Throw in some DTrace probes

nexus/db-queries/src/db/datastore/vpc.rs

@@ -302,6 +302,10 @@ impl DataStore {
         let vnis = VniSearchIter::new(vpc.vni.0);
         for (i, vni) in vnis.enumerate() {
             vpc.vni = Vni(vni);
+            let id = usdt::UniqueId::new();
+            crate::probes::vni__search__range__start!(|| {
+                (&id, u32::from(vni), VniSearchIter::STEP_SIZE)
+            });
             match self
                 .project_create_vpc_raw(
                     opctx,
@@ -310,9 +314,15 @@ impl DataStore {
                 )
                 .await
             {
-                Ok(Some(vpcs)) => return Ok(vpcs),
+                Ok(Some((authz_vpc, vpc))) => {
+                    crate::probes::vni__search__range__found!(|| {
+                        (&id, u32::from(vpc.vni.0))
+                    });
+                    return Ok((authz_vpc, vpc));
+                }
                 Err(e) => return Err(e),
                 Ok(None) => {
+                    crate::probes::vni__search__range__empty!(|| (&id));
                     debug!(
                         opctx.log,
                         "No VNIs available within current search range, retrying";
@@ -1172,6 +1182,7 @@ mod tests {
     // `project_create_vpc_raw` call.
     #[tokio::test]
     async fn test_project_create_vpc_raw_returns_none_on_vni_exhaustion() {
+        usdt::register_probes().unwrap();
         let logctx = dev::test_setup_log(
             "test_project_create_vpc_raw_returns_none_on_vni_exhaustion",
         );
@@ -1277,6 +1288,7 @@ mod tests {
     // and then check that we correctly retry
     #[tokio::test]
     async fn test_project_create_vpc_retries() {
+        usdt::register_probes().unwrap();
         let logctx = dev::test_setup_log("test_project_create_vpc_retries");
         let log = &logctx.log;
         let mut db = test_setup_database(&logctx.log).await;

nexus/db-queries/src/db/queries/vpc.rs

@@ -344,6 +344,8 @@ pub struct VniSearchIter {
 }
 
 impl VniSearchIter {
+    pub const STEP_SIZE: u32 = MAX_VNI_SEARCH_RANGE_SIZE;
+
     /// Create a search range, starting from the provided VNI.
     pub fn new(start: external::Vni) -> Self {
         let start = u32::from(start);

nexus/db-queries/src/lib.rs

@@ -17,3 +17,17 @@ extern crate newtype_derive;
 #[cfg(test)]
 #[macro_use]
 extern crate diesel;
+
+#[usdt::provider(provider = "nexus__db__queries")]
+mod probes {
+    // Fires before we start a search over a range for a VNI.
+    //
+    // Includes the starting VNI and the size of the range being searched.
+    fn vni__search__range__start(_: &usdt::UniqueId, start_vni: u32, size: u32) {}
+
+    // Fires when we successfully find a VNI.
+    fn vni__search__range__found(_: &usdt::UniqueId, vni: u32) {}
+
+    // Fires when we fail to find a VNI in the provided range.
+    fn vni__search__range__empty(_: &usdt::UniqueId) {}
+}