perfschema: use glibc gettid if available

cmake/os/WindowsCache.cmake

@@ -322,6 +322,7 @@ SET(HAVE_SCHED_GETCPU CACHE INTERNAL "")
 SET(HAVE_NANOSLEEP CACHE INTERNAL "")
 SET(HAVE_PTHREAD_THREADID_NP CACHE INTERNAL "")
 SET(HAVE_SYS_GETTID CACHE INTERNAL "")
+SET(HAVE_GETTID CACHE INTERNAL "")
 SET(HAVE_INTEGER_PTHREAD_SELF CACHE INTERNAL "")
 SET(HAVE_PTHREAD_GETTHREADID_NP CACHE INTERNAL "")
 SET(HAVE_TIMER_DELETE CACHE INTERNAL "")

storage/perfschema/CMakeLists.txt

@@ -290,6 +290,9 @@ int main(int ac, char **av)
 }"
 HAVE_PTHREAD_THREADID_NP)
 
+# gettid() library function (glibc-2.30+)
+CHECK_SYMBOL_EXISTS(gettid unistd.h HAVE_GETTID)
+
 # Check for gettid() system call
 CHECK_C_SOURCE_COMPILES("
 #include <sys/types.h>

storage/perfschema/my_thread.h

@@ -50,12 +50,14 @@ static inline my_thread_os_id_t my_thread_os_id()
   pthread_threadid_np(nullptr, &tid64);
   return (pid_t)tid64;
 #else
+#ifdef HAVE_GETTID
+  /* Linux glibc-2.30+ */
+  return gettid();
+#else
 #ifdef HAVE_SYS_GETTID
   /*
-    Linux.
+    Linux before glibc-2.30
     See man gettid
-    See GLIBC Bug 6399 - gettid() should have a wrapper
-    https://sourceware.org/bugzilla/show_bug.cgi?id=6399
   */
   return syscall(SYS_gettid);
 #else
@@ -82,7 +84,8 @@ static inline my_thread_os_id_t my_thread_os_id()
 #endif /* HAVE_PTHREAD_GETTHREADID_NP */
 #endif /* _WIN32 */
 #endif /* HAVE_SYS_GETTID */
-#endif /* HAVE_SYS_THREAD_SELFID */
+#endif /* HAVE_GETTID */
+#endif /* HAVE_PTHREAD_THREADID_NP */
 }
 
 #define CHANNEL_NAME_LENGTH MAX_CONNECTION_NAME

storage/perfschema/pfs_config.h.cmake

 #cmakedefine HAVE_PTHREAD_THREADID_NP 1
 #cmakedefine HAVE_SYS_GETTID 1
+#cmakedefine HAVE_GETTID
 #cmakedefine HAVE_GETTHRID 1
 #cmakedefine HAVE_PTHREAD_GETTHREADID_NP 1
 #cmakedefine HAVE_INTEGER_PTHREAD_SELF 1