Summary:	ASTERISK-24909: Add clustering of the AstDB using PJSIP
Reporter:	Matt Jordan (mjordan)	Labels:
Date Opened:	2015-03-25 10:35:18	Date Closed:	2015-06-11 19:54:26
Priority:	Major	Regression?	No
Status:	Closed/Complete	Components:	Core/AstDB Resources/res_pjsip_publish_asterisk
Versions:		Frequency of Occurrence
Related Issues:
Environment:		Attachments:
Description:	As described on the [asterisk-dev mailing list|http://lists.digium.com/pipermail/asterisk-dev/2015-March/073192.html], I got some inspiration from seeing Kamailio's htable implementation, and thought a similar mechanism would work for the Asterisk Database. This patch is the result. This patch provides a mechanism to mark families within the AstDB as "shared." The marking of a family as shared is independent of the existance of the family, and is independent of the updates already made to the family. Shared families are subject to distribution with other Asterisk instances, as well as subject to updates from other Asterisk instances. Two strategies for sharing are implemented: h4. Global A 'global' shared family shares the family/key space with all other Asterisk instances. Say we have shared family 'foo', and we have two Asterisk instances. Say the first Asterisk instance (ast1) updates a key in family 'foo' to the following: {code}  ast1    /foo/key = bar {code} The second Asterisk instance (ast2) would then receive an update in its AstDB: {code}  ast2    /foo/key = bar {code} If ast2 later updates the same key in its local AstDB to 'foobar', ast1 will receive a notification to update the same key in its AstDB: {code}  ast2    /foo/key = foobar  ast1    /foo/key = foobar {code} h4. Unique A 'unique' shared family shares its values with other Asterisk instances, however, updates from other Asterisk instances are placed in unique families in the local AstDB for each Asterisk instance. Again, say we have shared family 'foo', and we have two Asterisk instances - ast1 and ast2. ast1 has an EID of 11:11:11:11:11:11, while ast2 has an EID of ff:ff:ff:ff:ff:ff. Say ast1 updates a key in family 'foo': {code}  ast1    /foo/key = bar {code} ast2 would receive the update for family 'foo', but instead of updating its local copy, it would instead store the value in a new family for ast1 corresponding to its EID: {code}  ast2    /11:11:11:11:11:11/foo/key = bar {code} If ast2 later updates the same ky in its local AstDB to 'foobar', the received value from ast1 will not be updated. However, ast1 will receive the update, and store the value in a new family for ast2 corresponding to its EID: {code}  ast2    /foo/key = foobar    /11:11:11:11:11:11/foo/key = bar  ast1    /foo/key = bar    /ff:ff:ff:ff:ff:ff/foo/key = foobar {code} In order to manipulate shared families, two new dialplan functions have been added, DB_SHARED and DB_SHARED_EXISTS. DB_SHARED allows for creation of a shared family, as well as deletion, while DB_SHARED_EXISTS returns whether or not a family is shared: {code}  same => n,Set(DB_SHARED(put,global)=foo)      ; share family 'foo' globally  same => n,Set(DB_SHARED(put,unique)=foobar)   ; share family 'foobar' uniquely  same => n,NoOp(${DB_SHARED_EXISTS(foo)})      ; returns '1'  same => n,Set(DB_SHARED(delete)=foo)          ; remove shared family status for 'foo' {code} CLI commands were also added to create/delete shared families, and the output of 'database show|showkey' updated to show the shared status of a family/key/value tuple. Finally, a mechanism for sharing AstDB information was added to the PJSIP stack's res_pjsip_publish_asterisk. This includes a new event type, 'asterisk-db', which contains the values being created/deleted. Necessary configuration parameters were added to the existing configuration objects that support inbound/outbound PUBLISH support. An example of a PUBLISH request with the new event type is shown below: {noformat} PUBLISH sip:ast1@127.0.0.1:5061 SIP/2.0 Via: SIP/2.0/UDP 127.0.0.1:5060;rport;branch=z9hG4bKPj1eb182a7-a0aa-4d73-995d-d2ad4b096db2 From: <sip:ast1@127.0.0.1>;tag=7b294642-06ae-4ecf-8637-db8ba2dc4397 To: <sip:ast1@127.0.0.1> Call-ID: b9463adc-e364-440d-8ce1-842372813b08 CSeq: 48111 PUBLISH Event: asterisk-db Expires: 3600 Max-Forwards: 70 User-Agent: Asterisk PBX SVN-mjordan-trunk-astdb-cluster-URL:-r432916M-/trunk Content-Type: application/json Content-Length:   156 {"type":"dbstate","eid":"11:11:11:11:11:11","dbstate":{"verb":"put","family":"global_shared","share_type":"global","entries":[{"data":"foo","key":"key1"}]}} {noformat} As a note on the power of the frameworks in Asterisk 13 - in this case, both Stasis and PJSIP - the vast bulk of this was written on two plane flights, plus a weekend or so of test writing and cleanup.
Comments:	By: Matt Jordan (mjordan) 2015-06-11 19:54:26.609-0500 While this was a fun patch, we decided (per discussion on the review and on the asterisk-dev list) that it would be better to do this sort of thing using a third party tool/library, and not to throw too much stuff into Asterisk or the PJSIP stack for it.