[PATCH] Fix build on macOS
Tom Tromey
tromey@adacore.com
Tue Dec 10 21:47:00 GMT 2019
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 template adapter
function that handles both styles of pthread_setname_np. This is a
technique I learned from Alexandre Oliva, and avoids the need for a
complicated autoconf check.
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 template
function.
(thread_pool::set_thread_count): Don't call pthread_setname_np.
(thread_pool::thread_function): Call set_thread_name.
Change-Id: Id7bf28d99ca27a893a9fc87ebb90b15a9c2a9cb4
---
gdb/ChangeLog | 8 ++++++++
gdb/gdbsupport/thread-pool.c | 31 +++++++++++++++++++++++++++----
2 files changed, 35 insertions(+), 4 deletions(-)
diff --git a/gdb/gdbsupport/thread-pool.c b/gdb/gdbsupport/thread-pool.c
index d19ae02e3ef..8e24570ee96 100644
--- a/gdb/gdbsupport/thread-pool.c
+++ b/gdb/gdbsupport/thread-pool.c
@@ -36,8 +36,28 @@
#endif
#ifdef USE_PTHREAD_SETNAME_NP
+
#include <pthread.h>
-#endif
+
+/* 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. */
+
+template<typename R, typename A1, typename A2>
+void
+set_thread_name (R (*set_name) (A1, A2), const char *name)
+{
+ set_name (pthread_self (), name);
+}
+
+template<typename R, typename A1>
+void
+set_thread_name (R (*set_name) (A1), const char *name)
+{
+ set_name (name);
+}
+
+#endif /* USE_PTHREAD_SETNAME_NP */
namespace gdb
{
@@ -75,9 +95,6 @@ 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 +132,12 @@ 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;
--
2.21.0
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