Commit Message
>>>>> "Simon" == Simon Marchi <simark@simark.ca> writes:
Simon> I think a version without templates would make it a bit simpler to understand:
Yeah, duh. I wonder why I thought that was needed.
Fixing this taught me that the macOS man page for pthread_setname_np is
incorrect, in that it says the function returns void, whereas
<pthread.h> declares it returning int.
Here's v2.
Tom
commit 3e82417785ea486a2b683e7d7a0cbda88bca1e9a
Author: Tom Tromey <tromey@adacore.com>
Date: Tue Dec 10 14:16:19 2019 -0700
Fix build on macOS
PR build/25268 points out that the build fails on macOS, because on
macOS the "pthread_setname_np" function takes a single argument.
This patch fixes the problem, by introducing a new adapter function
that handles both styles of pthread_setname_np.
This change also meant moving the pthread_setname_np call to the
thread function, because macOS only permits setting the name of the
current thread. This means that there can be a brief window when gdb
will see the wrong name; but I think this is a minor concern.
Tested by rebuilding on x86-64 Fedora 30, and on macOS High Sierra.
On Linux I also debugged gdb to ensure that the thread names are still
set correctly.
gdb/ChangeLog
2019-12-10 Tom Tromey <tromey@adacore.com>
PR build/25268:
* gdbsupport/thread-pool.c (set_thread_name): New function.
(thread_pool::set_thread_count): Don't call pthread_setname_np.
(thread_pool::thread_function): Call set_thread_name.
Change-Id: Id7bf28d99ca27a893a9fc87ebb90b15a9c2a9cb4
Comments
On 2019-12-11 8:52 a.m., Tom Tromey wrote:
> @@ -36,8 +37,31 @@
> #endif
>
> #ifdef USE_PTHREAD_SETNAME_NP
> +
> #include <pthread.h>
> -#endif
> +
> +DIAGNOSTIC_PUSH
> +DIAGNOSTIC_IGNORE_UNUSED_FUNCTION
> +
> +/* Handle platform discrepancies in pthread_setname_np: macOS uses a
> + single-argument form, while Linux uses a two-argument form. This
> + wrapper template handles the difference. */
This comment still mentions "template", you might want to change it?
Otherwise, that LGTM.
Simon
@@ -1,3 +1,10 @@
+2019-12-10 Tom Tromey <tromey@adacore.com>
+
+ PR build/25268:
+ * gdbsupport/thread-pool.c (set_thread_name): New function.
+ (thread_pool::set_thread_count): Don't call pthread_setname_np.
+ (thread_pool::thread_function): Call set_thread_name.
+
2019-12-10 Christian Biesinger <cbiesinger@google.com>
* gdbsupport/safe-strerror.c: Supress the unused function warning
@@ -25,6 +25,7 @@
#include "gdbsupport/alt-stack.h"
#include "gdbsupport/block-signals.h"
#include <algorithm>
+#include "diagnostics.h"
/* On the off chance that we have the pthread library on a Windows
host, but std::thread is not using it, avoid calling
@@ -36,8 +37,31 @@
#endif
#ifdef USE_PTHREAD_SETNAME_NP
+
#include <pthread.h>
-#endif
+
+DIAGNOSTIC_PUSH
+DIAGNOSTIC_IGNORE_UNUSED_FUNCTION
+
+/* Handle platform discrepancies in pthread_setname_np: macOS uses a
+ single-argument form, while Linux uses a two-argument form. This
+ wrapper template handles the difference. */
+
+static void
+set_thread_name (int (*set_name) (pthread_t, const char *), const char *name)
+{
+ set_name (pthread_self (), name);
+}
+
+static void
+set_thread_name (void (*set_name) (const char *), const char *name)
+{
+ set_name (name);
+}
+
+DIAGNOSTIC_POP
+
+#endif /* USE_PTHREAD_SETNAME_NP */
namespace gdb
{
@@ -75,9 +99,6 @@ thread_pool::set_thread_count (size_t num_threads)
for (size_t i = m_thread_count; i < num_threads; ++i)
{
std::thread thread (&thread_pool::thread_function, this);
-#ifdef USE_PTHREAD_SETNAME_NP
- pthread_setname_np (thread.native_handle (), "gdb worker");
-#endif
thread.detach ();
}
}
@@ -115,6 +136,12 @@ thread_pool::post_task (std::function<void ()> func)
void
thread_pool::thread_function ()
{
+#ifdef USE_PTHREAD_SETNAME_NP
+ /* This must be done here, because on macOS one can only set the
+ name of the current thread. */
+ set_thread_name (pthread_setname_np, "gdb worker");
+#endif
+
/* Ensure that SIGSEGV is delivered to an alternate signal
stack. */
gdb::alternate_signal_stack signal_stack;