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[php-gni] More notes on thread safety for PHP

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le: 31. 10. 2005 [11:54]
braulio Braulio Solano Rojas Inscrit depuis: 16.05.2008 Interventions: 2	Hi! Jesús had you time to read the articles from Zend? http://www.zend.com/php/internals/extension-writing1.php http://www.zend.com/php/internals/extension-writing2.php As you can see PHP is part a Virtual Machine like Java. In fact you can have scripts in opcodes just ready to run. Thread safety is provided by the Zend Engine. Sometimes PHP is compiled for multi-threaded platforms like IIS or Apache. That is where all those macros for thread safety are handy. When PHP is a CGI it does not matter very much since it runs one time and variables or functions are in their own address space and are not shared. I believe I have an error in function php_isis_subrow_array with thread safety. But I am not sure. See this comment (from php_isis.h): /* In every utility function you add that needs to use variables in php_isis_globals, call TSRM_FETCH(); after declaring other variables used by that function, or better yet, pass in TSRMG_CC after the last function argument and declare your utility function with TSRMG_DC after the last declared argument. Always refer to the globals in your function as ISIS_G(variable). You are encouraged to rename these macros something shorter, see examples in any other php module directory. */ I saved it because I never understood it very well. In fact I believe it is very important, but the writing is actually ambiguous to me. And as you can see it seems there are two ways of achieving what that paragraph means (good bye orthogonality). In php_isis_subrow_array I believe I am not using globals from php_isis_globals, but I am doing something wrong that makes the extension not thread safe. TSRM macros are used almost very well in the extension (and I have to notice that it was the first time I was doing that kind of stuff). There are other issues like for instance isis_terms. As you can see results are saved in a variable like this one: union { OpenIsisRec set; char buf[10000]; } result; I do not know how OpenIsis library handles this. Therefore I do not know what happens if the result is bigger than 10000 bytes. Maybe this is why Róger asked for isis_terms_by_range, which I do not like since the extension should be maintained as simple as possible and what can be done in PHP land should be done there. But in this case an exception must be made since isis_terms by itself does not work well. Well, as you can see thread safety can be considered as avoiding "Segmentation fault". Saludos, B. ------------------------------------------ Posted to Phorum via PhorumMail
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