PHP implements two scenarios in which multiple processes simultaneously write to the same file share

Test Centers: Understanding of functions

fopen: Open file or URL

Parameter 1: File address or URL  parameter The 2:mode parameter specifies the type of access required to the stream  ' r ' read-only open, pointing the file pointer to the file header.  the ' r+ '    read-write mode opens, pointing the file pointer to the file header. The  ' W ' Write method opens, pointing the file pointer to the file header and truncating the file size to zero. If the file does not exist, try to create it. The  ' w+ '    read-write mode opens, pointing the file pointer to the file header and truncating the file size to zero. If the file does not exist, try to create it.  ' A ' writes open, pointing the file pointer at the end of the file. If the file does not exist, try to create it.  the ' A + '    read-write mode opens, pointing the file pointer at the end of the file. If the file does not exist, try to create it.

Fwrite: Writing Files

Parameter 1: FileName file system pointer  parameter 2: Content to write String type  return value: Write successfully returns the number of characters written, failure returns false

Flock: Lightweight consultation file lock

Parameter 1: File system pointer, is a resource (resource) typically created by fopen ().　　　　  Parameter 2: Mode  Lock_sh Get a shared lock (read program).  LOCK_EX obtains an exclusive lock (written program.  Lock_un Release Lock (whether shared or exclusive).  If you do not want flock () to block when locked, it is LOCK_NB (not yet supported on Windows).    return value: Returns TRUE on success, or FALSE on failure.

Fclose: Close an open file pointer

Parameter 1: File name  parameter 2: Returns TRUE on success, or FALSE on failure.

Programme I

function WriteData ($filepath, $data)   {       $fp = fopen ($filepath, ' a ');        do{           Usleep (+);       } while (!flock ($FP, LOCK_EX));  The LOCK_EX acquires an exclusive lock (written program) that locks the lock to write, the lock is      $res = fwrite ($fp, $data. " \ n ");       Flock ($FP, lock_un);    Lock_un release Lock (whether shared or exclusive).      fclose ($fp);        return $res;   }

Scenario two (self-tagging method)

function write_file ($filename, $content) {$lock = $filename.      '. Lck ';      $write _length = 0;          while (true) {if (file_exists ($lock)) {usleep (100);              } else {Touch ($lock);              $write _length = file_put_contents ($filename, $content, file_append);          Break      }} if (File_exists ($lock)) {unlink ($lock);  } return $write _length; }