How to get the progress of copying - php

Question

I have this code that copies files and is there a possibility of getting progress of how much has been copied?
<?php
$src = '../www/';
$dst = '../../backup/';
function recurse_copy($src,$dst) {
$dir = opendir($src);
#mkdir($dst);
while(false !== ( $file = readdir($dir)) ) {
if (( $file != '.' ) && ( $file != '..' )) {
if ( is_dir($src . '/' . $file) ) {
recurse_copy($src . '/' . $file,$dst . '/' . $file);
}else {
copy($src . '/' . $file,$dst . '/' . $file);
}
}
}
closedir($dir);
}
recurse_copy($src,$dst);
}
?>
And if it is possible to get that number by ajax response. That means that response has to be sent multiple times. But I don't know how to do that.

Answer 1

You can track the copied files using a third argument passed by reference.
function recurse_copy($src, $dst, &$copied) {
// recurse code
$copied[] = [ 'src' => $src, 'dst' => $dst, 'file' => $file ];
copy($src.'/'.$file, $dst.'/'.$file);
}
$copied = [];
recurse_copy($src, $dst, $copied);
print_r($copied);
Other ways might be closures (function assigned to variable) and the use statement or class-properties when you put your function in a class.
Edit
For progress as in live update, see echo and flush() to see semi-live which files are beeing copied. A progress within a file copy is not possible.

Answer 2

There are two ways:
Knowing how many files you are going to copy, so that you can show a %
Not knowing the total number of files
In the first case, you have to get the full list of files first and then do the copying. Depending on the size of the directory tree and number of files, it can add quite some overhead, but it has its benefits. You have to decide.
In any case, you have to add a third parameter to the function:
function recurse_copy($src, $dst, callable $progress_callback = function(){}) { ... }
Bear in mind that callable is only supported from PHP 5.4 onwards.
The signature of the callback function would be:
function handle_progress($action, $data) { ... }
Then you can invoke the callback function like this:
$progress_callback('start'); // or...
$progress_callback('start', ['total' => $numfiles]);
$progress_callback('progress', ['current' => $filename]); // or...
$progress_callback('progress', ['total' => $numfiles, 'current' => $numcurrent, 'currentfile' => $filename]);
$progress_callback('finish');
You decide which data to pass to the progress callback and what to do with it once in the handler.
Now, to be able to get the progress via AJAX, you have to create a task that runs independently of the HTTP request. You return the task ID, and with AJAX you poll the progress of that ID.
In the server, you would have to use some kind of queue/task system, e.g. Laravel queues. It's only an example; you can google for more.
In the function callback, you can save to disk/redis/whatever the progress of the current task.