lookupInHash() implementations have logic error - path aliases not found
>>> [!note] Migrated issue
<!-- Drupal.org comment -->
<!-- Migrated from issue #2728831. -->
Reported by: [das-peter](https://www.drupal.org/user/762870)
>>>
<h3 id="summary-problem-motivation">Problem/Motivation</h3>
<p>Looking up sources for aliases sometimes results in "not found" even if the alias exists.</p>
<p>Sounds similar to <span class="drupalorg-gitlab-issue-link drupalorg-gitlab-link-wrapper"><a href="https://git.drupalcode.org/project/redis/-/work_items/2625166" class="drupalorg-gitlab-link">https://git.drupalcode.org/project/redis/-/work_items/2625166</a></span> but isn't related to whitespaces - so here's a decicated ticket :)</p>
<p>The scenario is as follows:</p>
<ol>
<li>Look up path for specific language e.g. <code>contact-us-now</code> (<code>HGET prefix:path:s:en contact-us-now</code>)</li>
<li><code>Redis_Path_PhpRedis::lookupInHash()</code> will enable <code>$doNoneLookup</code></li>
<li>Now if <code>Redis_Path_PhpRedis::lookupInHash()</code> doesn't find a language specific item it goes and tries to find a language neutral one (<code>HGET prefix:path:s:und contact-us-now</code>)</li>
<li>But if the language neutral item was explicitly set to not existent (<code>Redis_Path_HashLookupInterface::VALUE_NULL</code> = <code>!</code>) no return restore will happen due this code: <code>if (!$ret && $previous) {</code> - this again leads to returning FALSE which means "item not existent" even thought we actually just don't know if there's a language specific item.</li>
</ol>
<h3 id="summary-proposed-resolution">Proposed resolution</h3>
<p>I suggest to change the return restore condition to following:</p>
<div class="codeblock">
<pre><span style="color: #000000"><span style="color: #0000BB"><?php<br> </span><span style="color: #FF8000">// If the language specific item was explicitly set to not-existent<br> // and there's no language neutral item ensure the return is set to<br> // not-existent.<br> // OR<br> // If the language neutral item is explicitly set to not-existent but<br> // the language specific item is set to not found set the return to<br> // not found - this will allow a lookup of the language specific item<br> // and a proper cache set to not-existent if applicable.<br> </span><span style="color: #007700">if ((!</span><span style="color: #0000BB">$ret </span><span style="color: #007700">&& </span><span style="color: #0000BB">$previous</span><span style="color: #007700">) || (</span><span style="color: #0000BB">self</span><span style="color: #007700">::</span><span style="color: #0000BB">VALUE_NULL </span><span style="color: #007700">=== </span><span style="color: #0000BB">$ret </span><span style="color: #007700">&& empty(</span><span style="color: #0000BB">$previous</span><span style="color: #007700">))) {<br> </span><span style="color: #FF8000">// Restore null placeholder else we loose conversion to false<br> // and drupal_lookup_path() would attempt saving it once again.<br> </span><span style="color: #0000BB">$ret </span><span style="color: #007700">= </span><span style="color: #0000BB">$previous</span><span style="color: #007700">;<br> }<br></span><span style="color: #0000BB">?></span></span></pre></div>
<p>As the added comment states. If the language neutral item is explicitly set to not-existent, but the language specific item just isn't found we shouldn't skip looking up the language specific item by returning FALSE but we should do a look up and ensure the language specific item is set to the appropriate value in the cache.<br>
This will also avoid the language neutral lookup in sub-sequent requests which means it's a tiny bit more efficient (while not leading to inconsistencies e.g. due the language specific item being evicted when running redis as LRU).</p>
<h3 id="summary-remaining-tasks">Remaining tasks</h3>
<p>Reviews needed.</p>
<h3 id="summary-ui-changes">User interface changes</h3>
<p>None</p>
<h3 id="summary-api-changes">API changes</h3>
<p>Well the return of <code>Redis_Path_PhpRedis::lookupInHash()</code> / <code>Redis_Path_Predis::lookupInHash()</code> will change in some scenarios but that's fair I guess :)</p>
<h3 id="summary-data-model-changes">Data model changes</h3>
<p>None.</p>
>>> [!note] Pre-migration files
- [redis-path-handling-inconsistency.patch](https://www.drupal.org/files/issues/redis-path-handling-inconsistency.patch)
>>>
issue
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