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.
SplFileObject::flock
(PHP 5 >= 5.1.0, PHP 7, PHP 8)
SplFileObject::flock — Portable file locking
Beschreibung
Locks or unlocks the file in the same portable way as flock().
Parameter-Liste
-
operation -
operationis one of the following:-
LOCK_SHto acquire a shared lock (reader). -
LOCK_EXto acquire an exclusive lock (writer). -
LOCK_UNto release a lock (shared or exclusive).
It is also possible to add
LOCK_NBas a bitmask to one of the above operations, if flock() should not block during the locking attempt. -
-
wouldBlock -
Set to
trueif the lock would block (EWOULDBLOCK errno condition).
Rückgabewerte
Gibt bei Erfolg true zurück. Bei einem Fehler wird false zurückgegeben.
Beispiele
Beispiel #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!";
}
?>
add a note
User Contributed Notes 2 notes
digitalprecision at gmail dot com ¶
13 years ago
Ahmed Rain ¶
2 years ago
@digitalprecision What you said is not completely true, ftruncate(0); is needed if there was a write to the file before the lock is acquired. You also may need fseek(0); to move back the file pointer to the beginning of the file
<?php
$file = new SplFileObject("/tmp/lock.txt", "w");
$file->fwrite("xxxxx"); // write something before the lock is acquired
sleep(5); // wait for 5 seconds
if ($file->flock(LOCK_EX)) { // do an exclusive lock
$file->fwrite("Write something here\n");
$file->flock(LOCK_UN); // release the lock
} else {
echo "Couldn't get the lock!";
}
?>
"lock.txt" content:
xxxxxWrite something here
