From f32506447fae80edf8987a2ef3264a29de33b998 Mon Sep 17 00:00:00 2001
From: Philipp Schuster <philipp.schuster@cyberus-technology.de>
Date: Thu, 9 Apr 2026 09:32:14 +0200
Subject: [PATCH] vmm: add helper to measure successful operation duration

Add a small helper that returns both the successful result of an
operation and the time it took to complete.

Subsequent migration instrumentation uses this to keep timing code
compact and consistent.

On-behalf-of: SAP philipp.schuster@sap.com
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
---
 vmm/src/lib.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/vmm/src/lib.rs b/vmm/src/lib.rs
index 92bf4c6b7..c64abac20 100644
--- a/vmm/src/lib.rs
+++ b/vmm/src/lib.rs
@@ -563,6 +563,17 @@ pub fn start_vmm_thread(
     })
 }
 
+/// Measures the time of the callback, in case it returns `Ok`.
+fn measure_ok<T, E, F>(f: F) -> result::Result<(T, Duration), E>
+where
+    F: FnOnce() -> result::Result<T, E>,
+{
+    let begin = Instant::now();
+    let value = f()?;
+    let duration = begin.elapsed();
+    Ok((value, duration))
+}
+
 #[derive(Clone, Deserialize, Serialize)]
 struct VmMigrationConfig {
     vm_config: Arc<Mutex<VmConfig>>,