perf: optimize OpamString.split

master_changes.md

@@ -103,6 +103,7 @@ users)
 ## Test
 
 ## Benchmarks
+  * Add benchmarks for `opam show` [#6212 @kit-ty-kate]
 
 ## Reftests
 ### Tests

src/core/opamStd.ml

@@ -692,9 +692,27 @@ module OpamString = struct
   let rcut_at = cut_at_aux String.rindex
 
   let split s c =
-    (* old compat version (Re 1.2.0)
-       {[Re_str.split (Re_str.regexp (Printf.sprintf "[%c]+" c)) s]} *)
-    Re.(split (compile (rep1 (char c)))) s
+    let rec loop acc in_run slice_start len i s c =
+      if (i : int) < (len : int) then
+        if (String.get s i : char) = (c : char) then
+          if not in_run then
+            if (i : int) > (slice_start : int) then
+              loop (String.sub s slice_start (i - slice_start) :: acc)
+                true slice_start len (i + 1) s c
+            else
+              loop acc true slice_start len (i + 1) s c
+          else
+            loop acc in_run slice_start len (i + 1) s c
+        else if in_run then
+          loop acc false i len (i + 1) s c
+        else
+          loop acc in_run slice_start len (i + 1) s c
+      else if not in_run && (slice_start : int) < (len : int) then
+        String.sub s slice_start (len - slice_start) :: acc
+      else
+        acc
+    in
+    List.rev (loop [] false 0 (String.length s) 0 s c)
 
   let split_delim s c =
     let tokens = Re.(split_full (compile (char c)) s) in

tests/bench/bench.ml

@@ -99,6 +99,24 @@ let () =
     launch (fmt "%s switch create six --empty" bin);
     time_cmd ~exit:0 (fmt "%s list --installed --short --safe --color=never ocp-indent ocp-index merlin" bin)
   in
+  launch (fmt "%s switch create seven --empty" bin);
+  launch (fmt "%s install -y --fake dune" bin);
+  let time_show_installed =
+    Gc.compact ();
+    time_cmd ~exit:0 (fmt "%s show dune" bin)
+  in
+  let time_show_with_depexts =
+    Gc.compact ();
+    time_cmd ~exit:0 (fmt "%s show conf-pkg-config" bin)
+  in
+  let time_show_raw =
+    Gc.compact ();
+    time_cmd ~exit:0 (fmt "%s show --raw conf-pkg-config" bin)
+  in
+  let time_show_precise =
+    Gc.compact ();
+    time_cmd ~exit:0 (fmt "%s show --raw conf-pkg-config.2" bin)
+  in
   let json = fmt {|{
   "results": [
     {
@@ -148,6 +166,26 @@ let () =
           "name": "opam list --installed on non-installed packages",
           "value": %f,
           "units": "secs"
+        },
+        {
+          "name": "opam show of an installed package",
+          "value": %f,
+          "units": "secs"
+        },
+        {
+          "name": "opam show with depexts",
+          "value": %f,
+          "units": "secs"
+        },
+        {
+          "name": "opam show --raw pkgname",
+          "value": %f,
+          "units": "secs"
+        },
+        {
+          "name": "opam show --raw pkgname.version",
+          "value": %f,
+          "units": "secs"
         }
       ]
     },
@@ -172,6 +210,10 @@ let () =
       time_install_check_installed
       time_install_check_not_installed
       time_list_installed_noninstalled_packages
+      time_show_installed
+      time_show_with_depexts
+      time_show_raw
+      time_show_precise
       bin_size
   in
   print_endline json