php - How to avoid getting contents of the same file by separate script instances? -

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php - How to avoid getting contents of the same file by separate script instances? -

let's we've got: files: a.txt, b.txt , c.txt script: script.php

we want allow script file's name (any of them), contents , delete same script runs separately can't same file.

so far:

$scan = scandir('dir'); unset($scan[0], $scan[1]); shuffle($scan); $file = $scan[0]; $contents = file_get_contents($file); if(unlink($file) !== false) homecoming $contents;

use file locking flock.

i think algorithm be:

open file get lock flock check file still exists. if has disappeared, go 7 read file delete it unlock close file, ignoring failure

step 3 required because process waiting lock 1 bound lose file, have been deleted time lock acquired.

i think deleting file when open quite safe; subsequent file operations fail. there nil wrong deleting file locked because locks not associated files, they're maintained table of file descriptors.

i think should close file @ end, though has been deleted, there operating scheme resources need cleaned up. i'm not sure if close fail or not, can ignore failure (most people ignore homecoming value close() anyway).

php

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