app_cdr,app_forkcdr,func_cdr: Synchronize with engine when manipulating state

When doing the rework of the CDR engine that pushed all of the logic into cdr.c
and made it respond to changes in channel state over Stasis, we knew that
accessing the CDR engine from the dialplan would be "slightly"
non-deterministic. Dialplan threads would be accessing CDRs while Stasis
threads would be updating the state of said CDRs - whereas in the past,
everything happened on the dialplan threads. Tests have shown that "slightly"
is in reality "very".

This patch synchronizes things by making the dialplan applications/functions
that manipulate CDRs do so over Stasis. ForkCDR, NoCDR, ResetCDR, CDR, and
CDR_PROP now all use Stasis to send their requests over to the CDR engine,
and synchronize on the channel Stasis topic via a subscription so that they
return their values/control to the dialplan at the appropriate time.

While going through this, the following changes were also made:
 * DISA, which can reset the CDR when a user successfully authenticates, now
   just uses the ResetCDR app to do this. This prevents having to duplicate
   the same Stasis synchronization logic in that application.
 * Answer no longer disables CDRs. It actually didn't work anyway - calling
   DISABLE on the channel's CDR doesn't stop the CDR from getting the Answer
   time - it just kills all CDRs on that channel, which isn't what the caller
   would intend.

(closes issue ASTERISK-22884)
(closes issue ASTERISK-22886)

Review: https://reviewboard.asterisk.org/r/3057/
........

Merged revisions 404294 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@404295 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 9 insertions, 0 deletions

diff --git a/UPGRADE-12.txt b/UPGRADE-12.txt
index 6486f3e47..e65cedc21 100644
--- a/UPGRADE-12.txt
+++ b/UPGRADE-12.txt
@@ -101,10 +101,19 @@ AgentMonitorOutgoing
  - This application has been removed. It was a holdover from when
    AgentCallbackLogin was removed.
 
+Answer
+ - It is no longer possible to bypass updating the CDR when answering a
+   channel. CDRs are based on the channel state and will be updated when
+   the channel is Answered.
+
 ControlPlayback
  - The channel variable CPLAYBACKSTATUS may now return the value
    'REMOTESTOPPED' when playback is stopped by an external entity.
 
+DISA
+ - This application now has a dependency on the app_cdr module. It uses this
+   module to hide the CDR created prior to execution of the DISA application.
+
 DumpChan:
  - The output of DumpChan no longer includes the DirectBridge or IndirectBridge
    fields. Instead, if a channel is in a bridge, it includes a BridgeID field