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ruby--ruby/spec/ruby/library/fiber/current_spec.rb
Koichi Sasada bf3b2a4374 relax Fiber#transfer's restriction
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).
2020-10-12 22:58:41 +09:00

63 lines
1.4 KiB
Ruby

require_relative '../../spec_helper'
require 'fiber'
describe "Fiber.current" do
it "returns the root Fiber when called outside of a Fiber" do
root = Fiber.current
root.should be_an_instance_of(Fiber)
# We can always transfer to the root Fiber; it will never die
5.times do
root.transfer.should be_nil
root.alive?.should be_true
end
end
it "returns the current Fiber when called from a Fiber" do
fiber = Fiber.new do
this = Fiber.current
this.should be_an_instance_of(Fiber)
this.should == fiber
this.alive?.should be_true
end
fiber.resume
end
it "returns the current Fiber when called from a Fiber that transferred to another" do
states = []
fiber = Fiber.new do
states << :fiber
this = Fiber.current
this.should be_an_instance_of(Fiber)
this.should == fiber
this.alive?.should be_true
end
fiber2 = Fiber.new do
states << :fiber2
fiber.transfer
flunk
end
fiber3 = Fiber.new do
states << :fiber3
fiber2.transfer
ruby_version_is '3.0' do
states << :fiber3_terminated
end
ruby_version_is '' ... '3.0' do
flunk
end
end
fiber3.resume
ruby_version_is "" ... "3.0" do
states.should == [:fiber3, :fiber2, :fiber]
end
ruby_version_is "3.0" do
states.should == [:fiber3, :fiber2, :fiber, :fiber3_terminated]
end
end
end