PHP 組み込み関数とカスタム関数を使用して配列を重複排除した場合のパフォーマンスの比較

$array = range(1, 1000000);
$iterations = 100;

function test_array_unique($array, $iterations) {
  $total_time = 0;
  for ($i = 0; $i < $iterations; $i++) {
    $start_time = microtime(true);
    $result = array_unique($array);
    $end_time = microtime(true);
    $total_time += $end_time - $start_time;
  }
  $avg_time = $total_time / $iterations;
  echo "array_unique: $avg_time seconds\n";
}

function test_array_reverse_array_filter($array, $iterations) {
  $total_time = 0;
  for ($i = 0; $i < $iterations; $i++) {
    $start_time = microtime(true);
    $result = array_filter(array_reverse($array), 'array_unique');
    $end_time = microtime(true);
    $total_time += $end_time - $start_time;
  }
  $avg_time = $total_time / $iterations;
  echo "array_reverse + array_filter: $avg_time seconds\n";
}

function test_hash_table($array, $iterations) {
  $total_time = 0;
  for ($i = 0; $i < $iterations; $i++) {
    $start_time = microtime(true);
    $result = array_values(array_filter($array, function ($value) {
      static $hash_table = [];
      if (isset($hash_table[$value])) {
        return false;
      }
      $hash_table[$value] = true;
      return true;
    }));
    $end_time = microtime(true);
    $total_time += $end_time - $start_time;
  }
  $avg_time = $total_time / $iterations;
  echo "hash table: $avg_time seconds\n";
}

function test_loop($array, $iterations) {
  $total_time = 0;
  for ($i = 0; $i < $iterations; $i++) {
    $start_time = microtime(true);
    $result = array_values(array_filter($array, function ($value) use (&$array) {
      for ($j = 0; $j < count($array); $j++) {
        if ($j == $i) {
          continue;
        }
        if ($value == $array[$j]) {
          return false;
        }
      }
      return true;
    }));
    $end_time = microtime(true);
    $total_time += $end_time - $start_time;
  }
  $avg_time = $total_time / $iterations;
  echo "loop: $avg_time seconds\n";
}

test_array_unique($array, $iterations);
test_array_reverse_array_filter($array, $iterations);
test_hash_table($array, $iterations);
test_loop($array, $iterations);