rfc:native-tls

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rfc:native-tls [2014/11/19 18:48]
ab
rfc:native-tls [2017/09/22 13:28] (current)
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   * Date: 2014-11-19   * Date: 2014-11-19
   * Author: Anatol Belski, ab@php.net   * Author: Anatol Belski, ab@php.net
-  * Status: Draft /* (or Under Discussion or Accepted or Declined) */ +  * Status: Accepted
-  /* * First Published at: http://wiki.php.net/rfc/your_rfc_name */+
  
 ===== Introduction ===== ===== Introduction =====
-Currently, to access module globals in TS mode, a global resource array is used. That array contains globals from all the threads and the right globals are identified by the thread key. The thread key is passed to every function requiring access to the globals. Or, it has to be fetched on demand. Consequently+Currently, to access module globals in TS mode, a global resource array is used. That array contains globals from all the threads and per thread globals are identified by the thread key. The thread key is passed to every function requiring access to the globals. Or, it has to be fetched on demand. Consequently
  
   * many functions have to take an additional argument used only in TS mode, that makes code to be overloaded with TSRMLS_* macros   * many functions have to take an additional argument used only in TS mode, that makes code to be overloaded with TSRMLS_* macros
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 ===== Proposal ===== ===== Proposal =====
-The redundancy of passing thread id explicitly should be removed where possible. Ideally, one global thread specific variable should be used to hold the thread key (while it's not possible exactly the way on every platform, see the implementation details).+The technique of passing thread id explicitly should be removed where possible. Ideally, one global thread specific variable should be used to hold the thread key (while it's not possible exactly the way on every platform, see the implementation details)
 + 
 +The current patch focuses on stability and code quality improvement more than on performance. Whereby the latest tests show that the patched version is at least as fast as the mainstream.
  
 ===== Backward Incompatible Changes ===== ===== Backward Incompatible Changes =====
-  thread id isn'passed explicitly anymore+  thread id will not be passed explicitly anymore, many signatures have to loose their TSRM_* parts 
 +  * a few places with "#ifdef ZTS" have to be reworked to fetch the thread key the new way 
 + 
 +===== Implementation details ===== 
 +The current implementation is done by the following scheme 
 + 
 +  - all the TSRMLS_* macros was made placebo 
 +  - TSRMG macro which is used to access the globals now can have two variants 
 +    - using the tsrm_tls_cache() function which fetches the thread specific globals using the underlaying platform API (for example pthreads on linux or windows specific on windows) 
 +    - using a previously defined pointer which is global within a binary unit and is updated per thread 
 +  - core was ported to use the static per binary unit cache (the second variant above), the enablement was done step by step 
 + 
 +As also described in the base RFC, the main difficulty to make this process cross platform is that not every compiler (for instance Visual Studio) support sharing a thread specific variable between shared objects. For that reason, the function call to tsrm_get_ls_cache() is needed at least once per thread in order to work with the thread specific resources. Such an operation is needed to be done within every binary unit. 
 + 
 +In the patch, almost any macros accessing globals, like EG, CG, etc. are ported to use a local TSRMLS pointer which is static to that binary unit (i.e. shared extension or SAPI bin/dll/so). For that three steps are required 
 + 
 +  - defining a tsrmls cache holder for a binary unit (ZEND_TSRMLS_CACHE_DEFINE macro) 
 +  - externing that pointer in a header file so other C files can use it (ZEND_TSRMLS_CACHE_EXTERN macro) 
 +  - integrate a mechanism to update that pointer per thread and binary unit (ZEND_TSRMLS_CACHE_UPDATE macro) 
 + 
 +These are also the steps required to port an extension/SAPI to be compatible with the patch. The porting was done step by step and the static TSRMLS cache is only enabled when ZEND_ENABLE_STATIC_TSRMLS_CACHE macro is defined from the config.* script. Otherwise the method with dynamic cache fetching per tsrm_get_ls_cache() is used. 
 + 
 +**Currently all the ocurrencies with TSRMLS_* macros evaluate to empty but left at their places, so then the diff shows the real change done. They are going to be removed once the RFC is accepted and before it was merged**
  
 ===== Proposed PHP Version(s) ===== ===== Proposed PHP Version(s) =====
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 ==== To Existing Extensions ==== ==== To Existing Extensions ====
 See implementation details. See implementation details.
 +
 +==== To operating systems ====
 +A potential incompatibility to not widely used operating systems can be introduced. Any Unix (like) OS using pthreads or other threads implementation supported by the TSRM layer, or any x86/x64 Windows system, are supported. That covers good 99% of the target OSes (please read the base RFC for more details).
  
 ===== Open Issues ===== ===== Open Issues =====
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   * depending on compiler evolution, fetching thread id per function could be replaced with a real global variable shared across all the binary units (.so, .dll, .exe)   * depending on compiler evolution, fetching thread id per function could be replaced with a real global variable shared across all the binary units (.so, .dll, .exe)
  
-===== Proposed Voting Choices ===== +===== Vote ===== 
-yes, no +<doodle title="Native TLS" auth="ab" voteType="single" closed="true"> 
- +   * Yes 
-50%+1 majority required+   * No 
 +</doodle> 
 +\\ 
 +The vote starts on 12/10/2014 at 21:00 CET and ends on 12/17/2014 at 21:00 CET. 50%+1 majority required.
  
 ===== Patches and Tests ===== ===== Patches and Tests =====
rfc/native-tls.1416422894.txt.gz · Last modified: 2017/09/22 13:28 (external edit)