Re: add pthread_set_name_np support

[Timo Myyrä]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: timo.myyra@bittivirhe.fi (Timo Myyrä)
>> Date: Sat, 27 Jun 2020 13:49:24 +0300
>> 
>> While browsing the emacs code I noticed that pthread_set_name_np is not
>> supported by emacs currently. Here's simple diff to add it.
>> I'm not that well versed in autoconf, probably should check 
>> pthread_set_name_np
>> within the pthread_setname_np block so both won't get enabled at the same 
>> time.
>> 
>> Also I'm not sure if name should be padded, quickly looking OpenBSD sources
>> didn't indicate that padding would be required. LLVM code base seems to pad 
>> name
>> argument to max 16 chars on FreeBSD and 32 on OpenBSD.
>> 
>> Thoughts?
>
> Thanks, we already have support for pthread_setname_np in what is soon
> going to be released as Emacs 27.1.  Please take a look at the
> emacs-27 branch of the Emacs Git repository.

Hi,

OpenBSD and seems that FreeBSD don't have pthread_setname_np, they use
pthread_set_name_np instead.

But I got feedback that previous diff had typos so here is a better diff.
I included the padding of max process name though it doesn't seem necessary on 
OpenBSD.


Timo


diff --git a/configure.ac b/configure.ac
index b1b8c846e1..f198894e02 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4187,7 +4187,8 @@ AC_DEFUN
 sendto recvfrom getsockname getifaddrs freeifaddrs \
 gai_strerror sync \
 getpwent endpwent getgrent endgrent \
-cfmakeraw cfsetspeed __executable_start log2 pthread_setname_np)
+cfmakeraw cfsetspeed __executable_start log2 pthread_setname_np \
+pthread_set_name_np)
 LIBS=$OLD_LIBS
 
 if test "$ac_cv_func_pthread_setname_np" = "yes"; then
@@ -4222,6 +4223,23 @@ AC_DEFUN
   fi
 fi
 
+if test "$ac_cv_func_pthread_set_name_np" = "yes"; then
+  AC_CACHE_CHECK(
+   [whether pthread_set_name_np is supported],
+   [emacs_cv_pthread_set_name_np],
+   [AC_COMPILE_IFELSE(
+     [AC_LANG_PROGRAM(
+       [[#include <pthread.h>][#include <pthread_np.h>]],
+       [[pthread_setname_np (1, "a");]])],
+     [emacs_cv_pthread_set_name_np=yes],
+     [emacs_cv_pthread_set_name_np=no])])
+  if test "$emacs_cv_pthread_set_name_np" = "yes"; then
+    AC_DEFINE(
+      HAVE_PTHREAD_SET_NAME_NP, 1,
+      [Define to 1 if pthread_set_name_np is supported.])
+  fi
+fi
+
 dnl No need to check for posix_memalign if aligned_alloc works.
 AC_CHECK_FUNCS([aligned_alloc posix_memalign], [break])
 AC_CHECK_DECLS([aligned_alloc], [], [], [[#include <stdlib.h>]])
diff --git a/src/systhread.c b/src/systhread.c
index 0d600d6895..57005bacc3 100644
--- a/src/systhread.c
+++ b/src/systhread.c
@@ -26,6 +26,10 @@ Copyright (C) 2012-2020 Free Software Foundation, Inc.
 #include "nsterm.h"
 #endif
 
+#ifdef HAVE_PTHREAD_SET_NAME_NP
+#include <pthread_np.h>
+#endif
+
 #ifndef THREADS_ENABLED
 
 void
@@ -206,7 +210,7 @@ sys_thread_equal (sys_thread_t t, sys_thread_t u)
 void
 sys_thread_set_name (const char *name)
 {
-#ifdef HAVE_PTHREAD_SETNAME_NP
+#if defined HAVE_PTHREAD_SETNAME_NP || defined HAVE_PTHREAD_SET_NAME_NP
   /* We need to truncate here otherwise pthread_setname_np
      fails to set the name.  TASK_COMM_LEN is what the length
      is called in the Linux kernel headers (Bug#38632).  */
@@ -218,10 +222,13 @@ #define TASK_COMM_LEN 16
   pthread_setname_np (p_name);
 # elif defined HAVE_PTHREAD_SETNAME_NP_3ARG
   pthread_setname_np (pthread_self (), "%s", p_name);
+# elif HAVE_PTHREAD_SET_NAME_NP
+  pthread_set_name_np (pthread_self (), p_name);
 # else
   pthread_setname_np (pthread_self (), p_name);
 # endif
 #endif
+
 }
 
 bool