1 files changed, 91 insertions, 1 deletions
diff --git a/rpkid/rpki/async.py b/rpkid/rpki/async.py
index 74a23385..9bf91304 100644
--- a/rpkid/rpki/async.py
+++ b/rpkid/rpki/async.py
@@ -18,7 +18,8 @@ OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 PERFORMANCE OF THIS SOFTWARE.
 """
 
-import rpki.log
+import asyncore
+import rpki.log, rpki.sundial
 
 class iterator(object):
   """Iteration construct for event-driven code.  Takes three
@@ -54,3 +55,92 @@ class iterator(object):
     except StopIteration:
       if self.done_callback is not None:
         self.done_callback()
+
+
+class timer(object):
+  """Timer construct for event-driven code.
+
+  This is a virtual class, users must subclass it and define an expired() method.
+  """
+
+  ## @var queue
+  # Timer queue, shared by all timer instances (there can be only one queue).
+
+  queue = []
+
+  def set(self, when):
+    """Set a timer.  Argument can be a datetime, to specify an
+    absolute time, a timedelta, to specify an offset time, or None, to
+    indicate that the timer should expire immediately, which can be
+    useful in avoiding an excessively deep call stack.
+    """
+    if when is None:
+      self.when = rpki.sundial.now()
+    elif isinstance(when, rpki.sundial.timedelta):
+      self.when = rpki.sundial.now() + when
+    else:
+      self.when = when
+    assert isinstance(self.when, rpki.sundial.datetime)
+    self.queue.append(self)
+    self.queue.sort()
+
+  def __cmp__(self, other):
+    return cmp(self.when, other.when)
+
+  def cancel(self):
+    """Cancel a timer, if it was set."""
+    try:
+      self.queue.remove(self)
+    except ValueError:
+      pass
+
+  def expired(self):
+    """Handle a timer that has expired.  Subclass must define this."""
+    raise NotImplementedError
+
+  @classmethod
+  def runq(cls):
+    """Run the timer queue: for each timer whose call time has passed,
+    pull the timer off the queue and call its expired() handler.
+    """
+    while cls.queue and rpki.sundial.now() >= cls.queue[0].when:
+      cls.queue.pop(0).expired()
+
+  def __repr__(self):
+    return "<%s %s>" % (self.__class__.__name__, repr(self.when))
+
+  @classmethod
+  def seconds_until_wakeup(cls):
+    """Calculate delay until next timer expires, or None if no timers
+    are set and we should wait indefinitely.  Rounds up to avoid
+    spinning in select() or poll().  We could calculate fractional
+    seconds in the right units instead, but select() and poll() don't
+    even take the same units (argh!), and we're not doing anything
+    that hair-triggered, so rounding up is simplest.
+    """
+    if not cls.queue:
+      return None
+    now = rpki.sundial.now()
+    if now >= cls.queue[0].when:
+      return 0
+    else:
+      delay = cls.queue[0].when - now
+      seconds = delay.convert_to_seconds()
+      if delay.microseconds:
+        seconds += 1
+      return seconds
+
+  @classmethod
+  def clear(cls):
+    """Cancel every timer on the queue.  We could just throw away the
+    queue content, but this way we can notify subclasses that provide
+    their own cancel() method.
+    """
+    while cls.queue:
+      cls.queue.pop(0).cancel()
+
+def event_loop():
+  """Replacement for asyncore.loop(), adding timer support."""
+  while asyncore.socket_map:
+    asyncore.poll(timer.seconds_until_wakeup(), asyncore.socket_map)
+    timer.runq()