summaryrefslogtreecommitdiffstats
path: root/daemon/commands.c
blob: 18468183f2e0173c48925e91fb8c9924fb92fbdb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
// SPDX-License-Identifier: GPL-3.0-or-later

#include "common.h"
#include "database/engine/rrdenginelib.h"

static uv_thread_t thread;
static uv_loop_t* loop;
static uv_async_t async;
static struct completion completion;
static uv_pipe_t server_pipe;

char cmd_prefix_by_status[] = {
        CMD_PREFIX_INFO,
        CMD_PREFIX_ERROR,
        CMD_PREFIX_ERROR
};

static int command_server_initialized = 0;
static int command_thread_error;
static int command_thread_shutdown;
static unsigned clients = 0;

struct command_context {
    /* embedded client pipe structure at address 0 */
    uv_pipe_t client;

    uv_work_t work;
    uv_write_t write_req;
    cmd_t idx;
    char *args;
    char *message;
    cmd_status_t status;
    char command_string[MAX_COMMAND_LENGTH];
    unsigned command_string_size;
};

/* Forward declarations */
static cmd_status_t cmd_help_execute(char *args, char **message);
static cmd_status_t cmd_reload_health_execute(char *args, char **message);
static cmd_status_t cmd_save_database_execute(char *args, char **message);
static cmd_status_t cmd_reopen_logs_execute(char *args, char **message);
static cmd_status_t cmd_exit_execute(char *args, char **message);
static cmd_status_t cmd_fatal_execute(char *args, char **message);
static cmd_status_t cmd_reload_claiming_state_execute(char *args, char **message);
static cmd_status_t cmd_reload_labels_execute(char *args, char **message);
static cmd_status_t cmd_read_config_execute(char *args, char **message);
static cmd_status_t cmd_write_config_execute(char *args, char **message);
static cmd_status_t cmd_ping_execute(char *args, char **message);
static cmd_status_t cmd_aclk_state(char *args, char **message);

static command_info_t command_info_array[] = {
        {"help", cmd_help_execute, CMD_TYPE_HIGH_PRIORITY},                  // show help menu
        {"reload-health", cmd_reload_health_execute, CMD_TYPE_ORTHOGONAL},   // reload health configuration
        {"save-database", cmd_save_database_execute, CMD_TYPE_ORTHOGONAL},   // save database for memory mode save
        {"reopen-logs", cmd_reopen_logs_execute, CMD_TYPE_ORTHOGONAL},       // Close and reopen log files
        {"shutdown-agent", cmd_exit_execute, CMD_TYPE_EXCLUSIVE},            // exit cleanly
        {"fatal-agent", cmd_fatal_execute, CMD_TYPE_HIGH_PRIORITY},          // exit with fatal error
        {"reload-claiming-state", cmd_reload_claiming_state_execute, CMD_TYPE_ORTHOGONAL}, // reload claiming state
        {"reload-labels", cmd_reload_labels_execute, CMD_TYPE_ORTHOGONAL},   // reload the labels
        {"read-config", cmd_read_config_execute, CMD_TYPE_CONCURRENT},
        {"write-config", cmd_write_config_execute, CMD_TYPE_ORTHOGONAL},
        {"ping", cmd_ping_execute, CMD_TYPE_ORTHOGONAL},
        {"aclk-state", cmd_aclk_state, CMD_TYPE_ORTHOGONAL}
};

/* Mutexes for commands of type CMD_TYPE_ORTHOGONAL */
static uv_mutex_t command_lock_array[CMD_TOTAL_COMMANDS];
/* Commands of type CMD_TYPE_EXCLUSIVE are writers */
static uv_rwlock_t exclusive_rwlock;
/*
 * Locking order:
 * 1. exclusive_rwlock
 * 2. command_lock_array[]
 */

/* Forward declarations */
static void cmd_lock_exclusive(unsigned index);
static void cmd_lock_orthogonal(unsigned index);
static void cmd_lock_idempotent(unsigned index);
static void cmd_lock_high_priority(unsigned index);

static command_lock_t *cmd_lock_by_type[] = {
        cmd_lock_exclusive,
        cmd_lock_orthogonal,
        cmd_lock_idempotent,
        cmd_lock_high_priority
};

/* Forward declarations */
static void cmd_unlock_exclusive(unsigned index);
static void cmd_unlock_orthogonal(unsigned index);
static void cmd_unlock_idempotent(unsigned index);
static void cmd_unlock_high_priority(unsigned index);

static command_lock_t *cmd_unlock_by_type[] = {
        cmd_unlock_exclusive,
        cmd_unlock_orthogonal,
        cmd_unlock_idempotent,
        cmd_unlock_high_priority
};

static cmd_status_t cmd_help_execute(char *args, char **message)
{
    (void)args;

    *message = mallocz(MAX_COMMAND_LENGTH);
    strncpyz(*message,
             "\nThe commands are (arguments are in brackets):\n"
             "help\n"
             "    Show this help menu.\n"
             "reload-health\n"
             "    Reload health configuration.\n"
             "reload-labels\n"
             "    Reload all labels.\n"
             "save-database\n"
             "    Save internal DB to disk for memory mode save.\n"
             "reopen-logs\n"
             "    Close and reopen log files.\n"
             "shutdown-agent\n"
             "    Cleanup and exit the netdata agent.\n"
             "fatal-agent\n"
             "    Log the state and halt the netdata agent.\n"
             "reload-claiming-state\n"
             "    Reload agent claiming state from disk.\n"
             "ping\n"
             "    Return with 'pong' if agent is alive.\n"
             "aclk-state [json]\n"
             "    Returns current state of ACLK and Cloud connection. (optionally in json)\n",
             MAX_COMMAND_LENGTH - 1);
    return CMD_STATUS_SUCCESS;
}

static cmd_status_t cmd_reload_health_execute(char *args, char **message)
{
    (void)args;
    (void)message;

    error_log_limit_unlimited();
    info("COMMAND: Reloading HEALTH configuration.");
    health_reload();
    error_log_limit_reset();

    return CMD_STATUS_SUCCESS;
}

static cmd_status_t cmd_save_database_execute(char *args, char **message)
{
    (void)args;
    (void)message;

    error_log_limit_unlimited();
    info("COMMAND: Saving databases.");
    rrdhost_save_all();
    info("COMMAND: Databases saved.");
    error_log_limit_reset();

    return CMD_STATUS_SUCCESS;
}

static cmd_status_t cmd_reopen_logs_execute(char *args, char **message)
{
    (void)args;
    (void)message;

    error_log_limit_unlimited();
    info("COMMAND: Reopening all log files.");
    reopen_all_log_files();
    error_log_limit_reset();

    return CMD_STATUS_SUCCESS;
}

static cmd_status_t cmd_exit_execute(char *args, char **message)
{
    (void)args;
    (void)message;

    error_log_limit_unlimited();
    info("COMMAND: Cleaning up to exit.");
    netdata_cleanup_and_exit(0);
    exit(0);

    return CMD_STATUS_SUCCESS;
}

static cmd_status_t cmd_fatal_execute(char *args, char **message)
{
    (void)args;
    (void)message;

    fatal("COMMAND: netdata now exits.");

    return CMD_STATUS_SUCCESS;
}

static cmd_status_t cmd_reload_claiming_state_execute(char *args, char **message)
{
    (void)args;
    (void)message;
#if defined(DISABLE_CLOUD) || !defined(ENABLE_ACLK)
    info("The claiming feature has been explicitly disabled");
    *message = strdupz("This agent cannot be claimed, it was built without support for Cloud");
    return CMD_STATUS_FAILURE;
#endif
    error_log_limit_unlimited();
    info("COMMAND: Reloading Agent Claiming configuration.");
    load_claiming_state();
    registry_update_cloud_base_url();
    rrdpush_claimed_id(localhost);
    error_log_limit_reset();
    return CMD_STATUS_SUCCESS;
}

static cmd_status_t cmd_reload_labels_execute(char *args, char **message)
{
    (void)args;
    info("COMMAND: reloading host labels.");
    reload_host_labels();

    BUFFER *wb = buffer_create(10);

    rrdhost_rdlock(localhost);
    netdata_rwlock_rdlock(&localhost->labels.labels_rwlock);
    struct label *l = localhost->labels.head;
    while (l != NULL) {
        buffer_sprintf(wb,"Label [source id=%s]: \"%s\" -> \"%s\"\n", translate_label_source(l->label_source), l->key, l->value);
        l = l->next;
    }
    netdata_rwlock_unlock(&localhost->labels.labels_rwlock);
    rrdhost_unlock(localhost);

    (*message)=strdupz(buffer_tostring(wb));
    buffer_free(wb);

    return CMD_STATUS_SUCCESS;
}

static cmd_status_t cmd_read_config_execute(char *args, char **message)
{
    size_t n = strlen(args);
    char *separator = strchr(args,'|');
    if (separator == NULL)
        return CMD_STATUS_FAILURE;
    char *separator2 = strchr(separator + 1,'|');
    if (separator2 == NULL)
        return CMD_STATUS_FAILURE;

    char *temp = callocz(n + 1, 1);
    strcpy(temp, args);
    size_t offset = separator - args;
    temp[offset] = 0;
    size_t offset2 = separator2 - args;
    temp[offset2] = 0;

    const char *conf_file = temp; /* "cloud" is cloud.conf, otherwise netdata.conf */
    struct config *tmp_config = strcmp(conf_file, "cloud") ? &netdata_config : &cloud_config;

    char *value = appconfig_get(tmp_config, temp + offset + 1, temp + offset2 + 1, NULL);
    if (value == NULL)
    {
        error("Cannot execute read-config conf_file=%s section=%s / key=%s because no value set", conf_file,
              temp + offset + 1, temp + offset2 + 1);
        freez(temp);
        return CMD_STATUS_FAILURE;
    }
    else
    {
        (*message) = strdupz(value);
        freez(temp);
        return CMD_STATUS_SUCCESS;
    }

}

static cmd_status_t cmd_write_config_execute(char *args, char **message)
{
    UNUSED(message);
    info("write-config %s", args);
    size_t n = strlen(args);
    char *separator = strchr(args,'|');
    if (separator == NULL)
        return CMD_STATUS_FAILURE;
    char *separator2 = strchr(separator + 1,'|');
    if (separator2 == NULL)
        return CMD_STATUS_FAILURE;
    char *separator3 = strchr(separator2 + 1,'|');
    if (separator3 == NULL)
        return CMD_STATUS_FAILURE;
    char *temp = callocz(n + 1, 1);
    strcpy(temp, args);
    size_t offset = separator - args;
    temp[offset] = 0;
    size_t offset2 = separator2 - args;
    temp[offset2] = 0;
    size_t offset3 = separator3 - args;
    temp[offset3] = 0;

    const char *conf_file = temp; /* "cloud" is cloud.conf, otherwise netdata.conf */
    struct config *tmp_config = strcmp(conf_file, "cloud") ? &netdata_config : &cloud_config;

    appconfig_set(tmp_config, temp + offset + 1, temp + offset2 + 1, temp + offset3 + 1);
    info("write-config conf_file=%s section=%s key=%s value=%s",conf_file, temp + offset + 1, temp + offset2 + 1,
         temp + offset3 + 1);
    freez(temp);
    return CMD_STATUS_SUCCESS;
}

static cmd_status_t cmd_ping_execute(char *args, char **message)
{
    (void)args;

    *message = strdupz("pong");

    return CMD_STATUS_SUCCESS;
}

static cmd_status_t cmd_aclk_state(char *args, char **message)
{
    info("COMMAND: Reopening aclk/cloud state.");
    if (strstr(args, "json"))
        *message = aclk_state_json();
    else
        *message = aclk_state();

    return CMD_STATUS_SUCCESS;
}

static void cmd_lock_exclusive(unsigned index)
{
    (void)index;

    uv_rwlock_wrlock(&exclusive_rwlock);
}

static void cmd_lock_orthogonal(unsigned index)
{
    uv_rwlock_rdlock(&exclusive_rwlock);
    uv_mutex_lock(&command_lock_array[index]);
}

static void cmd_lock_idempotent(unsigned index)
{
    (void)index;

    uv_rwlock_rdlock(&exclusive_rwlock);
}

static void cmd_lock_high_priority(unsigned index)
{
    (void)index;
}

static void cmd_unlock_exclusive(unsigned index)
{
    (void)index;

    uv_rwlock_wrunlock(&exclusive_rwlock);
}

static void cmd_unlock_orthogonal(unsigned index)
{
    uv_rwlock_rdunlock(&exclusive_rwlock);
    uv_mutex_unlock(&command_lock_array[index]);
}

static void cmd_unlock_idempotent(unsigned index)
{
    (void)index;

    uv_rwlock_rdunlock(&exclusive_rwlock);
}

static void cmd_unlock_high_priority(unsigned index)
{
    (void)index;
}

static void pipe_close_cb(uv_handle_t* handle)
{
    /* Also frees command context */
    freez(handle);
}

static void pipe_write_cb(uv_write_t* req, int status)
{
    (void)status;
    uv_pipe_t *client = req->data;

    uv_close((uv_handle_t *)client, pipe_close_cb);
    --clients;
    info("Command Clients = %u\n", clients);
}

static inline void add_char_to_command_reply(char *reply_string, unsigned *reply_string_size, char character)
{
    reply_string[(*reply_string_size)++] = character;
}

static inline void add_string_to_command_reply(char *reply_string, unsigned *reply_string_size, char *str)
{
    unsigned len;

    len = strlen(str);
    strncpyz(reply_string + *reply_string_size, str, len);
    *reply_string_size += len;
}

static void send_command_reply(struct command_context *cmd_ctx, cmd_status_t status, char *message)
{
    int ret;
    char reply_string[MAX_COMMAND_LENGTH] = {'\0', };
    char exit_status_string[MAX_EXIT_STATUS_LENGTH + 1] = {'\0', };
    unsigned reply_string_size = 0;
    uv_buf_t write_buf;
    uv_stream_t *client = (uv_stream_t *)(uv_pipe_t *)cmd_ctx;

    snprintfz(exit_status_string, MAX_EXIT_STATUS_LENGTH, "%u", status);
    add_char_to_command_reply(reply_string, &reply_string_size, CMD_PREFIX_EXIT_CODE);
    add_string_to_command_reply(reply_string, &reply_string_size, exit_status_string);
    add_char_to_command_reply(reply_string, &reply_string_size, '\0');

    if (message) {
        add_char_to_command_reply(reply_string, &reply_string_size, cmd_prefix_by_status[status]);
        add_string_to_command_reply(reply_string, &reply_string_size, message);
    }

    cmd_ctx->write_req.data = client;
    write_buf.base = reply_string;
    write_buf.len = reply_string_size;
    ret = uv_write(&cmd_ctx->write_req, (uv_stream_t *)client, &write_buf, 1, pipe_write_cb);
    if (ret) {
        error("uv_write(): %s", uv_strerror(ret));
    }
    info("COMMAND: Sending reply: \"%s\"", reply_string);
}

cmd_status_t execute_command(cmd_t idx, char *args, char **message)
{
    cmd_status_t status;
    cmd_type_t type = command_info_array[idx].type;

    cmd_lock_by_type[type](idx);
    status = command_info_array[idx].func(args, message);
    cmd_unlock_by_type[type](idx);

    return status;
}

static void after_schedule_command(uv_work_t *req, int status)
{
    struct command_context *cmd_ctx = req->data;

    (void)status;

    send_command_reply(cmd_ctx, cmd_ctx->status, cmd_ctx->message);
    if (cmd_ctx->message)
        freez(cmd_ctx->message);
}

static void schedule_command(uv_work_t *req)
{
    struct command_context *cmd_ctx = req->data;

    cmd_ctx->status = execute_command(cmd_ctx->idx, cmd_ctx->args, &cmd_ctx->message);
}

/* This will alter the state of the command_info_array.cmd_str
*/
static void parse_commands(struct command_context *cmd_ctx)
{
    char *message = NULL, *pos, *lstrip, *rstrip;
    cmd_t i;
    cmd_status_t status;

    status = CMD_STATUS_FAILURE;

    /* Skip white-space characters */
    for (pos = cmd_ctx->command_string ; isspace(*pos) && ('\0' != *pos) ; ++pos) {;}
    for (i = 0 ; i < CMD_TOTAL_COMMANDS ; ++i) {
        if (!strncmp(pos, command_info_array[i].cmd_str, strlen(command_info_array[i].cmd_str))) {
            if (CMD_EXIT == i) {
                /* musl C does not like libuv workqueues calling exit() */
                execute_command(CMD_EXIT, NULL, NULL);
            }
            for (lstrip=pos + strlen(command_info_array[i].cmd_str); isspace(*lstrip) && ('\0' != *lstrip); ++lstrip) {;}
            for (rstrip=lstrip+strlen(lstrip)-1; rstrip>lstrip && isspace(*rstrip); *(rstrip--) = 0 );

            cmd_ctx->work.data = cmd_ctx;
            cmd_ctx->idx = i;
            cmd_ctx->args = lstrip;
            cmd_ctx->message = NULL;

            fatal_assert(0 == uv_queue_work(loop, &cmd_ctx->work, schedule_command, after_schedule_command));
            break;
        }
    }
    if (CMD_TOTAL_COMMANDS == i) {
        /* no command found */
        message = strdupz("Illegal command. Please type \"help\" for instructions.");
        send_command_reply(cmd_ctx, status, message);
        freez(message);
    }
}

static void pipe_read_cb(uv_stream_t *client, ssize_t nread, const uv_buf_t *buf)
{
    struct command_context *cmd_ctx = (struct command_context *)client;

    if (0 == nread) {
        info("%s: Zero bytes read by command pipe.", __func__);
    } else if (UV_EOF == nread) {
        info("EOF found in command pipe.");
        parse_commands(cmd_ctx);
    } else if (nread < 0) {
        error("%s: %s", __func__, uv_strerror(nread));
    }

    if (nread < 0) { /* stop stream due to EOF or error */
        (void)uv_read_stop((uv_stream_t *)client);
    } else if (nread) {
        size_t to_copy;

        to_copy = MIN(nread, MAX_COMMAND_LENGTH - 1 - cmd_ctx->command_string_size);
        memcpy(cmd_ctx->command_string + cmd_ctx->command_string_size, buf->base, to_copy);
        cmd_ctx->command_string_size += to_copy;
        cmd_ctx->command_string[cmd_ctx->command_string_size] = '\0';
    }
    if (buf && buf->len) {
        freez(buf->base);
    }

    if (nread < 0 && UV_EOF != nread) {
        uv_close((uv_handle_t *)client, pipe_close_cb);
        --clients;
        info("Command Clients = %u\n", clients);
    }
}

static void alloc_cb(uv_handle_t *handle, size_t suggested_size, uv_buf_t *buf)
{
    (void)handle;

    buf->base = mallocz(suggested_size);
    buf->len = suggested_size;
}

static void connection_cb(uv_stream_t *server, int status)
{
    int ret;
    uv_pipe_t *client;
    struct command_context *cmd_ctx;
    fatal_assert(status == 0);

    /* combined allocation of client pipe and command context */
    cmd_ctx = mallocz(sizeof(*cmd_ctx));
    client = (uv_pipe_t *)cmd_ctx;
    ret = uv_pipe_init(server->loop, client, 1);
    if (ret) {
        error("uv_pipe_init(): %s", uv_strerror(ret));
        freez(cmd_ctx);
        return;
    }
    ret = uv_accept(server, (uv_stream_t *)client);
    if (ret) {
        error("uv_accept(): %s", uv_strerror(ret));
        uv_close((uv_handle_t *)client, pipe_close_cb);
        return;
    }

    ++clients;
    info("Command Clients = %u\n", clients);
    /* Start parsing a new command */
    cmd_ctx->command_string_size = 0;
    cmd_ctx->command_string[0] = '\0';

    ret = uv_read_start((uv_stream_t*)client, alloc_cb, pipe_read_cb);
    if (ret) {
        error("uv_read_start(): %s", uv_strerror(ret));
        uv_close((uv_handle_t *)client, pipe_close_cb);
        --clients;
        info("Command Clients = %u\n", clients);
        return;
    }
}

static void async_cb(uv_async_t *handle)
{
    uv_stop(handle->loop);
}

static void command_thread(void *arg)
{
    int ret;
    uv_fs_t req;

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

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

    ret = uv_pipe_init(loop, &server_pipe, 0);
    if (ret) {
        error("uv_pipe_init(): %s", uv_strerror(ret));
        command_thread_error = ret;
        goto error_after_pipe_init;
    }
    (void)uv_fs_unlink(loop, &req, PIPENAME, NULL);
    uv_fs_req_cleanup(&req);
    ret = uv_pipe_bind(&server_pipe, PIPENAME);
    if (ret) {
        error("uv_pipe_bind(): %s", uv_strerror(ret));
        command_thread_error = ret;
        goto error_after_pipe_bind;
    }
    ret = uv_listen((uv_stream_t *)&server_pipe, SOMAXCONN, connection_cb);
    if (ret) {
        /* Fallback to backlog of 1 */
        info("uv_listen() failed with backlog = %d, falling back to backlog = 1.", SOMAXCONN);
        ret = uv_listen((uv_stream_t *)&server_pipe, 1, connection_cb);
    }
    if (ret) {
        error("uv_listen(): %s", uv_strerror(ret));
        command_thread_error = ret;
        goto error_after_uv_listen;
    }

    command_thread_error = 0;
    command_thread_shutdown = 0;
    /* wake up initialization thread */
    complete(&completion);

    while (command_thread_shutdown == 0) {
        uv_run(loop, UV_RUN_DEFAULT);
    }
    /* cleanup operations of the event loop */
    info("Shutting down command event loop.");
    uv_close((uv_handle_t *)&async, NULL);
    uv_close((uv_handle_t*)&server_pipe, NULL);
    uv_run(loop, UV_RUN_DEFAULT); /* flush all libuv handles */

    info("Shutting down command loop complete.");
    fatal_assert(0 == uv_loop_close(loop));
    freez(loop);

    return;

error_after_uv_listen:
error_after_pipe_bind:
    uv_close((uv_handle_t*)&server_pipe, NULL);
error_after_pipe_init:
    uv_close((uv_handle_t *)&async, NULL);
error_after_async_init:
    uv_run(loop, UV_RUN_DEFAULT); /* flush all libuv handles */
    fatal_assert(0 == uv_loop_close(loop));
error_after_loop_init:
    freez(loop);

    /* wake up initialization thread */
    complete(&completion);
}

static void sanity_check(void)
{
    /* The size of command_info_array must be CMD_TOTAL_COMMANDS elements */
    BUILD_BUG_ON(CMD_TOTAL_COMMANDS != sizeof(command_info_array) / sizeof(command_info_array[0]));
}

void commands_init(void)
{
    cmd_t i;
    int error;

    sanity_check();
    if (command_server_initialized)
        return;

    info("Initializing command server.");
    for (i = 0 ; i < CMD_TOTAL_COMMANDS ; ++i) {
        fatal_assert(0 == uv_mutex_init(&command_lock_array[i]));
    }
    fatal_assert(0 == uv_rwlock_init(&exclusive_rwlock));

    init_completion(&completion);
    error = uv_thread_create(&thread, command_thread, NULL);
    if (error) {
        error("uv_thread_create(): %s", uv_strerror(error));
        goto after_error;
    }
    /* wait for worker thread to initialize */
    wait_for_completion(&completion);
    destroy_completion(&completion);
    uv_thread_set_name_np(thread, "DAEMON_COMMAND");

    if (command_thread_error) {
        error = uv_thread_join(&thread);
        if (error) {
            error("uv_thread_create(): %s", uv_strerror(error));
        }
        goto after_error;
    }

    command_server_initialized = 1;
    return;

after_error:
    error("Failed to initialize command server. The netdata cli tool will be unable to send commands.");
}

void commands_exit(void)
{
    cmd_t i;

    if (!command_server_initialized)
        return;

    command_thread_shutdown = 1;
    info("Shutting down command server.");
    /* wake up event loop */
    fatal_assert(0 == uv_async_send(&async));
    fatal_assert(0 == uv_thread_join(&thread));

    for (i = 0 ; i < CMD_TOTAL_COMMANDS ; ++i) {
        uv_mutex_destroy(&command_lock_array[i]);
    }
    uv_rwlock_destroy(&exclusive_rwlock);
    info("Command server has stopped.");
    command_server_initialized = 0;
}