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This is an automatically generated e-mail. To reply, visit:
<a href="https://reviewboard.asterisk.org/r/1835/">https://reviewboard.asterisk.org/r/1835/</a>
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<p style="margin-top: 0;">On March 29th, 2012, 9:50 a.m., <b>Mark Michelson</b> wrote:</p>
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<a href="https://reviewboard.asterisk.org/r/1835/diff/1/?file=26924#file26924line938" style="color: black; font-weight: bold; text-decoration: underline;">/trunk/include/asterisk/astobj2.h</a>
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(Diff revision 1)
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<td colspan="2"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "></pre></td>
<td colspan="2"><pre style="font-size: 8pt; line-height: 140%; margin: 0; ">enum ao2_container_opts {</pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> * \brief Reject duplicate objects in container.</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> *</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> * \details Don't link the same object into the container twice.</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> * However, you can link a different object with the same key.</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> *</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> * \note It is assumed that the objects are located where the</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> * container key says they should be located.</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> */</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">AO2_CONTAINER_ALLOC_OPT_DUPS_OBJ_REJECT</span> <span class="o">=</span> <span class="p">(</span><span class="mi">2</span> <span class="o"><<</span> <span class="mi">1</span><span class="p">),</span></pre></td>
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<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">How do you plan to detect a duplicate object?</pre>
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<p>On March 29th, 2012, 11:30 a.m., <b>rmudgett</b> wrote:</p>
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<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Duplicate objects are easily detectable in sorted containers. Unsorted containers must be searched. I will note that the duplicate option is only applicable to sorted containers.</pre>
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<p>On March 29th, 2012, 2:02 p.m., <b>Mark Michelson</b> wrote:</p>
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<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">To clarify my question more, how do you differentiate between duplicate objects and objects with duplicate keys?
I suppose that my definition of what a duplicate key is may be different from yours. For instance, if you have an object type foo, and it has a field bar within it like:
struct foo {
char *bar;
};
Then it is reasonable to assume that we might compare foos by using the comparison function:
int cmp_foo(void *obj, void *arg, int flags)
{
struct foo *foo1 = obj;
struct foo *foo2 = arg;
return !strcmp(foo1->bar, foo2->bar) ? CMP_MATCH : 0;
}
Similarly, we may choose to hash foos using the hash function
int hash_foo(const void *obj, int flags)
{
struct foo *foo = obj;
return ast_str_hash(foo->bar);
}
Now, how do we determine if two foos are duplicates? Is it because cmp_foo() returns CMP_MATCH? Doesn't that just mean the objects have duplicate keys? Or would two foos be considered to have duplicate keys if hash_foo() returns the same value for two foos? If the latter, then what does it mean for an object to have duplicate keys if it is not in a hash container?</pre>
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<p>On March 29th, 2012, 2:49 p.m., <b>rmudgett</b> wrote:</p>
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<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Your elaboration further points out reasons why the container must be provided a sort_fn to use the duplicate options. Otherwise there is no way to tell if an object is a duplicate except if the object pointer is equal.</pre>
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<p>On March 29th, 2012, 5:10 p.m., <b>Mark Michelson</b> wrote:</p>
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<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">If I've distilled what you've just said correctly, then sort_fn() is what is used to determine whether an item is a duplicate object, but the cmp_fn() is what is used to determine whether two objects have duplicate keys. So for some objects, it's possible these definitions could overlap, but for others, it's not quite the case.</pre>
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<pre style="margin-left: 1em; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">The cmp_fn is used to select objects from the container. They either match the selection criteria or they don't (CMP_MATCH returned). The cmp_fn also can abort a container traversal (CMP_STOP returned).
The sort_fn is used to sort objects in the container. An object is equal/duplicate when the sort_fn returns zero.
The hash_fn is a specialized function for hash containers to determine what bucket to look in for an object.
If an ao2_callback has an OBJ_KEY or OBJ_POINTER flag then the hash_fn and sort_fn are used to locate an object in the container. The cmp_fn then is used to determine if any located objects are to be selected.
All three functions must handle the OBJ_KEY and OBJ_POINTER flags if they are used because all three are given the ao2_callback arg pointer as the object/key.</pre>
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<p>- rmudgett</p>
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<p>On March 29th, 2012, 5:06 p.m., rmudgett wrote:</p>
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<div>Review request for Asterisk Developers, Mark Michelson and Matt Jordan.</div>
<div>By rmudgett.</div>
<p style="color: grey;"><i>Updated March 29, 2012, 5:06 p.m.</i></p>
<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;">RFC to add proposed API enhancements for containers.
API allows for sorted containers, insertion options, duplicate handling options, and traversal order options.
Also has several documentation corrections.</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;">It compiles but doesn't link. This is a RFC. :)</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/include/asterisk/astobj2.h <span style="color: grey">(360828)</span></li>
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<p><a href="https://reviewboard.asterisk.org/r/1835/diff/" style="margin-left: 3em;">View Diff</a></p>
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