Block cache should be BLOCK_NO_CACHE

Version with patch bot .module and .install files

This is critical to UI bacause ALL users see same block with COUNT from user who open the page first...

Docs
http://api.drupal.org/api/function/hook_block/6
http://api.drupal.org/api/constant/BLOCK_CACHE_PER_USER/6

@litwol 6.x-1.0-rc2 still defines block without BLOCK_CACHE_PER_USER so update_6002 is needed.

CVS DRUPAL-6--1 already holds BLOCK_CACHE_PER_USER definition for block but there's not update function in .install

This patch should wait till #370960: Remove t() from all schema descriptions

@Berdir update block table - not cache

Sorry, blocks not cache
patch against -6--1

@litwol Agree exactly

There are some ideas - previous way is wrong

1) Quick solution - set block->cache to BLOCK_NO_CACHE and check for new messages on every page request
2) Advanced - leave BLOCK_CACHE_PER_USER but make some logic for sending messages
- clear cache per recipient when message is sent
- clear own cache when user oen a message

Suppose 2 is little hard to implement but it brings some perfomance (I'll try)

But wanna know opinion of maintainers

At this moment I see 2 blocks + menuitem they all brings same functionality (notify users about new messages)

All of them call only one function privatemsg_unread_count() which executes query only once and staticaly caches the result so no matter how offen it called.

Menu item updates on *privatemsg_title_callback*

This 2 blocks never updates (I found no cache_clear_all) they should called on send for all recipients

$block = new stdClass();
$block->module = 'privatemsg';
$block->delta = 'privatemsg-menu'; //privatemsg-new
$block->cache = BLOCK_CACHE_PER_USER;

//Calculate hash for block but only for current user
$cid = _block_get_cache_id($block);
cache_clear_all($cid, 'cache_block');

I use this code in some parts but when I need clear cache for different users I need to know there $theme $language
So I change the _block_get_cache_id by my own function

function _mymodule_clear_cache($uid) {
  if (variable_get('block_cache', 0)) {
    global $theme;
    $save = $theme;
    $themes = list_themes();
    foreach ($themes as $tmp) {
      $theme = $tmp->name;
      $block = new stdClass();
      $block->module = 'click2bookmark';
      $block->delta = 0;
      $block->cache = BLOCK_CACHE_PER_USER;
      if ($cid = _block_get_cache_id($block)) {
        cache_clear_all($cid, 'cache_block');
      }
    }
    $theme = $save;
  }
}

This function work only for current user but clears cache for all user's themes (all themes)
It's easy to change (copy/paste) *_block_get_cache_id* code to make cache_id depending on needs

Agree exactly... I just forget about multiple recipients and there themes-languages

Code that generate this blocks are lightweigh so caching is optional

RTBS patch from #14

Just reroll against current state