path: root/database/rrddim.c

// SPDX-License-Identifier: GPL-3.0-or-later

#define NETDATA_RRD_INTERNALS
#include "rrd.h"
#include "storage_engine.h"

// ----------------------------------------------------------------------------
// RRDDIM index

struct rrddim_constructor {
    RRDSET *st;
    const char *id;
    const char *name;
    collected_number multiplier;
    collected_number divisor;
    RRD_ALGORITHM algorithm;
    RRD_MEMORY_MODE memory_mode;

    enum {
        RRDDIM_REACT_NONE    = 0,
        RRDDIM_REACT_NEW     = (1 << 0),
        RRDDIM_REACT_UPDATED = (1 << 2),
    } react_action;

};

// isolated call to appear
// separate in statistics
static void *rrddim_alloc_db(size_t entries) {
    return callocz(entries, sizeof(storage_number));
}

static void rrddim_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddim, void *constructor_data) {
    struct rrddim_constructor *ctr = constructor_data;
    RRDDIM *rd = rrddim;
    RRDSET *st = ctr->st;
    RRDHOST *host = st->rrdhost;

    rd->flags = RRDDIM_FLAG_NONE;

    rd->id = string_strdupz(ctr->id);
    rd->name = (ctr->name && *ctr->name)?rrd_string_strdupz(ctr->name):string_dup(rd->id);

    rd->algorithm = ctr->algorithm;
    rd->multiplier = ctr->multiplier;
    rd->divisor = ctr->divisor;
    if(!rd->divisor) rd->divisor = 1;

    rd->update_every = st->update_every;

    rd->rrdset = st;

    if(rrdset_flag_check(st, RRDSET_FLAG_STORE_FIRST))
        rd->collections_counter = 1;

    if(ctr->memory_mode == RRD_MEMORY_MODE_MAP || ctr->memory_mode == RRD_MEMORY_MODE_SAVE) {
        if(!rrddim_memory_load_or_create_map_save(st, rd, ctr->memory_mode)) {
            info("Failed to use memory mode %s for chart '%s', dimension '%s', falling back to ram", (ctr->memory_mode == RRD_MEMORY_MODE_MAP)?"map":"save", rrdset_name(st), rrddim_name(rd));
            ctr->memory_mode = RRD_MEMORY_MODE_RAM;
        }
    }

    if(ctr->memory_mode == RRD_MEMORY_MODE_RAM) {
        size_t entries = st->entries;
        if(!entries) entries = 5;

        rd->db = netdata_mmap(NULL, entries * sizeof(storage_number), MAP_PRIVATE, 1);
        if(!rd->db) {
            info("Failed to use memory mode ram for chart '%s', dimension '%s', falling back to alloc", rrdset_name(st), rrddim_name(rd));
            ctr->memory_mode = RRD_MEMORY_MODE_ALLOC;
        }
        else rd->memsize = entries * sizeof(storage_number);
    }

    if(ctr->memory_mode == RRD_MEMORY_MODE_ALLOC || ctr->memory_mode == RRD_MEMORY_MODE_NONE) {
        size_t entries = st->entries;
        if(entries < 5) entries = 5;

        rd->db = rrddim_alloc_db(entries);
        rd->memsize = entries * sizeof(storage_number);
    }

    rd->rrd_memory_mode = ctr->memory_mode;

    if (unlikely(rrdcontext_find_dimension_uuid(st, rrddim_id(rd), &(rd->metric_uuid)))) {
        uuid_generate(rd->metric_uuid);
        bool found_in_sql = false; (void)found_in_sql;

//        bool found_in_sql = true;
//        if(unlikely(sql_find_dimension_uuid(st, rd, &rd->metric_uuid))) {
//            found_in_sql = false;
//            uuid_generate(rd->metric_uuid);
//        }

#ifdef NETDATA_INTERNAL_CHECKS
        char uuid_str[UUID_STR_LEN];
        uuid_unparse_lower(rd->metric_uuid, uuid_str);
        error_report("Dimension UUID for host %s chart [%s] dimension [%s] not found in context. It is now set to %s (%s)",
                     string2str(host->hostname),
                     string2str(st->name),
                     string2str(rd->name),
                     uuid_str, found_in_sql ? "found in sqlite" : "newly generated");
#endif
    }

    // initialize the db tiers
    {
        size_t initialized = 0;
        for(size_t tier = 0; tier < storage_tiers ; tier++) {
            STORAGE_ENGINE *eng = host->db[tier].eng;
            rd->tiers[tier] = callocz(1, sizeof(struct rrddim_tier));
            rd->tiers[tier]->tier_grouping = host->db[tier].tier_grouping;
            rd->tiers[tier]->collect_ops = &eng->api.collect_ops;
            rd->tiers[tier]->query_ops = &eng->api.query_ops;
            rd->tiers[tier]->db_metric_handle = eng->api.metric_get_or_create(rd, host->db[tier].instance, rd->rrdset->storage_metrics_groups[tier]);
            storage_point_unset(rd->tiers[tier]->virtual_point);
            initialized++;

            // internal_error(true, "TIER GROUPING of chart '%s', dimension '%s' for tier %d is set to %d", rd->rrdset->name, rd->name, tier, rd->tiers[tier]->tier_grouping);
        }

        if(!initialized)
            error("Failed to initialize all db tiers for chart '%s', dimension '%s", rrdset_name(st), rrddim_name(rd));

        if(!rd->tiers[0])
            error("Failed to initialize the first db tier for chart '%s', dimension '%s", rrdset_name(st), rrddim_name(rd));
    }

    // initialize data collection for all tiers
    {
        size_t initialized = 0;
        for (size_t tier = 0; tier < storage_tiers; tier++) {
            if (rd->tiers[tier]) {
                rd->tiers[tier]->db_collection_handle = rd->tiers[tier]->collect_ops->init(rd->tiers[tier]->db_metric_handle, st->rrdhost->db[tier].tier_grouping * st->update_every);
                initialized++;
            }
        }

        if(!initialized)
            error("Failed to initialize data collection for all db tiers for chart '%s', dimension '%s", rrdset_name(st), rrddim_name(rd));
    }

    if(rrdset_number_of_dimensions(st) != 0) {
        RRDDIM *td;
        dfe_start_write(st->rrddim_root_index, td) {
            if(!td) break;
        }
        dfe_done(td);

        if(td && (td->algorithm != rd->algorithm || ABS(td->multiplier) != ABS(rd->multiplier) || ABS(td->divisor) != ABS(rd->divisor))) {
            if(!rrdset_flag_check(st, RRDSET_FLAG_HETEROGENEOUS)) {
#ifdef NETDATA_INTERNAL_CHECKS
                info("Dimension '%s' added on chart '%s' of host '%s' is not homogeneous to other dimensions already present (algorithm is '%s' vs '%s', multiplier is " COLLECTED_NUMBER_FORMAT " vs " COLLECTED_NUMBER_FORMAT ", divisor is " COLLECTED_NUMBER_FORMAT " vs " COLLECTED_NUMBER_FORMAT ").",
                     rrddim_name(rd),
                     rrdset_name(st),
                     rrdhost_hostname(host),
                     rrd_algorithm_name(rd->algorithm), rrd_algorithm_name(td->algorithm),
                     rd->multiplier, td->multiplier,
                     rd->divisor, td->divisor
                );
#endif
                rrdset_flag_set(st, RRDSET_FLAG_HETEROGENEOUS);
            }
        }
    }

    rrddim_flag_set(rd, RRDDIM_FLAG_PENDING_HEALTH_INITIALIZATION);
    rrdset_flag_set(rd->rrdset, RRDSET_FLAG_PENDING_HEALTH_INITIALIZATION);
    rrdhost_flag_set(rd->rrdset->rrdhost, RRDHOST_FLAG_PENDING_HEALTH_INITIALIZATION);

    // let the chart resync
    rrdset_flag_set(st, RRDSET_FLAG_SYNC_CLOCK);
    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);

    ml_new_dimension(rd);

    ctr->react_action = RRDDIM_REACT_NEW;

    internal_error(false, "RRDDIM: inserted dimension '%s' of chart '%s' of host '%s'",
                   rrddim_name(rd), rrdset_name(st), rrdhost_hostname(st->rrdhost));

}

static void rrddim_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddim, void *rrdset) {
    RRDDIM *rd = rrddim;
    RRDSET *st = rrdset;
    RRDHOST *host = st->rrdhost;

    internal_error(false, "RRDDIM: deleting dimension '%s' of chart '%s' of host '%s'",
                   rrddim_name(rd), rrdset_name(st), rrdhost_hostname(host));

    rrdcontext_removed_rrddim(rd);

    ml_delete_dimension(rd);

    debug(D_RRD_CALLS, "rrddim_free() %s.%s", rrdset_name(st), rrddim_name(rd));

    size_t tiers_available = 0, tiers_said_yes = 0;
    for(size_t tier = 0; tier < storage_tiers ;tier++) {
        if(rd->tiers[tier] && rd->tiers[tier]->db_collection_handle) {
            tiers_available++;

            if(rd->tiers[tier]->collect_ops->finalize(rd->tiers[tier]->db_collection_handle))
                tiers_said_yes++;

            rd->tiers[tier]->db_collection_handle = NULL;
        }
    }

    if (tiers_available == tiers_said_yes && tiers_said_yes && rd->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE) {
        /* This metric has no data and no references */
        metaqueue_delete_dimension_uuid(&rd->metric_uuid);
    }

    rrddimvar_delete_all(rd);

    // free(rd->annotations);
    //#ifdef ENABLE_ACLK
    //    if (!netdata_exit)
    //        aclk_send_dimension_update(rd);
    //#endif

    // this will free MEMORY_MODE_SAVE and MEMORY_MODE_MAP structures
    rrddim_memory_file_free(rd);

    for(size_t tier = 0; tier < storage_tiers ;tier++) {
        if(!rd->tiers[tier]) continue;

        STORAGE_ENGINE* eng = host->db[tier].eng;
        eng->api.metric_release(rd->tiers[tier]->db_metric_handle);

        freez(rd->tiers[tier]);
        rd->tiers[tier] = NULL;
    }

    if(rd->db) {
        if(rd->rrd_memory_mode == RRD_MEMORY_MODE_RAM)
            netdata_munmap(rd->db, rd->memsize);
        else
            freez(rd->db);
    }

    string_freez(rd->id);
    string_freez(rd->name);
}

static bool rrddim_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddim, void *new_rrddim, void *constructor_data) {
    (void)new_rrddim; // it is NULL

    struct rrddim_constructor *ctr = constructor_data;
    RRDDIM *rd = rrddim;
    RRDSET *st = ctr->st;

    ctr->react_action = RRDDIM_REACT_NONE;

    int rc = rrddim_reset_name(st, rd, ctr->name);
    rc += rrddim_set_algorithm(st, rd, ctr->algorithm);
    rc += rrddim_set_multiplier(st, rd, ctr->multiplier);
    rc += rrddim_set_divisor(st, rd, ctr->divisor);

    for(size_t tier = 0; tier < storage_tiers ;tier++) {
        if (rd->tiers[tier] && !rd->tiers[tier]->db_collection_handle)
            rd->tiers[tier]->db_collection_handle =
                rd->tiers[tier]->collect_ops->init(rd->tiers[tier]->db_metric_handle, st->rrdhost->db[tier].tier_grouping * st->update_every);
    }

    if(rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED)) {
        rrddim_flag_clear(rd, RRDDIM_FLAG_ARCHIVED);

        rrddim_flag_set(rd, RRDDIM_FLAG_PENDING_HEALTH_INITIALIZATION);
        rrdset_flag_set(rd->rrdset, RRDSET_FLAG_PENDING_HEALTH_INITIALIZATION);
        rrdhost_flag_set(rd->rrdset->rrdhost, RRDHOST_FLAG_PENDING_HEALTH_INITIALIZATION);
    }

    if(unlikely(rc))
        ctr->react_action = RRDDIM_REACT_UPDATED;

    return ctr->react_action == RRDDIM_REACT_UPDATED;
}

static void rrddim_react_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddim, void *constructor_data) {
    struct rrddim_constructor *ctr = constructor_data;
    RRDDIM *rd = rrddim;
    RRDSET *st = ctr->st;

    if(ctr->react_action & (RRDDIM_REACT_UPDATED | RRDDIM_REACT_NEW)) {
        rrddim_flag_set(rd, RRDDIM_FLAG_METADATA_UPDATE);
        rrdset_flag_set(rd->rrdset, RRDSET_FLAG_METADATA_UPDATE);
        rrdhost_flag_set(rd->rrdset->rrdhost, RRDHOST_FLAG_METADATA_UPDATE);
    }

    if(ctr->react_action == RRDDIM_REACT_UPDATED) {
        // the chart needs to be updated to the parent
        rrdset_flag_set(st, RRDSET_FLAG_SYNC_CLOCK);
        rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
    }

    rrdcontext_updated_rrddim(rd);
}

void rrddim_index_init(RRDSET *st) {
    if(!st->rrddim_root_index) {
        st->rrddim_root_index = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);

        dictionary_register_insert_callback(st->rrddim_root_index, rrddim_insert_callback, NULL);
        dictionary_register_conflict_callback(st->rrddim_root_index, rrddim_conflict_callback, NULL);
        dictionary_register_delete_callback(st->rrddim_root_index, rrddim_delete_callback, st);
        dictionary_register_react_callback(st->rrddim_root_index, rrddim_react_callback, st);
    }
}

void rrddim_index_destroy(RRDSET *st) {
    dictionary_destroy(st->rrddim_root_index);
    st->rrddim_root_index = NULL;
}

static inline RRDDIM *rrddim_index_find(RRDSET *st, const char *id) {
    return dictionary_get(st->rrddim_root_index, id);
}

// ----------------------------------------------------------------------------
// RRDDIM - find a dimension

inline RRDDIM *rrddim_find(RRDSET *st, const char *id) {
    debug(D_RRD_CALLS, "rrddim_find() for chart %s, dimension %s", rrdset_name(st), id);

    return rrddim_index_find(st, id);
}

inline RRDDIM_ACQUIRED *rrddim_find_and_acquire(RRDSET *st, const char *id) {
    debug(D_RRD_CALLS, "rrddim_find() for chart %s, dimension %s", rrdset_name(st), id);

    return (RRDDIM_ACQUIRED *)dictionary_get_and_acquire_item(st->rrddim_root_index, id);
}

RRDDIM *rrddim_acquired_to_rrddim(RRDDIM_ACQUIRED *rda) {
    if(unlikely(!rda))
        return NULL;

    return (RRDDIM *) dictionary_acquired_item_value((const DICTIONARY_ITEM *)rda);
}

void rrddim_acquired_release(RRDDIM_ACQUIRED *rda) {
    if(unlikely(!rda))
        return;

    RRDDIM *rd = rrddim_acquired_to_rrddim(rda);
    dictionary_acquired_item_release(rd->rrdset->rrddim_root_index, (const DICTIONARY_ITEM *)rda);
}

// This will not return dimensions that are archived
RRDDIM *rrddim_find_active(RRDSET *st, const char *id) {
    RRDDIM *rd = rrddim_find(st, id);

    if (unlikely(rd && rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED)))
        return NULL;

    return rd;
}

// ----------------------------------------------------------------------------
// RRDDIM rename a dimension

inline int rrddim_reset_name(RRDSET *st, RRDDIM *rd, const char *name) {
    if(unlikely(!name || !*name || !strcmp(rrddim_name(rd), name)))
        return 0;

    debug(D_RRD_CALLS, "rrddim_reset_name() from %s.%s to %s.%s", rrdset_name(st), rrddim_name(rd), rrdset_name(st), name);

    STRING *old = rd->name;
    rd->name = rrd_string_strdupz(name);
    string_freez(old);

    rrddimvar_rename_all(rd);

    rd->exposed = 0;
    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);

    return 1;
}

inline int rrddim_set_algorithm(RRDSET *st, RRDDIM *rd, RRD_ALGORITHM algorithm) {
    if(unlikely(rd->algorithm == algorithm))
        return 0;

    debug(D_RRD_CALLS, "Updating algorithm of dimension '%s/%s' from %s to %s", rrdset_id(st), rrddim_name(rd), rrd_algorithm_name(rd->algorithm), rrd_algorithm_name(algorithm));
    rd->algorithm = algorithm;
    rd->exposed = 0;
    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
    rrdset_flag_set(st, RRDSET_FLAG_HOMOGENEOUS_CHECK);
    rrdcontext_updated_rrddim_algorithm(rd);
    return 1;
}

inline int rrddim_set_multiplier(RRDSET *st, RRDDIM *rd, collected_number multiplier) {
    if(unlikely(rd->multiplier == multiplier))
        return 0;

    debug(D_RRD_CALLS, "Updating multiplier of dimension '%s/%s' from " COLLECTED_NUMBER_FORMAT " to " COLLECTED_NUMBER_FORMAT, rrdset_id(st), rrddim_name(rd), rd->multiplier, multiplier);
    rd->multiplier = multiplier;
    rd->exposed = 0;
    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
    rrdset_flag_set(st, RRDSET_FLAG_HOMOGENEOUS_CHECK);
    rrdcontext_updated_rrddim_multiplier(rd);
    return 1;
}

inline int rrddim_set_divisor(RRDSET *st, RRDDIM *rd, collected_number divisor) {
    if(unlikely(rd->divisor == divisor))
        return 0;

    debug(D_RRD_CALLS, "Updating divisor of dimension '%s/%s' from " COLLECTED_NUMBER_FORMAT " to " COLLECTED_NUMBER_FORMAT, rrdset_id(st), rrddim_name(rd), rd->divisor, divisor);
    rd->divisor = divisor;
    rd->exposed = 0;
    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
    rrdset_flag_set(st, RRDSET_FLAG_HOMOGENEOUS_CHECK);
    rrdcontext_updated_rrddim_divisor(rd);
    return 1;
}

// ----------------------------------------------------------------------------

// get the timestamp of the last entry in the round-robin database
time_t rrddim_last_entry_t(RRDDIM *rd) {
    time_t latest = rd->tiers[0]->query_ops->latest_time(rd->tiers[0]->db_metric_handle);

    for(size_t tier = 1; tier < storage_tiers ;tier++) {
        if(unlikely(!rd->tiers[tier])) continue;

        time_t t = rd->tiers[tier]->query_ops->latest_time(rd->tiers[tier]->db_metric_handle);
        if(t > latest)
            latest = t;
    }

    return latest;
}

time_t rrddim_first_entry_t_of_tier(RRDDIM *rd, size_t tier) {
    if(unlikely(tier > storage_tiers || !rd->tiers[tier]))
        return 0;

    return rd->tiers[tier]->query_ops->oldest_time(rd->tiers[tier]->db_metric_handle);
}

time_t rrddim_first_entry_t(RRDDIM *rd) {
    time_t oldest = 0;

    for(size_t tier = 0; tier < storage_tiers ;tier++) {
        time_t t = rrddim_first_entry_t_of_tier(rd, tier);
        if(t != 0 && (oldest == 0 || t < oldest))
            oldest = t;
    }

    return oldest;
}

RRDDIM *rrddim_add_custom(RRDSET *st
                          , const char *id
                          , const char *name
                          , collected_number multiplier
                          , collected_number divisor
                          , RRD_ALGORITHM algorithm
                          , RRD_MEMORY_MODE memory_mode
                          ) {
    struct rrddim_constructor tmp = {
        .st = st,
        .id = id,
        .name = name,
        .multiplier = multiplier,
        .divisor = divisor,
        .algorithm = algorithm,
        .memory_mode = memory_mode,
    };

    RRDDIM *rd = dictionary_set_advanced(st->rrddim_root_index, tmp.id, -1, NULL, sizeof(RRDDIM), &tmp);
    return(rd);
}

// ----------------------------------------------------------------------------
// RRDDIM remove / free a dimension

void rrddim_free(RRDSET *st, RRDDIM *rd) {
    dictionary_del(st->rrddim_root_index, string2str(rd->id));
}


// ----------------------------------------------------------------------------
// RRDDIM - set dimension options

int rrddim_hide(RRDSET *st, const char *id) {
    debug(D_RRD_CALLS, "rrddim_hide() for chart %s, dimension %s", rrdset_name(st), id);

    RRDHOST *host = st->rrdhost;

    RRDDIM *rd = rrddim_find(st, id);
    if(unlikely(!rd)) {
        error("Cannot find dimension with id '%s' on stats '%s' (%s) on host '%s'.", id, rrdset_name(st), rrdset_id(st), rrdhost_hostname(host));
        return 1;
    }
    if (!rrddim_flag_check(rd, RRDDIM_FLAG_META_HIDDEN)) {
        rrddim_flag_set(rd, RRDDIM_FLAG_META_HIDDEN);
        metaqueue_dimension_update_flags(rd);
    }

    rrddim_option_set(rd, RRDDIM_OPTION_HIDDEN);
    rrdcontext_updated_rrddim_flags(rd);
    return 0;
}

int rrddim_unhide(RRDSET *st, const char *id) {
    debug(D_RRD_CALLS, "rrddim_unhide() for chart %s, dimension %s", rrdset_name(st), id);

    RRDHOST *host = st->rrdhost;
    RRDDIM *rd = rrddim_find(st, id);
    if(unlikely(!rd)) {
        error("Cannot find dimension with id '%s' on stats '%s' (%s) on host '%s'.", id, rrdset_name(st), rrdset_id(st), rrdhost_hostname(host));
        return 1;
    }
    if (rrddim_flag_check(rd, RRDDIM_FLAG_META_HIDDEN)) {
        rrddim_flag_clear(rd, RRDDIM_FLAG_META_HIDDEN);
        metaqueue_dimension_update_flags(rd);
    }

    rrddim_option_clear(rd, RRDDIM_OPTION_HIDDEN);
    rrdcontext_updated_rrddim_flags(rd);
    return 0;
}

inline void rrddim_is_obsolete(RRDSET *st, RRDDIM *rd) {
    debug(D_RRD_CALLS, "rrddim_is_obsolete() for chart %s, dimension %s", rrdset_name(st), rrddim_name(rd));

    if(unlikely(rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED))) {
        info("Cannot obsolete already archived dimension %s from chart %s", rrddim_name(rd), rrdset_name(st));
        return;
    }
    rrddim_flag_set(rd, RRDDIM_FLAG_OBSOLETE);
    rrdset_flag_set(st, RRDSET_FLAG_OBSOLETE_DIMENSIONS);
    rrdhost_flag_set(st->rrdhost, RRDHOST_FLAG_PENDING_OBSOLETE_DIMENSIONS);
    rrdcontext_updated_rrddim_flags(rd);
}

inline void rrddim_isnot_obsolete(RRDSET *st __maybe_unused, RRDDIM *rd) {
    debug(D_RRD_CALLS, "rrddim_isnot_obsolete() for chart %s, dimension %s", rrdset_name(st), rrddim_name(rd));

    rrddim_flag_clear(rd, RRDDIM_FLAG_OBSOLETE);
    rrdcontext_updated_rrddim_flags(rd);
}

// ----------------------------------------------------------------------------
// RRDDIM - collect values for a dimension

inline collected_number rrddim_set_by_pointer(RRDSET *st, RRDDIM *rd, collected_number value) {
    struct timeval now;
    now_realtime_timeval(&now);

    return rrddim_timed_set_by_pointer(st, rd, now, value);
}

collected_number rrddim_timed_set_by_pointer(RRDSET *st __maybe_unused, RRDDIM *rd, struct timeval collected_time, collected_number value) {
    debug(D_RRD_CALLS, "rrddim_set_by_pointer() for chart %s, dimension %s, value " COLLECTED_NUMBER_FORMAT, rrdset_name(st), rrddim_name(rd), value);

    rd->last_collected_time = collected_time;
    rd->collected_value = value;
    rd->updated = 1;
    rd->collections_counter++;

    collected_number v = (value >= 0) ? value : -value;
    if (unlikely(v > rd->collected_value_max))
        rd->collected_value_max = v;

    return rd->last_collected_value;
}


collected_number rrddim_set(RRDSET *st, const char *id, collected_number value) {
    RRDHOST *host = st->rrdhost;
    RRDDIM *rd = rrddim_find(st, id);
    if(unlikely(!rd)) {
        error("Cannot find dimension with id '%s' on stats '%s' (%s) on host '%s'.", id, rrdset_name(st), rrdset_id(st), rrdhost_hostname(host));
        return 0;
    }

    return rrddim_set_by_pointer(st, rd, value);
}


// ----------------------------------------------------------------------------
// compatibility layer for RRDDIM files v019

#define RRDDIMENSION_MAGIC_V019  "NETDATA RRD DIMENSION FILE V019"

struct avl_element_v019 {
    void *avl_link[2];
    signed char avl_balance;
};

struct rrddim_map_save_v019 {
    struct avl_element_v019 avl;                    // ignored
    void *id;                                       // ignored
    void *name;                                     // ignored
    uint32_t algorithm;                             // print warning on mismatch - update on load
    uint32_t rrd_memory_mode;                       // ignored
    long long multiplier;                           // print warning on mismatch - update on load
    long long divisor;                              // print warning on mismatch - update on load
    uint32_t flags;                                 // ignored
    uint32_t hash;                                  // ignored
    uint32_t hash_name;                             // ignored
    void *cache_filename;                           // ignored - we use it to keep the filename to save back
    size_t collections_counter;                     // ignored
    void *state;                                    // ignored
    size_t unused[8];                               // ignored
    long long collected_value_max;                  // ignored
    unsigned int updated:1;                         // ignored
    unsigned int exposed:1;                         // ignored
    struct timeval last_collected_time;             // check to reset all - ignored after load
    long double calculated_value;                   // ignored
    long double last_calculated_value;              // ignored
    long double last_stored_value;                  // ignored
    long long collected_value;                      // ignored
    long long last_collected_value;                 // load and save
    long double collected_volume;                   // ignored
    long double stored_volume;                      // ignored
    void *next;                                     // ignored
    void *rrdset;                                   // ignored
    long entries;                                   // check to reset all - update on load
    int update_every;                               // check to reset all - update on load
    size_t memsize;                                 // check to reset all - update on load
    char magic[sizeof(RRDDIMENSION_MAGIC_V019) + 1];// check to reset all - update on load
    void *variables;                                // ignored
    storage_number values[];                        // the array of values
};

size_t rrddim_memory_file_header_size(void) {
    return sizeof(struct rrddim_map_save_v019);
}

void rrddim_memory_file_update(RRDDIM *rd) {
    if(!rd || !rd->rd_on_file) return;
    struct rrddim_map_save_v019 *rd_on_file = rd->rd_on_file;

    rd_on_file->last_collected_time.tv_sec = rd->last_collected_time.tv_sec;
    rd_on_file->last_collected_time.tv_usec = rd->last_collected_time.tv_usec;
    rd_on_file->last_collected_value = rd->last_collected_value;
}

void rrddim_memory_file_free(RRDDIM *rd) {
    if(!rd || !rd->rd_on_file) return;

    // needed for memory mode map, to save the latest state
    rrddim_memory_file_update(rd);

    struct rrddim_map_save_v019 *rd_on_file = rd->rd_on_file;
    freez(rd_on_file->cache_filename);
    netdata_munmap(rd_on_file, rd_on_file->memsize);

    // remove the pointers from the RRDDIM
    rd->rd_on_file = NULL;
    rd->db = NULL;
}

const char *rrddim_cache_filename(RRDDIM *rd) {
    if(!rd || !rd->rd_on_file) return NULL;
    struct rrddim_map_save_v019 *rd_on_file = rd->rd_on_file;
    return rd_on_file->cache_filename;
}

void rrddim_memory_file_save(RRDDIM *rd) {
    if(!rd || !rd->rd_on_file) return;

    rrddim_memory_file_update(rd);

    struct rrddim_map_save_v019 *rd_on_file = rd->rd_on_file;
    if(rd_on_file->rrd_memory_mode != RRD_MEMORY_MODE_SAVE) return;

    memory_file_save(rd_on_file->cache_filename, rd_on_file, rd_on_file->memsize);
}

bool rrddim_memory_load_or_create_map_save(RRDSET *st, RRDDIM *rd, RRD_MEMORY_MODE memory_mode) {
    if(memory_mode != RRD_MEMORY_MODE_SAVE && memory_mode != RRD_MEMORY_MODE_MAP)
        return false;

    struct rrddim_map_save_v019 *rd_on_file = NULL;

    unsigned long size = sizeof(struct rrddim_map_save_v019) + (st->entries * sizeof(storage_number));

    char filename[FILENAME_MAX + 1];
    char fullfilename[FILENAME_MAX + 1];
    rrdset_strncpyz_name(filename, rrddim_id(rd), FILENAME_MAX);
    snprintfz(fullfilename, FILENAME_MAX, "%s/%s.db", st->cache_dir, filename);

    rd_on_file = (struct rrddim_map_save_v019 *)netdata_mmap(fullfilename, size,
        ((memory_mode == RRD_MEMORY_MODE_MAP) ? MAP_SHARED : MAP_PRIVATE), 1);

    if(unlikely(!rd_on_file)) return false;

    struct timeval now;
    now_realtime_timeval(&now);

    int reset = 0;
    rd_on_file->magic[sizeof(RRDDIMENSION_MAGIC_V019)] = '\0';
    if(strcmp(rd_on_file->magic, RRDDIMENSION_MAGIC_V019) != 0) {
        info("Initializing file %s.", fullfilename);
        memset(rd_on_file, 0, size);
        reset = 1;
    }
    else if(rd_on_file->memsize != size) {
        error("File %s does not have the desired size, expected %lu but found %lu. Clearing it.", fullfilename, size, (unsigned long int) rd_on_file->memsize);
        memset(rd_on_file, 0, size);
        reset = 1;
    }
    else if(rd_on_file->update_every != st->update_every) {
        error("File %s does not have the same update frequency, expected %d but found %d. Clearing it.", fullfilename, st->update_every, rd_on_file->update_every);
        memset(rd_on_file, 0, size);
        reset = 1;
    }
    else if(dt_usec(&now, &rd_on_file->last_collected_time) > (rd_on_file->entries * rd_on_file->update_every * USEC_PER_SEC)) {
        info("File %s is too old (last collected %llu seconds ago, but the database is %ld seconds). Clearing it.", fullfilename, dt_usec(&now, &rd_on_file->last_collected_time) / USEC_PER_SEC, rd_on_file->entries * rd_on_file->update_every);
        memset(rd_on_file, 0, size);
        reset = 1;
    }

    if(!reset) {
        rd->last_collected_value = rd_on_file->last_collected_value;

        if(rd_on_file->algorithm != rd->algorithm)
            info("File %s does not have the expected algorithm (expected %u '%s', found %u '%s'). Previous values may be wrong.",
                 fullfilename, rd->algorithm, rrd_algorithm_name(rd->algorithm), rd_on_file->algorithm, rrd_algorithm_name(rd_on_file->algorithm));

        if(rd_on_file->multiplier != rd->multiplier)
            info("File %s does not have the expected multiplier (expected " COLLECTED_NUMBER_FORMAT ", found " COLLECTED_NUMBER_FORMAT "). Previous values may be wrong.", fullfilename, rd->multiplier, rd_on_file->multiplier);

        if(rd_on_file->divisor != rd->divisor)
            info("File %s does not have the expected divisor (expected " COLLECTED_NUMBER_FORMAT ", found " COLLECTED_NUMBER_FORMAT "). Previous values may be wrong.", fullfilename, rd->divisor, rd_on_file->divisor);
    }

    // zero the entire header
    memset(rd_on_file, 0, sizeof(struct rrddim_map_save_v019));

    // set the important fields
    strcpy(rd_on_file->magic, RRDDIMENSION_MAGIC_V019);
    rd_on_file->algorithm = rd->algorithm;
    rd_on_file->multiplier = rd->multiplier;
    rd_on_file->divisor = rd->divisor;
    rd_on_file->entries = st->entries;
    rd_on_file->update_every = rd->update_every;
    rd_on_file->memsize = size;
    rd_on_file->rrd_memory_mode = memory_mode;
    rd_on_file->cache_filename = strdupz(fullfilename);

    rd->db = &rd_on_file->values[0];
    rd->rd_on_file = rd_on_file;
    rd->memsize = size;
    rrddim_memory_file_update(rd);

    return true;
}