php detecting local file changes

hedgehog

i've used php to scan a directory structure and display the contents in the past (hypothetically let's say, a list of images in a directory, maybe also a thumbnail directory, etcetera).

currently i'm working on a gallery that could potentially have thousands of images.

since i don't want php doing all that work every time a user loads a page, i'm setting up a cache that retains the last known list of images and their related thumbnails in mysql.

let's pretend the user in charge of maintaining images for the gallery has a copy of photoshop and does their editing on a machine that has the image gallery drive mapped to their machine, and can simply copy / save the images right into that directory.

other than a timed script that checks for new files in that folder overnight, or one that checks for changes when the user loads the page, is there any way to have... i guess some kind of wrapper that automatically detects that a new file has been created, and alerts php?

would php/gtk solve this? or would it need to be C / Java / etc?

thanks in advance for any insight;
-adam

BDKR

Can fileatime() or filectime() provide any help for you?

hedgehog

Originally posted by BDKR
Can fileatime() or filectime() provide any help for you?

sadly, only when i'm checking existing files and updating the cache with those.

the bit that's tricky is figuring out when a user has created a new file on the server before any web browser has even opened.

i'm not sure what sort of extensions php-gtk provides, but i'm imagining i could perhaps code something in where a user could right click the new file and select an "add to image gallery" option, and instead of firing up a browser, it'd launch a tiny background php-gtk app that would update the cache with the new file.

i'm not fussed about adding the menu option (or even just putting it in the windows 'send to...' folder: (it's a winddows-only application for now) but mainly i suppose the question is talking to mysql without firing up a browser. ideally using php.

Installer

If you put your images in immediate subdirectories of a master directory and your traffic isn't real heavy and you don't mind making an occasional user wait while the updating is done, then something like this (included in appropriate scripts) might work:

$dir = dir('./images_top');
while (($entry = $dir->read()) !== false) {
    if (is_dir($entry) && ($entry != '.') && ($entry != '..')) {
        $last_update = trim(file_get_contents($entry . '/last_update.txt'));
        $last_change = filemtime($entry);
        if ($last_change > $last_update) {
            update($entry); // Renew cache and write time file
        }
    }
}

Or, for a database:

$query = "SELECT dir, updatetime FROM directories WHERE type = 'image'";
$result = mysql_query($query);
while ($row = mysql_fetch_array($result)) {
    $last_update = $row['updatetime'];
    $last_change = filemtime($row['dir']);
    if ($last_change > $last_update) {
        update($row['dir']);
    }
}

hedgehog

yeah. to be honest, i don't really know why i'm trying to avoid that scenario so aggressively; you're right in that it's really probably the simplest way to go about it.

i guess i was hoping there was a php+gtk signal or event that could make it realtime, so if i had a browser window open, it'd automagically show the new image.

then again maybe i could use XMLHttprequest to open a page that runs this loop on every $m minutes the page is open, and add to the gallery that way.

it's the want for near-wysiwyg type of display updates that makes me a bit fussy i guess.

ah well, it's just a personal project anyway 😛