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require_relative 'concern/dereferenceable_shared'
module Concurrent
RSpec.describe MVar do
context 'behavior' do
# dereferenceable
def dereferenceable_subject(value, opts = {})
MVar.new(value, opts)
end
it_should_behave_like :dereferenceable
end
describe '#initialize' do
it 'accepts no initial value' do
m = MVar.new
expect(m).to be_empty
end
it 'accepts an empty initial value' do
m = MVar.new(MVar::EMPTY)
expect(m).to be_empty
end
it 'accepts an initial value' do
m = MVar.new(14)
expect(m).not_to be_empty
end
it 'accepts a nil initial value' do
m = MVar.new(nil)
expect(m).not_to be_empty
end
end
describe '#take' do
it 'sets the MVar to empty' do
m = MVar.new(14)
m.take
expect(m).to be_empty
end
it 'returns the value on a full MVar' do
m = MVar.new(14)
expect(m.take).to eq 14
end
it 'waits for another thread to #put' do
m = MVar.new
in_thread {
sleep(0.1)
m.put 14
}
expect(m.take).to eq 14
end
it 'returns TIMEOUT on timeout on an empty MVar' do
m = MVar.new
expect(m.take(0.1)).to eq MVar::TIMEOUT
end
end
describe '#borrow' do
it 'yields current value to the block and puts back value' do
m = MVar.new(14)
expect { |b| m.borrow(&b) }.to yield_with_args(14)
expect(m.take).to eq(14)
end
it 'puts back value even if an exception is raised' do
m = MVar.new(14)
expect { m.borrow { fail 'boom!' } }.to raise_error('boom!')
expect(m.take).to eq(14)
end
it 'returns the returned value of the block' do
m = MVar.new(14)
expect(m.borrow { 2 }).to eq(2)
expect(m.take).to eq(14)
end
it 'returns TIMEOUT on timeout on an empty MVar' do
m = MVar.new
expect(m.borrow(0.1) { }).to eq MVar::TIMEOUT
end
end
describe '#put' do
it 'sets the MVar to be empty' do
m = MVar.new(14)
m.take
expect(m).to be_empty
end
it 'sets a new value on an empty MVar' do
m = MVar.new
m.put 14
expect(m.take).to eq 14
end
it 'waits for another thread to #take' do
m = MVar.new(14)
in_thread {
sleep(0.1)
m.take
}
expect(m.put(14)).to eq 14
end
it 'returns TIMEOUT on timeout on a full MVar' do
m = MVar.new(14)
expect(m.put(14, 0.1)).to eq MVar::TIMEOUT
end
it 'returns the value' do
m = MVar.new
expect(m.put(14)).to eq 14
end
end
describe '#empty?' do
it 'returns true on an empty MVar' do
m = MVar.new
expect(m).to be_empty
end
it 'returns false on a full MVar' do
m = MVar.new(14)
expect(m).not_to be_empty
end
end
describe '#full?' do
it 'returns false on an empty MVar' do
m = MVar.new
expect(m).not_to be_full
end
it 'returns true on a full MVar' do
m = MVar.new(14)
expect(m).to be_full
end
end
describe '#modify' do
it 'raises an exception when no block given' do
m = MVar.new(14)
expect { m.modify }.to raise_error(ArgumentError)
end
it 'modifies a full MVar' do
m = MVar.new(14)
m.modify { |v| v + 2 }
expect(m.take).to eq 16
end
it 'returns the unmodified value' do
m = MVar.new(14)
expect(m.modify { |v| v + 2 }).to eq 14
end
it 'waits for another thread to #put' do
m = MVar.new
in_thread {
sleep(0.1)
m.put 14
}
expect(m.modify { |v| v + 2 }).to eq 14
end
it 'is atomic' do
m = MVar.new(0)
# #modify conceptually does #take and #put - but it should be atomic.
# Check that another #put can't sneak it during the #modify.
in_thread {
m.modify do |v|
sleep(0.5)
1
end
}
sleep(0.1)
expect(m.put(2, 0.5)).to eq MVar::TIMEOUT
expect(m.take).to eq 1
end
it 'returns TIMEOUT on timeout on an empty MVar' do
m = MVar.new
expect(m.modify(0.1) { |v| v + 2 }).to eq MVar::TIMEOUT
end
end
describe '#try_put!' do
it 'returns true an empty MVar' do
m = MVar.new
expect(m.try_put!(14)).to eq true
end
it 'returns false on a full MVar' do
m = MVar.new(14)
expect(m.try_put!(14)).to eq false
end
it 'sets an empty MVar to be full' do
m = MVar.new
m.try_put! 14
expect(m).to be_full
end
end
describe '#try_take!' do
it 'returns EMPTY an empty MVar' do
m = MVar.new
expect(m.try_take!).to eq MVar::EMPTY
end
it 'returns the value on a full MVar' do
m = MVar.new(14)
expect(m.try_take!).to eq 14
end
it 'sets a full MVar to be empty' do
m = MVar.new(14)
m.try_take!
expect(m).to be_empty
end
end
describe '#set!' do
it 'sets an empty MVar to be full' do
m = MVar.new
m.set! 14
expect(m).to be_full
end
it 'sets a full MVar to be full' do
m = MVar.new(2)
m.set! 14
expect(m).to be_full
expect(m.take).to eq 14
end
it 'returns EMPTY on an empty MVar' do
m = MVar.new
expect(m.set!(2)).to eq MVar::EMPTY
end
it 'returns the original value on a full MVar' do
m = MVar.new(14)
expect(m.set!(2)).to eq 14
end
end
describe '#modify!' do
it 'raises an exception when no block given' do
m = MVar.new(14)
expect { m.modify! }.to raise_error(ArgumentError)
end
it 'modifies a full MVar' do
m = MVar.new(14)
m.modify! { |v| v + 2 }
expect(m.take).to eq 16
end
it 'modifies an empty MVar' do
m = MVar.new
m.modify! { |v| 14 }
expect(m.take).to eq 14
end
it 'can be used to set a full MVar to empty' do
m = MVar.new(14)
m.modify! { |v| MVar::EMPTY }
expect(m).to be_empty
end
it 'can be used to set an empty MVar to empty' do
m = MVar.new
m.modify! { |v| MVar::EMPTY }
expect(m).to be_empty
end
it 'returns the unmodified value' do
m = MVar.new(14)
expect(m.modify! { |v| v + 2 }).to eq 14
end
end
context 'spurious wake ups' do
let(:m) { MVar.new }
before(:each) do
def m.simulate_spurious_wake_up
@mutex.synchronize do
@full_condition.broadcast
@empty_condition.broadcast
end
end
end
describe '#take' do
it 'waits for another thread to #put' do
in_thread { sleep(0.5); m.put 14 }
in_thread { sleep(0.1); m.simulate_spurious_wake_up }
expect(m.take).to eq 14
end
it 'returns TIMEOUT on timeout on an empty MVar' do
result = nil
in_thread { result = m.take(0.3) }
sleep(0.1)
in_thread { m.simulate_spurious_wake_up }
sleep(0.1)
expect(result).to be_nil
sleep(0.2)
expect(result).to eq MVar::TIMEOUT
end
end
describe '#modify' do
it 'waits for another thread to #put' do
in_thread { sleep(0.5); m.put 14 }
in_thread { sleep(0.1); m.simulate_spurious_wake_up }
expect(m.modify { |v| v + 2 }).to eq 14
end
it 'returns TIMEOUT on timeout on an empty MVar' do
result = nil
in_thread { result = m.modify(0.3) { |v| v + 2 } }
sleep(0.1)
in_thread { m.simulate_spurious_wake_up }
sleep(0.1)
expect(result).to be_nil
sleep(0.2)
expect(result).to eq MVar::TIMEOUT
end
end
describe '#put' do
before(:each) { m.put(42) }
it 'waits for another thread to #take' do
in_thread { sleep(0.5); m.take }
in_thread { sleep(0.1); m.simulate_spurious_wake_up }
expect(m.put(14)).to eq 14
end
it 'returns TIMEOUT on timeout on a full MVar', notravis: true do
# TODO (pitr-ch 15-Oct-2016): fails on jruby
result = nil
in_thread { result = m.put(14, 0.3) }
sleep(0.1)
in_thread { m.simulate_spurious_wake_up }
sleep(0.1)
expect(result).to be_nil
sleep(0.2)
expect(result).to eq MVar::TIMEOUT
end
end
end
end
end
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