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

#include "common.h"

#define GLOBAL_STATS_RESET_WEB_USEC_MAX 0x01


static struct global_statistics {
    volatile uint16_t connected_clients;

    volatile uint64_t web_requests;
    volatile uint64_t web_usec;
    volatile uint64_t web_usec_max;
    volatile uint64_t bytes_received;
    volatile uint64_t bytes_sent;
    volatile uint64_t content_size;
    volatile uint64_t compressed_content_size;

    volatile uint64_t web_client_count;

    volatile uint64_t rrdr_queries_made;
    volatile uint64_t rrdr_db_points_read;
    volatile uint64_t rrdr_result_points_generated;
} global_statistics = {
        .connected_clients = 0,
        .web_requests = 0,
        .web_usec = 0,
        .bytes_received = 0,
        .bytes_sent = 0,
        .content_size = 0,
        .compressed_content_size = 0,
        .web_client_count = 1,

        .rrdr_queries_made = 0,
        .rrdr_db_points_read = 0,
        .rrdr_result_points_generated = 0,
};

#if defined(HAVE_C___ATOMIC) && !defined(NETDATA_NO_ATOMIC_INSTRUCTIONS)
#else
netdata_mutex_t global_statistics_mutex = NETDATA_MUTEX_INITIALIZER;

static inline void global_statistics_lock(void) {
    netdata_mutex_lock(&global_statistics_mutex);
}

static inline void global_statistics_unlock(void) {
    netdata_mutex_unlock(&global_statistics_mutex);
}
#endif


void rrdr_query_completed(uint64_t db_points_read, uint64_t result_points_generated) {
#if defined(HAVE_C___ATOMIC) && !defined(NETDATA_NO_ATOMIC_INSTRUCTIONS)
    __atomic_fetch_add(&global_statistics.rrdr_queries_made, 1, __ATOMIC_SEQ_CST);
    __atomic_fetch_add(&global_statistics.rrdr_db_points_read, db_points_read, __ATOMIC_SEQ_CST);
    __atomic_fetch_add(&global_statistics.rrdr_result_points_generated, result_points_generated, __ATOMIC_SEQ_CST);
#else
    #warning NOT using atomic operations - using locks for global statistics
    if (web_server_is_multithreaded)
        global_statistics_lock();

    global_statistics.rrdr_queries_made++;
    global_statistics.rrdr_db_points_read += db_points_read;
    global_statistics.rrdr_result_points_generated += result_points_generated;

    if (web_server_is_multithreaded)
        global_statistics_unlock();
#endif
}

void finished_web_request_statistics(uint64_t dt,
                                     uint64_t bytes_received,
                                     uint64_t bytes_sent,
                                     uint64_t content_size,
                                     uint64_t compressed_content_size) {
#if defined(HAVE_C___ATOMIC) && !defined(NETDATA_NO_ATOMIC_INSTRUCTIONS)
    uint64_t old_web_usec_max = global_statistics.web_usec_max;
    while(dt > old_web_usec_max)
        __atomic_compare_exchange(&global_statistics.web_usec_max, &old_web_usec_max, &dt, 1, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);

    __atomic_fetch_add(&global_statistics.web_requests, 1, __ATOMIC_SEQ_CST);
    __atomic_fetch_add(&global_statistics.web_usec, dt, __ATOMIC_SEQ_CST);
    __atomic_fetch_add(&global_statistics.bytes_received, bytes_received, __ATOMIC_SEQ_CST);
    __atomic_fetch_add(&global_statistics.bytes_sent, bytes_sent, __ATOMIC_SEQ_CST);
    __atomic_fetch_add(&global_statistics.content_size, content_size, __ATOMIC_SEQ_CST);
    __atomic_fetch_add(&global_statistics.compressed_content_size, compressed_content_size, __ATOMIC_SEQ_CST);
#else
#warning NOT using atomic operations - using locks for global statistics
    if (web_server_is_multithreaded)
        global_statistics_lock();

    if (dt > global_statistics.web_usec_max)
        global_statistics.web_usec_max = dt;

    global_statistics.web_requests++;
    global_statistics.web_usec += dt;
    global_statistics.bytes_received += bytes_received;
    global_statistics.bytes_sent += bytes_sent;
    global_statistics.content_size += content_size;
    global_statistics.compressed_content_size += compressed_content_size;

    if (web_server_is_multithreaded)
        global_statistics_unlock();
#endif
}

uint64_t web_client_connected(void) {
#if defined(HAVE_C___ATOMIC) && !defined(NETDATA_NO_ATOMIC_INSTRUCTIONS)
    __atomic_fetch_add(&global_statistics.connected_clients, 1, __ATOMIC_SEQ_CST);
    uint64_t id = __atomic_fetch_add(&global_statistics.web_client_count, 1, __ATOMIC_SEQ_CST);
#else
    if (web_server_is_multithreaded)
        global_statistics_lock();

    global_statistics.connected_clients++;
    uint64_t id = global_statistics.web_client_count++;

    if (web_server_is_multithreaded)
        global_statistics_unlock();
#endif

    return id;
}

void web_client_disconnected(void) {
#if defined(HAVE_C___ATOMIC) && !defined(NETDATA_NO_ATOMIC_INSTRUCTIONS)
    __atomic_fetch_sub(&global_statistics.connected_clients, 1, __ATOMIC_SEQ_CST);
#else
    if (web_server_is_multithreaded)
        global_statistics_lock();

    global_statistics.connected_clients--;

    if (web_server_is_multithreaded)
        global_statistics_unlock();
#endif
}


static inline void global_statistics_copy(struct global_statistics *gs, uint8_t options) {
#if defined(HAVE_C___ATOMIC) && !defined(NETDATA_NO_ATOMIC_INSTRUCTIONS)
    gs->connected_clients            = __atomic_fetch_add(&global_statistics.connected_clients, 0, __ATOMIC_SEQ_CST);
    gs->web_requests                 = __atomic_fetch_add(&global_statistics.web_requests, 0, __ATOMIC_SEQ_CST);
    gs->web_usec                     = __atomic_fetch_add(&global_statistics.web_usec, 0, __ATOMIC_SEQ_CST);
    gs->web_usec_max                 = __atomic_fetch_add(&global_statistics.web_usec_max, 0, __ATOMIC_SEQ_CST);
    gs->bytes_received               = __atomic_fetch_add(&global_statistics.bytes_received, 0, __ATOMIC_SEQ_CST);
    gs->bytes_sent                   = __atomic_fetch_add(&global_statistics.bytes_sent, 0, __ATOMIC_SEQ_CST);
    gs->content_size                 = __atomic_fetch_add(&global_statistics.content_size, 0, __ATOMIC_SEQ_CST);
    gs->compressed_content_size      = __atomic_fetch_add(&global_statistics.compressed_content_size, 0, __ATOMIC_SEQ_CST);
    gs->web_client_count             = __atomic_fetch_add(&global_statistics.web_client_count, 0, __ATOMIC_SEQ_CST);

    gs->rrdr_queries_made            = __atomic_fetch_add(&global_statistics.rrdr_queries_made, 0, __ATOMIC_SEQ_CST);
    gs->rrdr_db_points_read          = __atomic_fetch_add(&global_statistics.rrdr_db_points_read, 0, __ATOMIC_SEQ_CST);
    gs->rrdr_result_points_generated = __atomic_fetch_add(&global_statistics.rrdr_result_points_generated, 0, __ATOMIC_SEQ_CST);

    if(options & GLOBAL_STATS_RESET_WEB_USEC_MAX) {
        uint64_t n = 0;
        __atomic_compare_exchange(&global_statistics.web_usec_max, &gs->web_usec_max, &n, 1, __ATOMIC_SEQ_CST,
                                  __ATOMIC_SEQ_CST);
    }
#else
    global_statistics_lock();

    memcpy(gs, (const void *)&global_statistics, sizeof(struct global_statistics));

    if (options & GLOBAL_STATS_RESET_WEB_USEC_MAX)
        global_statistics.web_usec_max = 0;

    global_statistics_unlock();
#endif
}

void global_statistics_charts(void) {
    static unsigned long long old_web_requests = 0,
                              old_web_usec = 0,
                              old_content_size = 0,
                              old_compressed_content_size = 0;

    static collected_number compression_ratio = -1,
                            average_response_time = -1;

    struct global_statistics gs;
    struct rusage me, thread;

    global_statistics_copy(&gs, GLOBAL_STATS_RESET_WEB_USEC_MAX);
    getrusage(RUSAGE_THREAD, &thread);
    getrusage(RUSAGE_SELF, &me);

    {
        static RRDSET *st_cpu_thread = NULL;
        static RRDDIM *rd_cpu_thread_user = NULL,
                      *rd_cpu_thread_system = NULL;

#ifdef __FreeBSD__
        if (unlikely(!st_cpu_thread)) {
            st_cpu_thread = rrdset_create_localhost(
                    "netdata"
                    , "plugin_freebsd_cpu"
                    , NULL
                    , "freebsd"
                    , NULL
                    , "NetData FreeBSD Plugin CPU usage"
                    , "milliseconds/s"
                    , "netdata"
                    , "stats"
                    , 132000
                    , localhost->rrd_update_every
                    , RRDSET_TYPE_STACKED
            );
#else
        if (unlikely(!st_cpu_thread)) {
            st_cpu_thread = rrdset_create_localhost(
                    "netdata"
                    , "plugin_proc_cpu"
                    , NULL
                    , "proc"
                    , NULL
                    , "NetData Proc Plugin CPU usage"
                    , "milliseconds/s"
                    , "netdata"
                    , "stats"
                    , 132000
                    , localhost->rrd_update_every
                    , RRDSET_TYPE_STACKED
            );
#endif

            rd_cpu_thread_user   = rrddim_add(st_cpu_thread, "user",   NULL, 1, 1000, RRD_ALGORITHM_INCREMENTAL);
            rd_cpu_thread_system = rrddim_add(st_cpu_thread, "system", NULL, 1, 1000, RRD_ALGORITHM_INCREMENTAL);
        }
        else
            rrdset_next(st_cpu_thread);

        rrddim_set_by_pointer(st_cpu_thread, rd_cpu_thread_user,   thread.ru_utime.tv_sec * 1000000ULL + thread.ru_utime.tv_usec);
        rrddim_set_by_pointer(st_cpu_thread, rd_cpu_thread_system, thread.ru_stime.tv_sec * 1000000ULL + thread.ru_stime.tv_usec);
        rrdset_done(st_cpu_thread);
    }

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

    {
        static RRDSET *st_cpu = NULL;
        static RRDDIM *rd_cpu_user   = NULL,
                      *rd_cpu_system = NULL;

        if (unlikely(!st_cpu)) {
            st_cpu = rrdset_create_localhost(
                    "netdata"
                    , "server_cpu"
                    , NULL
                    , "netdata"
                    , NULL
                    , "NetData CPU usage"
                    , "milliseconds/s"
                    , "netdata"
                    , "stats"
                    , 130000
                    , localhost->rrd_update_every
                    , RRDSET_TYPE_STACKED
            );

            rd_cpu_user   = rrddim_add(st_cpu, "user",   NULL, 1, 1000, RRD_ALGORITHM_INCREMENTAL);
            rd_cpu_system = rrddim_add(st_cpu, "system", NULL, 1, 1000, RRD_ALGORITHM_INCREMENTAL);
        }
        else
            rrdset_next(st_cpu);

        rrddim_set_by_pointer(st_cpu, rd_cpu_user,   me.ru_utime.tv_sec * 1000000ULL + me.ru_utime.tv_usec);
        rrddim_set_by_pointer(st_cpu, rd_cpu_system, me.ru_stime.tv_sec * 1000000ULL + me.ru_stime.tv_usec);
        rrdset_done(st_cpu);
    }

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

    {
        static RRDSET *st_clients = NULL;
        static RRDDIM *rd_clients = NULL;

        if (unlikely(!st_clients)) {
            st_clients = rrdset_create_localhost(
                    "netdata"
                    , "clients"
                    , NULL
                    , "netdata"
                    , NULL
                    , "NetData Web Clients"
                    , "connected clients"
                    , "netdata"
                    , "stats"
                    , 130200
                    , localhost->rrd_update_every
                    , RRDSET_TYPE_LINE
            );

            rd_clients = rrddim_add(st_clients, "clients", NULL, 1, 1, RRD_ALGORITHM_ABSOLUTE);
        }
        else
            rrdset_next(st_clients);

        rrddim_set_by_pointer(st_clients, rd_clients, gs.connected_clients);
        rrdset_done(st_clients);
    }

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

    {
        static RRDSET *st_reqs = NULL;
        static RRDDIM *rd_requests = NULL;

        if (unlikely(!st_reqs)) {
            st_reqs = rrdset_create_localhost(
                    "netdata"
                    , "requests"
                    , NULL
                    , "netdata"
                    , NULL
                    , "NetData Web Requests"
                    , "requests/s"
                    , "netdata"
                    , "stats"
                    , 130300
                    , localhost->rrd_update_every
                    , RRDSET_TYPE_LINE
            );

            rd_requests = rrddim_add(st_reqs, "requests", NULL, 1, 1, RRD_ALGORITHM_INCREMENTAL);
        }
        else
            rrdset_next(st_reqs);

        rrddim_set_by_pointer(st_reqs, rd_requests, (collected_number) gs.web_requests);
        rrdset_done(st_reqs);
    }

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

    {
        static RRDSET *st_bytes = NULL;
        static RRDDIM *rd_in = NULL,
                      *rd_out = NULL;

        if (unlikely(!st_bytes)) {
            st_bytes = rrdset_create_localhost(
                    "netdata"
                    , "net"
                    , NULL
                    , "netdata"
                    , NULL
                    , "NetData Network Traffic"
                    , "kilobits/s"
                    , "netdata"
                    , "stats"
                    , 130000
                    , localhost->rrd_update_every
                    , RRDSET_TYPE_AREA
            );

            rd_in  = rrddim_add(st_bytes, "in",  NULL,  8, BITS_IN_A_KILOBIT, RRD_ALGORITHM_INCREMENTAL);
            rd_out = rrddim_add(st_bytes, "out", NULL, -8, BITS_IN_A_KILOBIT, RRD_ALGORITHM_INCREMENTAL);
        }
        else
            rrdset_next(st_bytes);

        rrddim_set_by_pointer(st_bytes, rd_in, (collected_number) gs.bytes_received);
        rrddim_set_by_pointer(st_bytes, rd_out, (collected_number) gs.bytes_sent);
        rrdset_done(st_bytes);
    }

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

    {
        static RRDSET *st_duration = NULL;
        static RRDDIM *rd_average = NULL,
                      *rd_max     = NULL;

        if (unlikely(!st_duration)) {
            st_duration = rrdset_create_localhost(
                    "netdata"
                    , "response_time"
                    , NULL
                    , "netdata"
                    , NULL
                    , "NetData API Response Time"
                    , "milliseconds/request"
                    , "netdata"
                    , "stats"
                    , 130400
                    , localhost->rrd_update_every
                    , RRDSET_TYPE_LINE
            );

            rd_average = rrddim_add(st_duration, "average", NULL, 1, 1000, RRD_ALGORITHM_ABSOLUTE);
            rd_max = rrddim_add(st_duration, "max", NULL, 1, 1000, RRD_ALGORITHM_ABSOLUTE);
        }
        else
            rrdset_next(st_duration);

        uint64_t gweb_usec = gs.web_usec;
        uint64_t gweb_requests = gs.web_requests;

        uint64_t web_usec = (gweb_usec >= old_web_usec) ? gweb_usec - old_web_usec : 0;
        uint64_t web_requests = (gweb_requests >= old_web_requests) ? gweb_requests - old_web_requests : 0;

        old_web_usec = gweb_usec;
        old_web_requests = gweb_requests;

        if (web_requests)
            average_response_time = (collected_number) (web_usec / web_requests);

        if (unlikely(average_response_time != -1))
            rrddim_set_by_pointer(st_duration, rd_average, average_response_time);
        else
            rrddim_set_by_pointer(st_duration, rd_average, 0);

        rrddim_set_by_pointer(st_duration, rd_max, ((gs.web_usec_max)?(collected_number)gs.web_usec_max:average_response_time));
        rrdset_done(st_duration);
    }

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

    {
        static RRDSET *st_compression = NULL;
        static RRDDIM *rd_savings = NULL;

        if (unlikely(!st_compression)) {
            st_compression = rrdset_create_localhost(
                    "netdata"
                    , "compression_ratio"
                    , NULL
                    , "netdata"
                    , NULL
                    , "NetData API Responses Compression Savings Ratio"
                    , "percentage"
                    , "netdata"
                    , "stats"
                    , 130500
                    , localhost->rrd_update_every
                    , RRDSET_TYPE_LINE
            );

            rd_savings = rrddim_add(st_compression, "savings", NULL, 1, 1000, RRD_ALGORITHM_ABSOLUTE);
        }
        else
            rrdset_next(st_compression);

        // since we don't lock here to read the global statistics
        // read the smaller value first
        unsigned long long gcompressed_content_size = gs.compressed_content_size;
        unsigned long long gcontent_size = gs.content_size;

        unsigned long long compressed_content_size = gcompressed_content_size - old_compressed_content_size;
        unsigned long long content_size = gcontent_size - old_content_size;

        old_compressed_content_size = gcompressed_content_size;
        old_content_size = gcontent_size;

        if (content_size && content_size >= compressed_content_size)
            compression_ratio = ((content_size - compressed_content_size) * 100 * 1000) / content_size;

        if (compression_ratio != -1)
            rrddim_set_by_pointer(st_compression, rd_savings, compression_ratio);

        rrdset_done(st_compression);
    }

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

    if(gs.rrdr_queries_made) {
        static RRDSET *st_rrdr_queries = NULL;
        static RRDDIM *rd_queries = NULL;

        if (unlikely(!st_rrdr_queries)) {
            st_rrdr_queries = rrdset_create_localhost(
                    "netdata"
                    , "queries"
                    , NULL
                    , "queries"
                    , NULL
                    , "NetData API Queries"
                    , "queries/s"
                    , "netdata"
                    , "stats"
                    , 130500
                    , localhost->rrd_update_every
                    , RRDSET_TYPE_LINE
            );

            rd_queries = rrddim_add(st_rrdr_queries, "queries", NULL, 1, 1, RRD_ALGORITHM_INCREMENTAL);
        }
        else
            rrdset_next(st_rrdr_queries);

        rrddim_set_by_pointer(st_rrdr_queries, rd_queries, (collected_number)gs.rrdr_queries_made);

        rrdset_done(st_rrdr_queries);
    }

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

    if(gs.rrdr_db_points_read || gs.rrdr_result_points_generated) {
        static RRDSET *st_rrdr_points = NULL;
        static RRDDIM *rd_points_read = NULL;
        static RRDDIM *rd_points_generated = NULL;

        if (unlikely(!st_rrdr_points)) {
            st_rrdr_points = rrdset_create_localhost(
                    "netdata"
                    , "db_points"
                    , NULL
                    , "queries"
                    , NULL
                    , "NetData API Points"
                    , "points/s"
                    , "netdata"
                    , "stats"
                    , 130501
                    , localhost->rrd_update_every
                    , RRDSET_TYPE_AREA
            );

            rd_points_read = rrddim_add(st_rrdr_points, "read", NULL, 1, 1, RRD_ALGORITHM_INCREMENTAL);
            rd_points_generated = rrddim_add(st_rrdr_points, "generated", NULL, -1, 1, RRD_ALGORITHM_INCREMENTAL);
        }
        else
            rrdset_next(st_rrdr_points);

        rrddim_set_by_pointer(st_rrdr_points, rd_points_read, (collected_number)gs.rrdr_db_points_read);
        rrddim_set_by_pointer(st_rrdr_points, rd_points_generated, (collected_number)gs.rrdr_result_points_generated);

        rrdset_done(st_rrdr_points);
    }

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

#ifdef ENABLE_DBENGINE
    RRDHOST *host;
    unsigned long long stats_array[RRDENG_NR_STATS] = {0};
    unsigned long long local_stats_array[RRDENG_NR_STATS];
    unsigned dbengine_contexts = 0, counted_multihost_db = 0, i;

    rrd_rdlock();
    rrdhost_foreach_read(host) {
        if (host->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE && !rrdhost_flag_check(host, RRDHOST_FLAG_ARCHIVED)) {
            if (&multidb_ctx == host->rrdeng_ctx) {
                if (counted_multihost_db)
                    continue; /* Only count multi-host DB once */
                counted_multihost_db = 1;
            }
            ++dbengine_contexts;
            /* get localhost's DB engine's statistics */
            rrdeng_get_37_statistics(host->rrdeng_ctx, local_stats_array);
            for (i = 0 ; i < RRDENG_NR_STATS ; ++i) {
                /* aggregate statistics across hosts */
                stats_array[i] += local_stats_array[i];
            }
        }
    }
    rrd_unlock();

    if (dbengine_contexts) {
        /* deduplicate global statistics by getting the ones from the last context */
        stats_array[30] = local_stats_array[30];
        stats_array[31] = local_stats_array[31];
        stats_array[32] = local_stats_array[32];
        stats_array[34] = local_stats_array[34];
        stats_array[36] = local_stats_array[36];

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

        {
            static RRDSET *st_compression = NULL;
            static RRDDIM *rd_savings = NULL;

            if (unlikely(!st_compression)) {
                st_compression = rrdset_create_localhost(
                        "netdata"
                        , "dbengine_compression_ratio"
                        , NULL
                        , "dbengine"
                        , NULL
                        , "NetData DB engine data extents' compression savings ratio"
                        , "percentage"
                        , "netdata"
                        , "stats"
                        , 130502
                        , localhost->rrd_update_every
                        , RRDSET_TYPE_LINE
                );

                rd_savings = rrddim_add(st_compression, "savings", NULL, 1, 1000, RRD_ALGORITHM_ABSOLUTE);
            }
            else
                rrdset_next(st_compression);

            unsigned long long ratio;
            unsigned long long compressed_content_size = stats_array[12];
            unsigned long long content_size = stats_array[11];

            if (content_size) {
                // allow negative savings
                ratio = ((content_size - compressed_content_size) * 100 * 1000) / content_size;
            } else {
                ratio = 0;
            }
            rrddim_set_by_pointer(st_compression, rd_savings, ratio);

            rrdset_done(st_compression);
        }

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

        {
            static RRDSET *st_pg_cache_hit_ratio = NULL;
            static RRDDIM *rd_hit_ratio = NULL;

            if (unlikely(!st_pg_cache_hit_ratio)) {
                st_pg_cache_hit_ratio = rrdset_create_localhost(
                        "netdata"
                        , "page_cache_hit_ratio"
                        , NULL
                        , "dbengine"
                        , NULL
                        , "NetData DB engine page cache hit ratio"
                        , "percentage"
                        , "netdata"
                        , "stats"
                        , 130503
                        , localhost->rrd_update_every
                        , RRDSET_TYPE_LINE
                );

                rd_hit_ratio = rrddim_add(st_pg_cache_hit_ratio, "ratio", NULL, 1, 1000, RRD_ALGORITHM_ABSOLUTE);
            }
            else
                rrdset_next(st_pg_cache_hit_ratio);

            static unsigned long long old_hits = 0;
            static unsigned long long old_misses = 0;
            unsigned long long hits = stats_array[7];
            unsigned long long misses = stats_array[8];
            unsigned long long hits_delta;
            unsigned long long misses_delta;
            unsigned long long ratio;

            hits_delta = hits - old_hits;
            misses_delta = misses - old_misses;
            old_hits = hits;
            old_misses = misses;

            if (hits_delta + misses_delta) {
                ratio = (hits_delta * 100 * 1000) / (hits_delta + misses_delta);
            } else {
                ratio = 0;
            }
            rrddim_set_by_pointer(st_pg_cache_hit_ratio, rd_hit_ratio, ratio);

            rrdset_done(st_pg_cache_hit_ratio);
        }

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

        {
            static RRDSET *st_pg_cache_pages = NULL;
            static RRDDIM *rd_descriptors = NULL;
            static RRDDIM *rd_populated = NULL;
            static RRDDIM *rd_dirty = NULL;
            static RRDDIM *rd_backfills = NULL;
            static RRDDIM *rd_evictions = NULL;
            static RRDDIM *rd_used_by_collectors = NULL;

            if (unlikely(!st_pg_cache_pages)) {
                st_pg_cache_pages = rrdset_create_localhost(
                        "netdata"
                        , "page_cache_stats"
                        , NULL
                        , "dbengine"
                        , NULL
                        , "NetData dbengine page cache statistics"
                        , "pages"
                        , "netdata"
                        , "stats"
                        , 130504
                        , localhost->rrd_update_every
                        , RRDSET_TYPE_LINE
                );

                rd_descriptors = rrddim_add(st_pg_cache_pages, "descriptors", NULL, 1, 1, RRD_ALGORITHM_ABSOLUTE);
                rd_populated = rrddim_add(st_pg_cache_pages, "populated", NULL, 1, 1, RRD_ALGORITHM_ABSOLUTE);
                rd_dirty = rrddim_add(st_pg_cache_pages, "dirty", NULL, 1, 1, RRD_ALGORITHM_ABSOLUTE);
                rd_backfills = rrddim_add(st_pg_cache_pages, "backfills", NULL, 1, 1, RRD_ALGORITHM_INCREMENTAL);
                rd_evictions = rrddim_add(st_pg_cache_pages, "evictions", NULL, -1, 1, RRD_ALGORITHM_INCREMENTAL);
                rd_used_by_collectors = rrddim_add(st_pg_cache_pages, "used_by_collectors", NULL, 1, 1,
                                                   RRD_ALGORITHM_ABSOLUTE);
            }
            else
                rrdset_next(st_pg_cache_pages);

            rrddim_set_by_pointer(st_pg_cache_pages, rd_descriptors, (collected_number)stats_array[27]);
            rrddim_set_by_pointer(st_pg_cache_pages, rd_populated, (collected_number)stats_array[3]);
            rrddim_set_by_pointer(st_pg_cache_pages, rd_dirty, (collected_number)stats_array[0] + stats_array[4]);
            rrddim_set_by_pointer(st_pg_cache_pages, rd_backfills, (collected_number)stats_array[9]);
            rrddim_set_by_pointer(st_pg_cache_pages, rd_evictions, (collected_number)stats_array[10]);
            rrddim_set_by_pointer(st_pg_cache_pages, rd_used_by_collectors, (collected_number)stats_array[0]);
            rrdset_done(st_pg_cache_pages);
        }

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

        {
            static RRDSET *st_long_term_pages = NULL;
            static RRDDIM *rd_total = NULL;
            static RRDDIM *rd_insertions = NULL;
            static RRDDIM *rd_deletions = NULL;
            static RRDDIM *rd_flushing_pressure_deletions = NULL;

            if (unlikely(!st_long_term_pages)) {
                st_long_term_pages = rrdset_create_localhost(
                        "netdata"
                , "dbengine_long_term_page_stats"
                , NULL
                , "dbengine"
                , NULL
                , "NetData dbengine long-term page statistics"
                , "pages"
                , "netdata"
                , "stats"
                , 130505
                , localhost->rrd_update_every
                , RRDSET_TYPE_LINE
                );

                rd_total = rrddim_add(st_long_term_pages, "total", NULL, 1, 1, RRD_ALGORITHM_ABSOLUTE);
                rd_insertions = rrddim_add(st_long_term_pages, "insertions", NULL, 1, 1, RRD_ALGORITHM_INCREMENTAL);
                rd_deletions = rrddim_add(st_long_term_pages, "deletions", NULL, -1, 1, RRD_ALGORITHM_INCREMENTAL);
                rd_flushing_pressure_deletions = rrddim_add(st_long_term_pages, "flushing_pressure_deletions", NULL, -1,
                                                            1, RRD_ALGORITHM_INCREMENTAL);
            }
            else
                rrdset_next(st_long_term_pages);

            rrddim_set_by_pointer(st_long_term_pages, rd_total, (collected_number)stats_array[2]);
            rrddim_set_by_pointer(st_long_term_pages, rd_insertions, (collected_number)stats_array[5]);
            rrddim_set_by_pointer(st_long_term_pages, rd_deletions, (collected_number)stats_array[6]);
            rrddim_set_by_pointer(st_long_term_pages, rd_flushing_pressure_deletions,
                                  (collected_number)stats_array[36]);
            rrdset_done(st_long_term_pages);
        }

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

        {
            static RRDSET *st_io_stats = NULL;
            static RRDDIM *rd_reads = NULL;
            static RRDDIM *rd_writes = NULL;

            if (unlikely(!st_io_stats)) {
                st_io_stats = rrdset_create_localhost(
                "netdata"
                , "dbengine_io_throughput"
                , NULL
                , "dbengine"
                , NULL
                , "NetData DB engine I/O throughput"
                , "MiB/s"
                , "netdata"
                , "stats"
                , 130506
                , localhost->rrd_update_every
                , RRDSET_TYPE_LINE
                );

                rd_reads = rrddim_add(st_io_stats, "reads", NULL, 1, 1024 * 1024, RRD_ALGORITHM_INCREMENTAL);
                rd_writes = rrddim_add(st_io_stats, "writes", NULL, -1, 1024 * 1024, RRD_ALGORITHM_INCREMENTAL);
            }
            else
                rrdset_next(st_io_stats);

            rrddim_set_by_pointer(st_io_stats, rd_reads, (collected_number)stats_array[17]);
            rrddim_set_by_pointer(st_io_stats, rd_writes, (collected_number)stats_array[15]);
            rrdset_done(st_io_stats);
        }

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

        {
            static RRDSET *st_io_stats = NULL;
            static RRDDIM *rd_reads = NULL;
            static RRDDIM *rd_writes = NULL;

            if (unlikely(!st_io_stats)) {
                st_io_stats = rrdset_create_localhost(
                        "netdata"
                        , "dbengine_io_operations"
                        , NULL
                        , "dbengine"
                        , NULL
                        , "NetData DB engine I/O operations"
                        , "operations/s"
                        , "netdata"
                        , "stats"
                        , 130507
                        , localhost->rrd_update_every
                        , RRDSET_TYPE_LINE
                );

                rd_reads = rrddim_add(st_io_stats, "reads", NULL, 1, 1, RRD_ALGORITHM_INCREMENTAL);
                rd_writes = rrddim_add(st_io_stats, "writes", NULL, -1, 1, RRD_ALGORITHM_INCREMENTAL);
            }
            else
                rrdset_next(st_io_stats);

            rrddim_set_by_pointer(st_io_stats, rd_reads, (collected_number)stats_array[18]);
            rrddim_set_by_pointer(st_io_stats, rd_writes, (collected_number)stats_array[16]);
            rrdset_done(st_io_stats);
        }

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

        {
            static RRDSET *st_errors = NULL;
            static RRDDIM *rd_fs_errors = NULL;
            static RRDDIM *rd_io_errors = NULL;
            static RRDDIM *pg_cache_over_half_dirty_events = NULL;

            if (unlikely(!st_errors)) {
                st_errors = rrdset_create_localhost(
                        "netdata"
                        , "dbengine_global_errors"
                        , NULL
                        , "dbengine"
                        , NULL
                        , "NetData DB engine errors"
                        , "errors/s"
                        , "netdata"
                        , "stats"
                        , 130508
                        , localhost->rrd_update_every
                        , RRDSET_TYPE_LINE
                );

                rd_io_errors = rrddim_add(st_errors, "io_errors", NULL, 1, 1, RRD_ALGORITHM_INCREMENTAL);
                rd_fs_errors = rrddim_add(st_errors, "fs_errors", NULL, 1, 1, RRD_ALGORITHM_INCREMENTAL);
                pg_cache_over_half_dirty_events = rrddim_add(st_errors, "pg_cache_over_half_dirty_events", NULL, 1, 1,
                                                             RRD_ALGORITHM_INCREMENTAL);
            }
            else
                rrdset_next(st_errors);

            rrddim_set_by_pointer(st_errors, rd_io_errors, (collected_number)stats_array[30]);
            rrddim_set_by_pointer(st_errors, rd_fs_errors, (collected_number)stats_array[31]);
            rrddim_set_by_pointer(st_errors, pg_cache_over_half_dirty_events, (collected_number)stats_array[34]);
            rrdset_done(st_errors);
        }

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

        {
            static RRDSET *st_fd = NULL;
            static RRDDIM *rd_fd_current = NULL;
            static RRDDIM *rd_fd_max = NULL;

            if (unlikely(!st_fd)) {
                st_fd = rrdset_create_localhost(
                        "netdata"
                        , "dbengine_global_file_descriptors"
                        , NULL
                        , "dbengine"
                        , NULL
                        , "NetData DB engine File Descriptors"
                        , "descriptors"
                        , "netdata"
                        , "stats"
                        , 130509
                        , localhost->rrd_update_every
                        , RRDSET_TYPE_LINE
                );

                rd_fd_current = rrddim_add(st_fd, "current", NULL, 1, 1, RRD_ALGORITHM_ABSOLUTE);
                rd_fd_max = rrddim_add(st_fd, "max", NULL, 1, 1, RRD_ALGORITHM_ABSOLUTE);
            }
            else
                rrdset_next(st_fd);

            rrddim_set_by_pointer(st_fd, rd_fd_current, (collected_number)stats_array[32]);
            /* Careful here, modify this accordingly if the File-Descriptor budget ever changes */
            rrddim_set_by_pointer(st_fd, rd_fd_max, (collected_number)rlimit_nofile.rlim_cur / 4);
            rrdset_done(st_fd);
        }

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

        {
            static RRDSET *st_ram_usage = NULL;
            static RRDDIM *rd_cached = NULL;
            static RRDDIM *rd_pinned = NULL;
            static RRDDIM *rd_metadata = NULL;

            collected_number cached_pages, pinned_pages, API_producers, populated_pages, metadata, pages_on_disk,
            page_cache_descriptors;

            if (unlikely(!st_ram_usage)) {
                st_ram_usage = rrdset_create_localhost(
                "netdata"
                , "dbengine_ram"
                , NULL
                , "dbengine"
                , NULL
                , "NetData DB engine RAM usage"
                , "MiB"
                , "netdata"
                , "stats"
                , 130510
                , localhost->rrd_update_every
                , RRDSET_TYPE_STACKED
                );

                rd_cached = rrddim_add(st_ram_usage, "cache", NULL, 1, 256, RRD_ALGORITHM_ABSOLUTE);
                rd_pinned = rrddim_add(st_ram_usage, "collectors", NULL, 1, 256, RRD_ALGORITHM_ABSOLUTE);
                rd_metadata = rrddim_add(st_ram_usage, "metadata", NULL, 1, 1048576, RRD_ALGORITHM_ABSOLUTE);
            }
            else
                rrdset_next(st_ram_usage);

            API_producers = (collected_number)stats_array[0];
            pages_on_disk = (collected_number)stats_array[2];
            populated_pages = (collected_number)stats_array[3];
            page_cache_descriptors = (collected_number)stats_array[27];

            if (API_producers * 2 > populated_pages) {
                pinned_pages = API_producers;
            } else{
                pinned_pages = API_producers * 2;
            }
            cached_pages = populated_pages - pinned_pages;

            metadata = page_cache_descriptors * sizeof(struct page_cache_descr);
            metadata += pages_on_disk * sizeof(struct rrdeng_page_descr);
            /* This is an empirical estimation for Judy array indexing and extent structures */
            metadata += pages_on_disk * 58;

            rrddim_set_by_pointer(st_ram_usage, rd_cached, cached_pages);
            rrddim_set_by_pointer(st_ram_usage, rd_pinned, pinned_pages);
            rrddim_set_by_pointer(st_ram_usage, rd_metadata, metadata);
            rrdset_done(st_ram_usage);
        }
    }
#endif

}
