SubProcess: use child_watch_add

This fixes performance issues introduced by commit
9c664779a16f6cbca8a5ffe7f6b0c68572819723.

diff --git a/pym/_emerge/SubProcess.py b/pym/_emerge/SubProcess.py
index 01004a874f36b6ca363bc610591058d3bfa4e207..9c033c562684de2d8622162486ce42355bada179 100644 (file)
--- a/pym/_emerge/SubProcess.py
+++ b/pym/_emerge/SubProcess.py
@@ -20,9 +20,6 @@ class SubProcess(AbstractPollTask):
        # we've sent a kill signal to our subprocess.
        _cancel_timeout = 1000 # 1 second
 
-       # Poll interval for process exit status.
-       _waitpid_interval = 1000 # 1 second
-
        def _poll(self):
                if self.returncode is not None:
                        return self.returncode
@@ -95,37 +92,18 @@ class SubProcess(AbstractPollTask):
                return self.returncode
 
        def _waitpid_loop(self):
-               if not self._waitpid_cb():
-                       return
-
-               timeout_id = self.scheduler.timeout_add(
-                       self._waitpid_interval, self._waitpid_cb)
+               source_id = self.scheduler.child_watch_add(
+                       self.pid, self._waitpid_cb)
                try:
                        while self.returncode is None:
                                self.scheduler.iteration()
                finally:
-                       self.scheduler.source_remove(timeout_id)
-
-       def _waitpid_cb(self):
-               if self.returncode is not None:
-                       return False
-               try:
-                       # With waitpid and WNOHANG, only check the
-                       # first element of the tuple since the second
-                       # element may vary (bug #337465).
-                       wait_retval = os.waitpid(self.pid, os.WNOHANG)
-               except OSError as e:
-                       if e.errno != errno.ECHILD:
-                               raise
-                       del e
-                       self._set_returncode((self.pid, 1 << 8))
-                       return False
-               else:
-                       if wait_retval[0] != 0:
-                               self._set_returncode(wait_retval)
-                               return False
+                       self.scheduler.source_remove(source_id)
 
-               return True
+       def _waitpid_cb(self, pid, condition, user_data):
+               if pid != self.pid:
+                       raise AssertionError("expected pid %s, got %s" % (self.pid, pid))
+               self._set_returncode((pid, condition))
 
        def _orphan_process_warn(self):
                pass