> On Aug. 5, 2014, 3:57 p.m., Matt Jordan wrote:
> > /team/group/rls/res/res_pjsip_pubsub.c, lines 1091-1105
> > <https://reviewboard.asterisk.org/r/3723/diff/3/?file=65309#file65309line1091>
> >
> > This is really more of a general question then a specific finding,
> > however:
> >
> > What is the threading model for updating/iterating/destroying children
> > in a tree? What all threads can access a subscription's children? Does a
> > subscription need to be locked?
{quote}
What is the threading model for updating/iterating/destroying children in a
tree?
{quote}
The tree, after creation, is immutable by convention. Children are never
updated/added/destroyed after the initial tree creation.
{quote}
What all threads can access a subscription's children?
{quote}
Since the tree is immutable, any thread may access the subscription's children,
so long as they have a reference to the tree root. If we switched to a model
where changes to list configuration could allow for the tree to be altered
mid-subscription, we would force any tasks that modified the tree or iterated
over it to be pushed to the subscription's serializer. Currently, most
iterations are performed in the serializer anyway. The exceptions are
iterations that occur due to certain callbacks from PJSIP that terminate the
subscription (such as a subscription timeout). The AMI command that shows
subscriptions may also eventually iterate over child subscriptions, too. It
does not, currently though.
{quote}
Does a subscription need to be locked?
{quote}
Nope. The tree structure is immutable, and any other subscription data is
altered only in the subscription's serializer, so there is no need for a lock.
- Mark
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviewboard.asterisk.org/r/3723/#review12986
-----------------------------------------------------------
On July 25, 2014, 8:57 p.m., Mark Michelson wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/3723/
> -----------------------------------------------------------
>
> (Updated July 25, 2014, 8:57 p.m.)
>
>
> Review request for Asterisk Developers.
>
>
> Bugs: ASTERISK-23869
> https://issues.asterisk.org/jira/browse/ASTERISK-23869
>
>
> Repository: Asterisk
>
>
> Description
> -------
>
> This adds NOTIFY support for resource list subscriptions. The way this works
> is as follows:
>
> When an initial SUBSCRIBE arrives and the subscription tree is built, all
> leaf nodes are called into in order to generate their initial NOTIFY bodies
> and store these on their respective subscription nodes.
>
> Sending a NOTIFY requires traversing the tree. List subscriptions will
> generate a multipart/related body with an RLMI part and parts corresponding
> to the leaves of the list (at least they will eventually. ASTERISK-23867
> involves doing this part). Single-resource subscriptions read the stored body
> on the subscription and uses that to populate the NOTIFY body.
>
> Leaf nodes in the subscription tree, when they have a state change occur,
> call ast_sip_subscription_notify(), as they previously did.
> ast_sip_subscription_notify() creates the NOTIFY body for the subscription
> and stores that on the subscription in the body_text ast_str field. The
> subscription tree is then told to send a NOTIFY if no batching is enabled or
> to start a batched NOTIFY if batching is enabled.
>
> When a resource resubscribes or terminates their subscription, a NOTIFY is
> now automatically generated by the pubsub core instead of calling into
> subscription handlers. The NOTIFY is built the same way as previously, using
> stored NOTIFY bodies on the subscription. This NOTIFY can also cause batched
> notification, when the timer fires, not to actually send their batch since it
> would be redundant.
>
> You'll notice the code has been refactored slightly, and a new struct,
> sip_subscription_tree, has invaded res_pjsip_pubsub. This is because, as I
> was separating the "real" and "virtual" parts of ast_sip_subscriptions out, I
> realized that I essentially had two distinct structures. Thus, I separated
> the real/meta/base elements of a subscription into the sip_subscription_tree,
> and the resource-specific parts into the ast_sip_subscription struct.
> sip_subscription_tree is used more heavily in the pubsub core now, whereas
> ast_sip_subscription acts as a handle for subscription handlers to use plus a
> repository for resource-specific data.
>
>
> Diffs
> -----
>
> /team/group/rls/res/res_pjsip_pubsub.c 418321
> /team/group/rls/res/res_pjsip_mwi.c 418321
> /team/group/rls/res/res_pjsip_exten_state.c 418321
> /team/group/rls/include/asterisk/res_pjsip_pubsub.h 418321
>
> Diff: https://reviewboard.asterisk.org/r/3723/diff/
>
>
> Testing
> -------
>
> With this set of changes, I'm still not able to perform RLS-specific tests
> since there is still no method of generating multipart/related or RLMI
> bodies. However, with these changes, I did run the gamut of subscription
> tests in the testsuite and they all pass. This at least means that there are
> no detectable regressions at this point.
>
>
> Thanks,
>
> Mark Michelson
>
>
--
_____________________________________________________________________
-- Bandwidth and Colocation Provided by http://www.api-digital.com --
asterisk-dev mailing list
To UNSUBSCRIBE or update options visit:
http://lists.digium.com/mailman/listinfo/asterisk-dev
