PHP RFC: Zend VM Pause API

• Version: 0.9
• Date: 2017-11-01
• Author: Haitao Lv, php@lvht.net
• Status: Obsolete
• First Published at: http://wiki.php.net/rfc/zend-vm-pause-api

This RPC has been obsolete. Please see https://github.com/php/php-src/pull/2902 for more detail.

There is no API for change the Zend VM's execute flow. The only approach to change the Zend VM's execute flow is introducing a new keyword and making a new opline, and use ZEND_VM_RETURN/ZEND_VM_CONTINUE macro in its handler.

So it is impossible to change the Zend VM's execute flow in an zend extension. As a result, any feature, like Fiber, related to Zend VM's execute flow cannot be implemented by a standalone extension.

This PRFC propose a new vm_interrupt type, by which some zend extension could make the zend vm execution pause and return. So we can implement feature like Fiber in a standalone extension.

diff --git a/Zend/zend_vm_def.h b/Zend/zend_vm_def.h
index 183072033607..bd7408e824fc 100644
--- a/Zend/zend_vm_def.h
+++ b/Zend/zend_vm_def.h
@@ -8893,13 +8893,19 @@ 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 (UNEXPECTED(interrupt_type == 2)) {
+			ZEND_VM_RETURN();
+		} else {
+			ZEND_VM_ENTER();
+		}
 	}
 	ZEND_VM_CONTINUE();
 }

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PHP 7.3

But I would like this patch could be backported to PHP 7.1 and PHP 7.2.

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50%+1

https://github.com/php/php-src/pull/2902

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