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This is an automatically generated e-mail. To reply, visit:
<a href="https://reviewboard.asterisk.org/r/2721/">https://reviewboard.asterisk.org/r/2721/</a>
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<a href="https://reviewboard.asterisk.org/r/2721/diff/1/?file=43333#file43333line1317" style="color: black; font-weight: bold; text-decoration: underline;">/trunk/main/bridge_channel.c</a>
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(Diff revision 1)
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<td colspan="4"><pre style="font-size: 8pt; line-height: 140%; margin: 0; ">static void bridge_channel_dissolve_check(struct ast_bridge_channel *bridge_channel)</pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="n">AST_LIST_TRAVERSE</span><span class="p">(</span><span class="o">&</span><span class="n">bridge</span><span class="o">-></span><span class="n">channels</span><span class="p">,</span> <span class="n">other</span><span class="p">,</span> <span class="n">entry</span><span class="p">)</span> <span class="p">{</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="tb"> </span><span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">ast_test_flag</span><span class="p">(</span><span class="o">&</span><span class="n">other</span><span class="o">-></span><span class="n">features</span><span class="o">-></span><span class="n">feature_flags</span><span class="p">,</span> <span class="n">AST_BRIDGE_CHANNEL_FLAG_LONELY</span><span class="p">))</span> <span class="p">{</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="tb"> </span><span class="tb"> </span><span class="n">ast_log</span><span class="p">(</span><span class="n">LOG_NOTICE</span><span class="p">,</span> <span class="s">"Loneliness lowered</span><span class="se">\n</span><span class="s">"</span><span class="p">);</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="tb"> </span><span class="tb"> </span><span class="n">all_lonely</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="tb"> </span><span class="tb"> </span><span class="k">break</span><span class="p">;</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="tb"> </span><span class="p">}</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="p">}</span></pre></td>
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<pre style="margin-left: 2em; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">This loop works in O(n) every time a channel is removed from a bridge. But since all n channels will eventually be removed from the bridge, this loop will have an effective cost of O(n^2) removing all channels from a bridge. For even a moderate number of channels in a bridge, this could be a big performance problem.
It may be better to count lonely channels as they are added/removed from the bridge, assuming that a channel can't become lonely/unlonely once it's in a bridge.</pre>
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<a href="https://reviewboard.asterisk.org/r/2721/diff/1/?file=43333#file43333line1325" style="color: black; font-weight: bold; text-decoration: underline;">/trunk/main/bridge_channel.c</a>
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(Diff revision 1)
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<td colspan="4"><pre style="font-size: 8pt; line-height: 140%; margin: 0; ">static void bridge_channel_dissolve_check(struct ast_bridge_channel *bridge_channel)</pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="k">if</span> <span class="p">(</span><span class="n">all_lonely</span><span class="p">)</span> <span class="p">{</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="tb"> </span><span class="n">AST_LIST_TRAVERSE</span><span class="p">(</span><span class="o">&</span><span class="n">bridge</span><span class="o">-></span><span class="n">channels</span><span class="p">,</span> <span class="n">other</span><span class="p">,</span> <span class="n">entry</span><span class="p">)</span> <span class="p">{</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="tb"> </span><span class="tb"> </span><span class="n">ast_bridge_channel_leave_bridge</span><span class="p">(</span><span class="n">other</span><span class="p">,</span> <span class="n">BRIDGE_CHANNEL_STATE_END_NO_DISSOLVE</span><span class="p">);</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="tb"> </span><span class="tb"> </span><span class="n">bridge_channel_internal_pull</span><span class="p">(</span><span class="n">other</span><span class="p">);</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="tb"> </span><span class="p">}</span></pre></td>
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<pre style="margin-left: 2em; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">bridge_channel_internal_pull() and bridge_channel_dissolve_check() are co-recursive. The code might actually work, just accidentally.
The internal_pull() function removes other from bridge->channels, which causes the loop to terminate early. The loop only pulls the first channel from the bridge.
But since internal_pull() calls dissolve_check(), it will recursively pull the first channel from the bridge until all the channels have been removed.
With enough lonely channels in a bridge, this could blow the stack.</pre>
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<p>- David</p>
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<p>On July 31st, 2013, 12:31 p.m. CDT, jrose wrote:</p>
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<div>Review request for Asterisk Developers, David Lee, Matt Jordan, and rmudgett.</div>
<div>By jrose.</div>
<p style="color: grey;"><i>Updated July 31, 2013, 12:31 p.m.</i></p>
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<b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>
<a href="https://issues.asterisk.org/jira/browse/ASTERISK-22117">ASTERISK-22117</a>
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<b style="color: #575012; font-size: 10pt;">Repository: </b>
Asterisk
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
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<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Channels with the lonely flag are supposed to leave a bridge if all of the channels in that bridge are also lonely at the time of a channel dissolving.
I also added this flag to ARI play and record on bridge channels.</pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
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<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Tested what happens to channels when a non-lonely channel leaves with and without the presence of non-lonely channels.
If only lonely channels were left, they hung up. This did produce an ARI playback error since the channel playback was interrupted.
If non-lonely channels were left, nothing would happen as anticipated.</pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
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<li>/trunk/main/core_unreal.c <span style="color: grey">(395852)</span></li>
<li>/trunk/res/ari/resource_bridges.c <span style="color: grey">(395852)</span></li>
<li>/trunk/include/asterisk/core_unreal.h <span style="color: grey">(395852)</span></li>
<li>/trunk/main/bridge_channel.c <span style="color: grey">(395852)</span></li>
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<p><a href="https://reviewboard.asterisk.org/r/2721/diff/" style="margin-left: 3em;">View Diff</a></p>
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