>
#include <stdint.h>

BEGIN_C_DECLS

/*
 * Thread-safe callback queue:
 *  - only one thread can dispatch
 *  - any thread can add and remove
 *  - add/remove operations are O(1)
 */

#define UCS_CALLBACKQ_FAST_COUNT   7     /* Max. number of fast-path callbacks */
#define UCS_CALLBACKQ_ID_NULL      (-1)  /* Invalid callback identifier */


/*
 * Forward declarations
 */
typedef struct ucs_callbackq       ucs_callbackq_t;
typedef struct ucs_callbackq_elem  ucs_callbackq_elem_t;


typedef unsigned (*ucs_callback_t)(void *arg);


typedef int (*ucs_callbackq_predicate_t)(const ucs_callbackq_elem_t *elem,
                                         void *arg);


enum ucs_callbackq_flags {
    UCS_CALLBACKQ_FLAG_FAST        = UCS_BIT(0), 
    UCS_CALLBACKQ_FLAG_ONESHOT     = UCS_BIT(1)  
};


struct ucs_callbackq_elem {
    ucs_callback_t                 cb;       
    void                           *arg;     
    unsigned                       flags;    
    int                            id;       
};


struct ucs_callbackq {
    ucs_callbackq_elem_t           fast_elems[UCS_CALLBACKQ_FAST_COUNT + 1];

    char                           priv[72];
};


ucs_status_t ucs_callbackq_init(ucs_callbackq_t *cbq);


void ucs_callbackq_cleanup(ucs_callbackq_t *cbq);


int ucs_callbackq_add(ucs_callbackq_t *cbq, ucs_callback_t cb, void *arg,
                      unsigned flags);


void ucs_callbackq_remove(ucs_callbackq_t *cbq, int id);


int ucs_callbackq_add_safe(ucs_callbackq_t *cbq, ucs_callback_t cb, void *arg,
                           unsigned flags);


void ucs_callbackq_remove_safe(ucs_callbackq_t *cbq, int id);


void ucs_callbackq_remove_if(ucs_callbackq_t *cbq, ucs_callbackq_predicate_t pred,
                             void *arg);


static inline unsigned ucs_callbackq_dispatch(ucs_callbackq_t *cbq)
{
    ucs_callbackq_elem_t *elem;
    ucs_callback_t cb;
    unsigned count;

    count = 0;
    for (elem = cbq->fast_elems; (cb = elem->cb) != NULL; ++elem) {
        count += cb(elem->arg);
    }
    return count;
}

END_C_DECLS

#endif