function _location_search_results_from_cache in Location 5

Helper function: this function is intended ONLY for use by _location_nearby_postalcodes(). It checks the cache for search-results on a given point and returns the appropriate subset if one exists.

Parameters

$lon: A floating point of the longitude coordinate of the search point

$lat : A floating point of the latitude coordinate of the search point

$distance: A floating point of the number of meters of the search radius

Return value

An array of previous search results. If a previous search result on the same point was for the same search-radius, that result is returned. If a previous search result on the same point was for a longer search-radius, a subset of that result is returned. If a previous search result on the same point was for a shorter search-radius, the cached search-result is thrown out and an empty array is returned. If no previous search-result on the same point is in the cache, an empty array.

1 call to _location_search_results_from_cache()

_location_nearby_postalcodes in ./location.inc

This is the main logic-level function for performing proximity postal-code searches. It calls a number of helper functions for finding postal_code results in each country, narrowing down results, formatting the returned array, and sorting the returned…

File

./location.inc, line 887

Code

function _location_search_results_from_cache($lon, $lat, $distance) {
  $cache_id_prefix = 'location_prox_search:' . round($lon, 3) . ':' . round($lat, 3) . ':';
  $result = db_query("SELECT cid FROM {cache} WHERE cid LIKE '%s%%'", $cache_id_prefix);
  if ($result_row = db_fetch_object($result)) {

    // A previous search has been done on the same search point, possibily with the an equal or different
    // search radius.
    $cached_key_fields = explode(':', $result_row->cid);
    $previous_search_radius = $cached_key_fields[3];

    // If the search-radius is less than or equal to the previous search-radius, then just use
    // the appropriate subset of the previous search result.
    // This is very convenient since previous search results are sorted in ascending order
    // by their distance from the search point.
    if ($distance <= $previous_search_radius) {
      $cached_search_results = cache_get($result_row->cid);
      $cached_search_results = unserialize($cached_search_results->data);

      // If the cached-search had the exact same search-radius, just return the entire search result's
      // array from before,
      // otherwise, go through the distance-sorted search results and pick them out until the distances
      // of each search result start being something greater than the current search-radius
      if ($distance == $previous_search_radius) {

        // DEBUG: commented code is for testing/debugging purposes

        //print 'POSTAL CODE SEARCH CACHING: Returning EXACT SAME of search results from before'."<br/>\n";
        return $cached_search_results;
      }
      else {
        $current_search_results = array();
        foreach ($cached_search_results as $key => $cached_result) {
          if ($cached_result['distance'] <= $distance) {
            $current_search_results[$key] = $cached_result;
          }
          else {
            break;
          }
        }

        // DEBUG: commented code is for testing/debugging purposes

        //print 'POSTAL CODE SEARCH CACHING: Returning SUBSET of a previous search\'s results'."<br/>\n";
        return $current_search_results;
      }
    }
    else {

      // If the previous search-radius on the same point is smaller than the current search-radius,
      // then delete the previous search from the cache to make way in the cache for the results of
      // the current, more comprehensive search being done on the same point, but on a larger radius.
      // Return an empty array to let the calling function know that it will have to do a new search.
      // DEBUG: commented code is for testing/debugging purposes

      //print 'POSTAL CODE SEARCH CACHING: Throwing out old search on a point because new search uses larger search-radius'."<br/>\n";
      cache_clear_all($result_row->cid, 'cache');
      return array();
    }
  }
  else {

    // This else-clause ties back to the first if-clause in this function.
    // It executes if no search has been done on this point.
    // If the {cache} table did not contain any useful cache id's, return the empty array.
    // This will let the calling function know that it has to do an original search.
    return array();
  }
}