C++ ITEM_ntotal函数代码示例

int do_item_link(item *it) {
    MEMCACHED_ITEM_LINK(ITEM_key(it), it->nbytes);
    assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0);
    assert(it->nbytes < (1024 * 1024));  /* 1MB max size */
    it->it_flags |= ITEM_LINKED;
    it->time = current_time;
    assoc_insert(it);

    STATS_LOCK();
    stats.curr_bytes += ITEM_ntotal(it);
    stats.curr_items += 1;
    stats.total_items += 1;
    STATS_UNLOCK();

#ifdef USE_REPLICATION
    /* Allocate a new CAS ID on link. */
    if(!(it->it_flags & ITEM_REPDATA))
        it->cas_id = get_cas_id();
#else
    /* Allocate a new CAS ID on link. */
    it->cas_id = get_cas_id();
#endif /* USE_REPLICATION */

    item_link_q(it);

    return 1;
}

//将item插入到哈希表和LRU队列中，hv为哈希值
int do_item_link(item *it, const uint32_t hv) {
    MEMCACHED_ITEM_LINK(ITEM_key(it), it->nkey, it->nbytes);
    //确保这个item已经从slab分配出去并且还没插入到LRU队列中
    assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0);
    mutex_lock(&cache_lock);
    //加入link标记
    it->it_flags |= ITEM_LINKED;
    it->time = current_time;

    STATS_LOCK();
    stats.curr_bytes += ITEM_ntotal(it);
    stats.curr_items += 1;
    stats.total_items += 1;
    STATS_UNLOCK();

    /* Allocate a new CAS ID on link. */
    ITEM_set_cas(it, (settings.use_cas) ? get_cas_id() : 0);
    //插入到hash表中
    assoc_insert(it, hv);
    //item插入到链表中
    item_link_q(it);
    //引用计数加1
    refcount_incr(&it->refcount);
    mutex_unlock(&cache_lock);

    return 1;
}

int item_free(item *it) {
    size_t ntotal = 0;
    if (NULL == it)
        return 0;

    /* ntotal may be wrong, if 'it' is not a full item. */
    ntotal = ITEM_ntotal(it);
    if (ntotal > settings.item_buf_size){
        if (settings.verbose > 1) {
            fprintf(stderr, "ntotal: %d, use free() directly.\n", ntotal);
        }
        free(it);   
    }else{
        if (0 != item_add_to_freelist(it)) {
            if (settings.verbose > 1) {
                fprintf(stderr, "ntotal: %d, add a item buffer to freelist fail, use free() directly.\n", ntotal);
            }
            free(it);   
        }else{
            if (settings.verbose > 1) {
                fprintf(stderr, "ntotal: %d, add a item buffer to freelist.\n", ntotal);
            }
        }
    }
    return 0;
}

/*@[email protected]*/
void do_item_stats_sizes(ADD_STAT add_stats, void *c) {

    /* max 1MB object, divided into 32 bytes size buckets */
    const int num_buckets = 32768;
    unsigned int *histogram = calloc(num_buckets, sizeof(int));

    if (histogram != NULL) {
        int i;

        /* build the histogram */
        for (i = 0; i < LARGEST_ID; i++) {
            item *iter = heads[i];
            while (iter) {
                int ntotal = ITEM_ntotal(iter);
                int bucket = ntotal / 32;
                if ((ntotal % 32) != 0) bucket++;
                if (bucket < num_buckets) histogram[bucket]++;
                iter = iter->next;
            }
        }

        /* write the buffer */
        for (i = 0; i < num_buckets; i++) {
            if (histogram[i] != 0) {
                char key[8];
                int klen = 0;
                klen = snprintf(key, sizeof(key), "%d", i * 32);
                assert(klen < sizeof(key));
                APPEND_STAT(key, "%u", histogram[i]);
            }
        }
        free(histogram);
    }
    add_stats(NULL, 0, NULL, 0, c);
}

/* 形成了一个完成的 item 后, 就要把它放入两个数据结构中, 一是 memcached 的哈希表,
memcached 运行过程中只有一个哈希表, 二是 item 所在的 slabclass 的 LRU 队列. */
int do_item_link(item *it, const uint32_t hv) {
    MEMCACHED_ITEM_LINK(ITEM_key(it), it->nkey, it->nbytes);
    assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0);
    mutex_lock(&cache_lock);
    it->it_flags |= ITEM_LINKED;
    it->time = current_time;

    STATS_LOCK();
    stats.curr_bytes += ITEM_ntotal(it);
    stats.curr_items += 1;
    stats.total_items += 1;
    STATS_UNLOCK();

    /* Allocate a new CAS ID on link. */
    ITEM_set_cas(it, (settings.use_cas) ? get_cas_id() : 0);

    /* 把 item 放入哈希表 */
    assoc_insert(it, hv);
    /* 把 item 放入 LRU 队列*/
    item_link_q(it);

    refcount_incr(&it->refcount);
    mutex_unlock(&cache_lock);

    return 1;
}

int do_item_link(item *it) {
    MEMCACHED_ITEM_LINK(ITEM_key(it), it->nkey, it->nbytes);
    assert((it->it_flags & (ITEM_LINKED|ITEM_SLABBED)) == 0);
    assert(it->nbytes < (1024 * 1024));  /* 1MB max size */
    it->it_flags |= ITEM_LINKED;
    it->time = current_time;
    assoc_insert(it);

#ifdef MOXI_ITEM_MALLOC
    it->refcount++;
#endif

    STATS_LOCK();
    stats.curr_bytes += ITEM_ntotal(it);
    stats.curr_items += 1;
    stats.total_items += 1;
    STATS_UNLOCK();

    /* Allocate a new CAS ID on link. */
    ITEM_set_cas(it, (settings.use_cas) ? get_cas_id() : 0);

    item_link_q(it);

    return 1;
}

/* I think there's no way for this to be accurate without using the CAS value.
 * Since items getting their time value bumped will pass this validation.
 */
void item_stats_sizes_remove(item *it) {
    if (stats_sizes_hist == NULL || stats_sizes_cas_min > ITEM_get_cas(it))
        return;
    int ntotal = ITEM_ntotal(it);
    int bucket = ntotal / 32;
    if ((ntotal % 32) != 0) bucket++;
    if (bucket < stats_sizes_buckets) stats_sizes_hist[bucket]--;
}

void item_unlink(item *it) {
    if (it->it_flags & ITEM_LINKED) {
        it->it_flags &= ~ITEM_LINKED;
        stats.curr_bytes -= ITEM_ntotal(it);
        stats.curr_items -= 1;
        assoc_delete(ITEM_key(it));
        item_unlink_q(it);
    }
    if (it->refcount == 0) item_free(it);
}

void do_item_unlink(item *it) {
    //    MEMCACHED_ITEM_UNLINK(ITEM_key(it), it->nbytes);
    if ((it->it_flags & ITEM_LINKED) != 0) {
        it->it_flags &= ~ITEM_LINKED;
        stats.curr_bytes -= ITEM_ntotal(it);
        stats.curr_items--;
        assoc_delete(ITEM_key(it), it->nkey);
        item_unlink_q(it);
        if (it->refcount == 0) item_free(it);
    }
}

void do_item_unlink(item *it) {
    if ((it->it_flags & ITEM_LINKED) != 0) {
        it->it_flags &= ~ITEM_LINKED;
        STATS_LOCK();
        stats.curr_bytes -= ITEM_ntotal(it);
        stats.curr_items -= 1;
        STATS_UNLOCK();
        assoc_delete(ITEM_key(it), it->nkey);
        item_unlink_q(it);
        if (it->refcount == 0) item_free(it);
    }
}

void item_free(item *it) {
    unsigned int ntotal = ITEM_ntotal(it);
    assert((it->it_flags & ITEM_LINKED) == 0);
    assert(it != heads[it->slabs_clsid]);
    assert(it != tails[it->slabs_clsid]);
    assert(it->refcount == 0);

    /* so slab size changer can tell later if item is already free or not */
    it->slabs_clsid = 0;
    it->it_flags |= ITEM_SLABBED;
    slabs_free(it, ntotal);
}

/*@[email protected]*/
char *do_item_stats_sizes(uint32_t (*add_stats)(char *buf,
                          const char *key, const uint16_t klen, const char *val,
                          const uint32_t vlen, void *cookie), void *c, int *bytes) {

    const int num_buckets = 32768;   /* max 1MB object, divided into 32 bytes size buckets */
    unsigned int *histogram = (unsigned int *)malloc((size_t)num_buckets * sizeof(int));
    char *buf = (char *)malloc(2 * 1024 * 1024); /* 2MB max response size */
    char *ptr = buf;
    uint32_t nbytes, linelen = 0;
    int i;

    if (histogram == 0 || buf == 0) {
        if (histogram) free(histogram);
        if (buf) free(buf);
        *bytes = -1;
        return NULL;
    }

    /* build the histogram */
    memset(histogram, 0, (size_t)num_buckets * sizeof(int));
    for (i = 0; i < LARGEST_ID; i++) {
        item *iter = heads[i];
        while (iter) {
            int ntotal = ITEM_ntotal(iter);
            int bucket = ntotal / 32;
            if ((ntotal % 32) != 0) bucket++;
            if (bucket < num_buckets) histogram[bucket]++;
            iter = iter->next;
        }
    }

    /* write the buffer */
    *bytes = 0;
    char key[128];
    char val[128];

    for (i = 0; i < num_buckets; i++) {
        if (histogram[i] != 0) {
            sprintf(key, "%d", i * 32);
            sprintf(val, "%u", histogram[i]);
            nbytes = add_stats(ptr, key, strlen(key), val, strlen(val), c);
            linelen += nbytes;
            ptr += nbytes;
        }
    }

    nbytes = add_stats(ptr, NULL, 0, NULL, 0, c);
    *bytes = linelen + nbytes;

    free(histogram);
    return buf;
}

/* FIXME: Is it necessary to keep this copy/pasted code? */
void do_item_unlink_nolock(item *it, const uint32_t hv) {
    MEMCACHED_ITEM_UNLINK(ITEM_key(it), it->nkey, it->nbytes);
    if ((it->it_flags & ITEM_LINKED) != 0) {
        it->it_flags &= ~ITEM_LINKED;
        STATS_LOCK();
        stats.curr_bytes -= ITEM_ntotal(it);
        stats.curr_items -= 1;
        STATS_UNLOCK();
        assoc_delete(ITEM_key(it), it->nkey, hv);
        item_unlink_q(it);
        do_item_remove(it);
    }
}

/* slawek */
void do_item_unlink_nolock_nostat(item *it, const uint32_t hv, uint64_t *items_removed, uint64_t *bytes_removed) {
    MEMCACHED_ITEM_UNLINK(ITEM_key(it), it->nkey, it->nbytes);
    if ((it->it_flags & ITEM_LINKED) != 0) {
        it->it_flags &= ~ITEM_LINKED;
        
        *items_removed += 1;
        *bytes_removed += ITEM_ntotal(it);
       
        assoc_delete(ITEM_key(it), it->nkey, hv);
        item_unlink_q(it);
        do_item_remove(it);
    }
}

void item_free(item *it) {
    size_t ntotal = ITEM_ntotal(it);
    unsigned int clsid;
    assert((it->it_flags & ITEM_LINKED) == 0);
    assert(it != heads[it->slabs_clsid]);
    assert(it != tails[it->slabs_clsid]);
    assert(it->refcount == 0);

    /* so slab size changer can tell later if item is already free or not */
    clsid = ITEM_clsid(it);
    DEBUG_REFCNT(it, 'F');
    slabs_free(it, ntotal, clsid);
}