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To: "internals@lists.php.net" <internals@lists.php.net>, "Christian Ferrari"
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Date: Wed, 30 May 2012 23:43:32 +0200
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Subject: Re: [PHP-DEV] PHP and two phase commit transactions
From: glopes@nebm.ist.utl.pt ("Gustavo Lopes")

On Wed, 30 May 2012 22:10:56 +0200, Christian Ferrari <camauz@yahoo.com>  
wrote:

> You correctly understood the only necessary changes are related to  
> open/close connection to the resource manager (database); this is a  
> consequence of XA and TX specifications.
> I've not completely understood your statement "add some hooks to the  
> several database extensions" and I would need some more details; is this  
> mailing list the right place to discuss about this type of details or is  
> there a better place?

What I meant was that you should not couple the database extensions to  
your C library. Instead of having:

	struct conection *conn;
#ifdef LIXA
	if (lixa_is_active()) {
		conn = lixa_whatever();
	} else {
#endif
		conn = do_default();
	}

prefer something like:

	extern struct connection (*get_connection_override)(void);
	...
	if (get_connection_override) {
		conn = get_connection_override();
	} else {
		conn = do_default();
	}

You can do this in different ways -- by having a PHP wide variable and  
generic function to retrieve and close connections that would be passed  
the type of resources an other parameters; you could have a different  
scheme for eachDB extension, etc. -- those details are relatively  
unimportant.

> 1. Is there any interest in "two phase commit" inside PHP community?  
> Without a real interest, every effort would be useless.

It is very difficult to determine the future demand for something that  
does not exist yet. Microsoft introduced filesystem transactions in  
Windows Vista, and it's considering deprecating them. But given the  
prevalence of JTA in the Java world and the developments in PHP in the  
last years I would not be surprised if there was significant demand for  
this. And given the current tendency to use more specialized databases  
(see JCR client implementations), it may become more important in the  
future.

> 2. Is there anyone available to help me in implementing the interface  
> between LIXA and database extensions in "the right way"? After some  
> analysis I discovered some database extensions are really sophisticated  
> and injecting a bug is simpler than adding a well implemented feature. I  
> wouldn't break some working code.
>

I can review your patches and help you along the way.

Note that stable branches generally do not receive new features, so you  
should develop against the development branch (master). If it's your  
thing, you can fork PHP on github: https://github.com/php/php-src

-- 
Gustavo Lopes