Databases
StackOverflow2013
Postsdbo
POAlternative to setInterval to see if file has been modified?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POAlternative to setInterval to see if file has been modified?
    primarykey
    data
    text
    <p>I'm trying to see if a file has been modified on the server. Currently, I've got setInterval checking every second. It's using AJAX to call a PHP script that checks the file length against what the JS thinks it should be. My question is, is there a better/more efficient way to do this?</p> <p>(I'm using a mutationObserver for something else and it got me wondering if there is something else similar that could help with this...)</p> <p><strong>JS:</strong></p> <pre><code>function checkFile() { var fReader = new XMLHttpRequest(); var params = "MODE=CHECK&amp;File=Data.txt"; fReader.open("POST","File.php",false); fReader.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); fReader.setRequestHeader("Content-length", params.length); fReader.setRequestHeader("Connection", "close"); fReader.send(params); return JSON.parse(fReader.responseText).CHECK &gt; myLength; } </code></pre> <p><strong>PHP:</strong></p> <pre><code>switch($MODE) { case('CHECK'): if(file_exists($_POST['File'])){ $return['CHECK'] = count(file($_POST['File'])); } break; case('GET'): $lines = file($_POST['File']); $length=$_POST['LEN'];#This is the number of lines JS has. $count = count($lines); if ($length &lt; $count) { $return['GET'] = array_slice($lines,$length); } else { #return all lines. $return['GET'] = $lines; } break; </code></pre> <h1>...</h1> <pre><code>} echo json_encode($return); </code></pre> <p>The only other idea I had was to have AJAX check the file asynchronously and split out the response to a separate function. The JS will send over a file count (in the params) and the PHP will check that against the count. If its different, it returns the difference, otherwise it returns something like null or "no change". Currently, i'm checking the file as above. If it's changed, i AJAX again with mode GET to actually get the changes...</p> <p>Ideas? Completely different approach? I'm open to unconventional approaches. (my browser of choice is Chrome, I'm using an extension already, so i could do something in there as well...).</p> <p>Thanks, Dave</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USDave
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POAlternative to setInterval to see if file has been modified?
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI think the title of your question might be a bit misleading, you don't appear to have any issue with the `setInterval` and I don't see any reason to not use a `setInterval`. I assume you simply just want to modify the function the interval is running?
      singulars
      1. POAlternative to setInterval to see if file has been modified?
      1. USNunners
    2. COthe byte length of a file is not enough to determine if the file has changed imo. It really sounds like a server side solution would be needed to me.
      singulars
      1. POAlternative to setInterval to see if file has been modified?
      1. USgwillie
    3. CO@Nunners: Sorry for the confusion. I feel that setInterval is a brute-force kinda approach and i'm wondering if there is a more elegant solution (potentially like Tibos idea of 'long-polling').
      singulars
      1. POAlternative to setInterval to see if file has been modified?
      1. USDave
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload