PHP file lock writing example analysis, _PHP tutorial

PHP file lock writing instance analysis,

This article describes the PHP file writing method with examples to cope with multi-threaded writing. The specific code is as follows:

function file_write($file_name, $text, $mode='a', $timeout=30){ 
  $handle = fopen($file_name, $mode); 
  while($timeout>0){ 
    if ( flock($handle, LOCK_EX) ) { // 排它性的锁定
      $timeout--; 
      sleep(1); 
    } 
  } 
  if ( $timeout > 0 ){ 
    fwrite($handle, $text.'\n'); 
    flock($handle, LOCK_UN); 
    fclose($handle); //释放锁定操作
    return true; 
  } 
  return false; 
}

Among themthe handle operated by the flock(int $handle, int $operation) function must be an open file pointer.

operation can be one of the following values:

To obtain a shared lock (reading program), set operation to LOCK_SH (set to 1 in versions prior to PHP 4.0.1).
To obtain an exclusive lock (writing program), set operation to LOCK_EX (set to 2 in versions prior to PHP 4.0.1).
To release a lock (whether shared or exclusive), set operation to LOCK_UN (set to 3 in versions prior to PHP 4.0.1).
If you don't want flock() to block on lock, add LOCK_NB to the operation (set to 4 in versions prior to PHP 4.0.1).

In addition, fclose() is used to release the lock operation and is called when the code execution is completed.