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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "collector.h"
#include "util.h"
// limits for CPU numbers
#define MAX_CPU_ID 9999999
#define MAX_CPU_DIGITS 7
// size of input buffer for reading lines
#define BUF_SIZE 256
static void *cpu_init(int argc, char *argv[]);
static void cpu_collect(scrape_req *req, void *ctx_ptr);
const struct collector cpu_collector = {
.name = "cpu",
.collect = cpu_collect,
.init = cpu_init,
};
struct cpu_context {
long clock_tick;
};
void *cpu_init(int argc, char *argv[]) {
(void) argc; (void) argv;
long clock_tick = sysconf(_SC_CLK_TCK);
if (clock_tick <= 0) {
perror("sysconf(_SC_CLK_TCK)");
return 0;
}
struct cpu_context *ctx = malloc(sizeof *ctx);
if (!ctx)
return 0;
ctx->clock_tick = clock_tick;
return ctx;
}
void cpu_collect(scrape_req *req, void *ctx_ptr) {
struct cpu_context *ctx = ctx_ptr;
// buffers
char cpu_label[MAX_CPU_DIGITS + 1] = "";
static const char *modes[] = {
"user", "nice", "system", "idle", "iowait", "irq", "softirq", "steal",
0,
};
const char *stat_labels[][2] = {
{ "cpu", cpu_label },
{ "mode", 0 }, // filled by code
{ 0, 0 },
};
const char *freq_labels[][2] = {
{ "cpu", cpu_label },
{ 0, 0 },
};
char buf[BUF_SIZE];
FILE *f;
// collect node_cpu_seconds_total metrics from /proc/stat
f = fopen("/proc/stat", "r");
if (f) {
while (fgets_line(buf, sizeof buf, f)) {
if (strncmp(buf, "cpu", 3) != 0 || (buf[3] < '0' || buf[3] > '9'))
continue;
char *at = buf + 3;
char *sep = strchr(at, ' ');
if (!sep || sep - at + 1 > (ptrdiff_t) sizeof cpu_label)
continue;
*sep = '\0';
strcpy(cpu_label, at);
at = sep + 1;
for (const char **mode = modes; *mode; mode++) {
while (*at == ' ')
at++;
sep = strpbrk(at, " \n");
if (!sep)
break;
*sep = '\0';
char *endptr;
double value = strtod(at, &endptr);
if (*endptr != '\0')
break;
value /= ctx->clock_tick;
stat_labels[1][1] = *mode;
scrape_write(req, "node_cpu_seconds_total", stat_labels, value);
at = sep + 1;
}
}
fclose(f);
}
// collect node_cpu_frequency_hertz metrics from /sys/devices/system/cpu/cpu*/cpufreq
for (int cpu = 0; cpu <= MAX_CPU_ID; cpu++) {
#define PATH_FORMAT "/sys/devices/system/cpu/cpu%d/cpufreq/scaling_cur_freq"
char path[sizeof PATH_FORMAT - 2 + MAX_CPU_DIGITS + 1];
snprintf(path, sizeof path, PATH_FORMAT, cpu);
f = fopen(path, "r");
if (!f)
break;
if (fgets(buf, sizeof buf, f)) {
char *endptr;
double value = strtod(buf, &endptr);
if (*endptr == '\0' || *endptr == '\n') {
value *= 1000;
snprintf(cpu_label, sizeof cpu_label, "%d", cpu);
scrape_write(req, "node_cpu_frequency_hertz", freq_labels, value);
}
}
fclose(f);
}
}
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