rfc:fiber

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rfc:fiber [2018/02/10 04:22] – lvhtrfc:fiber [2018/04/17 23:52] – lvht
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   * Version: 0.1   * Version: 0.1
   * Date: 2017-09-13   * Date: 2017-09-13
-  * Author: Haitao Lv, i@lvht.net+  * Author: Haitao Lv<i@lvht.net>, Dmitry Stogov<dmitry@zend.com>, Martin Schröder<m.schroeder2007@googlemail.com>
   * Status: Under Discussion   * Status: Under Discussion
   * First Published at: http://wiki.php.net/rfc/fiber   * First Published at: http://wiki.php.net/rfc/fiber
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 ===== Proposal ===== ===== Proposal =====
 ==== Why not make it as a Extension? ==== ==== Why not make it as a Extension? ====
 +Fiber is a major language feature, that allows significant benefits for asynchronous frameworks. Providing it as an optional extension, just doesn't make sense.
 +
 ==== Implementation ==== ==== Implementation ====
  
 +=== Proposed API ===
 <code php> <code php>
 final class Fiber { final class Fiber {
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   public const STATUS_DEAD      = 4;   public const STATUS_DEAD      = 4;
  
 +  /**
 +   * @param callable $callable any php callable to be paused
 +   * @param int $stack_size fiber stack init size
 +   */
   public function __construct(callable $callable = null, int stack_size = null) {}   public function __construct(callable $callable = null, int stack_size = null) {}
  
 +  /**
 +   * pause the current fiber and ~return~ the $arg1
 +   * as the Fiber::resume's return value.
 +   */
   public static function yield($arg1) {}   public static function yield($arg1) {}
 +  
 +  /**
 +   * Start or resume a fiber.
 +   * 
 +   * If the fiber is not started, call resume will init
 +   * the $callable with all args.
 +   *
 +   * If the fiber is paused, call resume will send the first arg
 +   * as the last Fiber::yield's return value.
 +   */
   public function resume($arg1...) {}   public function resume($arg1...) {}
- +   
-  /** @throws \UnexpectedValueException */ +  /** 
-  public function __wakeup(): void {} +   * Throw an exception into the fiber. 
- +   *  
-  /** @throws \Error */ +   * You code can use try/catch to process error in the 
-  private function __clone() {}+   * top level function call. Some framework make heavy 
 +   * usage of this feature. 
 +   */ 
 +  public function throw(Throwable $e) {}
 } }
 </code> </code>
  
 +=== Usage Demo ===
 <code php> <code php>
 function sub1() function sub1()
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 echo $fiber->resume("hello "); // echo "hello world" echo $fiber->resume("hello "); // echo "hello world"
 </code> </code>
 +
 +=== Implementation Detail ===
 +In our simple implementation, we only backup/restore the **zend stack**. If you pause a Fiber in some internal function call like `array_map`, the c stack frame maybe over write which will trigger coredump.
 +
 +Martin Schröder has another implementation at https://github.com/fiberphp/fiber-ext/pull/30. Martin's work backup/restore both the zend stack and the c stack.
 +
 +
 +^Property^Martin's Fiber^Our Fiber^
 +|Minimum Memory Usage|VM stack only (4 KB)|VM & C stack (4 KB + 4 KB)|
 +|Supported Architecturs|any platform supported by compiler|only x86 systems at this time|
 +|Yield in Internal Function|unsupported|supported|
 +|Yield in Iterator|unsupported|supported|
  
 ===== Backward Incompatible Changes ===== ===== Backward Incompatible Changes =====
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 ===== Open Issues ===== ===== Open Issues =====
-From Nikita +<blockquote>What happens if there are internal calls on the call stack?Say something like array_map(function() { await; }, [1, 2, 3]); inside a fiber. 
-<blockquote>What happens if there are internal calls on the call stack?Say something like array_map(function() { await; }, [1, 2, 3]); inside a fiber. Internal calls (using the C stack rather than the VM stack) are usually the problem with this kind of endeavor.+
 </blockquote> </blockquote>
  
-Fiber does not support yielding during the internal call. Calling Fiber::yield in a internal call will cause core dump. +Calling Fiber::yield in a internal call will trigger a fatal error. 
-However, avoiding yield in the internal still make sense and useful+ 
 +<blockquote>How do you determine when a fiber has returned? Separate methods similar to Generator would be better.</blockquote> 
 + 
 +Offering methods like **Fiber::alive()**,**Fiber::running()** makes any meaningful difference to check the return value of Fiber::status(). It is just a coding style issue. 
 + 
 +And as a language feature, Fiber should only offer the essential API and let other works to the userland code. 
 + 
 +<blockquote>Using Fiber::resume() to initialize the fiber and resume feels awkward. Separate methods again would be better.</blockquote> 
 + 
 +Both Ruby's Fiber and Lua's coroutine using the same **resume()** API to **init** and **resume** their coroutine. 
 + 
 +<blockquote>I think a keyword here would be beneficial, even if it has a minor BC impact.</blockquote> 
 + 
 +Introducing new keywords does not offer any essential benefit but only cause BC impact. 
 + 
 +Both Ruby's Fiber and Lua's coroutine use method to pause and resume their coroutine. 
 ===== Unaffected PHP Functionality ===== ===== Unaffected PHP Functionality =====
 None None
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 ===== Proposed Voting Choices ===== ===== Proposed Voting Choices =====
-Simple 50%+1 majority vote.+2/3+1 voting majority
  
 ===== Patches and Tests ===== ===== Patches and Tests =====
-coming soon. Current developing at https://github.com/fiberphp/fiber-ext +  * https://github.com/php/php-src/pull/3203 
- +  * <del>[[https://github.com/php/php-src/pull/2723]]</del> 
-  * <del>[[https://github.com/php/php-src/pull/2733|GitHub PR #2733]]</del>+  * <del>[[https://github.com/php/php-src/pull/2733]]</del> 
 +  * <del>[[https://github.com/php/php-src/pull/2886]]</del> 
 +  * <del>[[https://github.com/php/php-src/pull/2902]]</del>
  
 ===== Implementation ===== ===== Implementation =====
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 ===== Rejected Features ===== ===== Rejected Features =====
-Keep this updated with features that were discussed on the mail lists. 
rfc/fiber.txt · Last modified: 2018/06/12 07:40 by krakjoe

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