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docs: document RouteMonitor class.

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issue260
David Wilson 6 years ago
parent 95f95ce868
commit 0394dac2c7
2 changed files with 82 additions and 14 deletions
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8
docs/internals.rst
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@ -236,6 +236,14 @@ Responder Class
:members:
RouteMonitor Class
------------------
.. currentmodule:: mitogen.parent
.. autoclass:: RouteMonitor
:members:
Forwarder Class
---------------

88
mitogen/parent.py
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@ -1431,6 +1431,29 @@ class Context(mitogen.core.Context):
class RouteMonitor(object):
"""
Generate and respond to :data:`mitogen.core.ADD_ROUTE` and
:data:`mitogen.core.DEL_ROUTE` messages sent to the local context by
maintaining a table of available routes, and propagating messages towards
parents and siblings as appropriate.
:class:`RouteMonitor` is responsible for generating routing messages for
directly attached children. It learns of new children via
:meth:`notice_stream` called by :class:`Router`, and subscribes to their
``disconnect`` event to learn when they disappear.
In children, constructing this class overwrites the stub
:data:`mitogen.core.DEL_ROUTE` handler installed by
:class:`mitogen.core.ExternalContext`, which is expected behaviour when a
child is beging upgraded in preparation to become a parent of children of
its own.
:param Router router:
Router to install handlers on.
:param Context parent:
:data:`None` in the master process, or reference to the parent context
we should propagate route updates towards.
"""
def __init__(self, router, parent=None):
self.router = router
self.parent = parent
@ -1451,6 +1474,18 @@ class RouteMonitor(object):
self._routes_by_stream = {}
def _send_one(self, stream, handle, target_id, name):
"""
Compose and send an update message on a stream.
:param mitogen.core.Stream stream:
Stream to send it on.
:param int handle:
:data:`mitogen.core.ADD_ROUTE` or :data:`mitogen.core.DEL_ROUTE`
:param int target_id:
ID of the connecting or disconnecting context.
:param str name:
Context name or :data:`None`.
"""
data = str(target_id)
if name:
data = '%s:%s' % (target_id, mitogen.core.b(name))
@ -1462,20 +1497,34 @@ class RouteMonitor(object):
)
)
def _propagate(self, handle, target_id, name=None):
if not self.parent:
# self.parent is None in the master.
return
stream = self.router.stream_by_id(self.parent.context_id)
self._send_one(stream, handle, target_id, name)
def _propagate_up(self, handle, target_id, name=None):
"""
In a non-master context, propagate an update towards the master.
:param int handle:
:data:`mitogen.core.ADD_ROUTE` or :data:`mitogen.core.DEL_ROUTE`
:param int target_id:
ID of the connecting or disconnecting context.
:param str name:
For :data:`mitogen.core.ADD_ROUTE`, the name of the new context
assigned by its parent. This is used by parents to assign the
:attr:`mitogen.core.Context.name` attribute.
"""
if self.parent:
stream = self.router.stream_by_id(self.parent.context_id)
self._send_one(stream, handle, target_id, name)
def _child_propagate(self, handle, target_id):
def _propagate_down(self, handle, target_id):
"""
For DEL_ROUTE, we additionally want to broadcast the message to any
stream that has ever communicated with the disconnecting ID, so
core.py's :meth:`mitogen.core.Router._on_del_route` can turn the
message into a disconnect event.
:param int handle:
:data:`mitogen.core.ADD_ROUTE` or :data:`mitogen.core.DEL_ROUTE`
:param int target_id:
ID of the connecting or disconnecting context.
"""
for stream in itervalues(self.router._stream_by_id):
if target_id in stream.egress_ids:
@ -1488,7 +1537,7 @@ class RouteMonitor(object):
if/when that child disconnects.
"""
self._routes_by_stream[stream] = set([stream.remote_id])
self._propagate(mitogen.core.ADD_ROUTE, stream.remote_id,
self._propagate_up(mitogen.core.ADD_ROUTE, stream.remote_id,
stream.name)
mitogen.core.listen(
obj=stream,
@ -1513,14 +1562,19 @@ class RouteMonitor(object):
LOG.debug('%r is gone; propagating DEL_ROUTE for %r', stream, routes)
for target_id in routes:
self.router.del_route(target_id)
self._propagate(mitogen.core.DEL_ROUTE, target_id)
self._child_propagate(mitogen.core.DEL_ROUTE, target_id)
self._propagate_up(mitogen.core.DEL_ROUTE, target_id)
self._propagate_down(mitogen.core.DEL_ROUTE, target_id)
context = self.router.context_by_id(target_id, create=False)
if context:
mitogen.core.fire(context, 'disconnect')
def _on_add_route(self, msg):
"""
Respond to :data:`mitogen.core.ADD_ROUTE` by validating the source of
the message, updating the local table, and propagating the message
upwards.
"""
if msg.is_dead:
return
@ -1539,9 +1593,15 @@ class RouteMonitor(object):
LOG.debug('Adding route to %d via %r', target_id, stream)
self._routes_by_stream[stream].add(target_id)
self.router.add_route(target_id, stream)
self._propagate(mitogen.core.ADD_ROUTE, target_id, target_name)
self._propagate_up(mitogen.core.ADD_ROUTE, target_id, target_name)
def _on_del_route(self, msg):
"""
Respond to :data:`mitogen.core.DEL_ROUTE` by validating the source of
the message, updating the local table, propagating the message
upwards, and downwards towards any stream that every had a message
forwarded from it towards the disconnecting context.
"""
if msg.is_dead:
return
@ -1565,8 +1625,8 @@ class RouteMonitor(object):
self.router.del_route(target_id)
if stream.remote_id != mitogen.parent_id:
self._propagate(mitogen.core.DEL_ROUTE, target_id)
self._child_propagate(mitogen.core.DEL_ROUTE, target_id)
self._propagate_up(mitogen.core.DEL_ROUTE, target_id)
self._propagate_down(mitogen.core.DEL_ROUTE, target_id)
class Router(mitogen.core.Router):

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