[asterisk-dev] [Code Review] Convert ast_channel over to astobj2

Mark Michelson mmichelson at digium.com
Tue Mar 24 18:58:08 CDT 2009 

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Ship it!


Definitely looking good. Only two major findings this time and one is my fault. I'll get my part fixed, and if you get the other two fixed, this has my approval pending some heavy testing.

Good job on this massive conversion, Russell!


/trunk/apps/app_directed_pickup.c
<http://reviewboard.digium.com/r/203/#comment1584>

    A couple of changes:
    
    1. target should be unreffed unconditionally. As it is, if a channel tries to pick up a call to itself, you'll leak a reference.
    2. The comparison of chan->name to target->name is a bit weird here. I think just making sure that chan != target would work here.



/trunk/doc/CODING-GUIDELINES
<http://reviewboard.digium.com/r/203/#comment1585>

    This and the other hunk in CODING-GUIDELINES is not part of this work and should not be included here.



/trunk/main/autochan.c
<http://reviewboard.digium.com/r/203/#comment1587>

    Hmm, I think I've spotted a bug here that I introduced when moving from a global autochan list to having an autochan list for each channel.
    
    I actually need to move the autochan to the new channel here in addition to pointing the autochan->chan pointer to the new channel. By not doing so, I'm introducing a memory leak since any autochans left on the old channel will not get freed when ast_autochan_destroy is called. I'll get this fixed up ASAP.


- Mark


On 2009-03-23 15:57:14, Russell Bryant wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> http://reviewboard.digium.com/r/203/
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> 
> (Updated 2009-03-23 15:57:14)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Summary
> -------
> 
> This patch converts handling of the ast_channel data structure over to the astobj2 framework.  There is a lot that could be said about this, but the patch is a bit improvement for performance, stability, code maintainability, and ease of future code development.
> 
> The channel list is no longer an unsorted linked list.  The main container for channels is an astobj2 hash table.  All of the code related to searching for channels or iterating active channels has been rewritten.  Let n be the number of active channels.  Iterating the channel list has gone from O(n^2) to O(n).  Searching for a channel by name went from O(n) to O(1).  Searching for a channel by extension is still O(n), but uses a new method for doing so, which is more efficient.
> 
> The ast_channel object is now a reference counted object.  The benefits here are plentiful.  Some benefits directly related to issues in the previous code include:
> 
> 1) When threads other than the channel thread owning a channel wanted access to a channel, it had to hold the lock on it to ensure that it didn't go away.  This is no longer a requirement.  Holding a reference is sufficient.
> 
> 2) There are places that now require less dealing with channel locks.
> 
> 3) There are places where channel locks are held for much shorter periods of time.
> 
> 4) There are places where dealing with more than one channel at a time becomes _MUCH_ easier.  ChanSpy is a great example of this.  Writing code in the future that deals with multiple channels will be much easier.
> 
> Some additional information regarding channel locking and reference count handling can be found in channel.h, where a new section has been added that discusses some of the rules associated with it.
> 
> Mark Michelson also assisted with the development of this patch.  He did the conversion of ChanSpy and introduced a new API, ast_autochan, which makes it much easier to deal with holding on to a channel pointer for an extended period of time and having it get automatically updated if the channel gets masqueraded.
> 
> One final note is that currently, app_dahdichan will not compile.  I just haven't been motivated enough to do it.  Everything else should be good to go, though.  I think the best thing to do is to just add whatever is necessary to ChanSpy to allow DAHDIChan to become a wrapper for ChanSpy.
> 
> 
> Diffs
> -----
> 
>   /trunk/apps/app_channelredirect.c 183819 
>   /trunk/apps/app_chanspy.c 183819 
>   /trunk/apps/app_dahdiscan.c 183819 
>   /trunk/apps/app_directed_pickup.c 183819 
>   /trunk/apps/app_minivm.c 183819 
>   /trunk/apps/app_mixmonitor.c 183819 
>   /trunk/apps/app_senddtmf.c 183819 
>   /trunk/apps/app_softhangup.c 183819 
>   /trunk/apps/app_voicemail.c 183819 
>   /trunk/build_tools/cflags.xml 183819 
>   /trunk/channels/chan_agent.c 183819 
>   /trunk/channels/chan_bridge.c 183819 
>   /trunk/channels/chan_dahdi.c 183819 
>   /trunk/channels/chan_gtalk.c 183819 
>   /trunk/channels/chan_iax2.c 183819 
>   /trunk/channels/chan_local.c 183819 
>   /trunk/channels/chan_mgcp.c 183819 
>   /trunk/channels/chan_misdn.c 183819 
>   /trunk/channels/chan_sip.c 183819 
>   /trunk/channels/chan_unistim.c 183819 
>   /trunk/doc/CODING-GUIDELINES 183819 
>   /trunk/funcs/func_channel.c 183819 
>   /trunk/funcs/func_global.c 183819 
>   /trunk/funcs/func_logic.c 183819 
>   /trunk/funcs/func_odbc.c 183819 
>   /trunk/include/asterisk/autochan.h PRE-CREATION 
>   /trunk/include/asterisk/channel.h 183819 
>   /trunk/include/asterisk/lock.h 183819 
>   /trunk/main/Makefile 183819 
>   /trunk/main/autochan.c PRE-CREATION 
>   /trunk/main/channel.c 183819 
>   /trunk/main/cli.c 183819 
>   /trunk/main/devicestate.c 183819 
>   /trunk/main/features.c 183819 
>   /trunk/main/logger.c 183819 
>   /trunk/main/manager.c 183819 
>   /trunk/main/pbx.c 183819 
>   /trunk/res/res_agi.c 183819 
>   /trunk/res/res_clioriginate.c 183819 
>   /trunk/res/res_monitor.c 183819 
>   /trunk/res/snmp/agent.c 183819 
> 
> Diff: http://reviewboard.digium.com/r/203/diff
> 
> 
> Testing
> -------
> 
> I've done some basic testing making calls, transfers, etc., and I know Mark has done some, too.  However, this is one of those patches that seems like you can never test it enough.
> 
> Basically, any usage of Asterisk is useful testing for this.
> 
> 
> Thanks,
> 
> Russell
> 
>

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