From 40ea53a3e55ffe414912620484d0bea73af527ef Mon Sep 17 00:00:00 2001
From: Helmut Eller <eller.helmut@gmail.com>
Date: Tue, 16 Jul 2024 09:54:59 +0200
Subject: [PATCH 1/3] Add a igc--set-commit-limit function

* src/igc (Figc__set_commit_limit): New.
(mps_res_to_string): New helper.
(syms_of_igc): Register it.
* test/src/igc-tests.el (set-commit-limit-test): New.
---
 src/igc.c             | 35 +++++++++++++++++++++++++++++++++++
 test/src/igc-tests.el | 15 +++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/src/igc.c b/src/igc.c
index a74e62589a2..e29257650a8 100644
--- a/src/igc.c
+++ b/src/igc.c
@@ -4316,6 +4316,40 @@ igc_external_header (struct igc_header *h)
   return header_exthdr (h);
 }
 
+static const char *
+mps_res_to_string (mps_res_t res)
+{
+  switch (res)
+    {
+#define RES_CASE(prefix, id, doc)                                            \
+  case prefix##id:                                                           \
+    return #prefix #id " " doc;
+      _mps_RES_ENUM (RES_CASE, MPS_RES_);
+#undef RES_CASE
+    default:
+      return NULL;
+    }
+}
+
+DEFUN ("igc--set-commit-limit", Figc__set_commit_limit,
+       Sigc__set_commit_limit, 1, 1, 0, doc
+       : /* Set the arena commit limit to LIMIT.
+LIMIT can be an integer (number of bytes) or nil (no limit). */)
+(Lisp_Object limit)
+{
+  size_t nbytes
+      = NILP (limit) ? ~0 : check_uinteger_max (limit, SIZE_MAX - 1);
+  mps_res_t err = mps_arena_commit_limit_set (global_igc->arena, nbytes);
+  if (err != MPS_RES_OK)
+    {
+      const char *msg = mps_res_to_string (err);
+      xsignal3 (Qerror,
+		intern_c_string (Sigc__set_commit_limit.s.symbol_name),
+		make_fixnum (err), msg ? build_string (msg) : Qnil);
+    }
+  return Qnil;
+}
+
 static void
 make_arena (struct igc *gc)
 {
@@ -4853,6 +4887,7 @@ syms_of_igc (void)
   defsubr (&Sigc_info);
   defsubr (&Sigc__roots);
   defsubr (&Sigc__collect);
+  defsubr (&Sigc__set_commit_limit);
   defsubr (&Sigc__add_extra_dependency);
   defsubr (&Sigc__remove_extra_dependency);
   DEFSYM (Qambig, "ambig");
diff --git a/test/src/igc-tests.el b/test/src/igc-tests.el
index e69de29bb2d..59a0cb83909 100644
--- a/test/src/igc-tests.el
+++ b/test/src/igc-tests.el
@@ -0,0 +1,15 @@
+;;; igc-tests.el --- tests for src/igc.c -*- lexical-binding: t -*-
+
+(require 'ert)
+
+(ert-deftest set-commit-limit-test ()
+  (should (equal (igc--set-commit-limit (ash 1 30)) nil))
+  (should (equal (assoc-string "commit-limit" (igc-info))
+                 '("commit-limit" 1 1073741824 0)))
+  (should-error (igc--set-commit-limit -1)
+                :type 'args-out-of-range)
+  (should-error (igc--set-commit-limit (- (ash 1 64) 1))
+                :type 'args-out-of-range)
+  (should (equal (igc--set-commit-limit nil) nil))
+  (should (equal (assoc-string "commit-limit" (igc-info))
+                 '("commit-limit" 1 -1 0))))
-- 
2.39.2