lib: Support epoll APIs in thread management routine

This commit adds support for epoll APIs for better
performance. This is controlled by a configure option. Note that
epoll APIs are only available for Linux platforms. For BSD and
other linux platforms which do not support epoll APIs, poll APIs
are still used.

Signed-off-by: Kaifei Peng <[email protected]>
Signed-off-by: Mark Stapp <[email protected]>

Author: Mark Stapp

configure.ac

@@ -1599,6 +1599,24 @@ AC_CHECK_FUNCS([pollts], [
   AC_DEFINE([HAVE_POLLTS], [1], [have NetBSD pollts()])
 ])
 
+AC_ARG_ENABLE([epoll],
+  [AS_HELP_STRING([--enable-epoll], [Enable epoll support])],
+  [enable_epoll=yes],
+  [enable_epoll=no])
+
+if test "x$enable_epoll" = "xyes"; then
+    AC_CHECK_FUNC([epoll_pwait], [AC_DEFINE([HAVE_EPOLL_PWAIT], [1], [Define if you have epoll_pwait])])
+
+    # Define USE_EPOLL if any of the above is found
+    AC_MSG_CHECKING([for epoll API support])
+    if test "x$ac_cv_func_epoll_pwait" = "xyes" ; then
+        AC_DEFINE([USE_EPOLL], [1], [Define if any epoll API is supported])
+        AC_MSG_RESULT([yes])
+    else
+        AC_MSG_RESULT([no])
+    fi
+fi
+
 AC_CHECK_HEADER([asm-generic/unistd.h],
                 [AC_CHECK_DECL(__NR_setns,
                                AC_DEFINE([HAVE_NETNS], [1], [Have netns]),,