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

1 files changed, 3 insertions, 3 deletions

diff --git a/main/cli.c b/main/cli.c
index 6474f3e72..6ca0737ab 100644
--- a/main/cli.c
+++ b/main/cli.c
@@ -915,7 +915,7 @@ static char *handle_chanlist(struct ast_cli_entry *e, int cmd, struct ast_cli_ar
 		return CLI_SHOWUSAGE;
 
 
-	if (!(channels = stasis_cache_dump(ast_channel_topic_all_cached_by_name(), ast_channel_snapshot_type()))) {
+	if (!(channels = stasis_cache_dump(ast_channel_cache_by_name(), ast_channel_snapshot_type()))) {
 		ast_cli(a->fd, "Failed to retrieve cached channels\n");
 		return CLI_SUCCESS;
 	}
@@ -1438,7 +1438,7 @@ static char *handle_showchan(struct ast_cli_entry *e, int cmd, struct ast_cli_ar
 
 	now = ast_tvnow();
 
-	if (!(msg = stasis_cache_get(ast_channel_topic_all_cached_by_name(), ast_channel_snapshot_type(), a->argv[3]))) {
+	if (!(msg = stasis_cache_get(ast_channel_cache_by_name(), ast_channel_snapshot_type(), a->argv[3]))) {
 		ast_cli(a->fd, "%s is not a known channel\n", a->argv[3]);
 		return CLI_SUCCESS;
 	}
@@ -1571,7 +1571,7 @@ char *ast_complete_channels(const char *line, const char *word, int pos, int sta
 		return NULL;
 	}
 
-	if (!(cached_channels = stasis_cache_dump(ast_channel_topic_all_cached(), ast_channel_snapshot_type()))) {
+	if (!(cached_channels = stasis_cache_dump(ast_channel_cache(), ast_channel_snapshot_type()))) {
 		return NULL;
 	}