Issue 10784: adds os.getpriority() and os.setpriority() functions.

7 files changed, 146 insertions, 12 deletions

diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index a1aaf1e..cd8d45bd 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -286,6 +286,22 @@ process and user.
    .. versionchanged:: 3.2
       Added support for Windows.
 
+.. function:: getpriority(which, who)
+
+   .. index:: single: process; scheduling priority
+
+   Get program scheduling priority. The value *which* is one of
+   :const:`PRIO_PROCESS`, :const:`PRIO_PGRP`, or :const:`PRIO_USER`, and *who*
+   is interpreted relative to *which* (a process identifier for
+   :const:`PRIO_PROCESS`, process group identifier for :const:`PRIO_PGRP`, and a
+   user ID for :const:`PRIO_USER`). A zero value for *who* denotes
+   (respectively) the calling process, the process group of the calling process,
+   or the real user ID of the calling process.
+
+   Availability: Unix
+
+   .. versionadded:: 3.3
+
 .. function:: getresuid()
 
    Return a tuple (ruid, euid, suid) denoting the current process's
@@ -336,6 +352,15 @@ process and user.
 
    .. versionadded:: 3.2
 
+.. data:: PRIO_PROCESS
+          PRIO_PGRP
+          PRIO_USER
+
+   Parameters for :func:`getpriority` and :func:`setpriority` functions.
+
+   Availability: Unix.
+
+   .. versionadded:: 3.3
 
 .. function:: putenv(key, value)
 
@@ -405,6 +430,25 @@ process and user.
    Availability: Unix.
 
 
+.. function:: setpriority(which, who, priority)
+
+   .. index:: single: process; scheduling priority
+
+   Set program scheduling priority. The value *which* is one of
+   :const:`PRIO_PROCESS`, :const:`PRIO_PGRP`, or :const:`PRIO_USER`, and *who*
+   is interpreted relative to *which* (a process identifier for
+   :const:`PRIO_PROCESS`, process group identifier for :const:`PRIO_PGRP`, and a
+   user ID for :const:`PRIO_USER`). A zero value for *who* denotes
+   (respectively) the calling process, the process group of the calling process,
+   or the real user ID of the calling process.
+   *priority* is a value in the range -20 to 19. The default priority is 0;
+   lower priorities cause more favorable scheduling.
+
+   Availability: Unix
+
+   .. versionadded:: 3.3
+
+
 .. function:: setregid(rgid, egid)
 
    Set the current process's real and effective group ids.
diff --git a/Doc/whatsnew/3.3.rst b/Doc/whatsnew/3.3.rst
index 78d66fe..c0cb7cf 100644
--- a/Doc/whatsnew/3.3.rst
+++ b/Doc/whatsnew/3.3.rst
@@ -71,16 +71,22 @@ New, Improved, and Deprecated Modules
 os
 --
 
-The :mod:`os` module has a new :func:`~os.sendfile` function which provides an
-efficent "zero-copy" way for copying data from one file (or socket) descriptor
-to another.
-The phrase "zero-copy" refers to the fact that all of the copying of data
-between the two descriptors is done entirely by the kernel, with no copying of
-data into userspace buffers.
-:func:`~os.sendfile` can be used to efficiently copy data from a file on disk to
-a network socket, e.g. for downloading a file.
-
-(Patch submitted by Ross Lagerwall and Giampaolo Rodolà in :issue:`10882`.)
+* The :mod:`os` module has a new :func:`~os.sendfile` function which provides
+  an efficent "zero-copy" way for copying data from one file (or socket)
+  descriptor to another. The phrase "zero-copy" refers to the fact that all of
+  the copying of data between the two descriptors is done entirely by the
+  kernel, with no copying of data into userspace buffers. :func:`~os.sendfile`
+  can be used to efficiently copy data from a file on disk to a network socket,
+  e.g. for downloading a file.
+
+  (Patch submitted by Ross Lagerwall and Giampaolo Rodolà in :issue:`10882`.)
+
+* The :mod:`os` module has two new functions: :func:`~os.getpriority` and
+  :func:`~os.setpriority`. They can be used to get or set process
+  niceness/priority in a fashion similar to :func:`os.nice` but extended to all
+  processes instead of just the current one.
+
+  (Patch submitted by Giampaolo Rodolà in :issue:`10784`.)
 
 Optimizations
 =============
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index 4965786..29b6b9a 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -1268,6 +1268,24 @@ class LoginTests(unittest.TestCase):
         self.assertNotEqual(len(user_name), 0)
 
 
+@unittest.skipUnless(hasattr(os, 'getpriority') and hasattr(os, 'setpriority'),
+                     "needs os.getpriority and os.setpriority")
+class ProgramPriorityTests(unittest.TestCase):
+    """Tests for os.getpriority() and os.setpriority()."""
+
+    def test_set_get_priority(self):
+        base = os.getpriority(os.PRIO_PROCESS, os.getpid())
+        os.setpriority(os.PRIO_PROCESS, os.getpid(), base + 1)
+        try:
+            self.assertEqual(os.getpriority(os.PRIO_PROCESS, os.getpid()), base + 1)
+        finally:
+            try:
+                os.setpriority(os.PRIO_PROCESS, os.getpid(), base)
+            except OSError as err:
+                if err.errno != EACCESS:
+                    raise
+
+
 class SendfileTestServer(asyncore.dispatcher, threading.Thread):
 
     class Handler(asynchat.async_chat):
@@ -1535,6 +1553,7 @@ def test_main():
         LoginTests,
         LinkTests,
         TestSendfile,
+        ProgramPriorityTests,
     )
 
 if __name__ == "__main__":
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 56b2063..3226b32 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -2958,6 +2958,52 @@ posix_nice(PyObject *self, PyObject *args)
 }
 #endif /* HAVE_NICE */
 
+
+#ifdef HAVE_GETPRIORITY
+PyDoc_STRVAR(posix_getpriority__doc__,
+"getpriority(which, who) -> current_priority\n\n\
+Get program scheduling priority.");
+
+static PyObject *
+posix_getpriority(PyObject *self, PyObject *args)
+{
+    int which, who, retval;
+
+    if (!PyArg_ParseTuple(args, "ii", &which, &who))
+        return NULL;
+    errno = 0;
+    Py_BEGIN_ALLOW_THREADS
+    retval = getpriority(which, who);
+    Py_END_ALLOW_THREADS
+    if (errno != 0)
+        return posix_error();
+    return PyLong_FromLong((long)retval);
+}
+#endif /* HAVE_GETPRIORITY */
+
+
+#ifdef HAVE_SETPRIORITY
+PyDoc_STRVAR(posix_setpriority__doc__,
+"setpriority(which, who, prio) -> None\n\n\
+Set program scheduling priority.");
+
+static PyObject *
+posix_setpriority(PyObject *self, PyObject *args)
+{
+    int which, who, prio, retval;
+
+    if (!PyArg_ParseTuple(args, "iii", &which, &who, &prio))
+        return NULL;
+    Py_BEGIN_ALLOW_THREADS
+    retval = setpriority(which, who, prio);
+    Py_END_ALLOW_THREADS
+    if (retval == -1)
+        return posix_error();
+    Py_RETURN_NONE;
+}
+#endif /* HAVE_SETPRIORITY */
+
+
 PyDoc_STRVAR(posix_rename__doc__,
 "rename(old, new)\n\n\
 Rename a file or directory.");
@@ -8012,6 +8058,12 @@ static PyMethodDef posix_methods[] = {
 #ifdef HAVE_NICE
     {"nice",            posix_nice, METH_VARARGS, posix_nice__doc__},
 #endif /* HAVE_NICE */
+#ifdef HAVE_GETPRIORITY
+    {"getpriority",     posix_getpriority, METH_VARARGS, posix_getpriority__doc__},
+#endif /* HAVE_GETPRIORITY */
+#ifdef HAVE_SETPRIORITY
+    {"setpriority",     posix_setpriority, METH_VARARGS, posix_setpriority__doc__},
+#endif /* HAVE_SETPRIORITY */
 #ifdef HAVE_READLINK
     {"readlink",        posix_readlink, METH_VARARGS, posix_readlink__doc__},
 #endif /* HAVE_READLINK */
@@ -8459,6 +8511,16 @@ all_ins(PyObject *d)
 #ifdef O_EXLOCK
     if (ins(d, "O_EXLOCK", (long)O_EXLOCK)) return -1;
 #endif
+#ifdef PRIO_PROCESS
+    if (ins(d, "PRIO_PROCESS", (long)PRIO_PROCESS)) return -1;
+#endif
+#ifdef PRIO_PGRP
+    if (ins(d, "PRIO_PGRP", (long)PRIO_PGRP)) return -1;
+#endif
+#ifdef PRIO_USER
+    if (ins(d, "PRIO_USER", (long)PRIO_USER)) return -1;
+#endif
+
 
 /* MS Windows */
 #ifdef O_NOINHERIT
diff --git a/configure b/configure
index c775a85..cbc5293 100755
--- a/configure
+++ b/configure
@@ -9318,7 +9318,7 @@ for ac_func in alarm accept4 setitimer getitimer bind_textdomain_codeset chown \
  putenv readlink realpath \
  select sem_open sem_timedwait sem_getvalue sem_unlink sendfile setegid seteuid \
  setgid \
- setlocale setregid setreuid setresuid setresgid setsid setpgid setpgrp setuid setvbuf \
+ setlocale setregid setreuid setresuid setresgid setsid setpgid setpgrp setpriority setuid setvbuf \
  sigaction siginterrupt sigrelse snprintf strftime strlcpy \
  sysconf tcgetpgrp tcsetpgrp tempnam timegm times tmpfile tmpnam tmpnam_r \
  truncate uname unsetenv utimes waitpid wait3 wait4 \
diff --git a/configure.in b/configure.in
index 14b60ae..55cbd8f 100644
--- a/configure.in
+++ b/configure.in
@@ -2542,7 +2542,7 @@ AC_CHECK_FUNCS(alarm accept4 setitimer getitimer bind_textdomain_codeset chown \
  putenv readlink realpath \
  select sem_open sem_timedwait sem_getvalue sem_unlink sendfile setegid seteuid \
  setgid \
- setlocale setregid setreuid setresuid setresgid setsid setpgid setpgrp setuid setvbuf \
+ setlocale setregid setreuid setresuid setresgid setsid setpgid setpgrp setpriority setuid setvbuf \
  sigaction siginterrupt sigrelse snprintf strftime strlcpy \
  sysconf tcgetpgrp tcsetpgrp tempnam timegm times tmpfile tmpnam tmpnam_r \
  truncate uname unsetenv utimes waitpid wait3 wait4 \
diff --git a/pyconfig.h.in b/pyconfig.h.in
index d55c1cd..7236331 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -602,6 +602,9 @@
 /* Define to 1 if you have the `setpgrp' function. */
 #undef HAVE_SETPGRP
 
+/* Define to 1 if you have the `setpriority' function. */
+#undef HAVE_SETPRIORITY
+
 /* Define to 1 if you have the `setregid' function. */
 #undef HAVE_SETREGID