Re: Implemented fallocate() syscall in streams

On 13/06/2014 16:20, Julien Pauli wrote:

Hi, Hello :-),

I just wrote a patch to add fallocate() syscall support for streams. It relies on posix_fallocate(), so that it should support many Unixes. Linux's got a specification with a fallocate() function, more powerful than the posix call. fallocate() does write blocks to the underlying filesystem (not so many are supported, but the ones not supported should proxy to ftruncate()) and prevents sparse file creation whereas ftruncate() just updates inode information, leading to possible future out of space errors. I got a POC showing the diffs between both calls here : https://gist.github.com/jpauli/8afec7c4fc2b38f8ff27 I propose two APIs for PHP : - One that adds a function : fallocate() https://github.com/jpauli/php-src/tree/fallocate I prefer this one.

- One that relies on ftruncate() , and adds a <bool>$use_fallocate flag https://github.com/jpauli/php-src/tree/fallocate_flag Please, note that the latest proposal requires patches in different extensions, as I changed a PHP_API function signature. I don't know if Windows can support that. Pierre, Anatol ? :-) Tests are beeing written at the moment. I didn't implement this is user stream handlers, as this really is a low level implementation design that is kind of useless for usage in user streams. Thoughts ? If the first one is used, please, consider exposing it on the user-land of stream wrappers (exemple: stream_allocate) if possible.

Cheers. -- Ivan Enderlin Developer of Hoa http://hoa-project.net/ PhD. student at DISC/Femto-ST (Vesontio) and INRIA (Cassis) http://disc.univ-fcomte.fr/ and http://www.inria.fr/ Member of HTML and WebApps Working Group of W3C http://w3.org/