[ruby-core:47533] [ruby-trunk - Bug #6174] Fix collision of ConditionVariable#wait timeout and #signal (+ other cosmetic changes)

Issue #6174 has been updated by kosaki (Motohiro KOSAKI).


> Ok, now callback is wrapped to rb_ensure inside of rb_mutex_sleep_forever and rb_mutex_wait_for.

Unfortunately, this doesn't help us. Even if using rb_ensure, still your callback can be interruptible. and we have no guarantee to execute
a callback. 

I believe we need to implement [Feature #6762].


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Bug #6174: Fix collision of ConditionVariable#wait timeout and #signal (+ other cosmetic changes)
https://bugs.ruby-lang.org/issues/6174#change-29312

Author: funny_falcon (Yura Sokolov)
Status: Rejected
Priority: Normal
Assignee: kosaki (Motohiro KOSAKI)
Category: lib
Target version: 2.0.0
ruby -v: ruby 2.0.0dev (2012-03-17 trunk 35075) [i686-linux]


1. Currently, when Thread wakes on timeout, it could not remove itself from ConditionVariable waiters until it acquires lock.
So that, when ConditionVariable#signal is called, it will try to wakeup
such thread, instead of some one else.
https://github.com/funny-falcon/ruby/commit/24a9b6112477b2107ac9a19d0189a11fb97aa891
https://github.com/funny-falcon/ruby/commit/24a9b6112477b2107ac9a19d0189a11fb97aa891.patch

Simple way to avoid it, is to allow Mutex#sleep to recieve a block, which will be called right after Thread will awake, but before Mutex will be tried to lock
https://github.com/funny-falcon/ruby/commit/9e9157c5318926331dbe883416b69d38a58fea5d
https://github.com/funny-falcon/ruby/commit/9e9157c5318926331dbe883416b69d38a58fea5d.patch

2. Since MatzRuby use GVL for thread isolation, and native method could not be interrupted (unless it will), we could remove couple of calles to Mutex#synchronize
https://github.com/funny-falcon/ruby/commit/a9ad8d274b96f14519643fc63327394f72b83516
https://github.com/funny-falcon/ruby/commit/a9ad8d274b96f14519643fc63327394f72b83516.patch

3. Usage of hash with `compare_by_identity` allows remove call to Array#include? in a Queue. Also it allows to remove other call Mutex#synchronize from ConditionVariable#wait in case when we rely on GVL.
https://github.com/funny-falcon/ruby/commit/0da1887a04f7a0e4f9289d2167c2a6d0073651e1
https://github.com/funny-falcon/ruby/commit/0da1887a04f7a0e4f9289d2167c2a6d0073651e1.patch

4. And cosmetic changes to SizedQueue
https://github.com/funny-falcon/ruby/commit/60ed97557c8178bc78edf670f3d53d761e627bf0
https://github.com/funny-falcon/ruby/commit/60ed97557c8178bc78edf670f3d53d761e627bf0.patch

Pull request at once:
https://github.com/ruby/ruby/pull/104
https://github.com/ruby/ruby/pull/104.diff
https://github.com/ruby/ruby/pull/104.patch


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