Is there any way to check id a file is being accessed or modified by another process from a php script. i have attempted to use the filemtime(), fileatime() and filectime() functions but i have the script in a loop which is checking continuously but it seems once the script has been executed it will only take the time from the first time the file was checked.. an example would be uploading files to a FTP or SMB share i attempted this below
while(1==1)
{
$LastMod = filemtime("file");
if(($LastMod +60) > time())
{
echo "file in use please wait... last modified : $LastMod";
sleep(10);
}else{
process file
}
}
I know the file is constantly changing but the $LastMod variable is not updating but end process and execute again will pick up a new $LastMod from the file but dosnt seem to update each time the file is checked in the loop
I have also attempted this with looking at filesize() but get the same symptoms i also looked into flock() but as the file is created or modified outside PHP I don't see how this would work.
If anyone has any solutions please let me know
thanks Vip32
PS. using PHP to process the files as requires interaction with mysql and querying external websites
The file metadata functions all work off stat() output, which caches its data, as a stat() call is a relatively expensive function. You can empty that cache to force stat() to fetch fresh data with clearstatcache()
There are other mechanisms that allow you to monitor for file changes. Instead of doing a loop in PHP and repeatedly stat()ing, consider using an external monitoring app/script which can hook into the OS-provided mechanism and call your PHP script on-demand when the file truly does change.
Add clearstatcache(); to your loop:
while(true)
{
$LastMod = filemtime("file");
clearstatcache();
if(($LastMod +60) > time())
{
echo "file in use please wait... last modified : $LastMod";
sleep(10);
}else{
process file
}
}
Related
I have a case,
I have a remote server that contains so many generated transaction files (.txt) from 2015 until now. I must download it everyday real time. For now, i use PHP to download it all, but the method i think is not effectifely. First, I list all files, and then I read the component of the files such as the date modified, but this method is annoying. Make my program run slowly and take a very much time.
This is my code (I've used PHP Yii2),
public function actionDownloadfile(){
$contents=Yii::$app->ftpFs->listContents('/backup', ['timestamp','path','basename']); --> Much time needed while executing this line
var_dump($contents);
foreach ($contents as $value) {
if (date('Y-m-d',$value['timestamp']) == date('Y-m-d')){
echo "[".date('Y-m-d H:i:s')."] : Downloading file ".$value['basename']."\n";
$isi = Yii::$app->ftpFs->read($value['path']);
$dirOut = Yii::$app->params['out'];
$fileoutgoing = $dirOut."/".$value['basename'];
$file = fopen($fileoutgoing,"w");
fwrite($file,$isi);
}
}
}
i have a question,
Is that possible to list and download some files in ftp server just only on this current date without listing them all first?
Any solution either using PHP or Shell Script is OK.
Thank you so much (y)
In my cache system, I want it where if a new page is requested, a check is made to see if a file exists and if it doesn't then a copy is stored on the server, If it does exist, then it must not be overwritten.
The problem I have is that I may be using functions designed to be slow.
This is part of my current implementation to save files:
if (!file_exists($filename)){$h=fopen($filename,"wb");if ($h){fwrite($h,$c);fclose($h);}}
This is part of my implementation to load files:
if (($m=#filemtime($file)) !== false){
if ($m >= filemtime("sitemodification.file")){
$outp=file_get_contents($file);
header("Content-length:".strlen($outp),true);echo $outp;flush();exit();
}
}
What I want to do is replace this with a better set of functions meant for performance and yet still achieve the same functionality. All caching files including sitemodification.file reside on a ramdisk. I added a flush before exit in hopes that content will be outputted faster.
I can't use direct memory addressing at this time because the file sizes to be stored are all different.
Is there a set of functions I can use that can execute the code I provided faster by at least a few milliseconds, especially the loading files code?
I'm trying to keep my time to first byte low.
First, prefer is_file to file_exists and use file_put_contents:
if ( !is_file($filename) ) {
file_put_contents($filename,$c);
}
Then, use the proper function for this kind of work, readfile:
if ( ($m = #filemtime($file)) !== false && $m >= filemtime('sitemodification.file')) {
header('Content-length:'.filesize($file));
readfile($file);
}
}
You should see a little improvement but keep in mind that file accesses are slow and you check three times for files access before sending any content.
I have a script that re-writes a file every few hours. This file is inserted into end users html, via php include.
How can I check if my script, at this exact moment, is working (e.g. re-writing) the file when it is being called to user for display? Is it even an issue, in terms of what will happen if they access the file at the same time, what are the odds and will the user just have to wait untill the script is finished its work?
Thanks in advance!
More on the subject...
Is this a way forward using file_put_contents and LOCK_EX?
when script saves its data every now and then
file_put_contents($content,"text", LOCK_EX);
and when user opens the page
if (file_exists("text")) {
function include_file() {
$file = fopen("text", "r");
if (flock($file, LOCK_EX)) {
include_file();
}
else {
echo file_get_contents("text");
}
}
} else {
echo 'no such file';
}
Could anyone advice me on the syntax, is this a proper way to call include_file() after condition and how can I limit a number of such calls?
I guess this solution is also good, except same call to include_file(), would it even work?
function include_file() {
$time = time();
$file = filectime("text");
if ($file + 1 < $time) {
echo "good to read";
} else {
echo "have to wait";
include_file();
}
}
To check if the file is currently being written, you can use filectime() function to get the actual time the file is being written.
You can get current timestamp on top of your script in a variable and whenever you need to access the file, you can compare the current timestamp with the filectime() of that file, if file creation time is latest then the scenario occured when you have to wait for that file to be written and you can log that in database or another file.
To prevent this scenario from happening, you can change the script which is writing the file so that, it first creates temporary file and once it's done you just replace (move or rename) the temporary file with original file, this action would require very less time compared to file writing and make the scenario occurrence very rare possibility.
Even if read and replace operation occurs simultaneously, the time the read script has to wait will be very less.
Depending on the size of the file, this might be an issue of concurrency. But you might solve that quite easy: before starting to write the file, you might create a kind of "lock file", i.e. if your file is named "incfile.php" you might create an "incfile.php.lock". Once you're doen with writing, you will remove this file.
On the include side, you can check for the existance of the "incfile.php.lock" and wait until it's disappeared, need some looping and sleeping in the unlikely case of a concurrent access.
Basically, you should consider another solution by just writing the data which is rendered in to that file to a database (locks etc are available) and render that in a module which then gets included in your page. Solutions like yours are hardly to maintain on the long run ...
This question is old, but I add this answer because the other answers have no code.
function write_to_file(string $fp, string $string) : bool {
$timestamp_before_fwrite = date("U");
$stream = fopen($fp, "w");
fwrite($stream, $string);
while(is_resource($stream)) {
fclose($stream);
}
$file_last_changed = filemtime($fp);
if ($file_last_changed < $timestamp_before_fwrite) {
//File not changed code
return false;
}
return true;
}
This is the function I use to write to file, it first gets the current timestamp before making changes to the file, and then I compare the timestamp to the last time the file was changed.
There's a file in my server that is being updated every 5 minutes. The file is uploaded via ftp and gets updated when upload is completed.
I'm using a php script to get this file's data and I would like to ensure that each time my script reads this file, it's complete and valid (it's not being uploaded at the same time).
Is the following code safe and suitable for this check?
if ( (($handle = fopen('/var/import/data.csv', 'r')) !== FALSE) && (filesize('/var/import/data.csv')>10) ) {
....do stuff....
}
You should write a lockfile while the file is being updated, and delete it when the update is finished. Then check against said lockfile to know if you can read from it or not.
I'd treat the ftp upload as two stages
upload (as a new file)
rename (to overwrite the previous version)
This massively reduces the chance of your script seeing an incomplete file.
Alternatively, check the modified time of the file (mtime) and only access the file if it's older than, say, 30 seconds. Be sure to make this time longer than the upload time.
I experimenting with twitter streaming API,
I use Phirehose to connect to twitter and fetch the data but having problems storing it in files for further processing.
Basically what I want to do is to create a file named
date("YmdH")."."txt"
for every hour of connection.
Here is how my code looks like right now (not handling the hourly change of files)
public function enqueueStatus($status)
$data = json_decode($status,true);
if(isset($data['text'])/*more conditions here*/) {
$fp = fopen("/tmp/$time.txt");
fwirte ($status,$fp);
fclose($fp);
}
Help is as always much appreciated :)
You want the 'append' mode in fopen - this will either append to a file or create it.
if(isset($data['text'])/*more conditions here*/) {
$fp = fopen("/tmp/" . date("YmdH") . ".txt", "a");
fwrite ($status,$fp);
fclose($fp);
}
From the Phirehose googlecode wiki:
As of Phirehose version 0.2.2 there is
an example of a simple "ghetto queue"
included in the tarball (see file:
ghetto-queue-collect.php and
ghetto-queue-consume.php) that shows
how statuses could be easily collected
on to the filesystem for processing
and then picked up by a separate
process (consume).
This is a complete working sample of doing what you want to do. The rotation time interval is configurable too. Additionally there's another script to consume and process the written files too.
Now if only I could find a way to stop the whole sript, my log keeps filling up (the script continues execution) even if I close the browser tab :P