Don't use an arbitrary bound in histograms

I hit this trying to figure out how an mostly idle server was
reporting that no connection was idle for more than 30s.

Author: espindola

src/conn/mod.rs

@@ -1450,21 +1450,20 @@ mod test {
 
             let _ = conn.query_drop("DROP USER 'test_user'@'%'").await;
 
-            let query = format!("CREATE USER 'test_user'@'%' IDENTIFIED WITH {}", plug);
+            let query = format!("CREATE USER 'test_user'@'%' IDENTIFIED WITH {plug}");
             conn.query_drop(query).await.unwrap();
 
             if conn.inner.version < (8, 0, 11) {
-                conn.query_drop(format!("SET old_passwords = {}", val))
+                conn.query_drop(format!("SET old_passwords = {val}"))
                     .await
                     .unwrap();
                 conn.query_drop(format!(
-                    "SET PASSWORD FOR 'test_user'@'%' = PASSWORD('{}')",
-                    pass
+                    "SET PASSWORD FOR 'test_user'@'%' = PASSWORD('{pass}')"
                 ))
                 .await
                 .unwrap();
             } else {
-                conn.query_drop(format!("SET PASSWORD FOR 'test_user'@'%' = '{}'", pass))
+                conn.query_drop(format!("SET PASSWORD FOR 'test_user'@'%' = '{pass}'"))
                     .await
                     .unwrap();
             };
@@ -1481,11 +1480,11 @@ mod test {
         }
 
         if crate::test_misc::test_compression() {
-            assert!(format!("{:?}", conn).contains("Compression"));
+            assert!(format!("{conn:?}").contains("Compression"));
         }
 
         if crate::test_misc::test_ssl() {
-            assert!(format!("{:?}", conn).contains("Tls"));
+            assert!(format!("{conn:?}").contains("Tls"));
         }
 
         conn.disconnect().await?;
@@ -1781,9 +1780,8 @@ mod test {
         let mut conn = Conn::new(get_opts()).await?;
         for x in (MAX_PAYLOAD_LEN - 2)..=(MAX_PAYLOAD_LEN + 2) {
             let long_string = "A".repeat(x);
-            let result: Vec<(String, u8)> = conn
-                .query(format!(r"SELECT '{}', 231", long_string))
-                .await?;
+            let result: Vec<(String, u8)> =
+                conn.query(format!(r"SELECT '{long_string}', 231")).await?;
             assert_eq!((long_string, 231_u8), result[0]);
         }
         conn.disconnect().await?;
@@ -2318,7 +2316,7 @@ mod test {
             .tcp_port(listen_addr.port());
         let server_err = match Conn::new(opts).await {
             Err(Error::Server(server_err)) => server_err,
-            other => panic!("expected server error but got: {:?}", other),
+            other => panic!("expected server error but got: {other:?}"),
         };
         assert_eq!(
             server_err,

src/conn/pool/metrics.rs

@@ -68,7 +68,7 @@ impl MetricsHistogram {
 #[cfg(feature = "hdrhistogram")]
 impl Default for MetricsHistogram {
     fn default() -> Self {
-        let hdr = hdrhistogram::Histogram::new_with_bounds(1, 30 * 1_000_000, 2).unwrap();
+        let hdr = hdrhistogram::Histogram::new(2).unwrap();
         Self(std::sync::Mutex::new(hdr))
     }
 }

src/conn/pool/mod.rs

@@ -627,7 +627,7 @@ mod test {
 
             // now we'll kill connections..
             for id in ids {
-                master.query_drop(format!("KILL {}", id)).await?;
+                master.query_drop(format!("KILL {id}")).await?;
             }
 
             // now check, that they're still in the pool..

src/queryable/transaction.rs

@@ -154,7 +154,7 @@ impl<'a> Transaction<'a> {
         }
 
         if let Some(isolation_level) = isolation_level {
-            let query = format!("SET TRANSACTION ISOLATION LEVEL {}", isolation_level);
+            let query = format!("SET TRANSACTION ISOLATION LEVEL {isolation_level}");
             conn.as_mut().query_drop(query).await?;
         }