Split up flushing in multiple functions

Really useful - but I think it's better to separate flush & flush_wildcard because flush and flush_temp are same

  function flush($flush = NULL) {
    if (is_null($flush)) {
      $flush = time();
    }

Well, my only concern is that we are over-complicating something that could be a simple solution. Although I do want to keep the existing functionality of core, I also want to keep this something we can expand in the future.

Personally, I feel that CacheRouter's functionality of breaking out delete() and flush() into two modules is _more_ correct that the cache_clear_all which is a joke of a function overridden to do too many things. If you look at other cache systems, get, set, flush and delete are the only four functions you need. I added the ability to do $cache->delete('something:*', $table) because I wanted to match Drupal's core functionality, but it seems like something we shouldn't need if the cache is working correctly.

So since I am already doing it in delete, i suppose we could break out $cache->delete('something:*', $bin) into $cache->flush_wildcard('something:', $bin), but I really don't see the point. The functionality is already there.

At this time $cache->flush() deletes everything and should be implemented with timestamp parameter

take a look at bug #227228: cache_clear_all and cache_get fail to clear caches when Minimum cache lifetime is on
problem with cache_flush when cache_lifetime is not 0 - cleared only first cache

Suppose we can make cache_flush per bin - then eliminate this bug

every flush initiated by cache_clear_all with $cid=NULL so we need {prefix}{bin}_flush key to store flush time

When flush executed cleared only TEMP entries and expired (maybe useful for file-engine)

Delayed flush (when cache_lifetime !=0) in original cache.inc processed in cache_get() - in this situation we need separate logic for TEMP and PERM data (both of them looks like permanent but only temp goes cleared)

Summary
If cache_lifetime > 0 then we need flush parameter per bin and check in cache_get or hook_flush_caches implementation

@R.Muilwijk
I wrote #7 #8 about cacherouter not drupal

In DB.php engine logiс from core

but current realization of CR is different and should be fixed

I seen your patch for apc - it looks much promising

So this issue about delete-flush in CR, I wrote some thoughts about in #8

to illustrate full flush from core

    if ($wildcard) {
      if ($cid == '*') {
        db_query("DELETE FROM {". $table ."}");
      }
      else {
        db_query("DELETE FROM {". $table ."} WHERE cid LIKE '%s%%'", $cid);
      }
    }

I found no ability to implement this in memcache apc eacc because there's no enumeration of entries

Possible solution is to have some system backend to enumerate stored keys so memcachedb looks promising

IMO, Functions
1) delete key
2) delete key + mask
3) flush whole bin

flush by time should be implemented for engines which does not support automatic expiration

First we should fix $flush parameter before Release right now only Db-engine use this parameter by the wrong way

  function flush($time = NULL) {
    if (empty($time)) { // What about 0 value which means CACHE_PERMANENT ?????
      $time = time();
    }
    parent::flush($time);
    db_query("DELETE FROM {". $this->name ."} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, $time);
  }

@slantview as fixed #266588: Obey "expire" value on cache_clear_all(), like Drupal core

let's put $flush = NULL parameter into Cache class and use it when walking through lookup array for clearing expired values

Suppose before release all flush should look the same