Munin contributed plugins

/*

 * multicpu1sec C plugin

 */

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include <fcntl.h>

#include <time.h>

#include <sys/file.h>

#define PROC_STAT "/proc/stat"

int fail(char* msg) {

        perror(msg);

        return 1;

}

int config() {

        /* Get the number of CPU */

        int f;

        if ( !(f=open(PROC_STAT, O_RDONLY)) ) {

                return fail("cannot open " PROC_STAT);

        }

        // Starting with -1, since the first line is the "global cpu line"

        int ncpu = -1;

        const int buffer_size = 64 * 1024;

        char buffer[buffer_size];

        // whole /proc/stat can be read in 1 syscall

        if (read(f, buffer, buffer_size) <= 0) {

                return fail("cannot read " PROC_STAT);

        }

        // tokenization per-line

        char* line;

        char* newl = "\n";

        for (line = strtok(buffer, newl); line; line = strtok(NULL, newl)) {

                if (! strncmp(line, "cpu", 3)) ncpu ++;

        }

        close(f);

        printf(

                "graph_title multicpu1sec\n"

                "graph_category system::1sec\n"

                "graph_vlabel average cpu use %%\n"

                "graph_scale no\n"

                "graph_total All CPUs\n"

                "update_rate 1\n"

                "graph_data_size custom 1d, 10s for 1w, 1m for 1t, 5m for 1y\n"

        );

        int i;

        for (i = 0; i < ncpu; i++) {

                printf("cpu%d.label CPU %d\n", i, i);

                printf("cpu%d.draw %s\n", i, "AREASTACK");

                printf("cpu%d.type %s\n", i, "DERIVE");

                printf("cpu%d.min 0\n", i);

        }

        return 0;

}

char* pid_filename;

char* cache_filename;

/* Wait until the next second, and return the EPOCH */

time_t wait_until_next_second() {

        struct timespec tp;

        clock_gettime(CLOCK_REALTIME, &tp);

        time_t current_epoch = tp.tv_sec;

        long nsec_to_sleep = 1000*1000*1000 - tp.tv_nsec;

        /* Only sleep if needed */

        if (nsec_to_sleep > 0) {

                tp.tv_sec = 0;

                tp.tv_nsec = nsec_to_sleep;

                nanosleep(&tp, NULL);

        }

        return current_epoch + 1;

}

int acquire() {

        /* fork ourselves if not asked otherwise */

        char* no_fork = getenv("no_fork");

        if (! no_fork || strcmp("1", no_fork)) {

                if (fork()) return;

                // we are the child, complete the daemonization

                /* Close standard IO */

                fclose(stdin);

                fclose(stdout);

                fclose(stderr);

                /* create new session and process group */

                setsid();

        }

        /* write the pid */

        FILE* pid_file = fopen(pid_filename, "w");

        fprintf(pid_file, "%d\n", getpid());

        fclose(pid_file);

        /* Reading /proc/stat */

        int f = open(PROC_STAT, O_RDONLY);

        /* open the spoolfile */

        int cache_file = open(cache_filename, O_CREAT | O_APPEND | O_WRONLY);

        /* loop each second */

        while (1) {

                /* wait until next second */

                time_t epoch = wait_until_next_second();

                const int buffer_size = 64 * 1024;

                char buffer[buffer_size];

                if (lseek(f, 0, SEEK_SET) < 0) {

                        return fail("cannot seek " PROC_STAT);

                }

                // whole /proc/stat can be read in 1 syscall

                if (read(f, buffer, buffer_size) <= 0) {

                        return fail("cannot read " PROC_STAT);

                }

                // ignore the 1rst line

                char* line;

                const char* newl = "\n";

                line = strtok(buffer, newl);

                /* lock */

                flock(cache_file, LOCK_EX);

                for (line = strtok(NULL, newl); line; line = strtok(NULL, newl)) {

                        // Not on CPU lines anymore

                        if (strncmp(line, "cpu", 3)) break;

                        char cpu_id[64];

                        long usr, nice, sys, idle, iowait, irq, softirq;

                        sscanf(line, "%s %ld %ld %ld %ld %ld %ld %ld", cpu_id, &usr, &nice, &sys, &idle, &iowait, &irq, &softirq);

                        long used = usr + nice + sys + iowait + irq + softirq;

                        char out_buffer[1024];

                        sprintf(out_buffer, "%s.value %ld:%ld\n", cpu_id, epoch, used);

                        write(cache_file, out_buffer, strlen(out_buffer));

                }

                /* unlock */

                flock(cache_file, LOCK_UN);

        }

        close(cache_file);

        close(f);

        return 0;

}

int fetch() {

        FILE* cache_file = fopen(cache_filename, "r+");

        /* lock */

        flock(fileno(cache_file), LOCK_EX);

        /* cat the cache_file to stdout */

        char buffer[1024];

        while (fgets(buffer, 1024, cache_file)) {

                printf("%s", buffer);

        }

        ftruncate(fileno(cache_file), 0);

        fclose(cache_file);

        return 0;

}

int main(int argc, char **argv) {

        /* resolve paths */

        char *MUNIN_PLUGSTATE = getenv("MUNIN_PLUGSTATE");

        /* Default is current directory */

        if (! MUNIN_PLUGSTATE) MUNIN_PLUGSTATE = ".";

        size_t MUNIN_PLUGSTATE_length = strlen(MUNIN_PLUGSTATE);

        pid_filename = malloc(MUNIN_PLUGSTATE_length + strlen("/multicpu1sec.") + strlen("pid") + 1); pid_filename[0] = '\0';

        cache_filename = malloc(MUNIN_PLUGSTATE_length + strlen("/multicpu1sec.") + strlen("value") + 1); cache_filename[0] = '\0';

        strcat(pid_filename, MUNIN_PLUGSTATE);

        strcat(pid_filename, "/multicpu1sec.pid");

        strcat(cache_filename, MUNIN_PLUGSTATE);

        strcat(cache_filename, "/multicpu1sec.value");

        if (argc > 1) {

                char* first_arg = argv[1];

                if (! strcmp(first_arg, "config")) {

                        return config();

                }

                if (! strcmp(first_arg, "acquire")) {

                        return acquire();

                }

        }

        return fetch();

}