Unexpected Behaviour of PHP file rename() function used in my code for file renaming

Question

My code deletes a file and rename some files including the deleted file name to another file.But This code works unexpected behaviour.What is the problem..Or what's wrong in my code..

Edited

5 files

file1.jpg,file2,jpg,file3.jpg,file4.jpg,file5.jpg

$target = 2; //target file to delete
$total = 5; //total files

$name = 'file';
unlink($name.$target.".jpg");//deleting
usleep(10000000);//to find deleted or not afterdelete
for($i = $target+1;$i<=$total;$i++)
{
    rename($name.$i.".jpg" , $name.($i-1).".jpg");
}

My Expectation

file2 have to be deleted , then 

file3.jpg rename to file2.jpg
file4.jpg rename to file3.jpg
file5.jpg rename to file4.jpg

But, the result is not what i expected.

The Result

- file2.jpg deleted.correctly.("I am sure i put usleep() after unlink(),the image deleted")
- file3.jpg renamed to file2.jpg but the file3 content has file2.jpg content
- file4.jpg renamed to file3.jpg
- file5.jpg renamed to file4.jpg

sometimes it works as i expected but sometimes not,

-file3 renamed to file2
-file4 renamed to file3
-file5 renamed to file4 but have file3 content

Every time It works unexpectedly and differently

Initially

After Delete between Usleep()

Final result

I really dont understand what is happening for my code.Please someone help me..

Answer 1

My suggestion; cache the files' names:

$file1 = "var/www/magento/media/file1";
$file2 = "var/www/magento/media/file2";
$unresult = unlink($file1);
$reresult = rename($file2, $file1);

P.S: The code works just fine, (I even tested it!!); but take a look at the following:

<?php
$file1 = "file1.txt";
$file2 = "file2.txt";

// insert some contents into each file
file_put_contents($file1, "AAAA");
file_put_contents($file2, "BBBB");

// delete the first file, and then rename the second one to "file1"
$unresult = unlink($file1);
$reresult = rename($file2, $file1);

// now that the file is renamed, then there should be "BBBB" in the file named "file1.txt"
echo file_get_contents($file1); // Outputs: BBBB
?>

Answer 2

Your code is functionally correct and I suspect of the "file system refreshment" as of being the origin of the problem issue, however, as you've stated, the issue just happens occasionally.

It seems that there's no built-in "file-system refresh" function in PHP, however, the following is just a work around, but will do the trick: As of a "refreshment", after the renaming process, simply create a temporary empty file, and then delete it! Throughout my testes (I've also tested it in Windows), that "occasionally" adverb changed to "never"!

files are file_1.png, file_2.png, file_3.png, file_4.png, file_5.png, having their numeral suffixes as the files' contents.

<?php
$target = 2; //target file to delete
$total  = 5; //total files

$name = 'file_';
$fileToDelete = "$name$target.png";
unlink($fileToDelete); //delete
echo "Deleted: $fileToDelete<br/>";

for($i = $target+1; $i<=$total; $i++)
{
    $prev = $i-1;
    $from = "$name$i.png";
    $to   = "$name$prev.png";

    rename($from , $to);
    echo "file renamed: [$from -> $to]<br/>";
}
// refresh the file system!!
file_put_contents("tmp","");
unlink("tmp");
?>

The output is:

Deleted: file_2.png
file renamed: [file_3.png -> file_2.png]
file renamed: [file_4.png -> file_3.png]
file renamed: [file_5.png -> file_4.png]

the story through pictures: