update

ts/smartmetrics.pidusage.ts

@@ -0,0 +1,117 @@
+import * as fs from 'fs';
+import { execSync } from 'child_process';
+
+// Cached system constants
+let clkTck: number | null = null;
+let pageSize: number | null = null;
+
+function getClkTck(): number {
+  if (clkTck === null) {
+    try {
+      clkTck = parseInt(execSync('getconf CLK_TCK', { encoding: 'utf8' }).trim(), 10);
+    } catch {
+      clkTck = 100; // standard Linux default
+    }
+  }
+  return clkTck;
+}
+
+function getPageSize(): number {
+  if (pageSize === null) {
+    try {
+      pageSize = parseInt(execSync('getconf PAGESIZE', { encoding: 'utf8' }).trim(), 10);
+    } catch {
+      pageSize = 4096; // standard Linux default
+    }
+  }
+  return pageSize;
+}
+
+// History for CPU delta tracking
+interface ISnapshot {
+  utime: number;
+  stime: number;
+  timestamp: number; // hrtime in seconds
+}
+
+const history = new Map<number, ISnapshot>();
+
+function readProcStat(pid: number): { utime: number; stime: number; rss: number } | null {
+  try {
+    const stat = fs.readFileSync(`/proc/${pid}/stat`, 'utf8');
+    // Format: pid (comm) state ppid ... fields
+    // utime is field 14, stime is field 15, rss is field 24 (1-indexed)
+    const closeParenIdx = stat.lastIndexOf(')');
+    if (closeParenIdx === -1) return null;
+    const afterComm = stat.slice(closeParenIdx + 2);
+    const fields = afterComm.split(' ');
+    // fields[0] = state (field 3), so utime = fields[11] (field 14), stime = fields[12] (field 15), rss = fields[21] (field 24)
+    const utime = parseInt(fields[11], 10);
+    const stime = parseInt(fields[12], 10);
+    const rss = parseInt(fields[21], 10);
+    return { utime, stime, rss };
+  } catch {
+    return null;
+  }
+}
+
+function hrtimeSeconds(): number {
+  const [sec, nsec] = process.hrtime();
+  return sec + nsec / 1e9;
+}
+
+export interface IPidUsageResult {
+  cpu: number;
+  memory: number;
+}
+
+/**
+ * Get CPU percentage and memory usage for the given PIDs.
+ * CPU% is calculated as a delta between successive calls.
+ */
+export async function getPidUsage(
+  pids: number[]
+): Promise<Record<number, IPidUsageResult>> {
+  const tck = getClkTck();
+  const ps = getPageSize();
+  const result: Record<number, IPidUsageResult> = {};
+
+  for (const pid of pids) {
+    const stat = readProcStat(pid);
+    if (!stat) {
+      continue;
+    }
+
+    const now = hrtimeSeconds();
+    const totalTicks = stat.utime + stat.stime;
+    const memoryBytes = stat.rss * ps;
+
+    const prev = history.get(pid);
+    if (prev) {
+      const elapsedSeconds = now - prev.timestamp;
+      const ticksDelta = totalTicks - (prev.utime + prev.stime);
+      const cpuSeconds = ticksDelta / tck;
+      const cpuPercent = elapsedSeconds > 0 ? (cpuSeconds / elapsedSeconds) * 100 : 0;
+
+      result[pid] = {
+        cpu: cpuPercent,
+        memory: memoryBytes,
+      };
+    } else {
+      // First call for this PID — no delta available, report 0% cpu
+      result[pid] = {
+        cpu: 0,
+        memory: memoryBytes,
+      };
+    }
+
+    // Update history
+    history.set(pid, {
+      utime: stat.utime,
+      stime: stat.stime,
+      timestamp: now,
+    });
+  }
+
+  return result;
+}