[gnome-ostree] mainloop: Allow reentrancy and removing sources

[Colin Walters <walters src gnome org>]

commit 1a276d30c9f18d3cfd370c354ad0d51337bb67d9
Author: Colin Walters <walters verbum org>
Date:   Sat Oct 20 20:26:15 2012 -0400

    mainloop: Allow reentrancy and removing sources
    
    Timeouts now return ids, and should return False to be removed.
    
    Second, ensure that we're not iterating over lists when calling back
    to user code, since the user code may try to modify the list.

 src/ostbuild/pyostbuild/mainloop.py |   26 +++++++++++++++++---------
 1 files changed, 17 insertions(+), 9 deletions(-)
---
diff --git a/src/ostbuild/pyostbuild/mainloop.py b/src/ostbuild/pyostbuild/mainloop.py
index 40a67be..6661291 100644
--- a/src/ostbuild/pyostbuild/mainloop.py
+++ b/src/ostbuild/pyostbuild/mainloop.py
@@ -29,6 +29,7 @@ class Mainloop(object):
         self._timeouts = []
         self._pid_watches = {}
         self._fd_callbacks = {}
+        self._source_counter = 0
 
     @classmethod
     def get(cls, context):
@@ -55,7 +56,9 @@ class Mainloop(object):
         self._pid_watches[pid] = callback
 
     def timeout_add(self, ms, callback):
-        self._timeouts.append((ms, callback))
+        self._source_counter += 1
+        self._timeouts.append((self._source_counter, ms, callback))
+        return self._source_counter
 
     def quit(self):
         self._running = False
@@ -64,7 +67,7 @@ class Mainloop(object):
         min_timeout = None
         if len(self._pid_watches) > 0:
             min_timeout = 500
-        for (ms, callback) in self._timeouts:
+        for (source_id, ms, callback) in self._timeouts:
             if (min_timeout is None) or (ms < min_timeout):
                 min_timeout = ms
         origtime = time.time() * 1000
@@ -72,23 +75,28 @@ class Mainloop(object):
         fds = self.poll.poll(min_timeout)
         for fd in fds:
             self._fd_callbacks[fd]()
-        to_delete_pids = []
+        hit_pids = []
         for pid in self._pid_watches:
             (opid, status) = os.waitpid(pid, os.WNOHANG)
             if opid == pid:
-                to_delete_pids.append(pid)
-                self._pid_watches[pid](pid, status)
-        for pid in to_delete_pids:
+                hit_pids.append((pid, status))
+        for (pid, status) in hit_pids:
+            watch = self._pid_watches[pid]
             del self._pid_watches[pid]
+            watch(pid, status)
         newtime = time.time() * 1000
         diff = int(newtime - origtime)
         if diff < 0: diff = 0
-        for i,(ms, callback) in enumerate(self._timeouts):
+        new_timeouts = []
+        for i,(source_id, ms, callback) in enumerate(self._timeouts):
             remaining_ms = ms - diff
             if remaining_ms <= 0:
-                callback()
+                result = callback()
+                if result:
+                    new_timeouts.append((source_id, ms, callback))
             else:
-                self._timeouts[i] = (remaining_ms, callback)
+                new_timeouts.append((source_id, remaining_ms, callback))
+        self._timeouts = new_timeouts
 
     def run(self):
         self._running = True