4 Commits (0b625fcc697329af3ff1af426bd61d51830b7e40)

Author	SHA1	Message	Date
David M. Lee	9d21631aee	Optimize how Stasis forwards are dispatched ... This patch optimizes how forwards are dispatched in Stasis. Originally, forwards were dispatched as subscriptions that are invoked on the publishing thread. This did not account for the vast number of forwards we would end up having in the system, and the amount of work it would take to walk though the forward subscriptions. This patch modifies Stasis so that rather than walking the tree of forwards on every dispatch, when forwards and subscriptions are changed, the subscriber list for every topic in the tree is changed. This has a couple of benefits. First, this reduces the workload of dispatching messages. It also reduces contention when dispatching to different topics that happen to forward to the same aggregation topic (as happens with all of the channel, bridge and endpoint topics). Since forwards are no longer subscriptions, the bulk of this patch is simply changing stasis_subscription objects to stasis_forward objects (which, admittedly, I should have done in the first place.) Since this required me to yet again put in a growing array, I finally abstracted that out into a set of ast_vector macros in asterisk/vector.h. Review: https://reviewboard.asterisk.org/r/2883/ git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/12@400180 65c4cc65-6c06-0410-ace0-fbb531ad65f3	13 years ago
David M. Lee	f29d969a79	Stasis: address refcount races; implementation comments ... Change r395954 reordered some stasis object destruction, which should have been fine. Unfortunately, it caused some hard to reproduce issues related to objects being accessed after they had been destroyed. The patch in r396329 fixed the destruction order problem; this patch addresses the underlying issue. A few other stasis-related fixes were also added. * Add ref-bumps around areas where objects may get transitively destroyed. (For example, where we lock a topic, unref a subscription, which unrefs the topic, which explodes the topic when we try to unlock it.) * Wrote an extensive doxygen page about Stasis implementation, relationships between objects, lifecycles of objects, how the refcounting works, etc. Many other comments were added, corrected, or cleaned up. * Added an assert to the topic dtor to catch extra ref decrements. * Fixed type used after destruction errors for graceful shutdown in stasis_channels.c. * I added two unit tests in an attempt to catch destruction order issues. Since the underlying cause is a race condition, though, the tests rarely failed even when the code was wrong. * Fixed a leak in stasis_cache_pattern.c. (closes issue ASTERISK-22243) Review: https://reviewboard.asterisk.org/r/2746/ git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@396842 65c4cc65-6c06-0410-ace0-fbb531ad65f3	13 years ago
David M. Lee	b97d318b7b	Tweak caching topics to fix CEL tests ... The Stasis changes in r395954 had an unanticipated side effect: messages published directly to an _all topic does not get forwarded to the corresponding caching topic. This patch fixes that by changing how caching topics forward messages, and how the caching pattern forwards are setup. For the caching pattern, the all_topic is forwarded to the all_topic_cached. This forwards messages published directly to the all_topic to all_topic_cached. In order to avoid duplicate messages on all_topic_cached, caching topics were changed to no longer forward uncached messages. Subscribers to an individual caching topic should only expect to receive cache updates, and subscription change messages. Since individual caching topics are new, this shouldn't be a problem. There are a few minor changes to the pre-cache split behavior. * For topics changed to use the caching pattern, the all_topic_cached will forward snapshots in addition to cache updates. Since subscribers by design ignore unexpected messages, this should be fine. * Caching topics that don't use the caching pattern no longer forward non-cache updates. This makes no difference for the current caching topics. * mwi_topic_cached, channel_by_name_topic and presence_state_topic_cached have no subscribers * device_state_topic_cached's only subscriber only processes cache udpates (issue ASTERISK-22243) Review: https://reviewboard.asterisk.org/r/2738 git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@396329 65c4cc65-6c06-0410-ace0-fbb531ad65f3	13 years ago
David M. Lee	e1b959ccbb	Split caching out from the stasis_caching_topic. ... In working with res_stasis, I discovered a significant limitation to the current structure of stasis_caching_topics: you cannot subscribe to cache updates for a single channel/bridge/endpoint/etc. To address this, this patch splits the cache away from the stasis_caching_topic, making it a first class object. The stasis_cache object is shared amongst individual stasis_caching_topics that are created per channel/endpoint/etc. These are still forwarded to global whatever_all_cached topics, so their use from most of the code does not change. In making these changes, I noticed that we frequently used a similar pattern for bridges, endpoints and channels: single_topic ----------------> all_topic ^ | single_topic_cached ----+----> all_topic_cached | +----> cache This pattern was extracted as the 'Stasis Caching Pattern', defined in stasis_caching_pattern.h. This avoids a lot of duplicate code between the different domain objects. Since the cache is now disassociated from its upstream caching topics, this also necessitated a change to how the 'guaranteed' flag worked for retrieving from a cache. The code for handling the caching guarantee was extracted into a 'stasis_topic_wait' function, which works for any stasis_topic. (closes issue ASTERISK-22002) Review: https://reviewboard.asterisk.org/r/2672/ git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@395954 65c4cc65-6c06-0410-ace0-fbb531ad65f3	13 years ago