perf: optimize OpamString.split

.github/workflows/ci.ml

@@ -333,6 +333,7 @@ let main_build_job ~analyse_job ~cygwin_job ?section runner start_version ~oc ~w
   let host = host_of_platform platform in
   job ~oc ~workflow ~runs_on:(Runner [runner]) ?shell ?section ~needs ~matrix ("Build-" ^ name_of_platform platform)
     ++ only_on Linux (run "Install bubblewrap" ["sudo apt install bubblewrap"])
+    ++ only_on Linux (run "Disable AppArmor" ["echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns"])
     ++ only_on Windows (git_lf_checkouts ~cond:(Predicate(true, EndsWith("matrix.host", "-pc-cygwin"))) ~shell:"cmd" ~title:"Configure LF checkout for Cygwin" ())
     ++ checkout ()
     ++ only_on Windows (cache ~cond:(Predicate(true, Compare("matrix.build", "x86_64-pc-cygwin"))) Cygwin)
@@ -384,6 +385,7 @@ let main_test_job ~analyse_job ~build_linux_job ~build_windows_job:_ ~build_macO
     ++ only_on MacOS (install_sys_packages ["coreutils"; "gpatch"] ~descr:"Install gnu coreutils" [MacOS])
     ++ checkout ()
     ++ only_on Linux (run "Install bubblewrap" ["sudo apt install bubblewrap"])
+    ++ only_on Linux (run "Disable AppArmor" ["echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns"])
     ++ cache Archives
     ++ cache OCaml platform ocamlv host
     ++ build_cache OCaml platform ocamlv host
@@ -402,6 +404,7 @@ let cold_job ~analyse_job ~build_linux_job ~build_windows_job ~build_macOS_job ?
   let needs = [analyse_job; (match platform with Linux -> build_linux_job | Windows -> build_windows_job | MacOS -> build_macOS_job)] in
   job ~oc ~workflow ?section ~runs_on:(Runner [runner]) ~env:[("OPAM_COLD", "1")] ~needs ("Cold-" ^ name_of_platform platform)
     ++ only_on Linux (run "Install bubblewrap" ["sudo apt install bubblewrap"])
+    ++ only_on Linux (run "Disable AppArmor" ["echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns"])
     ++ checkout ()
     ++ cache Archives
     ++ run "Cold" [
@@ -420,6 +423,7 @@ let doc_job ~analyse_job ~build_linux_job ~build_windows_job ~build_macOS_job ?s
   let ocamlv = "${{ matrix.ocamlv }}" in
   job ~oc ~workflow ?section ~runs_on:(Runner [platform]) ~env ~needs ~matrix ("Doc-" ^ name_of_platform platform)
     ++ only_on Linux (run "Install bubblewrap" ["sudo apt install bubblewrap"])
+    ++ only_on Linux (run "Disable AppArmor" ["echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns"])
     ++ run "Install man2html" ["sudo apt install man2html"]
     ++ checkout ()
     ++ cache Archives
@@ -444,6 +448,7 @@ let solvers_job ~analyse_job ~build_linux_job ~build_windows_job ~build_macOS_jo
   let ocamlv = "${{ matrix.ocamlv }}" in
   job ~oc ~workflow ?section ~runs_on:(Runner [runner]) ~env ~needs ~matrix ("Solvers-" ^ name_of_platform platform)
     ++ only_on Linux (run "Install bubblewrap" ["sudo apt install bubblewrap"])
+    ++ only_on Linux (run "Disable AppArmor" ["echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns"])
     ++ checkout ()
     ++ cache Archives
     ++ cache OCaml platform ocamlv host
@@ -463,6 +468,7 @@ let upgrade_job ~analyse_job ~build_linux_job ~build_windows_job ~build_macOS_jo
   let ocamlv = "${{ matrix.ocamlv }}" in
   job ~oc ~workflow ?section ~runs_on:(Runner [runner]) ~needs ~matrix ("Upgrade-" ^ name_of_platform platform)
     ++ only_on Linux (run "Install bubblewrap" ["sudo apt install bubblewrap"])
+    ++ only_on Linux (run "Disable AppArmor" ["echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns"])
     ++ checkout ()
     ++ cache Opam12Root
     ++ cache OCaml platform ocamlv host

.github/workflows/main.yml

@@ -111,6 +111,8 @@ jobs:
     steps:
     - name: Install bubblewrap
       run: sudo apt install bubblewrap
+    - name: Disable AppArmor
+      run: echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns
     - name: Checkout tree
       uses: actions/checkout@v4
     - name: src_ext/archives and opam-repository Cache
@@ -288,6 +290,8 @@ jobs:
       uses: actions/checkout@v4
     - name: Install bubblewrap
       run: sudo apt install bubblewrap
+    - name: Disable AppArmor
+      run: echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns
     - name: src_ext/archives and opam-repository Cache
       id: archives
       uses: actions/cache@v4
@@ -394,6 +398,8 @@ jobs:
     steps:
     - name: Install bubblewrap
       run: sudo apt install bubblewrap
+    - name: Disable AppArmor
+      run: echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns
     - name: Checkout tree
       uses: actions/checkout@v4
     - name: src_ext/archives and opam-repository Cache
@@ -427,6 +433,8 @@ jobs:
     steps:
     - name: Install bubblewrap
       run: sudo apt install bubblewrap
+    - name: Disable AppArmor
+      run: echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns
     - name: Install man2html
       run: sudo apt install man2html
     - name: Checkout tree
@@ -483,6 +491,8 @@ jobs:
     steps:
     - name: Install bubblewrap
       run: sudo apt install bubblewrap
+    - name: Disable AppArmor
+      run: echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns
     - name: Checkout tree
       uses: actions/checkout@v4
     - name: src_ext/archives and opam-repository Cache
@@ -576,6 +586,8 @@ jobs:
     steps:
     - name: Install bubblewrap
       run: sudo apt install bubblewrap
+    - name: Disable AppArmor
+      run: echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns
     - name: Checkout tree
       uses: actions/checkout@v4
     - name: opam 1.2 root Cache

master_changes.md

@@ -200,6 +200,7 @@ users)
   * `OpamFile.Repos_config.t`: change the type to not allow repositories without an URL [#6249 @kit-ty-kate]
 
 ## opam-core
+  * `OpamStd.List.split`: Improve performance [#6210 @kit-ty-kate]
   * `OpamStd.Sys.{get_terminal_columns,uname,getconf,guess_shell_compat}`: Harden the process calls to account for failures [#6230 @kit-ty-kate - fix #6215]
   * `OpamStd.Sys.getconf`: was removed, replaced by `get_long_bit` [#6217 @kit-ty-kate]
   * `OpamStd.Sys.get_long_bit`: was added, which returns the output of the `getconf LONG_BIT` command [#6217 @kit-ty-kate]

src/core/opamStd.ml

@@ -692,9 +692,25 @@ 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 i slice_start len s c =
+      if (i : int) < (len : int) then
+        if s.[i] = (c : char) then
+          let acc =
+            if (slice_start : int) < (i : int) then
+              String.sub s slice_start (i - slice_start) :: acc
+            else
+              acc
+          in
+          let i = i+1 in
+          loop acc i i len s c
+        else
+          loop acc (i+1) slice_start len s c
+      else if (i : int) = (slice_start : int) then
+        acc
+      else
+        String.sub s slice_start (len - slice_start) :: acc
+    in
+    List.rev (loop [] 0 0 (String.length s) s c)
 
   let split_delim s c =
     let tokens = Re.(split_full (compile (char c)) s) in
@@ -1160,9 +1176,9 @@ module OpamSys = struct
     | SH_fish ->
       Some (List.fold_left Filename.concat (home ".config") ["fish"; "config.fish"])
     | SH_zsh  ->
-      let zsh_home f = 
+      let zsh_home f =
         try Filename.concat (Env.get "ZDOTDIR") f
-        with Not_found -> home f in 
+        with Not_found -> home f in
       Some (zsh_home ".zshrc")
     | SH_bash ->
       let shell =