netdata/database/sqlite/sqlite_aclk.c

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

#include "sqlite_functions.h"
#include "sqlite_aclk.h"

#include "sqlite_aclk_chart.h"
#include "sqlite_aclk_node.h"

#ifdef ENABLE_NEW_CLOUD_PROTOCOL
#include "../../aclk/aclk.h"
#endif

void sanity_check(void) {
    // make sure the compiler will stop on misconfigurations
    BUILD_BUG_ON(WORKER_UTILIZATION_MAX_JOB_TYPES < ACLK_MAX_ENUMERATIONS_DEFINED);
}

const char *aclk_sync_config[] = {
    "CREATE TABLE IF NOT EXISTS dimension_delete (dimension_id blob, dimension_name text, chart_type_id text, "
    "dim_id blob, chart_id blob, host_id blob, date_created);",

    "CREATE INDEX IF NOT EXISTS ind_h1 ON dimension_delete (host_id);",

    "CREATE TRIGGER IF NOT EXISTS tr_dim_del AFTER DELETE ON dimension BEGIN INSERT INTO dimension_delete "
    "(dimension_id, dimension_name, chart_type_id, dim_id, chart_id, host_id, date_created)"
    " select old.id, old.name, c.type||\".\"||c.id, old.dim_id, old.chart_id, c.host_id, strftime('%s') FROM"
    " chart c WHERE c.chart_id = old.chart_id; END;",

    "DELETE FROM dimension_delete WHERE host_id NOT IN"
    " (SELECT host_id FROM host) OR strftime('%s') - date_created > 604800;",

    NULL,
};

uv_mutex_t aclk_async_lock;
struct aclk_database_worker_config  *aclk_thread_head = NULL;
int retention_running = 0;

#ifdef ENABLE_NEW_CLOUD_PROTOCOL
static void stop_retention_run()
{
    uv_mutex_lock(&aclk_async_lock);
    retention_running = 0;
    uv_mutex_unlock(&aclk_async_lock);
}

static int request_retention_run()
{
    int rc = 0;
    uv_mutex_lock(&aclk_async_lock);
    if (unlikely(retention_running))
        rc = 1;
    else
        retention_running = 1;
    uv_mutex_unlock(&aclk_async_lock);
    return rc;
}
#endif

int claimed()
{
    int rc;
    rrdhost_aclk_state_lock(localhost);
    rc = (localhost->aclk_state.claimed_id != NULL);
    rrdhost_aclk_state_unlock(localhost);
    return rc;
}

void aclk_add_worker_thread(struct aclk_database_worker_config *wc)
{
    if (unlikely(!wc))
        return;

    uv_mutex_lock(&aclk_async_lock);
    if (unlikely(!wc->host)) {
        wc->next = aclk_thread_head;
        aclk_thread_head = wc;
    }
    uv_mutex_unlock(&aclk_async_lock);
    return;
}

void aclk_del_worker_thread(struct aclk_database_worker_config *wc)
{
    if (unlikely(!wc))
        return;

    uv_mutex_lock(&aclk_async_lock);
    struct aclk_database_worker_config **tmp = &aclk_thread_head;
    while (*tmp && (*tmp) != wc)
        tmp = &(*tmp)->next;
    if (*tmp)
        *tmp = wc->next;
    uv_mutex_unlock(&aclk_async_lock);
    return;
}

int aclk_worker_thread_exists(char *guid)
{
    int rc = 0;
    uv_mutex_lock(&aclk_async_lock);

    struct aclk_database_worker_config *tmp = aclk_thread_head;

    while (tmp && !rc) {
        rc = strcmp(tmp->uuid_str, guid) == 0;
        tmp = tmp->next;
    }
    uv_mutex_unlock(&aclk_async_lock);
    return rc;
}

void aclk_database_init_cmd_queue(struct aclk_database_worker_config *wc)
{
    wc->cmd_queue.head = wc->cmd_queue.tail = 0;
    wc->queue_size = 0;
    fatal_assert(0 == uv_cond_init(&wc->cmd_cond));
    fatal_assert(0 == uv_mutex_init(&wc->cmd_mutex));
}

int aclk_database_enq_cmd_noblock(struct aclk_database_worker_config *wc, struct aclk_database_cmd *cmd)
{
    unsigned queue_size;

    /* wait for free space in queue */
    uv_mutex_lock(&wc->cmd_mutex);
    if ((queue_size = wc->queue_size) == ACLK_DATABASE_CMD_Q_MAX_SIZE || wc->is_shutting_down) {
        uv_mutex_unlock(&wc->cmd_mutex);
        return 1;
    }

    fatal_assert(queue_size < ACLK_DATABASE_CMD_Q_MAX_SIZE);
    /* enqueue command */
    wc->cmd_queue.cmd_array[wc->cmd_queue.tail] = *cmd;
    wc->cmd_queue.tail = wc->cmd_queue.tail != ACLK_DATABASE_CMD_Q_MAX_SIZE - 1 ?
                         wc->cmd_queue.tail + 1 : 0;
    wc->queue_size = queue_size + 1;
    uv_mutex_unlock(&wc->cmd_mutex);
    return 0;
}

void aclk_database_enq_cmd(struct aclk_database_worker_config *wc, struct aclk_database_cmd *cmd)
{
    unsigned queue_size;

    /* wait for free space in queue */
    uv_mutex_lock(&wc->cmd_mutex);
    if (wc->is_shutting_down) {
        uv_mutex_unlock(&wc->cmd_mutex);
        return;
    }
    while ((queue_size = wc->queue_size) == ACLK_DATABASE_CMD_Q_MAX_SIZE) {
        uv_cond_wait(&wc->cmd_cond, &wc->cmd_mutex);
    }
    fatal_assert(queue_size < ACLK_DATABASE_CMD_Q_MAX_SIZE);
    /* enqueue command */
    wc->cmd_queue.cmd_array[wc->cmd_queue.tail] = *cmd;
    wc->cmd_queue.tail = wc->cmd_queue.tail != ACLK_DATABASE_CMD_Q_MAX_SIZE - 1 ?
                         wc->cmd_queue.tail + 1 : 0;
    wc->queue_size = queue_size + 1;
    uv_mutex_unlock(&wc->cmd_mutex);

    /* wake up event loop */
    int rc = uv_async_send(&wc->async);
    if (unlikely(rc))
        debug(D_ACLK_SYNC, "Failed to wake up event loop");
}

struct aclk_database_cmd aclk_database_deq_cmd(struct aclk_database_worker_config* wc)
{
    struct aclk_database_cmd ret;
    unsigned queue_size;

    uv_mutex_lock(&wc->cmd_mutex);
    queue_size = wc->queue_size;
    if (queue_size == 0 || wc->is_shutting_down) {
        memset(&ret, 0, sizeof(ret));
        ret.opcode = ACLK_DATABASE_NOOP;
        ret.completion = NULL;
        if (wc->is_shutting_down)
            uv_cond_signal(&wc->cmd_cond);
    } else {
        /* dequeue command */
        ret = wc->cmd_queue.cmd_array[wc->cmd_queue.head];
        if (queue_size == 1) {
            wc->cmd_queue.head = wc->cmd_queue.tail = 0;
        } else {
            wc->cmd_queue.head = wc->cmd_queue.head != ACLK_DATABASE_CMD_Q_MAX_SIZE - 1 ?
                                 wc->cmd_queue.head + 1 : 0;
        }
        wc->queue_size = queue_size - 1;
        /* wake up producers */
        uv_cond_signal(&wc->cmd_cond);
    }
    uv_mutex_unlock(&wc->cmd_mutex);

    return ret;
}

int aclk_worker_enq_cmd(char *node_id, struct aclk_database_cmd *cmd)
{
    if (unlikely(!node_id || !cmd))
        return 0;

    uv_mutex_lock(&aclk_async_lock);
    struct aclk_database_worker_config *wc = aclk_thread_head;

    while (wc) {
        if (!strcmp(wc->node_id, node_id))
            break;
        wc = wc->next;
    }
    uv_mutex_unlock(&aclk_async_lock);
    if (wc)
        aclk_database_enq_cmd(wc, cmd);
    return (wc == NULL);
}

struct aclk_database_worker_config *find_inactive_wc_by_node_id(char *node_id)
{
    if (unlikely(!node_id))
        return NULL;

    uv_mutex_lock(&aclk_async_lock);
    struct aclk_database_worker_config *wc = aclk_thread_head;

    while (wc) {
        if (!strcmp(wc->node_id, node_id))
            break;
        wc = wc->next;
    }
    uv_mutex_unlock(&aclk_async_lock);

    return (wc);
}

void aclk_sync_exit_all()
{
    rrd_rdlock();
    RRDHOST *host = localhost;
    while(host) {
        struct aclk_database_worker_config *wc = host->dbsync_worker;
        if (wc) {
            wc->is_shutting_down = 1;
            (void) aclk_database_deq_cmd(wc);
            uv_cond_signal(&wc->cmd_cond);
        }
        host = host->next;
    }
    rrd_unlock();

    uv_mutex_lock(&aclk_async_lock);
    struct aclk_database_worker_config *wc = aclk_thread_head;
    while (wc) {
        wc->is_shutting_down = 1;
        wc = wc->next;
    }
    uv_mutex_unlock(&aclk_async_lock);
}

int aclk_start_sync_thread(void *data, int argc, char **argv, char **column)
{
    char uuid_str[GUID_LEN + 1];
    UNUSED(data);
    UNUSED(argc);
    UNUSED(column);

    uuid_unparse_lower(*((uuid_t *) argv[0]), uuid_str);

    if (rrdhost_find_by_guid(uuid_str, 0) == localhost)
        return 0;

    sql_create_aclk_table(NULL, (uuid_t *) argv[0], (uuid_t *) argv[1]);
    return 0;
}

void sql_aclk_sync_init(void)
{
#ifdef ENABLE_NEW_CLOUD_PROTOCOL
    char *err_msg = NULL;
    int rc;

    if (unlikely(!db_meta)) {
        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE) {
            return;
        }
        error_report("Database has not been initialized");
        return;
    }

    info("SQLite aclk sync initialization");

    for (int i = 0; aclk_sync_config[i]; i++) {
        debug(D_ACLK_SYNC, "Executing %s", aclk_sync_config[i]);
        rc = sqlite3_exec(db_meta, aclk_sync_config[i], 0, 0, &err_msg);
        if (rc != SQLITE_OK) {
            error_report("SQLite error aclk sync initialization setup, rc = %d (%s)", rc, err_msg);
            error_report("SQLite failed statement %s", aclk_sync_config[i]);
            sqlite3_free(err_msg);
            return;
        }
    }
    info("SQLite aclk sync initialization completed");
    fatal_assert(0 == uv_mutex_init(&aclk_async_lock));

    rc = sqlite3_exec(db_meta, "SELECT ni.host_id, ni.node_id FROM host h, node_instance ni WHERE "
        "h.host_id = ni.host_id AND ni.node_id IS NOT NULL;", aclk_start_sync_thread, NULL, NULL);
#endif
    return;
}

static void async_cb(uv_async_t *handle)
{
    uv_stop(handle->loop);
    uv_update_time(handle->loop);
    debug(D_ACLK_SYNC, "%s called, active=%d.", __func__, uv_is_active((uv_handle_t *)handle));
}

#define TIMER_PERIOD_MS (1000)

static void timer_cb(uv_timer_t* handle)
{
    uv_stop(handle->loop);
    uv_update_time(handle->loop);

#ifdef ENABLE_NEW_CLOUD_PROTOCOL
    struct aclk_database_worker_config *wc = handle->data;
    struct aclk_database_cmd cmd;
    memset(&cmd, 0, sizeof(cmd));
    cmd.opcode = ACLK_DATABASE_TIMER;
    aclk_database_enq_cmd_noblock(wc, &cmd);

    time_t now =  now_realtime_sec();

    if (wc->cleanup_after && wc->cleanup_after < now) {
        cmd.opcode = ACLK_DATABASE_CLEANUP;
        if (!aclk_database_enq_cmd_noblock(wc, &cmd))
            wc->cleanup_after += ACLK_DATABASE_CLEANUP_INTERVAL;
    }

    if (aclk_use_new_cloud_arch && aclk_connected) {
        if (wc->rotation_after && wc->rotation_after < now) {
            cmd.opcode = ACLK_DATABASE_UPD_RETENTION;
            if (!aclk_database_enq_cmd_noblock(wc, &cmd))
                wc->rotation_after += ACLK_DATABASE_ROTATION_INTERVAL;
        }

        if (wc->chart_updates && !wc->chart_pending && wc->chart_payload_count) {
            cmd.opcode = ACLK_DATABASE_PUSH_CHART;
            cmd.count = ACLK_MAX_CHART_BATCH;
            cmd.param1 = ACLK_MAX_CHART_BATCH_COUNT;
            if (!aclk_database_enq_cmd_noblock(wc, &cmd)) {
                if (wc->retry_count)
                    info("Queued chart/dimension payload command %s, retry count = %u", wc->host_guid, wc->retry_count);
                wc->chart_pending = 1;
                wc->retry_count = 0;
            } else {
                wc->retry_count++;
                if (wc->retry_count % 100 == 0)
                    error_report("Failed to queue chart/dimension payload command %s, retry count = %u",
                        wc->host_guid,
                        wc->retry_count);
            }
        }

        if (wc->alert_updates && !wc->pause_alert_updates) {
            cmd.opcode = ACLK_DATABASE_PUSH_ALERT;
            cmd.count = ACLK_MAX_ALERT_UPDATES;
            aclk_database_enq_cmd_noblock(wc, &cmd);
        }
    }
#endif
}


#ifdef ENABLE_NEW_CLOUD_PROTOCOL
void after_send_retention(uv_work_t *req, int status)
{
    struct aclk_database_worker_config *wc = req->data;
    (void)status;
    stop_retention_run();
    wc->retention_running = 0;

    struct aclk_database_cmd cmd;
    memset(&cmd, 0, sizeof(cmd));
    cmd.opcode = ACLK_DATABASE_DIM_DELETION;
    if (aclk_database_enq_cmd_noblock(wc, &cmd))
        info("Failed to queue a dimension deletion message");

    cmd.opcode = ACLK_DATABASE_NODE_INFO;
    if (aclk_database_enq_cmd_noblock(wc, &cmd))
        info("Failed to queue a node update info message");
}


static void send_retention(uv_work_t *req)
{
    struct aclk_database_worker_config *wc = req->data;

    if (unlikely(wc->is_shutting_down))
        return;

    aclk_update_retention(wc);
}
#endif

#define MAX_CMD_BATCH_SIZE (256)

void aclk_database_worker(void *arg)
{
    worker_register("ACLKSYNC");
    worker_register_job_name(ACLK_DATABASE_NOOP,                 "noop");
#ifdef ENABLE_NEW_CLOUD_PROTOCOL
    worker_register_job_name(ACLK_DATABASE_ADD_CHART,            "chart add");
    worker_register_job_name(ACLK_DATABASE_ADD_DIMENSION,        "dimension add");
    worker_register_job_name(ACLK_DATABASE_PUSH_CHART,           "chart push");
    worker_register_job_name(ACLK_DATABASE_PUSH_CHART_CONFIG,    "chart conf push");
    worker_register_job_name(ACLK_DATABASE_RESET_CHART,          "chart reset");
    worker_register_job_name(ACLK_DATABASE_CHART_ACK,            "chart ack");
    worker_register_job_name(ACLK_DATABASE_UPD_RETENTION,        "retention check");
    worker_register_job_name(ACLK_DATABASE_DIM_DELETION,         "dimension delete");
    worker_register_job_name(ACLK_DATABASE_ORPHAN_HOST,          "node orphan");
#endif
    worker_register_job_name(ACLK_DATABASE_ALARM_HEALTH_LOG,     "alert log");
    worker_register_job_name(ACLK_DATABASE_CLEANUP,              "cleanup");
    worker_register_job_name(ACLK_DATABASE_DELETE_HOST,          "node delete");
    worker_register_job_name(ACLK_DATABASE_NODE_INFO,            "node info");
    worker_register_job_name(ACLK_DATABASE_PUSH_ALERT,           "alert push");
    worker_register_job_name(ACLK_DATABASE_PUSH_ALERT_CONFIG,    "alert conf push");
    worker_register_job_name(ACLK_DATABASE_PUSH_ALERT_SNAPSHOT,  "alert snapshot");
    worker_register_job_name(ACLK_DATABASE_QUEUE_REMOVED_ALERTS, "alerts check");
    worker_register_job_name(ACLK_DATABASE_TIMER,                "timer");

    struct aclk_database_worker_config *wc = arg;
    uv_loop_t *loop;
    int ret;
    enum aclk_database_opcode opcode;
    uv_timer_t timer_req;
    struct aclk_database_cmd cmd;
    unsigned cmd_batch_size;

    //aclk_database_init_cmd_queue(wc);

    char threadname[NETDATA_THREAD_NAME_MAX+1];
    if (wc->host)
        snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "AS_%s", wc->host->hostname);
    else {
        snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "AS_%s", wc->uuid_str);
        threadname[11] = '\0';
    }
    uv_thread_set_name_np(wc->thread, threadname);

    loop = wc->loop = mallocz(sizeof(uv_loop_t));
    ret = uv_loop_init(loop);
    if (ret) {
        error("uv_loop_init(): %s", uv_strerror(ret));
        goto error_after_loop_init;
    }
    loop->data = wc;

    ret = uv_async_init(wc->loop, &wc->async, async_cb);
    if (ret) {
        error("uv_async_init(): %s", uv_strerror(ret));
        goto error_after_async_init;
    }
    wc->async.data = wc;

    ret = uv_timer_init(loop, &timer_req);
    if (ret) {
        error("uv_timer_init(): %s", uv_strerror(ret));
        goto error_after_timer_init;
    }
    timer_req.data = wc;
    fatal_assert(0 == uv_timer_start(&timer_req, timer_cb, TIMER_PERIOD_MS, TIMER_PERIOD_MS));

//    wc->retry_count = 0;
    wc->node_info_send = (wc->host && !localhost);
//    aclk_add_worker_thread(wc);
    info("Starting ACLK sync thread for host %s -- scratch area %lu bytes", wc->host_guid, sizeof(*wc));

    memset(&cmd, 0, sizeof(cmd));
#ifdef ENABLE_NEW_CLOUD_PROTOCOL
    uv_work_t retention_work;
    sql_get_last_chart_sequence(wc);
    wc->chart_payload_count = sql_get_pending_count(wc);
    if (!wc->chart_payload_count)
        info("%s: No pending charts and dimensions detected during startup", wc->host_guid);
#endif

    wc->startup_time = now_realtime_sec();
    wc->cleanup_after = wc->startup_time + ACLK_DATABASE_CLEANUP_FIRST;
    wc->rotation_after = wc->startup_time + ACLK_DATABASE_ROTATION_DELAY;

    debug(D_ACLK_SYNC,"Node %s reports pending message count = %u", wc->node_id, wc->chart_payload_count);

    while (likely(!netdata_exit)) {
        worker_is_idle();
        uv_run(loop, UV_RUN_DEFAULT);

        /* wait for commands */
        cmd_batch_size = 0;
        do {
            if (unlikely(cmd_batch_size >= MAX_CMD_BATCH_SIZE))
                break;
            cmd = aclk_database_deq_cmd(wc);

            if (netdata_exit)
                break;

            opcode = cmd.opcode;
            ++cmd_batch_size;

            if(likely(opcode != ACLK_DATABASE_NOOP))
                worker_is_busy(opcode);

            switch (opcode) {
                case ACLK_DATABASE_NOOP:
                    /* the command queue was empty, do nothing */
                    break;

// MAINTENANCE
                case ACLK_DATABASE_CLEANUP:
                    debug(D_ACLK_SYNC, "Database cleanup for %s", wc->host_guid);
                    sql_maint_aclk_sync_database(wc, cmd);
                    if (wc->host == localhost)
                        sql_check_aclk_table_list(wc);
                    break;

                case ACLK_DATABASE_DELETE_HOST:
                    debug(D_ACLK_SYNC,"Cleaning ACLK tables for %s", (char *) cmd.data);
                    sql_delete_aclk_table_list(wc, cmd);
                    break;

// CHART / DIMENSION OPERATIONS
#ifdef ENABLE_NEW_CLOUD_PROTOCOL
                case ACLK_DATABASE_ADD_CHART:
                    debug(D_ACLK_SYNC, "Adding chart event for %s", wc->host_guid);
                    aclk_add_chart_event(wc, cmd);
                    break;
                case ACLK_DATABASE_ADD_DIMENSION:
                    debug(D_ACLK_SYNC, "Adding dimension event for %s", wc->host_guid);
                    aclk_add_dimension_event(wc, cmd);
                    break;
                case ACLK_DATABASE_PUSH_CHART:
                    debug(D_ACLK_SYNC, "Pushing chart info to the cloud for node %s", wc->host_guid);
                    aclk_send_chart_event(wc, cmd);
                    break;
                case ACLK_DATABASE_PUSH_CHART_CONFIG:
                    debug(D_ACLK_SYNC, "Pushing chart config info to the cloud for node %s", wc->host_guid);
                    aclk_send_chart_config(wc, cmd);
                    break;
                case ACLK_DATABASE_CHART_ACK:
                    debug(D_ACLK_SYNC, "ACK chart SEQ for %s to %"PRIu64, wc->uuid_str, (uint64_t) cmd.param1);
                    aclk_receive_chart_ack(wc, cmd);
                    break;
                case ACLK_DATABASE_RESET_CHART:
                    debug(D_ACLK_SYNC, "RESET chart SEQ for %s to %"PRIu64, wc->uuid_str, (uint64_t) cmd.param1);
                    aclk_receive_chart_reset(wc, cmd);
                    break;
#endif
// ALERTS
                case ACLK_DATABASE_PUSH_ALERT_CONFIG:
                    debug(D_ACLK_SYNC,"Pushing chart config info to the cloud for %s", wc->host_guid);
                    aclk_push_alert_config_event(wc, cmd);
                    break;
                case ACLK_DATABASE_PUSH_ALERT:
                    debug(D_ACLK_SYNC, "Pushing alert info to the cloud for %s", wc->host_guid);
                    aclk_push_alert_event(wc, cmd);
                    break;
                case ACLK_DATABASE_ALARM_HEALTH_LOG:
                    debug(D_ACLK_SYNC, "Pushing alarm health log to the cloud for %s", wc->host_guid);
                    aclk_push_alarm_health_log(wc, cmd);
                    break;
                case ACLK_DATABASE_PUSH_ALERT_SNAPSHOT:
                    debug(D_ACLK_SYNC, "Pushing alert snapshot to the cloud for node %s", wc->host_guid);
                    aclk_push_alert_snapshot_event(wc, cmd);
                    break;
                case ACLK_DATABASE_QUEUE_REMOVED_ALERTS:
                    debug(D_ACLK_SYNC, "Queueing removed alerts for node %s", wc->host_guid);
                    sql_process_queue_removed_alerts_to_aclk(wc, cmd);
                    break;

// NODE OPERATIONS
                case ACLK_DATABASE_NODE_INFO:
                    debug(D_ACLK_SYNC,"Sending node info for %s", wc->uuid_str);
                    sql_build_node_info(wc, cmd);
                    break;
#ifdef ENABLE_NEW_CLOUD_PROTOCOL
                case ACLK_DATABASE_DIM_DELETION:
                    debug(D_ACLK_SYNC,"Sending dimension deletion information %s", wc->uuid_str);
                    aclk_process_dimension_deletion(wc, cmd);
                    break;
                case ACLK_DATABASE_UPD_RETENTION:
                    if (unlikely(wc->retention_running))
                        break;

                    if (unlikely(request_retention_run())) {
                        wc->rotation_after = now_realtime_sec() + ACLK_DATABASE_RETENTION_RETRY;
                        break;
                    }

                    debug(D_ACLK_SYNC,"Sending retention info for %s", wc->uuid_str);
                    retention_work.data = wc;
                    wc->retention_running = 1;
                    if (unlikely(uv_queue_work(loop, &retention_work, send_retention, after_send_retention))) {
                        wc->retention_running = 0;
                        stop_retention_run();
                    }
                    break;

// NODE_INSTANCE DETECTION
                case ACLK_DATABASE_ORPHAN_HOST:
                    wc->host = NULL;
                    wc->is_orphan = 1;
                    aclk_add_worker_thread(wc);
                    break;
#endif
                case ACLK_DATABASE_TIMER:
                    if (unlikely(localhost && !wc->host && !wc->is_orphan)) {
                        if (claimed()) {
                            wc->host = rrdhost_find_by_guid(wc->host_guid, 0);
                            if (wc->host) {
                                info("HOST %s (%s) detected as active", wc->host->hostname, wc->host_guid);
                                snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "AS_%s", wc->host->hostname);
                                uv_thread_set_name_np(wc->thread, threadname);
                                wc->host->dbsync_worker = wc;
                                aclk_del_worker_thread(wc);
                                wc->node_info_send = 1;
                            }
                        }
                    }
                    if (wc->node_info_send && wc->host && localhost && claimed() && aclk_connected) {
                        cmd.opcode = ACLK_DATABASE_NODE_INFO;
                        cmd.completion = NULL;
                        wc->node_info_send = aclk_database_enq_cmd_noblock(wc, &cmd);
                    }
                    if (localhost == wc->host)
                        (void) sqlite3_wal_checkpoint(db_meta, NULL);
                    break;
                default:
                    debug(D_ACLK_SYNC, "%s: default.", __func__);
                    break;
            }
            if (cmd.completion)
                aclk_complete(cmd.completion);
        } while (opcode != ACLK_DATABASE_NOOP);
    }

    if (!uv_timer_stop(&timer_req))
        uv_close((uv_handle_t *)&timer_req, NULL);

    /* cleanup operations of the event loop */
    //info("Shutting down ACLK sync event loop for %s", wc->host_guid);

    /*
     * uv_async_send after uv_close does not seem to crash in linux at the moment,
     * it is however undocumented behaviour we need to be aware if this becomes
     * an issue in the future.
     */
    uv_close((uv_handle_t *)&wc->async, NULL);
    uv_run(loop, UV_RUN_DEFAULT);

    info("Shutting down ACLK sync event loop complete for host %s", wc->host_guid);
    /* TODO: don't let the API block by waiting to enqueue commands */
    uv_cond_destroy(&wc->cmd_cond);
/*  uv_mutex_destroy(&wc->cmd_mutex); */
    //fatal_assert(0 == uv_loop_close(loop));
    int rc;

    do {
        rc = uv_loop_close(loop);
    } while (rc != UV_EBUSY);

    freez(loop);

    rrd_rdlock();
    if (likely(wc->host))
        wc->host->dbsync_worker = NULL;
    freez(wc);
    rrd_unlock();

    worker_unregister();
    return;

error_after_timer_init:
    uv_close((uv_handle_t *)&wc->async, NULL);
error_after_async_init:
    fatal_assert(0 == uv_loop_close(loop));
error_after_loop_init:
    freez(loop);
    worker_unregister();
}

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

void sql_create_aclk_table(RRDHOST *host, uuid_t *host_uuid, uuid_t *node_id)
{
#ifdef ENABLE_ACLK
    char uuid_str[GUID_LEN + 1];
    char host_guid[GUID_LEN + 1];

    uuid_unparse_lower_fix(host_uuid, uuid_str);

    if (aclk_worker_thread_exists(uuid_str))
        return;

    uuid_unparse_lower(*host_uuid, host_guid);

    BUFFER *sql = buffer_create(ACLK_SYNC_QUERY_SIZE);

    buffer_sprintf(sql, TABLE_ACLK_CHART, uuid_str);
    db_execute(buffer_tostring(sql));
    buffer_flush(sql);

    buffer_sprintf(sql, TABLE_ACLK_CHART_PAYLOAD, uuid_str);
    db_execute(buffer_tostring(sql));
    buffer_flush(sql);

    buffer_sprintf(sql, TABLE_ACLK_CHART_LATEST, uuid_str);
    db_execute(buffer_tostring(sql));
    buffer_flush(sql);

    buffer_sprintf(sql, INDEX_ACLK_CHART, uuid_str, uuid_str);
    db_execute(buffer_tostring(sql));
    buffer_flush(sql);

    buffer_sprintf(sql, INDEX_ACLK_CHART_LATEST, uuid_str, uuid_str);
    db_execute(buffer_tostring(sql));
    buffer_flush(sql);

    buffer_sprintf(sql, TRIGGER_ACLK_CHART_PAYLOAD, uuid_str, uuid_str, uuid_str);
    db_execute(buffer_tostring(sql));
    buffer_flush(sql);

    buffer_sprintf(sql, TABLE_ACLK_ALERT, uuid_str);
    db_execute(buffer_tostring(sql));
    buffer_flush(sql);

    buffer_sprintf(sql, INDEX_ACLK_ALERT, uuid_str, uuid_str);
    db_execute(buffer_tostring(sql));

    buffer_free(sql);

    if (likely(host) && unlikely(host->dbsync_worker))
        return;

    struct aclk_database_worker_config *wc = callocz(1, sizeof(struct aclk_database_worker_config));
    if (likely(host))
        host->dbsync_worker = (void *) wc;
    wc->host = host;
    strcpy(wc->uuid_str, uuid_str);
    strcpy(wc->host_guid, host_guid);
    if (node_id && !uuid_is_null(*node_id))
        uuid_unparse_lower(*node_id, wc->node_id);
    wc->chart_updates = 0;
    wc->alert_updates = 0;
    wc->retry_count = 0;
    aclk_database_init_cmd_queue(wc);
    aclk_add_worker_thread(wc);
    fatal_assert(0 == uv_thread_create(&(wc->thread), aclk_database_worker, wc));
#else
    UNUSED(host);
    UNUSED(host_uuid);
    UNUSED(node_id);
#endif
    return;
}

void sql_maint_aclk_sync_database(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
{
    UNUSED(cmd);

    debug(D_ACLK, "Checking database for %s", wc->host_guid);

    BUFFER *sql = buffer_create(ACLK_SYNC_QUERY_SIZE);

    buffer_sprintf(sql,"DELETE FROM aclk_chart_%s WHERE date_submitted IS NOT NULL AND "
        "date_updated < strftime('%%s','now','-%d seconds');", wc->uuid_str, ACLK_DELETE_ACK_INTERNAL);
    db_execute(buffer_tostring(sql));
    buffer_flush(sql);

    buffer_sprintf(sql,"DELETE FROM aclk_chart_payload_%s WHERE unique_id NOT IN "
        "(SELECT unique_id FROM aclk_chart_%s) AND unique_id NOT IN (SELECT unique_id FROM aclk_chart_latest_%s);",
          wc->uuid_str,  wc->uuid_str, wc->uuid_str);
    db_execute(buffer_tostring(sql));
    buffer_flush(sql);

    buffer_sprintf(sql,"DELETE FROM aclk_alert_%s WHERE date_submitted IS NOT NULL AND "
        "date_cloud_ack < strftime('%%s','now','-%d seconds');", wc->uuid_str, ACLK_DELETE_ACK_ALERTS_INTERNAL);
    db_execute(buffer_tostring(sql));

    buffer_free(sql);
    return;
}

#define SQL_SELECT_HOST_BY_UUID  "SELECT host_id FROM host WHERE host_id = @host_id;"

static int is_host_available(uuid_t *host_id)
{
    sqlite3_stmt *res = NULL;
    int rc;

    if (unlikely(!db_meta)) {
        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
            error_report("Database has not been initialized");
        return 1;
    }

    rc = sqlite3_prepare_v2(db_meta, SQL_SELECT_HOST_BY_UUID, -1, &res, 0);
    if (unlikely(rc != SQLITE_OK)) {
        error_report("Failed to prepare statement to select node instance information for a node");
        return 1;
    }

    rc = sqlite3_bind_blob(res, 1, host_id, sizeof(*host_id), SQLITE_STATIC);
    if (unlikely(rc != SQLITE_OK)) {
        error_report("Failed to bind host_id parameter to select node instance information");
        goto failed;
    }
    rc = sqlite3_step(res);

    failed:
    if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
        error_report("Failed to finalize the prepared statement when checking host existence");

    return (rc == SQLITE_ROW);
}

// OPCODE: ACLK_DATABASE_DELETE_HOST
void sql_delete_aclk_table_list(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
{
    UNUSED(wc);
    char uuid_str[GUID_LEN + 1];
    char host_str[GUID_LEN + 1];

    int rc;
    uuid_t host_uuid;
    char *host_guid = (char *)cmd.data;

    if (unlikely(!host_guid))
        return;

    rc = uuid_parse(host_guid, host_uuid);
    freez(host_guid);
    if (rc)
        return;

    uuid_unparse_lower(host_uuid, host_str);
    uuid_unparse_lower_fix(&host_uuid, uuid_str);

    debug(D_ACLK_SYNC, "Checking if I should delete aclk tables for node %s", host_str);

    if (is_host_available(&host_uuid)) {
        debug(D_ACLK_SYNC, "Host %s exists, not deleting aclk sync tables", host_str);
        return;
    }

    debug(D_ACLK_SYNC, "Host %s does NOT exist, can delete aclk sync tables", host_str);

    sqlite3_stmt *res = NULL;
    BUFFER *sql = buffer_create(ACLK_SYNC_QUERY_SIZE);

    buffer_sprintf(sql,"SELECT 'drop '||type||' IF EXISTS '||name||';' FROM sqlite_schema " \
        "WHERE name LIKE 'aclk_%%_%s' AND type IN ('table', 'trigger', 'index');", uuid_str);

    rc = sqlite3_prepare_v2(db_meta, buffer_tostring(sql), -1, &res, 0);
    if (rc != SQLITE_OK) {
        error_report("Failed to prepare statement to clean up aclk tables");
        goto fail;
    }
    buffer_flush(sql);

    while (sqlite3_step(res) == SQLITE_ROW)
        buffer_strcat(sql, (char *) sqlite3_column_text(res, 0));

    rc = sqlite3_finalize(res);
    if (unlikely(rc != SQLITE_OK))
        error_report("Failed to finalize statement to clean up aclk tables, rc = %d", rc);

    db_execute(buffer_tostring(sql));

fail:
    buffer_free(sql);
    return;
}

static int sql_check_aclk_table(void *data, int argc, char **argv, char **column)
{
    struct aclk_database_worker_config *wc = data;
    UNUSED(argc);
    UNUSED(column);

    debug(D_ACLK_SYNC,"Scheduling aclk sync table check for node %s", (char *) argv[0]);
    struct aclk_database_cmd cmd;
    memset(&cmd, 0, sizeof(cmd));
    cmd.opcode = ACLK_DATABASE_DELETE_HOST;
    cmd.data = strdupz((char *) argv[0]);
    aclk_database_enq_cmd_noblock(wc, &cmd);
    return 0;
}

#define SQL_SELECT_ACLK_ACTIVE_LIST "SELECT REPLACE(SUBSTR(name,19),'_','-') FROM sqlite_schema " \
        "WHERE name LIKE 'aclk_chart_latest_%' AND type IN ('table');"

void sql_check_aclk_table_list(struct aclk_database_worker_config *wc)
{
    char *err_msg = NULL;
    debug(D_ACLK_SYNC,"Cleaning tables for nodes that do not exist");
    int rc = sqlite3_exec(db_meta, SQL_SELECT_ACLK_ACTIVE_LIST, sql_check_aclk_table, (void *) wc, &err_msg);
    if (rc != SQLITE_OK) {
        error_report("Query failed when trying to check for obsolete ACLK sync tables, %s", err_msg);
        sqlite3_free(err_msg);
    }
    db_execute("DELETE FROM dimension_delete WHERE host_id NOT IN (SELECT host_id FROM host) "
               " OR strftime('%s') - date_created > 604800;");
    return;
}

void aclk_data_rotated(void)
{
#ifdef ENABLE_NEW_CLOUD_PROTOCOL

    if (!aclk_use_new_cloud_arch || !aclk_connected)
        return;

    time_t next_rotation_time = now_realtime_sec()+ACLK_DATABASE_ROTATION_DELAY;
    rrd_rdlock();
    RRDHOST *this_host = localhost;
    while (this_host) {
        struct aclk_database_worker_config *wc = this_host->dbsync_worker;
        if (wc)
            wc->rotation_after = next_rotation_time;
        this_host = this_host->next;
    }
    rrd_unlock();

    struct aclk_database_worker_config *tmp = aclk_thread_head;

    uv_mutex_lock(&aclk_async_lock);
    while (tmp) {
        tmp->rotation_after = next_rotation_time;
        tmp = tmp->next;
    }
    uv_mutex_unlock(&aclk_async_lock);
#endif
    return;
}