From de26ef5c51740e2ee6ba2e087a843400edcf8329 Mon Sep 17 00:00:00 2001
From: Leah Neukirchen <leah@vuxu.org>
Date: Thu, 23 May 2024 20:40:42 +0200
Subject: add vmstat collector

---
 vmstat.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 vmstat.c

(limited to 'vmstat.c')

diff --git a/vmstat.c b/vmstat.c
new file mode 100644
index 0000000..3e21b0f
--- /dev/null
+++ b/vmstat.c
@@ -0,0 +1,64 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "scrape.h"
+#include "util.h"
+
+// size of input buffer for paths and lines
+#define BUF_SIZE 256
+
+static void vmstat_collect(scrape_req *req, void *ctx);
+
+const struct collector vmstat_collector = {
+  .name = "vmstat",
+  .collect = vmstat_collect,
+};
+
+static const struct {
+  const char *name;
+  const char *key;
+  unsigned key_len;
+} metrics[] = {
+  { .name = "node_vmstat_oom_kill", .key = "oom_kill ", .key_len = 9 },
+  { .name = "node_vmstat_pgfault",  .key = "pgfault ", .key_len = 8 },
+  { .name = "node_vmstat_pgmajfault",  .key = "pgmajfault ", .key_len = 11 },
+  { .name = "node_vmstat_pgpgin", .key = "pgpgin ", .key_len = 7 },
+  { .name = "node_vmstat_pgpgout", .key = "pgpgout ", .key_len = 8 },
+  { .name = "node_vmstat_pswpin", .key = "pswpin ", .key_len = 7 },
+  { .name = "node_vmstat_pswpout", .key = "pswpout ", .key_len = 8 },
+};
+#define NMETRICS (sizeof metrics / sizeof *metrics)
+
+static void vmstat_collect(scrape_req *req, void *ctx) {
+  (void) ctx;
+
+  // buffers
+
+  char buf[BUF_SIZE];
+
+  FILE *f;
+
+  // scan /proc/stat for metrics
+
+  f = fopen(PATH("/proc/vmstat"), "r");
+  if (!f)
+    return;
+
+  while (fgets_line(buf, sizeof buf, f)) {
+    for (size_t m = 0; m < NMETRICS; m++) {
+      if (strncmp(buf, metrics[m].key, metrics[m].key_len) != 0)
+        continue;
+
+      char *end;
+      double d = strtod(buf + metrics[m].key_len, &end);
+      if (*end != '\0' && *end != ' ' && *end != '\n')
+        continue;
+
+      scrape_write(req, metrics[m].name, 0, d);
+      break;
+    }
+  }
+
+  fclose(f);
+}
-- 
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