将文件保存为套接字并等到另一个进程写入结束

Question

Let's say that we have a program X that continuously write a file for example the /tmp/test.file

I have a script in PHP that serves this file to the client so that he can download/read it.

How i'm able to do this continuously as the data are being written in the /tmp/test.file?

If i use the below code

<?php

$fp = fopen("/tmp/test.file","r");
while(!feof($fp))
{
 echo fread($fp,4096);
}
fclose($fp);

It instantly stops because it reads the whole file until EOF so it doesnt care if another process is writing at this file.

Thank you

Answer 1

As a suggestion, use a continues Ajax call (for example 5 seconds interval) to the PHP script file, and get the file content via offset. You can store the current offset of file into SESSION or COOKIE.

You can get file offset by using PHP's ftell function.

As PHP's official document defines ftell():

ftell — Returns the current position of the file read/write pointer

Also, stream_get_contents() function might be useful as PHP's official document defines it:

stream_get_contents — Reads remainder of a stream into a string

then, In each interval, append the response data to a HTML tag.