Redis + PHP = AutoComplete

autocomplete.php

<?php

function init_suggest() {
  $redis = new Redis();
  $redis->pconnect('127.0.0.1', 6379);
  $redis->delete('autocomplete');

  $keyword = array(
      '全境封鎖',
      '火線獵殺',
      '煞爾達'
  );
  $size = count($keyword);
  for ($i = 0; $i < $size; $i++) {
      $result = _str_combination($keyword[$i]);
      foreach ($result as $value) {
          $redis->zAdd('autocomplete', 0, $value);
      }
  }
}

function _str_combination($keyword) {
  $size = mb_strlen($keyword);
  for ($i = 0; $i < $size; $i++) {
      $result[] = mb_substr($keyword, 0, $i + 1);
  }
  $result[$size - 1] = $result[$size - 1] . '*';
  return $result;
}
                          
public function autocomplete($keyword) {
  $keyword_size = mb_strlen($keyword);

  $redis = new Redis();
  $redis->pconnect('127.0.0.1', 6379);
  $search_index = $redis->zRank('autocomplete', $keyword);
  $search = $redis->zRange('autocomplete', $search_index, -1);

  $result = array();
  foreach ($search as $value) {
      if ( ! (mb_substr($value, 0, $keyword_size) == $keyword)) {
          continue;
      }
      if (mb_substr($value, -1) == '*') {
          $result[] = mb_substr($value, 0, mb_strlen($value) - 1);
      }
  }
  return $result;
}

執行 init_suggest() 把關鍵字拆解排列，並增加到 Redis sorted set 結構去，配合 ZRAND 找到字首的 index，並配合 ZRANGE 就可以取出範圍，每個 entry 遇到 * 就是完整的關鍵字