expose sched.h functions (closes #12655)

Doc/library/os.rst

@@ -2744,6 +2744,155 @@ used to determine the disposition of a process.
    Availability: Unix.
 
 
+Interface to the scheduler
+--------------------------
+
+These functions control how a process is allocated CPU time by the operating
+system. They are only available on some Unix platforms. For more detailed
+information, consult your Unix manpages.
+
+.. versionadded:: 3.3
+
+The following scheduling policies are exposed if they are a supported by the
+operating system.
+
+.. data:: SCHED_OTHER
+
+   The default scheduling policy.
+
+.. data:: SCHED_BATCH
+
+   Scheduling policy for CPU-intensive processes that tries to preserve
+   interactivity on the rest of the computer.
+
+.. data:: SCHED_IDLE
+
+   Scheduling policy for extremely low priority background tasks.
+
+.. data:: SCHED_SPORADIC
+
+   Scheduling policy for sporadic server programs.
+
+.. data:: SCHED_FIFO
+
+   A First In First Out scheduling policy.
+
+.. data:: SCHED_RR
+
+   A round-robin scheduling policy.
+
+.. data:: SCHED_RESET_ON_FORK
+
+   This flag can OR'ed with any other scheduling policy. When a process with
+   this flag set forks, its child's scheduling policy and priority are reset to
+   the default.
+
+
+.. class:: sched_param(sched_priority)
+
+   This class represents tunable scheduling parameters used in
+   :func:`sched_setparam`, :func:`sched_setscheduler`, and
+   :func:`sched_getparam`. It is immutable.
+
+   At the moment, there is only one possible parameter:
+
+   .. attribute:: sched_priority
+
+      The scheduling priority for a scheduling policy.
+
+
+.. function:: sched_get_priority_min(policy)
+
+   Get the minimum priority value for *policy*. *policy* is one of the
+   scheduling policy constants above.
+
+
+.. function:: sched_get_priority_max(policy)
+
+   Get the maximum priority value for *policy*. *policy* is one of the
+   scheduling policy constants above.
+
+
+.. function:: sched_setscheduler(pid, policy, param)
+
+   Set the scheduling policy for the process with PID *pid*. A *pid* of 0 means
+   the calling process. *policy* is one of the scheduling policy constants
+   above. *param* is a :class:`sched_param` instance.
+
+
+.. function:: sched_getscheduler(pid)
+
+   Return the scheduling policy for the process with PID *pid*. A *pid* of 0
+   means the calling process. The result is one of the scheduling policy
+   constants above.
+
+
+.. function:: sched_setparam(pid, param)
+
+   Set a scheduling parameters for the process with PID *pid*. A *pid* of 0 means
+   the calling process. *param* is a :class:`sched_param` instance.
+
+
+.. function:: sched_getparam(pid)
+
+   Return the scheduling parameters as a :class:`sched_param` instance for the
+   process with PID *pid*. A *pid* of 0 means the calling process.
+
+
+.. function:: sched_rr_get_interval(pid)
+
+   Return the round-robin quantum in seconds for the process with PID *pid*. A
+   *pid* of 0 means the calling process.
+
+
+.. function:: sched_yield()
+
+   Voluntarily relinquish the CPU.
+
+
+.. class:: cpu_set(ncpus)
+
+   :class:`cpu_set` represents a set of CPUs on which a process is eligible to
+   run. *ncpus* is the number of CPUs the set should describe. Methods on
+   :class:`cpu_set` allow CPUs to be add or removed.
+
+   :class:`cpu_set` supports the AND, OR, and XOR bitwise operations. For
+   example, given two cpu_sets, ``one`` and ``two``, ``one | two`` returns a
+   :class:`cpu_set` containing the cpus enabled both in ``one`` and ``two``.
+
+   .. method:: set(i)
+
+      Enable CPU *i*.
+
+   .. method:: clear(i)
+
+      Remove CPU *i*.
+
+   .. method:: isset(i)
+
+      Return ``True`` if CPU *i* is enabled in the set.
+
+   .. method:: count()
+
+      Return the number of enabled CPUs in the set.
+
+   .. method:: zero()
+
+      Clear the set completely.
+
+
+.. function:: sched_setaffinity(pid, mask)
+
+   Restrict the process with PID *pid* to a set of CPUs. *mask* is a
+   :class:`cpu_set` instance.
+
+
+.. function:: sched_getaffinity(pid, size)
+
+   Return the :class:`cpu_set` the process with PID *pid* is restricted to. The
+   result will contain *size* CPUs.
+
+
 .. _os-path:
 
 Miscellaneous System Information

Lib/test/test_posix.py

@@ -829,6 +829,138 @@ class PosixTester(unittest.TestCase):
         finally:
             posix.close(f)
 
+    requires_sched_h = unittest.skipUnless(hasattr(posix, 'sched_yield'),
+                                           "don't have scheduling support")
+
+    @requires_sched_h
+    def test_sched_yield(self):
+        # This has no error conditions (at least on Linux).
+        posix.sched_yield()
+
+    @requires_sched_h
+    def test_sched_priority(self):
+        # Round-robin usually has interesting priorities.
+        pol = posix.SCHED_RR
+        lo = posix.sched_get_priority_min(pol)
+        hi = posix.sched_get_priority_max(pol)
+        self.assertIsInstance(lo, int)
+        self.assertIsInstance(hi, int)
+        self.assertGreaterEqual(hi, lo)
+        self.assertRaises(OSError, posix.sched_get_priority_min, -23)
+        self.assertRaises(OSError, posix.sched_get_priority_max, -23)
+
+    @requires_sched_h
+    def test_get_and_set_scheduler_and_param(self):
+        possible_schedulers = [sched for name, sched in posix.__dict__.items()
+                               if name.startswith("SCHED_")]
+        mine = posix.sched_getscheduler(0)
+        self.assertIn(mine, possible_schedulers)
+        try:
+            init = posix.sched_getscheduler(1)
+        except OSError as e:
+            if e.errno != errno.EPERM:
+                raise
+        else:
+            self.assertIn(init, possible_schedulers)
+        self.assertRaises(OSError, posix.sched_getscheduler, -1)
+        self.assertRaises(OSError, posix.sched_getparam, -1)
+        param = posix.sched_getparam(0)
+        self.assertIsInstance(param.sched_priority, int)
+        posix.sched_setscheduler(0, mine, param)
+        posix.sched_setparam(0, param)
+        self.assertRaises(OSError, posix.sched_setparam, -1, param)
+        self.assertRaises(OSError, posix.sched_setscheduler, -1, mine, param)
+        self.assertRaises(TypeError, posix.sched_setscheduler, 0, mine, None)
+        self.assertRaises(TypeError, posix.sched_setparam, 0, 43)
+        param = posix.sched_param(None)
+        self.assertRaises(TypeError, posix.sched_setparam, 0, param)
+        large = 214748364700
+        param = posix.sched_param(large)
+        self.assertRaises(OverflowError, posix.sched_setparam, 0, param)
+        param = posix.sched_param(sched_priority=-large)
+        self.assertRaises(OverflowError, posix.sched_setparam, 0, param)
+
+    @requires_sched_h
+    def test_sched_rr_get_interval(self):
+        interval = posix.sched_rr_get_interval(0)
+        self.assertIsInstance(interval, float)
+        # Reasonable constraints, I think.
+        self.assertGreaterEqual(interval, 0.)
+        self.assertLess(interval, 1.)
+
+    @requires_sched_h
+    def test_sched_affinity(self):
+        mask = posix.sched_getaffinity(0, 1024)
+        self.assertGreaterEqual(mask.count(), 1)
+        self.assertIsInstance(mask, posix.cpu_set)
+        self.assertRaises(OSError, posix.sched_getaffinity, -1, 1024)
+        empty = posix.cpu_set(10)
+        posix.sched_setaffinity(0, mask)
+        self.assertRaises(OSError, posix.sched_setaffinity, 0, empty)
+        self.assertRaises(OSError, posix.sched_setaffinity, -1, mask)
+
+    @requires_sched_h
+    def test_cpu_set_basic(self):
+        s = posix.cpu_set(10)
+        self.assertEqual(len(s), 10)
+        self.assertEqual(s.count(), 0)
+        s.set(0)
+        s.set(9)
+        self.assertTrue(s.isset(0))
+        self.assertTrue(s.isset(9))
+        self.assertFalse(s.isset(5))
+        self.assertEqual(s.count(), 2)
+        s.clear(0)
+        self.assertFalse(s.isset(0))
+        self.assertEqual(s.count(), 1)
+        s.zero()
+        self.assertFalse(s.isset(0))
+        self.assertFalse(s.isset(9))
+        self.assertEqual(s.count(), 0)
+        self.assertRaises(ValueError, s.set, -1)
+        self.assertRaises(ValueError, s.set, 10)
+        self.assertRaises(ValueError, s.clear, -1)
+        self.assertRaises(ValueError, s.clear, 10)
+        self.assertRaises(ValueError, s.isset, -1)
+        self.assertRaises(ValueError, s.isset, 10)
+
+    @requires_sched_h
+    def test_cpu_set_cmp(self):
+        self.assertNotEqual(posix.cpu_set(11), posix.cpu_set(12))
+        l = posix.cpu_set(10)
+        r = posix.cpu_set(10)
+        self.assertEqual(l, r)
+        l.set(1)
+        self.assertNotEqual(l, r)
+        r.set(1)
+        self.assertEqual(l, r)
+
+    @requires_sched_h
+    def test_cpu_set_bitwise(self):
+        l = posix.cpu_set(5)
+        l.set(0)
+        l.set(1)
+        r = posix.cpu_set(5)
+        r.set(1)
+        r.set(2)
+        b = l & r
+        self.assertEqual(b.count(), 1)
+        self.assertTrue(b.isset(1))
+        b = l | r
+        self.assertEqual(b.count(), 3)
+        self.assertTrue(b.isset(0))
+        self.assertTrue(b.isset(1))
+        self.assertTrue(b.isset(2))
+        b = l ^ r
+        self.assertEqual(b.count(), 2)
+        self.assertTrue(b.isset(0))
+        self.assertFalse(b.isset(1))
+        self.assertTrue(b.isset(2))
+        b = l
+        b |= r
+        self.assertIs(b, l)
+        self.assertEqual(l.count(), 3)
+
 class PosixGroupsTester(unittest.TestCase):
 
     def setUp(self):
@@ -864,7 +996,6 @@ class PosixGroupsTester(unittest.TestCase):
             posix.setgroups(groups)
             self.assertListEqual(groups, posix.getgroups())
 
-
 def test_main():
     try:
         support.run_unittest(PosixTester, PosixGroupsTester)

Misc/NEWS

@@ -251,6 +251,11 @@ Core and Builtins
 Library
 -------
 
+- Issue #12655: Expose functions from sched.h in the os module: sched_yield(),
+  sched_setscheduler(), sched_getscheduler(), sched_setparam(),
+  sched_get_min_priority(), sched_get_max_priority(), sched_rr_get_interval(),
+  sched_getaffinity(), sched_setaffinity().
+
 - Issues #11104, #8688: Fix the behavior of distutils' sdist command with
   manually-maintained MANIFEST files.
 

configure

@@ -6092,7 +6092,7 @@ fi
 for ac_header in asm/types.h conio.h curses.h direct.h dlfcn.h errno.h \
 fcntl.h grp.h \
 ieeefp.h io.h langinfo.h libintl.h ncurses.h poll.h process.h pthread.h \
-shadow.h signal.h stdint.h stropts.h termios.h \
+sched.h shadow.h signal.h stdint.h stropts.h termios.h \
 unistd.h utime.h \
 sys/audioio.h sys/bsdtty.h sys/epoll.h sys/event.h sys/file.h sys/loadavg.h \
 sys/lock.h sys/mkdev.h sys/modem.h \
@@ -14418,8 +14418,8 @@ esac
 
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 # Files that config.status was made for.
-config_files="`echo $ac_config_files`"
-config_headers="`echo $ac_config_headers`"
+config_files="$ac_config_files"
+config_headers="$ac_config_headers"
 
 _ACEOF
 

configure.in

@@ -1301,7 +1301,7 @@ AC_HEADER_STDC
 AC_CHECK_HEADERS(asm/types.h conio.h curses.h direct.h dlfcn.h errno.h \
 fcntl.h grp.h \
 ieeefp.h io.h langinfo.h libintl.h ncurses.h poll.h process.h pthread.h \
-shadow.h signal.h stdint.h stropts.h termios.h \
+sched.h shadow.h signal.h stdint.h stropts.h termios.h \
 unistd.h utime.h \
 sys/audioio.h sys/bsdtty.h sys/epoll.h sys/event.h sys/file.h sys/loadavg.h \
 sys/lock.h sys/mkdev.h sys/modem.h \

pyconfig.h.in

@@ -650,6 +650,9 @@
 /* Define to 1 if you have the `round' function. */
 #undef HAVE_ROUND
 
+/* Define to 1 if you have the <sched.h> header file. */
+#undef HAVE_SCHED_H
+
 /* Define to 1 if you have the `select' function. */
 #undef HAVE_SELECT