C++ DEBUG_REFCNT函数代码示例

static hash_item *do_item_get(struct demo_engine *engine,
                              const char *key, const size_t nkey,
                              bool LRU_reposition)
{
    rel_time_t current_time = engine->server.core->get_current_time();
    hash_item *it = dm_assoc_find(engine, engine->server.core->hash(key, nkey, 0),
                                  key, nkey);

    if (it != NULL) {
        if (do_item_isvalid(engine, it, current_time)==false) {
            do_item_unlink(engine, it, ITEM_UNLINK_INVALID);
            it = NULL;
        }
    }
    if (it != NULL) {
        ITEM_REFCOUNT_INCR(it);
        DEBUG_REFCNT(it, '+');
    }

    if (engine->config.verbose > 2) {
        if (it == NULL) {
            logger->log(EXTENSION_LOG_INFO, NULL, "> NOT FOUND %s\n",
                        key);
        } else {
            logger->log(EXTENSION_LOG_INFO, NULL, "> FOUND KEY %s\n",
                        (const char*)dm_item_get_key(it));
        }
    }
    return it;
}

/** wrapper around assoc_find which does the lazy expiration/deletion logic */
item *do_item_get_notedeleted(const char *key, const size_t nkey, bool *delete_locked) {
    item *it = assoc_find(key, nkey);
    int was_found = 0;
    if (delete_locked) *delete_locked = false;

    if (settings.verbose > 2) {
        if (it == NULL) {
            fprintf(stderr, "> NOT FOUND %s", key);
        } else {
            fprintf(stderr, "> FOUND KEY %s", ITEM_key(it));
            was_found++;
        }
    }

    if (it != NULL && (it->it_flags & ITEM_DELETED)) {
        /* it's flagged as delete-locked.  let's see if that condition
           is past due, and the 5-second delete_timer just hasn't
           gotten to it yet... */
        if (!item_delete_lock_over(it)) {
            if (delete_locked) *delete_locked = true;
            it = NULL;
        }
    }

    if (it == NULL && was_found) {
        fprintf(stderr, " -nuked by delete lock");
        was_found--;
    }

    if (it != NULL && settings.oldest_live != 0 && settings.oldest_live <= current_time &&
        it->time <= settings.oldest_live) {
        do_item_unlink(it);           /* MTSAFE - cache_lock held */
        it = NULL;
    }

    if (it == NULL && was_found) {
        fprintf(stderr, " -nuked by flush");
        was_found--;
    }

    if (it != NULL && it->exptime != 0 && it->exptime <= current_time) {
        do_item_unlink(it);           /* MTSAFE - cache_lock held */
        it = NULL;
    }

    if (it == NULL && was_found) {
        fprintf(stderr, " -nuked by expire");
        was_found--;
    }

    if (it != NULL) {
        it->refcount++;
        DEBUG_REFCNT(it, '+');
    }

    if (settings.verbose > 2)
        fprintf(stderr, "\n");

    return it;
}

/** wrapper around assoc_find which does the lazy expiration logic */
hash_item *do_item_get(struct default_engine *engine,
                       const hash_key *key) {
    rel_time_t current_time = engine->server.core->get_current_time();
    hash_item *it = assoc_find(engine,
                               crc32c(hash_key_get_key(key),
                                      hash_key_get_key_len(key), 0),
                               key);
    int was_found = 0;

    if (engine->config.verbose > 2) {
        EXTENSION_LOGGER_DESCRIPTOR *logger;
        logger = (void*)engine->server.extension->get_extension(EXTENSION_LOGGER);
        if (it == NULL) {
            logger->log(EXTENSION_LOG_DEBUG, NULL,
                        "> NOT FOUND in bucket %d, %s",
                        hash_key_get_bucket_index(key),
                        hash_key_get_client_key(key));
        } else {
            logger->log(EXTENSION_LOG_DEBUG, NULL,
                        "> FOUND KEY in bucket %d, %s",
                        hash_key_get_bucket_index(item_get_key(it)),
                        hash_key_get_client_key(item_get_key(it)));
            was_found++;
        }
    }

    if (it != NULL && engine->config.oldest_live != 0 &&
        engine->config.oldest_live <= current_time &&
        it->time <= engine->config.oldest_live) {
        do_item_unlink(engine, it);           /* MTSAFE - items.lock held */
        it = NULL;
    }

    if (it == NULL && was_found) {
        EXTENSION_LOGGER_DESCRIPTOR *logger;
        logger = (void*)engine->server.extension->get_extension(EXTENSION_LOGGER);
        logger->log(EXTENSION_LOG_DEBUG, NULL, " -nuked by flush");
        was_found--;
    }

    if (it != NULL && it->exptime != 0 && it->exptime <= current_time) {
        do_item_unlink(engine, it);           /* MTSAFE - items.lock held */
        it = NULL;
    }

    if (it == NULL && was_found) {
        EXTENSION_LOGGER_DESCRIPTOR *logger;
        logger = (void*)engine->server.extension->get_extension(EXTENSION_LOGGER);
        logger->log(EXTENSION_LOG_DEBUG, NULL, " -nuked by expire");
        was_found--;
    }

    if (it != NULL) {
        it->refcount++;
        DEBUG_REFCNT(it, '+');
        do_item_update(engine, it);
    }

    return it;
}

/** wrapper around assoc_find which does the lazy expiration/deletion logic */
item *do_item_get_notedeleted(const char *key, const size_t nkey, bool *delete_locked) {
    item *it = assoc_find(key, nkey);
    if (delete_locked) *delete_locked = false;
    if (it != NULL && (it->it_flags & ITEM_DELETED)) {
        /* it's flagged as delete-locked.  let's see if that condition
           is past due, and the 5-second delete_timer just hasn't
           gotten to it yet... */
        if (!item_delete_lock_over(it)) {
            if (delete_locked) *delete_locked = true;
            it = NULL;
        }
    }
    if (it != NULL && settings.oldest_live != 0 && settings.oldest_live <= current_time &&
        it->time <= settings.oldest_live) {
        do_item_unlink(it);           /* MTSAFE - cache_lock held */
        it = NULL;
    }
    if (it != NULL && it->exptime != 0 && it->exptime <= current_time) {
        do_item_unlink(it);           /* MTSAFE - cache_lock held */
        it = NULL;
    }

    if (it != NULL) {
        it->refcount++;
        DEBUG_REFCNT(it, '+');
    }
    return it;
}

/** wrapper around assoc_find which does the lazy expiration logic */
item *do_item_get(const char *key, const size_t nkey, const uint32_t hv) {
    mutex_lock(&cache_lock);
    item *it = assoc_find(key, nkey, hv);
    if (it != NULL) {
        refcount_incr(&it->refcount);
        /* Optimization for slab reassignment. prevents popular items from
         * jamming in busy wait. Can only do this here to satisfy lock order
         * of item_lock, cache_lock, slabs_lock. */
        if (slab_rebalance_signal &&
            ((void *)it >= slab_rebal.slab_start && (void *)it < slab_rebal.slab_end)) {
            do_item_unlink_nolock(it, hv);
            do_item_remove(it);
            it = NULL;
        }
    }
    pthread_mutex_unlock(&cache_lock);
    int was_found = 0;

    if (settings.verbose > 2) {
        if (it == NULL) {
            fprintf(stderr, "> NOT FOUND %s", key);
        } else {
            fprintf(stderr, "> FOUND KEY %s", ITEM_key(it));
            was_found++;
        }
    }

    if (it != NULL) {
        if (settings.oldest_live != 0 && settings.oldest_live <= current_time &&
            it->time <= settings.oldest_live) {
            do_item_unlink(it, hv);
            do_item_remove(it);
            it = NULL;
            if (was_found) {
                fprintf(stderr, " -nuked by flush");
            }
        } else if (it->exptime != 0 && it->exptime <= current_time) {
            if (it->exptime + 10 < current_time) {
                do_item_unlink(it, hv);
                do_item_remove(it);
                if (was_found) {
                    fprintf(stderr, " -nuked by expire");
                }
            } else {
                /* re-active just expired items, to anti miss-storm */
                it->exptime = current_time + 10;
            }
            it = NULL;
        } else {
            it->it_flags |= ITEM_FETCHED;
            DEBUG_REFCNT(it, '+');
        }
    }

    if (settings.verbose > 2)
        fprintf(stderr, "\n");

    return it;
}

static void do_item_free(struct demo_engine *engine, hash_item *it)
{
    assert((it->iflag & ITEM_LINKED) == 0);
    assert(it->refcount == 0);

    it->slabs_clsid = 0;
    DEBUG_REFCNT(it, 'F');
    free(it);
}

void do_item_release(struct default_engine *engine, hash_item *it) {
    MEMCACHED_ITEM_REMOVE(item_get_key(it), it->nkey, it->nbytes);
    if (it->refcount != 0) {
        it->refcount--;
        DEBUG_REFCNT(it, '-');
    }
    if (it->refcount == 0 && (it->iflag & ITEM_LINKED) == 0) {
        item_free(engine, it);
    }
}

void do_item_remove(item *it) {
    if (it->refcount != 0) {
        it->refcount--;
        DEBUG_REFCNT(it, '-');
    }
    assert((it->it_flags & ITEM_DELETED) == 0 || it->refcount != 0);
    if (it->refcount == 0 && (it->it_flags & ITEM_LINKED) == 0) {
        item_free(it);
    }
}

void do_item_remove(item *it) {
    MEMCACHED_ITEM_REMOVE(ITEM_key(it), it->nkey, it->nbytes);
    assert((it->it_flags & ITEM_SLABBED) == 0);
    if (it->refcount != 0) {
        it->refcount--;
        DEBUG_REFCNT(it, '-');
    }
    if (it->refcount == 0 && (it->it_flags & ITEM_LINKED) == 0) {
        item_free(it);
    }
}

void item_free(item *it) {
    size_t 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;
    DEBUG_REFCNT(it, 'F');
    slabs_free(it, ntotal);
}

static void do_item_release(struct demo_engine *engine, hash_item *it)
{
    MEMCACHED_ITEM_REMOVE(dm_item_get_key(it), it->nkey, it->nbytes);
    if (it->refcount != 0) {
        ITEM_REFCOUNT_DECR(it);
        DEBUG_REFCNT(it, '-');
    }
    if (it->refcount == 0) {
        if ((it->iflag & ITEM_LINKED) == 0) {
            do_item_free(engine, it);
        }
    }
}

//将item内存置为空闲，以供再使用，这里的free不是把内存空间释放
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 = it->slabs_clsid;
    it->slabs_clsid = 0;  //free掉的 item的slabs_clsid设为0
    DEBUG_REFCNT(it, 'F');
    slabs_free(it, ntotal, clsid);
}

//释放item
void item_free(item *it) {
    size_t ntotal = ITEM_ntotal(it);//获得item的大小
    unsigned int clsid;
    assert((it->it_flags & ITEM_LINKED) == 0);//判断item的状态是否正确
    assert(it != heads[it->slabs_clsid]);//item不能为LRU的头指针
    assert(it != tails[it->slabs_clsid]);//item不能为LRU的尾指针
    assert(it->refcount == 0);//释放时，需保证引用次数为0

    /* so slab size changer can tell later if item is already free or not */
    clsid = it->slabs_clsid;
    it->slabs_clsid = 0;//断开slabclass的链接
    DEBUG_REFCNT(it, 'F');
    slabs_free(it, ntotal, clsid);//slabclass结构执行释放
}

//释放item
void item_free(item *it) {
		syslog(LOG_INFO, "[%s:%s:%d]", __FILE__, __func__, __LINE__);
    size_t ntotal = ITEM_ntotal(it);
    unsigned int clsid;
    assert((it->it_flags & ITEM_LINKED) == 0);//没有在hash表和LUR链中
    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 = it->slabs_clsid;
    it->slabs_clsid = 0;
    DEBUG_REFCNT(it, 'F');
    slabs_free(it, ntotal, clsid);
}

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

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

    //[TODO] allocate management
    zfree(it);
}