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|
require "spec"
require "wait_group"
private def block_until_pending_waiter(wg)
while wg.@waiting.empty?
Fiber.yield
end
end
private def forge_counter(wg, value)
wg.@counter.set(value)
end
describe WaitGroup do
describe "#add" do
it "can't decrement to a negative counter" do
wg = WaitGroup.new
wg.add(5)
wg.add(-3)
expect_raises(RuntimeError, "Negative WaitGroup counter") { wg.add(-5) }
end
it "resumes waiters when reaching negative counter" do
wg = WaitGroup.new(1)
spawn do
block_until_pending_waiter(wg)
wg.add(-2)
rescue RuntimeError
end
expect_raises(RuntimeError, "Negative WaitGroup counter") { wg.wait }
end
it "can't increment after reaching negative counter" do
wg = WaitGroup.new
forge_counter(wg, -1)
# check twice, to make sure the waitgroup counter wasn't incremented back
# to a positive value!
expect_raises(RuntimeError, "Negative WaitGroup counter") { wg.add(5) }
expect_raises(RuntimeError, "Negative WaitGroup counter") { wg.add(3) }
end
end
describe "#done" do
it "can't decrement to a negative counter" do
wg = WaitGroup.new
wg.add(1)
wg.done
expect_raises(RuntimeError, "Negative WaitGroup counter") { wg.done }
end
it "resumes waiters when reaching negative counter" do
wg = WaitGroup.new(1)
spawn do
block_until_pending_waiter(wg)
forge_counter(wg, 0)
wg.done
rescue RuntimeError
end
expect_raises(RuntimeError, "Negative WaitGroup counter") { wg.wait }
end
end
describe "#wait" do
it "immediately returns when counter is zero" do
channel = Channel(Nil).new(1)
spawn do
wg = WaitGroup.new(0)
wg.wait
channel.send(nil)
end
select
when channel.receive
# success
when timeout(1.second)
fail "expected #wait to not block the fiber"
end
end
it "immediately raises when counter is negative" do
wg = WaitGroup.new(0)
expect_raises(RuntimeError) { wg.done }
expect_raises(RuntimeError, "Negative WaitGroup counter") { wg.wait }
end
it "raises when counter is positive after wake up" do
wg = WaitGroup.new(1)
waiter = Fiber.current
spawn do
block_until_pending_waiter(wg)
waiter.enqueue
end
expect_raises(RuntimeError, "Positive WaitGroup counter (early wake up?)") { wg.wait }
end
end
it "waits until concurrent executions are finished" do
wg1 = WaitGroup.new
wg2 = WaitGroup.new
8.times do
wg1.add(16)
wg2.add(16)
exited = Channel(Bool).new(16)
16.times do
spawn do
wg1.done
wg2.wait
exited.send(true)
end
end
wg1.wait
16.times do
select
when exited.receive
fail "WaitGroup released group too soon"
else
end
wg2.done
end
16.times do
select
when x = exited.receive
x.should eq(true)
when timeout(1.millisecond)
fail "Expected channel to receive value"
end
end
end
end
it "increments the counter from executing fibers" do
wg = WaitGroup.new(16)
extra = Atomic(Int32).new(0)
16.times do
spawn do
wg.add(2)
2.times do
spawn do
extra.add(1)
wg.done
end
end
wg.done
end
end
wg.wait
extra.get.should eq(32)
end
it "takes a block to WaitGroup.wait" do
fiber_count = 10
completed = Array.new(fiber_count) { false }
WaitGroup.wait do |wg|
fiber_count.times do |i|
wg.spawn { completed[i] = true }
end
end
completed.should eq [true] * 10
end
# the test takes far too much time for the interpreter to complete
{% unless flag?(:interpreted) %}
it "stress add/done/wait" do
wg = WaitGroup.new
1000.times do
counter = Atomic(Int32).new(0)
2.times do
wg.add(1)
spawn do
counter.add(1)
wg.done
end
end
wg.wait
counter.get.should eq(2)
end
end
{% end %}
end
|
