/* mpmc.h — bounded lock-free queue of pointers (Dmitry Vyukov's algorithm).
 *
 * One implementation covers every cross-thread hand-off in the engine:
 *   - control-plane -> reactor command queues (MPSC usage)
 *   - reactor -> hash worker pool job queue   (MPMC usage)
 *   - worker -> reactor completion queue       (MPSC usage)
 * Wait-free in the common case, no per-op allocation. Capacity is fixed at
 * init and must be a power of two.
 */
#ifndef NAUT_MPMC_H
#define NAUT_MPMC_H

#include "naut/common.h"

typedef struct naut_mpmc_cell {
    _Atomic size_t seq;
    void          *data;
} naut_mpmc_cell;

typedef struct naut_mpmc {
    NAUT_CACHE_ALIGNED naut_mpmc_cell *buffer;
    size_t mask;
    NAUT_CACHE_ALIGNED _Atomic size_t enqueue_pos;
    NAUT_CACHE_ALIGNED _Atomic size_t dequeue_pos;
} naut_mpmc;

naut_err naut_mpmc_init(naut_mpmc *q, size_t capacity_pow2);
void     naut_mpmc_destroy(naut_mpmc *q);

/* Both return false without blocking when full/empty respectively. */
bool naut_mpmc_push(naut_mpmc *q, void *p);
bool naut_mpmc_pop(naut_mpmc *q, void **out);

#endif /* NAUT_MPMC_H */