Adds new connections_created statistic

With the new `connections_created` statistic users can know how many
connections have been created by the pool.

Author: pfreixes

bb8/src/api.rs

@@ -101,6 +101,8 @@ pub struct Statistics {
     pub get_timed_out: u64,
     /// Total time accumulated waiting for a connection.
     pub get_wait_time: Duration,
+    /// Total connections created.
+    pub connections_created: u64,
     /// Total connections that were closed due to be in broken state.
     pub connections_closed_broken: u64,
     /// Total connections that were closed due to be considered invalid.

bb8/src/inner.rs

@@ -196,6 +196,7 @@ where
                         .internals
                         .lock()
                         .put(conn, Some(approval), self.inner.clone());
+                    self.inner.statistics.record(StatsKind::Created);
                     return Ok(());
                 }
                 Err(e) => {

bb8/src/internals.rs

@@ -272,6 +272,7 @@ pub(crate) struct AtomicStatistics {
     pub(crate) get_waited: AtomicU64,
     pub(crate) get_timed_out: AtomicU64,
     pub(crate) get_wait_time_micros: AtomicU64,
+    pub(crate) connections_created: AtomicU64,
     pub(crate) connections_closed_broken: AtomicU64,
     pub(crate) connections_closed_invalid: AtomicU64,
     pub(crate) connections_closed_max_lifetime: AtomicU64,
@@ -295,6 +296,7 @@ impl AtomicStatistics {
 
     pub(crate) fn record(&self, kind: StatsKind) {
         match kind {
+            StatsKind::Created => &self.connections_created,
             StatsKind::ClosedBroken => &self.connections_closed_broken,
             StatsKind::ClosedInvalid => &self.connections_closed_invalid,
         }
@@ -320,6 +322,7 @@ impl From<&AtomicStatistics> for Statistics {
             get_waited: item.get_waited.load(Ordering::SeqCst),
             get_timed_out: item.get_timed_out.load(Ordering::SeqCst),
             get_wait_time: Duration::from_micros(item.get_wait_time_micros.load(Ordering::SeqCst)),
+            connections_created: item.connections_created.load(Ordering::SeqCst),
             connections_closed_broken: item.connections_closed_broken.load(Ordering::SeqCst),
             connections_closed_invalid: item.connections_closed_invalid.load(Ordering::SeqCst),
             connections_closed_max_lifetime: item
@@ -339,6 +342,7 @@ pub(crate) enum StatsGetKind {
 }
 
 pub(crate) enum StatsKind {
+    Created,
     ClosedBroken,
     ClosedInvalid,
 }

bb8/tests/test.rs

@@ -992,3 +992,23 @@ async fn test_state_get_contention() {
     assert_eq!(statistics.get_waited, 1);
     assert!(statistics.get_wait_time > Duration::from_micros(0));
 }
+
+#[tokio::test]
+async fn test_statistics_connections_created() {
+    let pool = Pool::builder()
+        .max_size(1)
+        .min_idle(1)
+        .build(OkManager::<FakeConnection>::new())
+        .await
+        .unwrap();
+    let (tx1, rx1) = oneshot::channel();
+    let clone = pool.clone();
+    tokio::spawn(async move {
+        let _ = clone.get().await.unwrap();
+        tx1.send(()).unwrap();
+    });
+    // wait until finished.
+    rx1.await.unwrap();
+
+    assert_eq!(pool.state().statistics.connections_created, 1);
+}