Merge pull request #4393 from sgoll/4392-transaction-instrumentation

Generate `InstrumentationEvent::BeginTransaction` for custom transaction SQL

CHANGELOG.md

@@ -23,6 +23,7 @@ Increasing the minimal supported Rust version will always be coupled at least wi
 in a way that makes the pools suitable for use in parallel tests.
 * Added `Json` and `Jsonb` support for the SQLite backend.
 * Fixed diesel thinking `a.eq_any(b)` was non-nullable even if `a` and `b` were nullable.
+* Generate `InstrumentationEvent::BeginTransaction` for immediate and exclusive transactions in SQLite
 
 ### Fixed
 

diesel/src/connection/transaction_manager.rs

@@ -316,15 +316,22 @@ impl AnsiTransactionManager {
         Conn: Connection<TransactionManager = Self>,
     {
         let state = Self::get_transaction_state(conn)?;
-        match state.transaction_depth() {
-            None => {
-                conn.batch_execute(sql)?;
-                Self::get_transaction_state(conn)?
-                    .change_transaction_depth(TransactionDepthChange::IncreaseDepth)?;
-                Ok(())
-            }
-            Some(_depth) => Err(Error::AlreadyInTransaction),
+        if let Some(_depth) = state.transaction_depth() {
+            return Err(Error::AlreadyInTransaction);
         }
+        let instrumentation_depth = NonZeroU32::new(1);
+        // Keep remainder of this method in sync with `begin_transaction()`.
+
+        conn.instrumentation().on_connection_event(
+            super::instrumentation::InstrumentationEvent::BeginTransaction {
+                depth: instrumentation_depth.expect("We know that 1 is not zero"),
+            },
+        );
+        conn.batch_execute(sql)?;
+        Self::get_transaction_state(conn)?
+            .change_transaction_depth(TransactionDepthChange::IncreaseDepth)?;
+
+        Ok(())
     }
 }
 
@@ -343,15 +350,17 @@ where
                 Cow::from(format!("SAVEPOINT diesel_savepoint_{transaction_depth}"))
             }
         };
+        let instrumentation_depth =
+            NonZeroU32::new(transaction_depth.map_or(0, NonZeroU32::get).wrapping_add(1));
+        let sql = &start_transaction_sql;
+        // Keep remainder of this method in sync with `begin_transaction_sql()`.
+
         conn.instrumentation().on_connection_event(
             super::instrumentation::InstrumentationEvent::BeginTransaction {
-                depth: NonZeroU32::new(
-                    transaction_depth.map_or(0, NonZeroU32::get).wrapping_add(1),
-                )
-                .expect("Transaction depth is too large"),
+                depth: instrumentation_depth.expect("Transaction depth is too large"),
             },
         );
-        conn.batch_execute(&start_transaction_sql)?;
+        conn.batch_execute(sql)?;
         Self::get_transaction_state(conn)?
             .change_transaction_depth(TransactionDepthChange::IncreaseDepth)?;