CP-51209: add hooks lock_acquired/released for bpftrace

Signed-off-by: Marcus Granado <[email protected]>

ocaml/database/db_lock.ml

@@ -79,6 +79,10 @@ module ReentrantLock : REENTRANT_LOCK = struct
 
   let current_tid () = Thread.(self () |> id)
 
+  let [@inline never][@specialize never] lock_acquired () = ()
+
+  let [@inline never][@specialize never] lock_released () = ()
+
   let lock l =
     let me = current_tid () in
     match Atomic.get l.holder with
@@ -91,6 +95,7 @@ module ReentrantLock : REENTRANT_LOCK = struct
         while not (Atomic.compare_and_set l.holder None intended) do
           Condition.wait l.condition l.lock
         done ;
+        lock_acquired ();
         let stats = l.statistics in
         let delta = Clock.Timer.span_to_s (Mtime_clock.count counter) in
         stats.total_time <- stats.total_time +. delta ;
@@ -109,7 +114,8 @@ module ReentrantLock : REENTRANT_LOCK = struct
           let () = Atomic.set l.holder None in
           Mutex.lock l.lock ;
           Condition.signal l.condition ;
-          Mutex.unlock l.lock
+          Mutex.unlock l.lock;
+          lock_released ();
         )
     | _ ->
         failwith