(dev/core#217) PrevNext - Allow swapping getCount() for purposes of…

… contact-search

The `getCount()` function is used by both contact-search and dedupe-merge use-cases.

* Contact-search
    * `CRM/Contact/Selector.php:            $countRow = CRM_Core_BAO_PrevNextCache::getCount($cacheKey, NULL, "entity_table = 'civicrm_contact'");`
* Dedupe-merge
    * `CRM/Contact/Page/AJAX.php:           $iTotal   = CRM_Core_BAO_PrevNextCache::getCount($cacheKeyString, $join, $whereClause, '=', $queryParams);`
    * `CRM/Contact/Page/DedupeMerge.php:    $total    = CRM_Core_BAO_PrevNextCache::getCount($cacheKeyString, NULL, ($onlyProcessSelected ? "pn.is_selected = 1" : NULL));`

Our aim in developing `CRM_Core_PrevNextCache_Interface` is to allow contact-search to swap a MySQL
backend with a Redis backend -- and dedupe-merge should continue as-is (whether or not Redis is
available).  This basically means:

* Contact-search switches to using `Civi::service('prevnext')->getCount()`
* Dedupe-merge continues using `CRM_Core_BAO_PrevNextCache::getCount()`

Note that the `Interface::getCount()` is simpler than the BAO's variant. This is good because:

* Contact-search doesn't need as many parameters.
* Dedupe-merge still needs all the parameters.
* Adding all parameters would make it hard to implement on other backends. (This is esp true of SQL-style options `$join` and `$where`.)

CRM/Contact/Selector.php

@@ -902,7 +902,7 @@ public function buildPrevNextCache($sort) {
     $sortByCharacter = CRM_Utils_Request::retrieve('sortByCharacter', 'String');
 
     //for text field pagination selection save
-    $countRow = CRM_Core_BAO_PrevNextCache::getCount($cacheKey, NULL, "entity_table = 'civicrm_contact'");
+    $countRow = Civi::service('prevnext')->getCount($cacheKey);
     // $sortByCharacter triggers a refresh in the prevNext cache
     if ($sortByCharacter && $sortByCharacter != 'all') {
       $cacheKey .= "_alphabet";

CRM/Core/PrevNextCache/Interface.php

@@ -121,4 +121,12 @@ public function getPositions($cacheKey, $id1, $id2);
    */
   public function deleteItem($id = NULL, $cacheKey = NULL, $entityTable = 'civicrm_contact');
 
+  /**
+   * Get count of matching rows.
+   *
+   * @param string $cacheKey
+   * @return int
+   */
+  public function getCount($cacheKey);
+
 }

CRM/Core/PrevNextCache/Sql.php

@@ -231,4 +231,14 @@ public function deleteItem($id = NULL, $cacheKey = NULL, $entityTable = 'civicrm
     CRM_Core_BAO_PrevNextCache::deleteItem($id, $cacheKey, $entityTable);
   }
 
+  /**
+   * Get count of matching rows.
+   *
+   * @param string $cacheKey
+   * @return int
+   */
+  public function getCount($cacheKey) {
+    return CRM_Core_BAO_PrevNextCache::getCount($cacheKey, NULL, "entity_table = 'civicrm_contact'");
+  }
+
 }