functions to enter/exit implicit spans

src/core/collector.ml

@@ -31,6 +31,23 @@ module type S = sig
       to be efficient to implement in async contexts.
      @since 0.3 *)
 
+  val enter_span :
+    __FUNCTION__:string option ->
+    __FILE__:string ->
+    __LINE__:int ->
+    data:(string * user_data) list ->
+    string ->
+    span
+  (** Enter a new implicit span. For many uses cases, {!with_span} will
+      be easier to use.
+      @since NEXT_RELEASE *)
+
+  val exit_span : span -> unit
+  (** Exit span. This should be called on the same thread
+      as the corresponding {!enter_span}, and nest properly with
+      other calls to enter/exit_span and {!with_span}.
+      @since NEXT_RELEASE *)
+
   val enter_manual_span :
     parent:explicit_span option ->
     flavor:[ `Sync | `Async ] option ->

src/core/trace_core.ml

@@ -29,6 +29,19 @@ let[@inline] with_span ?__FUNCTION__ ~__FILE__ ~__LINE__ ?data name f =
     with_span_collector_ collector ?__FUNCTION__ ~__FILE__ ~__LINE__ ?data name
       f
 
+let[@inline] enter_span ?__FUNCTION__ ~__FILE__ ~__LINE__
+    ?(data = data_empty_build_) name : span =
+  match A.get collector with
+  | None -> Collector.dummy_span
+  | Some (module C) ->
+    let data = data () in
+    C.enter_span ~__FUNCTION__ ~__FILE__ ~__LINE__ ~data name
+
+let[@inline] exit_span sp : unit =
+  match A.get collector with
+  | None -> ()
+  | Some (module C) -> C.exit_span sp
+
 let enter_explicit_span_collector_ (module C : Collector.S) ~parent ~flavor
     ?__FUNCTION__ ~__FILE__ ~__LINE__ ?(data = data_empty_build_) name :
     explicit_span =

src/core/trace_core.mli

@@ -34,6 +34,16 @@ val with_span :
     see {!enter_manual_span}.
 *)
 
+val enter_span :
+  ?__FUNCTION__:string ->
+  __FILE__:string ->
+  __LINE__:int ->
+  ?data:(unit -> (string * user_data) list) ->
+  string ->
+  span
+
+val exit_span : span -> unit
+
 val add_data_to_span : span -> (string * user_data) list -> unit
 (** Add structured data to the given active span (see {!with_span}).
     Behavior is not specified if the span has been exited.

src/tef/trace_tef.ml

@@ -386,6 +386,19 @@ let collector ~out () : collector =
       else
         Thread.id (Thread.self ())
 
+    let enter_span ~__FUNCTION__:fun_name ~__FILE__:_ ~__LINE__:_ ~data name :
+        span =
+      let span = Int64.of_int (A.fetch_and_add span_id_gen_ 1) in
+      let tid = get_tid_ () in
+      let time_us = now_us () in
+      B_queue.push events
+        (E_define_span { tid; name; time_us; id = span; fun_name; data });
+      span
+
+    let exit_span span : unit =
+      let time_us = now_us () in
+      B_queue.push events (E_exit_span { id = span; time_us })
+
     let with_span ~__FUNCTION__:fun_name ~__FILE__:_ ~__LINE__:_ ~data name f =
       let span = Int64.of_int (A.fetch_and_add span_id_gen_ 1) in
       let tid = get_tid_ () in