gnu: curl: Graft performance fixes.

curl 8.20 has a bug which causes high cpu usage
when built with `enable-threaded-resolver`.

* gnu/packages/patches/curl-fix-wakeup-consumption.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/curl.scm (curl/fixed): New variable.
  (curl)[replacement]: Use it here.

Fixes: https://codeberg.org/guix/guix/issues/10284
Merges: https://codeberg.org/guix/guix/pulls/10330
Reviewed-by: Yelninei <yelninei@tutamail.com>
Signed-off-by: Nguyễn Gia Phong <cnx@loang.net>

3 files changed, 47 insertions, 0 deletions

diff --git a/gnu/local.mk b/gnu/local.mk
index d828205b7cd..96a95525d43 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1181,6 +1181,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/cups-relax-root-ownership-check.patch            \
   %D%/packages/patches/cura-engine-gcc-14.patch                 \
   %D%/packages/patches/curl-use-ssl-cert-env.patch              \
+  %D%/packages/patches/curl-fix-wakeup-consumption.patch        \
   %D%/packages/patches/curlftpfs-fix-error-closing-file.patch   \
   %D%/packages/patches/curlftpfs-fix-file-names.patch           \
   %D%/packages/patches/curlftpfs-fix-memory-leak.patch          \
diff --git a/gnu/packages/curl.scm b/gnu/packages/curl.scm
index 78ca03096a5..96fb6e9213a 100644
--- a/gnu/packages/curl.scm
+++ b/gnu/packages/curl.scm
@@ -69,6 +69,7 @@
   (package
     (name "curl")
     (version "8.20.0")
+    (replacement curl/fixed)
     (source (origin
               (method url-fetch)
               (uri (string-append "https://curl.se/download/curl-"
@@ -180,6 +181,16 @@ tunneling, and so on.")
     (license (license:non-copyleft "file://COPYING"
                                    "See COPYING in the distribution."))))
 
+(define-public curl/fixed
+  (package
+    (inherit curl)
+    (name "curl")
+    (version "8.20.0")
+    (source (origin
+              (inherit (package-source curl))
+              (patches (search-patches "curl-use-ssl-cert-env.patch"
+                                       "curl-fix-wakeup-consumption.patch"))))))
+
 (define-deprecated-package gnurl
   curl)
 
diff --git a/gnu/packages/patches/curl-fix-wakeup-consumption.patch b/gnu/packages/patches/curl-fix-wakeup-consumption.patch
new file mode 100644
index 00000000000..f84eb729727
--- /dev/null
+++ b/gnu/packages/patches/curl-fix-wakeup-consumption.patch
@@ -0,0 +1,35 @@
+From 2a2104f3cff44bb28bb570a093be52bbeeed8f23 Mon Sep 17 00:00:00 2001
+From: Stefan Eissing <stefan@eissing.org>
+Date: Mon, 11 May 2026 14:56:04 +0200
+Subject: [PATCH] event: fix wakeup consumption
+
+The events on a multi wakeup socketpair were only consumed via
+curl_multi_poll()/curl_multi_wait() but not in event based processing on
+a curl_multi_socket() call. That led to busy loops as reported in
+
+Fixes #21547
+Reported-by: Earnestly on github
+Closes #21549
+
+original report: https://github.com/curl/curl/issues/21547
+original pull request: https://github.com/curl/curl/pull/21549
+---
+ lib/multi.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/lib/multi.c b/lib/multi.c
+index be32740a7097..5e84133f13fd 100644
+--- a/lib/multi.c
++++ b/lib/multi.c
+@@ -2703,6 +2703,11 @@ static CURLMcode multi_runsingle(struct Curl_multi *multi,
+   Curl_uint32_bset_remove(&multi->dirty, data->mid);
+ 
+   if(data == multi->admin) {
++#ifdef ENABLE_WAKEUP
++    /* Consume any pending wakeup signals before processing.
++     * This is necessary for event based processing. See #21547 */
++    (void)Curl_wakeup_consume(multi->wakeup_pair, TRUE);
++#endif
+ #ifdef USE_RESOLV_THREADED
+     Curl_async_thrdd_multi_process(multi);
+ #endif