Ejemplo n.º 1
0
void mcache_delete(mcache *m, char *key, int key_len) {
    (void)key_len;
    (void)key;
    assert(key);
    assert(key_len > 0);
    assert(key[key_len] == '\0' ||
           key[key_len] == ' ');

    if (m == NULL) {
        return;
    }

    if (m->lock) {
        cb_mutex_enter(m->lock);
    }

    if (m->map != NULL) {
        void *existing = genhash_find(m->map, key);
        if (existing != NULL) {
            mcache_item_unlink(m, existing);

            genhash_delete(m->map, key);

            m->tot_deletes++;

            if (settings.verbose > 1) {
                moxi_log_write("mcache delete: %s\n", key);
            }
        }
    }

    if (m->lock) {
        cb_mutex_exit(m->lock);
    }
}
Ejemplo n.º 2
0
static ENGINE_ERROR_CODE mock_get(ENGINE_HANDLE* handle,
                                  const void* cookie,
                                  item** item,
                                  const void* key,
                                  const int nkey) {
    *item = genhash_find(get_ht(handle), key, nkey);

    return *item ? ENGINE_SUCCESS : ENGINE_KEY_ENOENT;
}
Ejemplo n.º 3
0
static ENGINE_ERROR_CODE mock_get(ENGINE_HANDLE* handle,
                                  const void* cookie,
                                  item** itm,
                                  const void* key,
                                  const int nkey,
                                  uint16_t vbucket) {
    (void)cookie;
    (void)vbucket;
    *itm = genhash_find(get_ht(handle), key, nkey);

    return *itm ? ENGINE_SUCCESS : ENGINE_KEY_ENOENT;
}
Ejemplo n.º 4
0
static void
assert_hash_val(char *expected, genhash_t* h, const char* key)
{
    char *found=(char*)genhash_find(h, key);

    if(expected == NULL) {
        if(found != NULL) {
            fprintf(stderr, "Expected NULL for ``%s'', got ``%s''\n",
                    key, found);
            abort();
        }
    } else {
        if(strcmp(expected, found) != 0) {
            fprintf(stderr, "Expected ``%s'' for ``%s'', got ``%s''\n",
                    expected, key, found);
            abort();
        }
    }
}
Ejemplo n.º 5
0
/**
 * Observe callback. Called internally by libcouchbase's observe handlers
 */
void lcb_durability_dset_update(lcb_t instance,
                                lcb_durability_set_t *dset,
                                lcb_error_t err,
                                const lcb_observe_resp_t *resp)
{
    lcb_durability_entry_t *ent;

    /**
     * So we have two counters to decrement. One is the global 'done' counter
     * and the other is the iteration counter.
     *
     * The iteration counter is only decremented when we receive a NULL signal
     * in the callback, whereas the global counter is decremented once, whenever
     * the entry's criteria have been satisfied
     */

    if (resp->v.v0.key == NULL) {
        dset_done_waiting(dset);
        return;
    }

    if (dset->nentries == 1) {
        ent = &dset->single.ent;
    } else {
        ent = genhash_find(dset->ht, resp->v.v0.key, resp->v.v0.nkey);
    }

    if (ent->done) {
        /* ignore subsequent errors */
        return;
    }

    if (err != LCB_SUCCESS) {
        RESFLD(ent, err) = err;
        return;
    }

    RESFLD(ent, nresponses)++;

    if (resp->v.v0.cas && resp->v.v0.from_master) {

        RESFLD(ent, cas) = resp->v.v0.cas;

        if (REQFLD(ent, cas) && REQFLD(ent, cas) != resp->v.v0.cas) {
            RESFLD(ent, err) = LCB_KEY_EEXISTS;
            ent_set_resdone(ent);
            return;
        }
    }

    if (DSET_OPTFLD(ent->parent, check_delete)) {
        check_negative_durability(ent, resp);

    } else {
        check_positive_durability(ent, resp);
    }

    if (ent_is_complete(ent)) {
        /* clear any transient errors */
        RESFLD(ent, err) = LCB_SUCCESS;
        ent_set_resdone(ent);
    }

    (void)instance;

}
Ejemplo n.º 6
0
bool multiget_ascii_downstream(downstream *d, conn *uc,
    int (*emit_start)(conn *c, char *cmd, int cmd_len),
    int (*emit_skey)(conn *c, char *skey, int skey_len),
    int (*emit_end)(conn *c),
    mcache *front_cache) {
    assert(d != NULL);
    assert(d->downstream_conns != NULL);
    assert(d->multiget == NULL);
    assert(uc != NULL);
    assert(uc->noreply == false);

    proxy_td *ptd = d->ptd;
    assert(ptd != NULL);

    proxy_stats_cmd *psc_get =
        &ptd->stats.stats_cmd[STATS_CMD_TYPE_REGULAR][STATS_CMD_GET];
    proxy_stats_cmd *psc_get_key =
        &ptd->stats.stats_cmd[STATS_CMD_TYPE_REGULAR][STATS_CMD_GET_KEY];

    int nwrite = 0;
    int nconns = mcs_server_count(&d->mst);

    for (int i = 0; i < nconns; i++) {
        if (d->downstream_conns[i] != NULL &&
            cproxy_prep_conn_for_write(d->downstream_conns[i]) == false) {
            d->ptd->stats.stats.err_downstream_write_prep++;
            cproxy_close_conn(d->downstream_conns[i]);
            return false;
        }
    }

    if (uc->next != NULL) {
        // More than one upstream conn, so we need a hashtable
        // to track keys for de-deplication.
        //
        d->multiget = genhash_init(128, skeyhash_ops);
        if (settings.verbose > 1) {
            fprintf(stderr, "cproxy multiget hash table new\n");
        }
    }

    // Snapshot the volatile only once.
    //
    uint32_t msec_current_time_snapshot = msec_current_time;

    int   uc_num = 0;
    conn *uc_cur = uc;

    while (uc_cur != NULL) {
        assert(uc_cur->cmd == -1);
        assert(uc_cur->item == NULL);
        assert(uc_cur->state == conn_pause);
        assert(IS_ASCII(uc_cur->protocol));
        assert(IS_PROXY(uc_cur->protocol));

        char *command = uc_cur->cmd_start;
        assert(command != NULL);

        char *space = strchr(command, ' ');
        assert(space > command);

        int cmd_len = space - command;
        assert(cmd_len == 3 || cmd_len == 4); // Either get or gets.

        int cas_emit = (command[3] == 's');

        if (settings.verbose > 1) {
            fprintf(stderr, "forward multiget %s (%d %d)\n",
                    command, cmd_len, uc_num);
        }

        while (space != NULL) {
            char *key = space + 1;
            char *next_space = strchr(key, ' ');
            int   key_len;

            if (next_space != NULL) {
                key_len = next_space - key;
            } else {
                key_len = strlen(key);

                // We've reached the last key.
                //
                psc_get->read_bytes += (key - command + key_len);
            }

            // This key_len check helps skip consecutive spaces.
            //
            if (key_len > 0) {
                ptd->stats.stats.tot_multiget_keys++;

                psc_get_key->seen++;
                psc_get_key->read_bytes += key_len;

                // Update key-based statistics.
                //
                bool do_key_stats =
                    matcher_check(&ptd->key_stats_matcher,
                                  key, key_len, true) == true &&
                    matcher_check(&ptd->key_stats_unmatcher,
                                  key, key_len, false) == false;

                if (do_key_stats) {
                    touch_key_stats(ptd, key, key_len,
                                    msec_current_time_snapshot,
                                    STATS_CMD_TYPE_REGULAR,
                                    STATS_CMD_GET_KEY,
                                    1, 0, 0,
                                    key_len, 0);
                }

                // Handle a front cache hit by queuing response.
                //
                // Note, front cache stats are part of mcache.
                //
                if (!cas_emit) {
                    item *it = mcache_get(front_cache, key, key_len,
                                          msec_current_time_snapshot);
                    if (it != NULL) {
                        assert(it->nkey == key_len);
                        assert(strncmp(ITEM_key(it), key, it->nkey) == 0);

                        cproxy_upstream_ascii_item_response(it, uc_cur, 0);

                        psc_get_key->hits++;
                        psc_get_key->write_bytes += it->nbytes;

                        if (do_key_stats) {
                            touch_key_stats(ptd, key, key_len,
                                            msec_current_time_snapshot,
                                            STATS_CMD_TYPE_REGULAR,
                                            STATS_CMD_GET_KEY,
                                            0, 1, 0,
                                            0, it->nbytes);
                        }

                        // The refcount was inc'ed by mcache_get() for us.
                        //
                        item_remove(it);

                        goto loop_next;
                    }
                }

                bool self = false;

                conn *c = cproxy_find_downstream_conn(d, key, key_len,
                                                      &self);
                if (c != NULL) {
                    if (self) {
                        // Optimization for talking with ourselves,
                        // to avoid extra network hop.
                        //
                        ptd->stats.stats.tot_optimize_self++;

                        item *it = item_get(key, key_len);
                        if (it != NULL) {
                            cproxy_upstream_ascii_item_response(it, uc_cur,
                                                                cas_emit);

                            psc_get_key->hits++;
                            psc_get_key->write_bytes += it->nbytes;

                            if (do_key_stats) {
                                touch_key_stats(ptd, key, key_len,
                                                msec_current_time_snapshot,
                                                STATS_CMD_TYPE_REGULAR,
                                                STATS_CMD_GET_KEY,
                                                0, 1, 0,
                                                0, it->nbytes);
                            }

                            // The refcount was inc'ed by item_get() for us.
                            //
                            item_remove(it);

                            if (settings.verbose > 1) {
                                fprintf(stderr,
                                        "optimize self multiget hit: %s\n",
                                        key);
                            }
                        } else {
                            psc_get_key->misses++;

                            if (do_key_stats) {
                                touch_key_stats(ptd, key, key_len,
                                                msec_current_time_snapshot,
                                                STATS_CMD_TYPE_REGULAR,
                                                STATS_CMD_GET_KEY,
                                                0, 0, 1,
                                                0, 0);
                            }

                            if (settings.verbose > 1) {
                                fprintf(stderr,
                                        "optimize self multiget miss: %s\n",
                                        key);
                            }
                        }

                        goto loop_next;
                    }

                    // See if we've already requested this key via
                    // the multiget hash table, in order to
                    // de-deplicate repeated keys.
                    //
                    bool first_request = true;

                    if (d->multiget != NULL) {
                        // TODO: Use Trond's allocator here.
                        //
                        multiget_entry *entry =
                            calloc(1, sizeof(multiget_entry));
                        if (entry != NULL) {
                            entry->upstream_conn = uc_cur;
                            entry->opaque = 0;
                            entry->hits = 0;
                            entry->next = genhash_find(d->multiget, key);

                            genhash_update(d->multiget, key, entry);

                            if (entry->next != NULL) {
                                first_request = false;
                            }
                        } else {
                            // TODO: Handle out of multiget entry memory.
                        }
                    }

                    if (first_request) {
                        assert(c->item == NULL);
                        assert(c->state == conn_pause);
                        assert(IS_PROXY(c->protocol));
                        assert(c->ilist != NULL);
                        assert(c->isize > 0);

                        if (c->msgused <= 1 &&
                            c->msgbytes <= 0) {
                            emit_start(c, command, cmd_len);
                        }

                        // Provide the preceding space as optimization
                        // for ascii-to-ascii configuration.
                        //
                        emit_skey(c, key - 1, key_len + 1);
                    } else {
                        ptd->stats.stats.tot_multiget_keys_dedupe++;

                        if (settings.verbose > 1) {
                            char buf[KEY_MAX_LENGTH + 10];
                            memcpy(buf, key, key_len);
                            buf[key_len] = '\0';

                            fprintf(stderr,
                                    "%d cproxy multiget dedpue: %s\n",
                                    uc_cur->sfd, buf);
                        }
                    }
                } else {
                    // TODO: Handle when downstream conn is down.
                }
            }

        loop_next:
            space = next_space;
        }

        uc_num++;
        uc_cur = uc_cur->next;
    }

    for (int i = 0; i < nconns; i++) {
        conn *c = d->downstream_conns[i];
        if (c != NULL &&
            (c->msgused > 1 ||
             c->msgbytes > 0)) {
            emit_end(c);

            conn_set_state(c, conn_mwrite);
            c->write_and_go = conn_new_cmd;

            if (update_event(c, EV_WRITE | EV_PERSIST)) {
                nwrite++;

                if (uc->noreply) {
                    c->write_and_go = conn_pause;
                }
            } else {
                if (settings.verbose > 1) {
                    fprintf(stderr,
                            "Couldn't update cproxy write event\n");
                }

                d->ptd->stats.stats.err_oom++;
                cproxy_close_conn(c);
            }
        }
    }

    if (settings.verbose > 1) {
        fprintf(stderr, "forward multiget nwrite %d out of %d\n",
                nwrite, nconns);
    }

    d->downstream_used_start = nwrite;
    d->downstream_used       = nwrite;

    if (cproxy_dettach_if_noreply(d, uc) == false) {
        d->upstream_suffix = "END\r\n";

        cproxy_start_downstream_timeout(d, NULL);
    }

    return nwrite > 0;
}
Ejemplo n.º 7
0
void multiget_ascii_downstream_response(downstream *d, item *it) {
    assert(d);
    assert(it);
    assert(it->nkey > 0);
    assert(ITEM_key(it) != NULL);

    proxy_td *ptd = d->ptd;
    assert(ptd);

    proxy_stats_cmd *psc_get_key =
        &ptd->stats.stats_cmd[STATS_CMD_TYPE_REGULAR][STATS_CMD_GET_KEY];

    proxy *p = ptd->proxy;
    assert(p);

    uint32_t front_cache_lifespan =
        ptd->behavior_pool.base.front_cache_lifespan;

    if (front_cache_lifespan > 0) {
        if (matcher_check(&p->front_cache_matcher,
                          ITEM_key(it), it->nkey, true) == true &&
            matcher_check(&p->front_cache_unmatcher,
                           ITEM_key(it), it->nkey, false) == false) {
            mcache_set(&p->front_cache, it,
                       front_cache_lifespan + msec_current_time,
                       true, false);
        }
    }

    if (d->multiget != NULL) {
        // The ITEM_key is not NULL or space terminated.
        //
        char key_buf[KEY_MAX_LENGTH + 10];
        assert(it->nkey <= KEY_MAX_LENGTH);
        memcpy(key_buf, ITEM_key(it), it->nkey);
        key_buf[it->nkey] = '\0';

        multiget_entry *entry_first = genhash_find(d->multiget, key_buf);

        if (entry_first != NULL) {
            entry_first->hits++;

            multiget_entry *entry = entry_first;
            while (entry != NULL) {
                // The upstream might have been closed mid-request.
                //
                // TODO: Revisit the -1 cas_emit parameter.
                //
                conn *uc = entry->upstream_conn;
                if (uc != NULL) {
                    cproxy_upstream_ascii_item_response(it, uc, -1);

                    psc_get_key->hits++;
                    psc_get_key->write_bytes += it->nbytes;

                    if (matcher_check(&ptd->key_stats_matcher,
                                      ITEM_key(it), it->nkey, true) == true &&
                        matcher_check(&ptd->key_stats_unmatcher,
                                      ITEM_key(it), it->nkey, false) == false) {
                        touch_key_stats(ptd, ITEM_key(it), it->nkey,
                                        msec_current_time,
                                        STATS_CMD_TYPE_REGULAR,
                                        STATS_CMD_GET_KEY,
                                        0, 1, 0,
                                        0, it->nbytes);
                    }

                    if (entry != entry_first) {
                        ptd->stats.stats.tot_multiget_bytes_dedupe += it->nbytes;
                    }
                }

                entry = entry->next;
            }
        }
    } else {
        // TODO: We're not tracking miss stats in the simple case.
        // Do we always need to use a multiget hashtable?
        // Or, perhaps misses equals number of requests - number of hits.
        //
        conn *uc = d->upstream_conn;
        while (uc != NULL) {
            // TODO: Revisit the -1 cas_emit parameter.
            //
            cproxy_upstream_ascii_item_response(it, uc, -1);

            psc_get_key->hits++;
            psc_get_key->write_bytes += it->nbytes;

            if (matcher_check(&ptd->key_stats_matcher,
                              ITEM_key(it), it->nkey, true) == true &&
                matcher_check(&ptd->key_stats_unmatcher,
                              ITEM_key(it), it->nkey, false) == false) {
                touch_key_stats(ptd, ITEM_key(it), it->nkey,
                                msec_current_time,
                                STATS_CMD_TYPE_REGULAR,
                                STATS_CMD_GET_KEY,
                                0, 1, 0,
                                0, it->nbytes);
            }

            uc = uc->next;
        }
    }
}
Ejemplo n.º 8
0
void mcache_set(mcache *m, void *it,
                uint64_t exptime,
                bool add_only,
                bool mod_exptime_if_exists) {
    assert(it);
    assert(m->funcs);
    assert(m->funcs->item_get_next(it) == NULL);
    assert(m->funcs->item_get_prev(it) == NULL);

    if (m == NULL) {
        return;
    }

    /* TODO: Our lock areas are possibly too wide. */

    if (m->lock) {
        cb_mutex_enter(m->lock);
    }

    if (m->map != NULL) {
        /* Evict some items if necessary. */
        int i;
        for (i = 0; m->lru_tail != NULL && i < 20; i++) {
            void *last_it;
            if ((uint32_t)genhash_size(m->map) < m->max) {
                break;
            }

            last_it = m->lru_tail;

            mcache_item_unlink(m, last_it);

            if (m->key_alloc) {
                int  len = m->funcs->item_key_len(last_it);
                char buf[KEY_MAX_LENGTH + 10];
                memcpy(buf, m->funcs->item_key(last_it), len);
                buf[len] = '\0';

                genhash_delete(m->map, buf);
            } else {
                genhash_delete(m->map, m->funcs->item_key(last_it));
            }

            m->tot_evictions++;
        }

        if ((uint32_t)genhash_size(m->map) < m->max) {
            char *key     = m->funcs->item_key(it);
            int   key_len = m->funcs->item_key_len(it);
            char *key_buf = NULL;

            if (m->key_alloc) {
                /* The ITEM_key is not NULL or space terminated, */
                /* and we need a copy, too, for hashtable ownership. */

                /* TODO: Move this outside the lock area? */

                key_buf = malloc(key_len + 1);
                if (key_buf != NULL) {
                    memcpy(key_buf, key, key_len);
                    key_buf[key_len] = '\0';
                    key = key_buf;
                } else {
                    key = NULL;
                }
            }

            if (key != NULL) {
                void *existing = add_only ? genhash_find(m->map, key) : NULL;
                if (existing != NULL) {
                    mcache_item_unlink(m, existing);
                    mcache_item_touch(m, existing);

                    if (mod_exptime_if_exists) {
                        m->funcs->item_set_exptime(existing, exptime);
                    }

                    m->tot_add_skips++;

                    if (settings.verbose > 1) {
                        moxi_log_write("mcache add-skip: %s\n", key);
                    }

                    if (key_buf != NULL) {
                        free(key_buf);
                    }
                } else {
                    m->funcs->item_set_exptime(it, exptime);
                    m->funcs->item_add_ref(it);

                    genhash_update(m->map, key, it);

                    m->tot_adds++;
                    m->tot_add_bytes += m->funcs->item_len(it);

                    if (settings.verbose > 1) {
                        moxi_log_write("mcache add: %s\n", key);
                    }
                }
            } else {
                m->tot_add_fails++;
            }
        } else {
            m->tot_add_fails++;
        }
    }

    if (m->lock) {
        cb_mutex_exit(m->lock);
    }
}
Ejemplo n.º 9
0
void *mcache_get(mcache *m, char *key, int key_len,
                 uint64_t curr_time) {
    (void)key_len;
    assert(key);

    if (m == NULL) {
        return NULL;
    }

    assert(m->funcs);

    if (m->lock) {
        cb_mutex_enter(m->lock);
    }

    if (m->map != NULL) {
        void *it = genhash_find(m->map, key);
        if (it != NULL) {
            mcache_item_unlink(m, it);

            uint64_t exptime = m->funcs->item_get_exptime(it);
            if ((exptime <= 0) ||
                (exptime >= curr_time &&
                 exptime >= m->oldest_live)) {
                mcache_item_touch(m, it);

                m->funcs->item_add_ref(it); /* TODO: Need lock here? */

                m->tot_get_hits++;
                m->tot_get_bytes += m->funcs->item_len(it);

                if (m->lock) {
                    cb_mutex_exit(m->lock);
                }

                if (settings.verbose > 1) {
                    moxi_log_write("mcache hit: %s\n", key);
                }

                return it;
            }

            /* Handle item expiration. */

            m->tot_get_expires++;

            if (settings.verbose > 1) {
                moxi_log_write("mcache expire: %s\n", key);
            }

            genhash_delete(m->map, key);
        } else {
            m->tot_get_misses++;

            if (settings.verbose > 1) {
                moxi_log_write("mcache miss: %s\n", key);
            }
        }
    }

    if (m->lock) {
        cb_mutex_exit(m->lock);
    }

    return NULL;
}
Ejemplo n.º 10
0
bool protocol_stats_merge_name_val(genhash_t *merger,
                                   char *prefix,
                                   int   prefix_len,
                                   char *name,
                                   int   name_len,
                                   char *val,
                                   int   val_len) {

    char *key;
    int key_len;

    cb_assert(merger);
    cb_assert(name);
    cb_assert(val);

    key = name + name_len - 1;     /* Key part for merge rule lookup. */
    while (key >= name && *key != ':') { /* Scan for last colon. */
        key--;
    }
    if (key < name) {
        key = name;
    }
    key_len = name_len - (key - name);
    if (key_len > 0 && key_len < MERGE_BUF_SIZE) {
        char buf_name[MERGE_BUF_SIZE];
        char buf_key[MERGE_BUF_SIZE];
        char buf_val[MERGE_BUF_SIZE];
        char *prev;
        token_t prev_tokens[MAX_TOKENS];
        size_t prev_ntokens;
        bool ok;

        strncpy(buf_name, name, name_len);
        buf_name[name_len] = '\0';

        prev = (char *) genhash_find(merger, buf_name);
        if (prev == NULL) {
            char *hval = malloc(prefix_len + 1 +
                                name_len + 1 +
                                val_len + 1);
            if (hval != NULL) {
                memcpy(hval, prefix, prefix_len);
                hval[prefix_len] = ' ';

                memcpy(hval + prefix_len + 1, name, name_len);
                hval[prefix_len + 1 + name_len] = ' ';

                memcpy(hval + prefix_len + 1 + name_len + 1, val, val_len);
                hval[prefix_len + 1 + name_len + 1 + val_len] = '\0';

                genhash_update(merger, hval + prefix_len + 1, hval);
            }

            return true;
        }

        strncpy(buf_key, key, key_len);
        buf_key[key_len] = '\0';

        if (strstr(protocol_stats_keys_first, buf_key) != NULL) {
            return true;
        }

        prev_ntokens = scan_tokens(prev, prev_tokens, MAX_TOKENS, NULL);
        if (prev_ntokens != 4) {
            return true;
        }

        strncpy(buf_val, val, val_len);
        buf_val[val_len] = '\0';

        if (strstr(protocol_stats_keys_smallest, buf_key) != NULL) {
            ok = protocol_stats_merge_smallest(prev_tokens[VALUE_TOKEN].value,
                                               prev_tokens[VALUE_TOKEN].length,
                                               buf_val, val_len,
                                               buf_val, MERGE_BUF_SIZE);
        } else {
            ok = protocol_stats_merge_sum(prev_tokens[VALUE_TOKEN].value,
                                          prev_tokens[VALUE_TOKEN].length,
                                          buf_val, val_len,
                                          buf_val, MERGE_BUF_SIZE);
        }

        if (ok) {
            int   vlen = strlen(buf_val);
            char *hval = malloc(prefix_len + 1 +
                                name_len + 1 +
                                vlen + 1);
            if (hval != NULL) {
                memcpy(hval, prefix, prefix_len);
                hval[prefix_len] = ' ';

                memcpy(hval + prefix_len + 1, name, name_len);
                hval[prefix_len + 1 + name_len] = ' ';

                strcpy(hval + prefix_len + 1 + name_len + 1, buf_val);
                hval[prefix_len + 1 + name_len + 1 + vlen] = '\0';

                genhash_update(merger, hval + prefix_len + 1, hval);

                free(prev);
            }
        }

        /* Note, if we couldn't merge, then just keep */
        /* the previous value. */

        return true;
    }

    return false;
}
Ejemplo n.º 11
0
/**
 * Observe callback. Called internally by libcouchbase's observe handlers
 */
void
lcb_durability_dset_update(lcb_t instance,
    lcb_DURSET *dset, lcb_error_t err, const lcb_RESPOBSERVE *resp)
{
    lcb_DURITEM *ent;

    /**
     * So we have two counters to decrement. One is the global 'done' counter
     * and the other is the iteration counter.
     *
     * The iteration counter is only decremented when we receive a NULL signal
     * in the callback, whereas the global counter is decremented once, whenever
     * the entry's criteria have been satisfied
     */

    if (resp->key == NULL) {
        dset_done_waiting(dset);
        return;
    }

    if (dset->nentries == 1) {
        ent = &dset->single.ent;
    } else {
        ent = genhash_find(dset->ht, resp->key, resp->nkey);
    }

    if (ent->done) {
        /* ignore subsequent errors */
        return;
    }

    if (err != LCB_SUCCESS) {
        RESFLD(ent, rc) = err;
        /* If it's a non-scheduling error then the item will be retried in the
         * next iteration */
        if (err == LCB_SCHEDFAIL_INTERNAL) {
            ent_set_resdone(ent);
        }
        return;
    }

    RESFLD(ent, nresponses)++;
    if (resp->cas && resp->ismaster) {
        RESFLD(ent, cas) = resp->cas;

        if (ent->reqcas && ent->reqcas != resp->cas) {
            RESFLD(ent, rc) = LCB_KEY_EEXISTS;
            ent_set_resdone(ent);
            return;
        }
    }

    if (DSET_OPTFLD(ent->parent, check_delete)) {
        check_negative_durability(ent, resp);
    } else {
        check_positive_durability(ent, resp);
    }

    if (ent_is_complete(ent)) {
        /* clear any transient errors */
        RESFLD(ent, rc) = LCB_SUCCESS;
        ent_set_resdone(ent);
    }

    (void)instance;

}