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|
require 'concurrent/atomic/semaphore'
RSpec.shared_examples :semaphore do
let(:semaphore) { described_class.new(3) }
describe '#initialize' do
it 'raises an exception if the initial count is not an integer' do
expect {
described_class.new('foo')
}.to raise_error(ArgumentError)
end
context 'when initializing with 0' do
let(:semaphore) { described_class.new(0) }
it do
expect(semaphore).to_not be nil
end
end
context 'when initializing with -1' do
let(:semaphore) { described_class.new(-1) }
it do
semaphore.release
expect(semaphore.available_permits).to eq 0
end
end
end
describe '#acquire' do
context 'without block' do
context 'permits available' do
it 'should return nil immediately' do
result = semaphore.acquire
expect(result).to be_nil
end
end
context 'not enough permits available' do
it 'should block thread until permits are available' do
semaphore.drain_permits
in_thread { sleep(0.2); semaphore.release }
result = semaphore.acquire
expect(result).to be_nil
expect(semaphore.available_permits).to eq 0
end
end
context 'when acquiring negative permits' do
it 'raises ArgumentError' do
expect {
semaphore.acquire(-1)
}.to raise_error(ArgumentError)
end
end
end
context 'with block' do
context 'permits available' do
it 'should acquire permits, run the block, release permits, and return block return value' do
available_permits = semaphore.available_permits
yielded = false
expected_result = Object.new
actual_result = semaphore.acquire do
expect(semaphore.available_permits).to eq(available_permits - 1)
yielded = true
expected_result
end
expect(semaphore.available_permits).to eq(available_permits)
expect(yielded).to be true
expect(actual_result).to be(expected_result)
end
it 'if the block raises, the permit is still released' do
expect {
expect {
semaphore.acquire do
raise 'boom'
end
}.to raise_error('boom')
}.to_not change { semaphore.available_permits }
end
end
context 'not enough permits available' do
it 'should block thread until permits are available' do
yielded = false
semaphore.drain_permits
in_thread { sleep(0.2); semaphore.release }
expected_result = Object.new
actual_result = semaphore.acquire do
yielded = true
expected_result
end
expect(actual_result).to be(expected_result)
expect(yielded).to be true
expect(semaphore.available_permits).to eq 1
end
end
context 'when acquiring negative permits' do
it 'raises ArgumentError' do
expect {
expect {
semaphore.acquire(-1) do
raise 'block should never run'
end
}.to raise_error(ArgumentError)
}.not_to change { semaphore.available_permits }
end
end
end
end
describe '#drain_permits' do
it 'drains all available permits' do
drained = semaphore.drain_permits
expect(drained).to eq 3
expect(semaphore.available_permits).to eq 0
end
it 'drains nothing in no permits are available' do
semaphore.reduce_permits 3
drained = semaphore.drain_permits
expect(drained).to eq 0
end
end
describe '#try_acquire' do
context 'without block' do
context 'without timeout' do
it 'acquires immediately if permits are available' do
result = semaphore.try_acquire(1)
expect(result).to be_truthy
end
it 'returns false immediately in no permits are available' do
result = semaphore.try_acquire(20)
expect(result).to be_falsey
end
context 'when trying to acquire negative permits' do
it do
expect {
semaphore.try_acquire(-1)
}.to raise_error(ArgumentError)
end
end
end
context 'with timeout' do
it 'acquires immediately if permits are available' do
result = semaphore.try_acquire(1, 5)
expect(result).to be_truthy
end
it 'acquires when permits are available within timeout' do
semaphore.drain_permits
in_thread { sleep 0.1; semaphore.release }
result = semaphore.try_acquire(1, 1)
expect(result).to be_truthy
end
it 'returns false on timeout' do
semaphore.drain_permits
result = semaphore.try_acquire(1, 0.1)
expect(result).to be_falsey
end
end
end
context 'with block' do
context 'without timeout' do
it 'acquires immediately if permits are available and returns block return value' do
yielded = false
available_permits = semaphore.available_permits
expected_result = Object.new
actual_result = semaphore.try_acquire(1) do
yielded = true
expect(semaphore.available_permits).to eq(available_permits - 1)
expected_result
end
expect(actual_result).to be(expected_result)
expect(yielded).to be true
expect(semaphore.available_permits).to eq available_permits
end
it 'releases permit if block raises' do
expect {
expect {
semaphore.try_acquire(1) do
raise 'boom'
end
}.to raise_error('boom')
}.not_to change { semaphore.available_permits }
end
it 'returns false immediately in no permits are available' do
expect {
result = semaphore.try_acquire(20) do
raise 'block should never run'
end
expect(result).to be_falsey
}.not_to change { semaphore.available_permits }
end
context 'when trying to acquire negative permits' do
it do
expect {
expect {
semaphore.try_acquire(-1) do
raise 'block should never run'
end
}.to raise_error(ArgumentError)
}.not_to change { semaphore.available_permits }
end
end
end
context 'with timeout' do
it 'acquires immediately if permits are available, and returns block return value' do
expect {
yielded = false
expected_result = Object.new
actual_result = semaphore.try_acquire(1, 5) do
yielded = true
expected_result
end
expect(actual_result).to be(expected_result)
expect(yielded).to be true
}.not_to change { semaphore.available_permits }
end
it 'releases permits if block raises' do
expect {
expect {
semaphore.try_acquire(1, 5) do
raise 'boom'
end
}.to raise_error('boom')
}.not_to change { semaphore.available_permits }
end
it 'acquires when permits are available within timeout, and returns block return value' do
yielded = false
semaphore.drain_permits
in_thread { sleep 0.1; semaphore.release }
expected_result = Object.new
actual_result = semaphore.try_acquire(1, 1) do
yielded = true
expected_result
end
expect(actual_result).to be(expected_result)
expect(yielded).to be true
expect(semaphore.available_permits).to be 1
end
it 'returns false on timeout' do
semaphore.drain_permits
result = semaphore.try_acquire(1, 0.1) do
raise 'block should never run'
end
expect(result).to be_falsey
expect(semaphore.available_permits).to be 0
end
end
end
end
describe '#reduce_permits' do
it 'raises ArgumentError if reducing by negative number' do
expect {
semaphore.reduce_permits(-1)
}.to raise_error(ArgumentError)
end
it 'reduces permits below zero' do
semaphore.reduce_permits 1003
expect(semaphore.available_permits).to eq(-1000)
end
it 'reduces permits' do
semaphore.reduce_permits 1
expect(semaphore.available_permits).to eq 2
semaphore.reduce_permits 2
expect(semaphore.available_permits).to eq 0
end
it 'reduces zero permits' do
semaphore.reduce_permits 0
expect(semaphore.available_permits).to eq 3
end
end
describe '#release' do
it 'increases the number of available permits by one' do
semaphore.release
expect(semaphore.available_permits).to eq 4
end
context 'when a number of permits is specified' do
it 'increases the number of available permits by the specified value' do
semaphore.release(2)
expect(semaphore.available_permits).to eq 5
end
context 'when permits is set to negative number' do
it do
expect {
semaphore.release(-1)
}.to raise_error(ArgumentError)
end
end
end
end
end
module Concurrent
RSpec.describe MutexSemaphore do
it_should_behave_like :semaphore
end
if Concurrent.on_jruby?
RSpec.describe JavaSemaphore do
it_should_behave_like :semaphore
end
end
RSpec.describe Semaphore do
if Concurrent.on_jruby?
it 'inherits from JavaSemaphore' do
expect(Semaphore.ancestors).to include(JavaSemaphore)
end
else
it 'inherits from MutexSemaphore' do
expect(Semaphore.ancestors).to include(MutexSemaphore)
end
end
end
end
|
