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RFC - Zend VM Pause API

php.internals

Haitao Lv

8 years ago

Hi, internals,

I propose to introduce a new zend vm pause api, and here is the RPF

https://wiki.php.net/rfc/zend-vm-pause-api

Please gave your comment.

Thank you.

Dmitry Stogov

8 years ago

Hi,

It should be possible do similar things using EG(vm_interrupt) and zend_interrupt_function() callback (introduced in php-7.1)

ext/pcntl implements asynchronous signal handling using this.

Thanks. Dmitry.

________________________________
From: Haitao Lv <i@lvht.net>
Sent: Wednesday, November 1, 2017 4:19:07 AM
To: PHP Internals
Subject: [PHP-DEV] RFC - Zend VM Pause API

Hi, internals,

I propose to introduce a new zend vm pause api, and here is the RPF

https://wiki.php.net/rfc/zend-vm-pause-api

Please gave your comment.

Thank you.

--
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To unsubscribe, visit: http://www.php.net/unsub.php

Haitao Lv

8 years ago

It seems that set EG(vm_interrupt) to 1 could not stop the vm execution but only execute the interrupt_function and continue the current execution.

However, my RFC propose to stop the current execution.

Haitao Lv

8 years ago

Would it proper to introduce the following path?

diff --git a/Zend/zend_vm_def.h b/Zend/zend_vm_def.h
index 9bed9f86bb..cf0935df74 100644
--- a/Zend/zend_vm_def.h
+++ b/Zend/zend_vm_def.h
@@ -8920,13 +8920,19 @@ ZEND_VM_DEFINE_OP(137, ZEND_OP_DATA);

ZEND_VM_HELPER(zend_interrupt_helper, ANY, ANY)
{
+       int8_t interrupt_type = EG(vm_interrupt);
+
EG(vm_interrupt) = 0;
if (EG(timed_out)) {
zend_timeout(0);
} else if (zend_interrupt_function) {
SAVE_OPLINE();
zend_interrupt_function(execute_data);
-               ZEND_VM_ENTER();
+               if (interrupt_type == 2) {
+                       ZEND_VM_RETURN();
+               } else {
+                       ZEND_VM_ENTER();
+               }
}
ZEND_VM_CONTINUE();
}

Haitao Lv

8 years ago

After discussion with Dmitry, I update my RFC. The RFC url is here

https://wiki.php.net/rfc/zend-vm-pause-api

And I propose to introduce a new interrupt type to make vm pause-and-return, not pause-and-continue.

As mentioned by Dmitry, features like Fiber could be implemented by current vm_interrupt implementation, theoretically. By using it, even init a function call will need to make our own op array.

So I propose this patch.

Thank you.

Dmitry Stogov

8 years ago

after zend_interrupt_function() callback VM continues execution using EG(current_execute_data).

callback may modify it in any way (e.g. unwind stack, or switch to another co-routine or continuation).


Thanks. Dmitry.

________________________________
From: Haitao Lv <i@lvht.net>
Sent: Wednesday, November 1, 2017 11:54:54 AM
To: Dmitry Stogov
Cc: PHP Internals
Subject: Re: [PHP-DEV] RFC - Zend VM Pause API

It seems that set EG(vm_interrupt) to 1 could not stop the vm execution but only execute the interrupt_function and continue the current execution.

However, my RFC propose to stop the current execution.

On 1 Nov 2017, at 16:07, Dmitry Stogov <dmitry@zend.com<mailto:dmitry@zend.com>> wrote:

Hi,

It should be possible do similar things using EG(vm_interrupt) and zend_interrupt_function() callback (introduced in php-7.1)
ext/pcntl implements asynchronous signal handling using this.

Thanks. Dmitry.
________________________________
From: Haitao Lv <i@lvht.net<mailto:i@lvht.net>>
Sent: Wednesday, November 1, 2017 4:19:07 AM
To: PHP Internals
Subject: [PHP-DEV] RFC - Zend VM Pause API

Hi, internals,

I propose to introduce a new zend vm pause api, and here is the RPF

https://wiki.php.net/rfc/zend-vm-pause-api

Please gave your comment.

Thank you.

--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: http://www.php.net/unsub.php

Dmitry Stogov

8 years ago

or just change execute_data->opline...

________________________________
From: Dmitry Stogov
Sent: Wednesday, November 1, 2017 12:14:22 PM
To: Haitao Lv
Cc: PHP Internals
Subject: Re: [PHP-DEV] RFC - Zend VM Pause API

after zend_interrupt_function() callback VM continues execution using EG(current_execute_data).

callback may modify it in any way (e.g. unwind stack, or switch to another co-routine or continuation).

Thanks. Dmitry.

________________________________
From: Haitao Lv <i@lvht.net>
Sent: Wednesday, November 1, 2017 11:54:54 AM
To: Dmitry Stogov
Cc: PHP Internals
Subject: Re: [PHP-DEV] RFC - Zend VM Pause API

It seems that set EG(vm_interrupt) to 1 could not stop the vm execution but only execute the interrupt_function and continue the current execution.

However, my RFC propose to stop the current execution.

On 1 Nov 2017, at 16:07, Dmitry Stogov <dmitry@zend.com<mailto:dmitry@zend.com>> wrote:

Hi,

It should be possible do similar things using EG(vm_interrupt) and zend_interrupt_function() callback (introduced in php-7.1)
ext/pcntl implements asynchronous signal handling using this.

Thanks. Dmitry.
________________________________
From: Haitao Lv <i@lvht.net<mailto:i@lvht.net>>
Sent: Wednesday, November 1, 2017 4:19:07 AM
To: PHP Internals
Subject: [PHP-DEV] RFC - Zend VM Pause API

Hi, internals,

I propose to introduce a new zend vm pause api, and here is the RPF

https://wiki.php.net/rfc/zend-vm-pause-api

Please gave your comment.

Thank you.

--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: http://www.php.net/unsub.php

Haitao Lv

8 years ago

Suppose we have a internal Coroutine class and it has a resume() method.

In order to resume the coroutine, we have to call the resume() function.

As the resume function is a internal method defined in c, we need call

zend_execute_ex(backuped_execute_data)

to resume the zend execution.

If we need to pause the coroutine, we set the EG(vm_interrupt) and interrupt_function,
and switch the execute data and stack. The zend vm will execute the old online.

However, we will never see the resume() method returned and never get its return value.

Haitao Lv

8 years ago

To make the discussion more detailed, please allow me to offer my implementation of use land coroutine(Fiber).

https://github.com/php/php-src/compare/master...fiberphp:fiber-ext?expand=1

Dmitry Stogov

8 years ago

I'm not sure, why do you need to exit from the current VM instance.

It should be possible to perform fiber scheduling and VM context switch directly in interrupt handler (like in real OS).

VM should handle this out of the box (at least VM interrupts were designed with context switch in mind).

In your case, I suppose, part of zend_fiber_resume() should be merged into fiber_interrupt_function().

Also you should handle only your own interrupts (like ext/pcntl does checking PCNTL_G(pending_signals)).

Sorry, I don't have a lot of time to review your sources.

However, the implementation is really interesting, and I'm glad, someone is working on this.

Thanks. Dmitry.

________________________________
From: Haitao Lv <i@lvht.net>
Sent: Wednesday, November 1, 2017 12:45:13 PM
To: Dmitry Stogov
Cc: PHP Internals
Subject: Re: [PHP-DEV] RFC - Zend VM Pause API

To make the discussion more detailed, please allow me to offer my implementation of use land coroutine(Fiber).

https://github.com/php/php-src/compare/master...fiberphp:fiber-ext?expand=1