chore(tinybench): emit benchmark markers

Author: not-matthias

packages/tinybench-plugin/src/walltime.ts

@@ -1,5 +1,8 @@
 import {
   calculateQuantiles,
+  InstrumentHooks,
+  MARKER_TYPE_BENCHMARK_END,
+  MARKER_TYPE_BENCHMARK_START,
   mongoMeasurement,
   msToNs,
   msToS,
@@ -64,17 +67,31 @@ class WalltimeBenchRunner extends BaseBenchRunner {
 
   private wrapTaskFunction(task: Task, isAsync: boolean): void {
     const { fn } = task as unknown as { fn: Fn };
+    const pid = process.pid;
+
+    // Emit per-round markers so the walltime instrument can bracket the actual
+    // benchmark body (excluding the harness) when attributing perf samples.
+    const finishRound = (roundStart: bigint): void => {
+      const roundEnd = InstrumentHooks.currentTimestamp();
+      InstrumentHooks.addMarker(pid, MARKER_TYPE_BENCHMARK_START, roundStart);
+      InstrumentHooks.addMarker(pid, MARKER_TYPE_BENCHMARK_END, roundEnd);
+    };
+
     if (isAsync) {
       // eslint-disable-next-line no-inner-declarations
       async function __codspeed_root_frame__() {
+        const roundStart = InstrumentHooks.currentTimestamp();
         await fn();
+        finishRound(roundStart);
       }
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
       (task as any).fn = __codspeed_root_frame__;
     } else {
       // eslint-disable-next-line no-inner-declarations
       function __codspeed_root_frame__() {
+        const roundStart = InstrumentHooks.currentTimestamp();
         fn();
+        finishRound(roundStart);
       }
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
       (task as any).fn = __codspeed_root_frame__;