[asterisk-dev] [Code Review] Start the process of opaque-ifying the ast_channel by replacing direct access to the 'name' field with accessor functions.

schmidts reviewboard at asterisk.org
Mon Jan 9 06:13:01 CST 2012 

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looks good for me so far. i didnt checked the whole diff completly but imho 98% of this is only replacing chan->name with ast_channel_name(chan).
i only have some questions.



/trunk/include/asterisk/channel.h
<https://reviewboard.asterisk.org/r/1655/#comment9550>

    just an idea. you could let name stay here and initialise it with a warning value like "please dont use chan->name directly anymore use ast_channel_name(chan) instead". so this could help devs to fix their own apps.



/trunk/main/channel.c
<https://reviewboard.asterisk.org/r/1655/#comment9551>

    adding the warning here about not to use name anymore see comment in channel.h



/trunk/main/channel.c
<https://reviewboard.asterisk.org/r/1655/#comment9552>

    just a very short question about locking here. Imho it is possible that the name of the channel, given as argument, could change after this, shouldnt this channel (arg) be locked too?



/trunk/main/channel.c
<https://reviewboard.asterisk.org/r/1655/#comment9548>

    you could use CMP_MATCH & CMP_STOP here cause channel name should be unique imho.
    
    same on the ast_channel_by_uniqueid_cp.



/trunk/main/channel.c
<https://reviewboard.asterisk.org/r/1655/#comment9549>

    see comment above, CMP_MATCH & CMP_STOP



/trunk/main/channel.c
<https://reviewboard.asterisk.org/r/1655/#comment9553>

    you should add this before the callback:
    
    if (ast_strlen_zero(name) && exten && context && (chan = ast_channel_callback....
    
    imho you would get an error message for each channel (see row 1448) if this is called with an empty name and no exten & context set. I dont know if this even could happen but row 1590 looks like it could be.


fine work and a good way to go.

- schmidts


On Jan. 6, 2012, 3:51 p.m., Terry Wilson wrote:
> 
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> 
> (Updated Jan. 6, 2012, 3:51 p.m.)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Summary
> -------
> 
> There would be many benefits to making the ast_channel an opaque handle, from increasing maintainability to presenting ways to kill masquerades. I propose that we kick things off by taking things a field at a time, renaming the field to '__do_not_use_${fieldname}' and then writing setters/getters and converting the existing code to using them. When all fields are done, we can move ast_channel to a C file from channel.h and lop off the '__do_not_use_'.
> 
> This patch sets up main/channel_interal_api.c to be the only file that actually accesses the ast_channel's fields directly. The intent would be for any API functions in channel.c to use the accessor functions. No more monkeying around with channel internals. We should use our own APIs.
> 
> The interesting changes in this patch are the addition of channel_internal_api.c, the moving of the AST_DATA stuff from channel.c to channel_internal_api.c (note: the AST_DATA stuff will have to be reworked to use accessor functions when ast_channel is really opaque), and some re-working of the way channel iterators/callbacks are handled so as to avoid creating fake ast_channels on the stack to pass in matching data by directly accessing fields (since "name" is a stringfield and the fake channel doesn't init the stringfields, you can't use the ast_channel_name_set() function). I went with ast_channel_name(chan) for a getter, and ast_channel_name_set(chan, name) for a setter.
> 
> Ideas welcome!
> 
> The majority of the grunt-work for this change was done by writing a semantic patch using Coccinelle ( http://coccinelle.lip6.fr/ ).
> 
> note: There are some extra changes to some of the h323 files to comment out variables that were set and not used so that I could get it to compile under dev-mode.
> 
> 
> Diffs
> -----
> 
>   /trunk/addons/chan_mobile.c 349871 
>   /trunk/addons/chan_ooh323.c 349871 
>   /trunk/addons/ooh323c/src/memheap.c 349871 
>   /trunk/apps/app_adsiprog.c 349871 
>   /trunk/apps/app_alarmreceiver.c 349871 
>   /trunk/apps/app_amd.c 349871 
>   /trunk/apps/app_chanisavail.c 349871 
>   /trunk/apps/app_chanspy.c 349871 
>   /trunk/apps/app_confbridge.c 349871 
>   /trunk/apps/app_dahdibarge.c 349871 
>   /trunk/apps/app_dahdiras.c 349871 
>   /trunk/apps/app_dial.c 349871 
>   /trunk/apps/app_directed_pickup.c 349871 
>   /trunk/apps/app_disa.c 349871 
>   /trunk/apps/app_dumpchan.c 349871 
>   /trunk/apps/app_externalivr.c 349871 
>   /trunk/apps/app_fax.c 349871 
>   /trunk/apps/app_flash.c 349871 
>   /trunk/apps/app_followme.c 349871 
>   /trunk/apps/app_getcpeid.c 349871 
>   /trunk/apps/app_jack.c 349871 
>   /trunk/apps/app_macro.c 349871 
>   /trunk/apps/app_meetme.c 349871 
>   /trunk/apps/app_milliwatt.c 349871 
>   /trunk/apps/app_minivm.c 349871 
>   /trunk/apps/app_mixmonitor.c 349871 
>   /trunk/apps/app_page.c 349871 
>   /trunk/apps/app_parkandannounce.c 349871 
>   /trunk/apps/app_playback.c 349871 
>   /trunk/apps/app_queue.c 349871 
>   /trunk/apps/app_readexten.c 349871 
>   /trunk/apps/app_record.c 349871 
>   /trunk/apps/app_rpt.c 349871 
>   /trunk/apps/app_sms.c 349871 
>   /trunk/apps/app_softhangup.c 349871 
>   /trunk/apps/app_stack.c 349871 
>   /trunk/apps/app_talkdetect.c 349871 
>   /trunk/apps/app_test.c 349871 
>   /trunk/apps/app_voicemail.c 349871 
>   /trunk/apps/app_waitforsilence.c 349871 
>   /trunk/bridges/bridge_multiplexed.c 349871 
>   /trunk/channels/chan_agent.c 349871 
>   /trunk/channels/chan_alsa.c 349871 
>   /trunk/channels/chan_console.c 349871 
>   /trunk/channels/chan_dahdi.c 349871 
>   /trunk/channels/chan_gtalk.c 349871 
>   /trunk/channels/chan_h323.c 349871 
>   /trunk/channels/chan_iax2.c 349871 
>   /trunk/channels/chan_jingle.c 349871 
>   /trunk/channels/chan_local.c 349871 
>   /trunk/channels/chan_mgcp.c 349871 
>   /trunk/channels/chan_misdn.c 349871 
>   /trunk/channels/chan_nbs.c 349871 
>   /trunk/channels/chan_oss.c 349871 
>   /trunk/channels/chan_phone.c 349871 
>   /trunk/channels/chan_sip.c 349871 
>   /trunk/channels/chan_skinny.c 349871 
>   /trunk/channels/chan_unistim.c 349871 
>   /trunk/channels/chan_usbradio.c 349871 
>   /trunk/channels/chan_vpb.cc 349871 
>   /trunk/channels/console_video.c 349871 
>   /trunk/channels/sig_analog.c 349871 
>   /trunk/channels/sig_pri.c 349871 
>   /trunk/channels/sig_ss7.c 349871 
>   /trunk/funcs/func_audiohookinherit.c 349871 
>   /trunk/funcs/func_channel.c 349871 
>   /trunk/funcs/func_frame_trace.c 349871 
>   /trunk/funcs/func_global.c 349871 
>   /trunk/funcs/func_groupcount.c 349871 
>   /trunk/funcs/func_lock.c 349871 
>   /trunk/include/asterisk/channel.h 349871 
>   /trunk/main/abstract_jb.c 349871 
>   /trunk/main/aoc.c 349871 
>   /trunk/main/app.c 349871 
>   /trunk/main/autochan.c 349871 
>   /trunk/main/bridging.c 349871 
>   /trunk/main/ccss.c 349871 
>   /trunk/main/cdr.c 349871 
>   /trunk/main/cel.c 349871 
>   /trunk/main/channel.c 349871 
>   /trunk/main/channel_internal_api.c PRE-CREATION 
>   /trunk/main/cli.c 349871 
>   /trunk/main/dial.c 349871 
>   /trunk/main/dsp.c 349871 
>   /trunk/main/features.c 349871 
>   /trunk/main/file.c 349871 
>   /trunk/main/indications.c 349871 
>   /trunk/main/manager.c 349871 
>   /trunk/main/pbx.c 349871 
>   /trunk/main/rtp_engine.c 349871 
>   /trunk/main/say.c 349871 
>   /trunk/main/udptl.c 349871 
>   /trunk/pbx/pbx_dundi.c 349871 
>   /trunk/pbx/pbx_lua.c 349871 
>   /trunk/pbx/pbx_realtime.c 349871 
>   /trunk/res/res_adsi.c 349871 
>   /trunk/res/res_agi.c 349871 
>   /trunk/res/res_calendar.c 349871 
>   /trunk/res/res_fax.c 349871 
>   /trunk/res/res_jabber.c 349871 
>   /trunk/res/res_monitor.c 349871 
>   /trunk/res/res_musiconhold.c 349871 
>   /trunk/res/res_mutestream.c 349871 
>   /trunk/res/snmp/agent.c 349871 
> 
> Diff: https://reviewboard.asterisk.org/r/1655/diff
> 
> 
> Testing
> -------
> 
> I ran it through the testsuite and seemed to get the same number of failures that I got without it. I also made some calls and tested out 'core show channel <tab>' and 'core show channel Console/dsp', and core show channels to make sure that the changes to the iterators seemed to work.
> 
> 
> Thanks,
> 
> Terry
> 
>

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