I've noticed that the discovered links block shown to anonymous and logged-in users are the same (and apparently incorrect) across many nodes, whereas those shown to the site admin are different (and presumably, more correct) in the same situation.

I notice that if I disable caching and reload the page the logged-in users see the same relevant discovered links as those shown to the site admin when viewing the same node.

This behavior makes no sense to me. Is this module incompatible with Drupal's normal and block caching mechanisms?



mcurry’s picture

Addendum: I've also noticed that the discovered links block is often empty (missing) for logged-in and anonymous users, but it appears as expected for the site admin. Once again, disabling caching fixes this.

The discovered links block is configured to be shown to all users (no roles checked, and all users must view the block, in the block settings page)

mcurry’s picture

Category: support » bug

Digging into the module source code, I see that the node's discovered links are updated in hook_block... which means that the block caching mechanism might interfere with discovered links updates.

According to the hook_block API docs, it appears the hook_block 'list' needs to return a 'cache' entry in order to override default caching:

This seems to fix it for me:

function relatedlinks_block($op = 'list', $delta = 0) {
  switch ($op) {
    case 'list':
      $blocks = array();

      $link_types = variable_get('relatedlinks_types', _relatedlinks_get_type_defaults());
      $top = TRUE;
      foreach ($link_types as $type => $config) {
        if ($config['enabled'] && ($config['block'] || $top)) {
          $top = FALSE;
          $blocks[$type]['info'] = t('Related links: ') . check_plain($config['name']);
          // Per hook_block API spec, it appears we need to add this to cache per node:
          $blocks[$type]['cache'] = BLOCK_CACHE_PER_NODE;

Or have I missed something here? Please advise.

mcurry’s picture

Title: Caching question: Discovered related links differ between logged-in users and site admin when caching enabled » Link update problems when block caching enabled

Changing issue title...

mcurry’s picture

Status: Active » Needs review
676 bytes

Attaching patch for consideration.

mcurry’s picture

Version: 6.x-1.x-dev » 6.x-1.0-beta2

Fixing version, since I'm working against the 6.x-1.0-beta2 branch (that's the last one I installed).

mcurry’s picture

Update: We may need to use BLOCK_NO_CACHE in order to ensure that hook_block() view ops are called on every node load:

          $blocks[$type]['cache'] = BLOCK_NO_CACHE;

Feedback welcome and wanted!

mcurry’s picture

Issue tags: +DrupalWTF

Ugh. It appears that D6 fails to pick up block caching mode changes once a block has been registered in the {blocks} table ( #235673: Changes to block caching mode not caught ), which is the case here - changing the ['cache'] = BLOCK_NO_CACHE (or BLOCK_CACHE_PER_PAGE) will have no effect if you've installed and used the module and relatedlinks blocks previously, and uninstalling the module through Drupal's uninstall feature does not remove existing relatedlinks blocks from the {blocks} table!

mysql> select delta, cache from blocks where module='relatedlinks';
| delta | cache |
| 2     |     1 |
| 3     |     1 |
2 rows in set (0.00 sec)

Note that the 'cache' column is set to 1, which is defined in blocks.module as BLOCK_CACHE_PER_ROLE. We need to manually update the {blocks} table to use -1 (defined in blocks.module as BLOCK_NO_CACHE) or 4 (BLOCK_CACHE_PER_PAGE).

mysql> update blocks set cache=4 where module='relatedlinks';
Query OK, 2 rows affected (1.35 sec)

mysql> select delta, cache from blocks where module='relatedlinks';
| delta | cache |
| 2     |     4 |
| 3     |     4 |
2 rows in set (0.00 sec)


mcurry’s picture

Related issue -- here's why uninstalling the module doesn't clean out the {block} table's entries for the module:
#735900: Deleting module's blocks when module is uninstalled

mattwmc’s picture

Hmm...is this why my links appear "stuck?"

I have Boost enabled and the related links are always showing the same links even after the cache is cleared.

Zen’s picture

Version: 6.x-1.0-beta2 » 6.x-1.x-dev
Status: Needs review » Fixed

Committed with BLOCK_NO_CACHE and an update function. Thanks for the patch.


Automatically closed -- issue fixed for 2 weeks with no activity.