How to make new version updating safe in PHP OpCache? - php

Question

My php project is now working on Apache with mod_php. I want to open OpCache to accelerate my code. But I'm worry about if it's safe to update the code.
The validate_timestamps should be 0. Because the code may expire when you update new version, and this can make the code of new version call the code of old version.
But even if I set validate_timestamps=0, this can also happen. When I update the code file, one of the code file that hasn't been cached is called. And thus this code file is in new version while the caller is in old version. Maybe I can load all the code files into cache before the server start?
If I find a way to make sure all the files in the project dir are loaded into cache before the Apache start to serve requests, I can update new version code first, and then clear all the OpCache. But does it have an impact on those working requests? Will they run an old logic and then be switch into a new one?
Besides, how to clear all the OpCache in an atom time? If it takes time to clear all the OpCache, the problem is still there, right?
Can anyone help me? Thank you very much!
Let me show an example.
I have two files on my directory, and the Apache's working directory is also there.
The entry file is index.php.
<?php
echo "verson 1: index";
// do some work
sleep(1);
// not all APIs will call this library
// I just use rand to represent a probability
if (rand(0,100) == 1) {
require_once BASEPATH.'lib.php';
t = new Tester();
t->func1();
}
And the other php file is lib.php.
<?php
echo "---- version 1: lib";
class Tester {
function __construct() {
echo "---- new Tester in lib.php";
}
public function func1() {
echo "---- Tester.func1()";
}
}
Now I'm going to upload my new version code.
In the new version, I declare a new function func2() in Tester and delete the old function func1(). I call it in the index.php.
index.php
<?php
echo "version 2: index";
// do some work
sleep(1);
// not all APIs will call this library
// I just use rand to represent a probability
if (rand(0,100) == 1) {
require_once BASEPATH.'lib.php';
t = new Tester();
t->func2();
}
lib.php
<?php
echo "---- version 2: lib";
class Tester {
function __construct() {
echo "---- new Tester in lib.php";
}
public function func2() {
echo "---- Tester.func2()";
}
}
I close the OpCache. I upload the index.php first and then the other one lib.php. At the moment between I finish to upload the index.php and begin to upload lib.php, a request is running into the "rand case". Then I will get an error about "func2() not defined", because the lib.php is still the old one at that time.
If I open the OpCache, it's the same if I don't set validate_timestamps to 0.
After I set validate_timestamps to 0, the opcode will not expire. So I must call opcache_reset manually after I finish to upload index.php and lib.php. At that moment, a request also runs into the "rand case". If the opcache_reset operation takes a period of time, and it doesn't block the request running, the error "func2() not defined" may also occur.
How to make all the requests safe when I upgrade my code version?