relax Fiber#transfer's restriction #3636
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eregon
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eregon
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test/ruby/test_fiber.rb
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| @@ -409,5 +480,5 @@ def test_machine_stack_gc | |||
| sleep 5 # pause until thread cache wait time runs out. Native thread exits. | |||
| GC.start | |||
| RUBY | |||
| end | |||
| end if false | |||
eregon
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| end | ||
| ruby_version_is '3.0' do | ||
| fiber2.resume.should == :fiber2 | ||
| end |
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It's better to have ruby_version_is outside of it "description" do, so the description can explain the difference in behavior. I can do that after this PR is merged.
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cont.c
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| rb_raise(rb_eFiberError, "attempt to transfer to a resuming fiber"); | ||
| } | ||
| if (fiber->yielding) { | ||
| rb_raise(rb_eFiberError, "attempt to transfer to an yielding fiber"); |
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to a yielding fiber (replied on Redmine)
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Using Fiber#transfer with Fiber#resume for a same Fiber is limited (once Fiber#transfer is called for a fiber, the fiber can not be resumed more). This restriction was introduced to protect the resume/yield chain, but we realized that it is too much to protect the chain. Instead of the current restriction, we introduce some other protections. (1) can not transfer to the resuming fiber. (2) can not transfer to the yielding fiber. (3) can not resume transferred fiber. (4) can not yield from not-resumed fiber. [Bug #17221] Also at the end of a transferred fiber, it had continued on root fiber. However, if the root fiber resumed a fiber (and that fiber can resumed another fiber), this behavior also breaks the resume/yield chain. So at the end of a transferred fiber, switch to the edge of resume chain from root fiber. For example, root fiber resumed f1 and f1 resumed f2, transferred to f3 and f3 terminated, then continue from the fiber f2 (it was continued from root fiber without this patch).
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Using Fiber#transfer with Fiber#resume for a same Fiber is
limited (once Fiber#transfer is called for a fiber, the fiber
can not resume more). This restriction is introduced to protect
the resume/yield chain, but we realized that it is too much to
protect the resume/yield chain. Instead of the current restriction,
we introduce some other protection.
(1) can not transfer to the resuming fiber.
(2) can not transfer to the yielding fiber.
(3) can not resume transferred fiber.
https://bugs.ruby-lang.org/issues/17221