For the record, the example given here has an explicit command to truncate the file, however with a 'write mode' of 'w', it will do this for you automatically, so the truncate call is not needed.
(PHP 5 >= 5.1.0, PHP 7)
SplFileObject::flock — Portable file locking
$operation
[, int &$wouldblock
] ) : boolLocks or unlocks the file in the same portable way as flock().
operation
operation is one of the following:
LOCK_SH to acquire a shared lock (reader).
LOCK_EX to acquire an exclusive lock (writer).
LOCK_UN to release a lock (shared or exclusive).
LOCK_NB to not block while locking.
wouldblock
Set to TRUE if the lock would block (EWOULDBLOCK errno condition).
成功时返回 TRUE， 或者在失败时返回 FALSE。
Example #1 SplFileObject::flock() example
<?php
$file = new SplFileObject("/tmp/lock.txt", "w");
if ($file->flock(LOCK_EX)) { // do an exclusive lock
$file->ftruncate(0); // truncate file
$file->fwrite("Write something here\n");
$file->flock(LOCK_UN); // release the lock
} else {
echo "Couldn't get the lock!";
}
?>
| 版本 | 说明 |
|---|---|
| 5.5.22, 5.6.6 |
Added support for the wouldblock parameter on
Windows.
|
| 5.3.2 | The automatic unlocking when the file's resource handle is closed was removed. Unlocking now always has to be done manually. |
For the record, the example given here has an explicit command to truncate the file, however with a 'write mode' of 'w', it will do this for you automatically, so the truncate call is not needed.