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|
module Concurrent
RSpec.describe ReadWriteLock do
context '#write_locked?' do
it 'returns true when the write lock is held' do
latch_1 = Concurrent::CountDownLatch.new(1)
latch_2 = Concurrent::CountDownLatch.new(1)
in_thread do
subject.with_write_lock do
latch_1.count_down
latch_2.wait(1)
end
end
latch_1.wait(1)
expect(subject).to be_write_locked
latch_2.count_down
end
it 'returns false when the write lock is not held' do
expect(subject).to_not be_write_locked
end
it 'returns false when the write lock is not held but there are readers' do
latch = Concurrent::CountDownLatch.new(1)
in_thread do
subject.with_read_lock do
latch.wait(1)
end
end
expect(subject).to_not be_write_locked
latch.count_down
end
end
context '#has_waiters?' do
it 'returns false when no locks are held' do
expect(subject).to_not have_waiters
end
it 'returns false when there are readers but no writers' do
latch = Concurrent::CountDownLatch.new(1)
in_thread do
subject.with_read_lock do
latch.wait(1)
end
end
expect(subject).to_not have_waiters
latch.count_down
end
it 'returns true when the write lock is held and there are waiting readers' do
latch_1 = Concurrent::CountDownLatch.new(1)
latch_2 = Concurrent::CountDownLatch.new(1)
latch_3 = Concurrent::CountDownLatch.new(1)
in_thread do
latch_1.wait(1)
subject.acquire_write_lock
latch_2.count_down
latch_3.wait(1)
subject.release_write_lock
end
in_thread do
latch_2.wait(1)
subject.acquire_read_lock
subject.release_read_lock
end
latch_1.count_down
latch_2.wait(1)
expect(subject).to have_waiters
latch_3.count_down
end
it 'returns true when the write lock is held and there are waiting writers' do
latch_1 = Concurrent::CountDownLatch.new(1)
latch_2 = Concurrent::CountDownLatch.new(1)
latch_3 = Concurrent::CountDownLatch.new(1)
t1 = in_thread do
latch_1.wait(1)
subject.acquire_write_lock
latch_2.count_down
latch_3.wait(1)
subject.release_write_lock
end
t2 = in_thread do
latch_2.wait(1)
subject.acquire_write_lock
subject.release_write_lock
end
latch_1.count_down
latch_2.wait(1)
expect(subject).to have_waiters
latch_3.count_down
join_with [t1, t2]
end
end
context '#with_read_lock' do
it 'acquires the lock' do
expect(subject).to receive(:acquire_read_lock).with(no_args)
subject.with_read_lock { nil }
end
it 'returns the value of the block operation' do
expected = 100
actual = subject.with_read_lock { expected }
expect(actual).to eq expected
end
it 'releases the lock' do
expect(subject).to receive(:release_read_lock).with(no_args)
subject.with_read_lock { nil }
end
it 'raises an exception if no block is given' do
expect {
subject.with_read_lock
}.to raise_error(ArgumentError)
end
it 'raises an exception if maximum lock limit is exceeded' do
counter = Concurrent::AtomicFixnum.new(ReadWriteLock::MAX_READERS)
allow(Concurrent::AtomicFixnum).to receive(:new).with(anything).and_return(counter)
expect {
subject.with_read_lock { nil }
}.to raise_error(Concurrent::ResourceLimitError)
end
it 'releases the lock when an exception is raised' do
expect(subject).to receive(:release_read_lock).with(any_args)
begin
subject.release_read_lock { raise StandardError }
rescue
end
end
end
context '#with_write_lock' do
it 'acquires the lock' do
expect(subject).to receive(:acquire_write_lock).with(no_args)
subject.with_write_lock { nil }
end
it 'returns the value of the block operation' do
expected = 100
actual = subject.with_write_lock { expected }
expect(actual).to eq expected
end
it 'releases the lock' do
expect(subject).to receive(:release_write_lock).with(no_args)
subject.with_write_lock { nil }
end
it 'raises an exception if no block is given' do
expect {
subject.with_write_lock
}.to raise_error(ArgumentError)
end
it 'raises an exception if maximum lock limit is exceeded' do
counter = Concurrent::AtomicFixnum.new(ReadWriteLock::MAX_WRITERS)
allow(Concurrent::AtomicFixnum).to receive(:new).with(anything).and_return(counter)
expect {
subject.with_write_lock { nil }
}.to raise_error(Concurrent::ResourceLimitError)
end
it 'releases the lock when an exception is raised' do
expect(subject).to receive(:release_write_lock).with(any_args)
begin
subject.with_write_lock { raise StandardError }
rescue
end
end
end
context '#acquire_read_lock' do
it 'increments the lock count' do
counter = Concurrent::AtomicFixnum.new(0)
allow(Concurrent::AtomicFixnum).to receive(:new).with(anything).and_return(counter)
subject.acquire_read_lock
expect(counter.value).to eq 1
end
it 'waits for a running writer to finish' do
latch_1 = Concurrent::CountDownLatch.new(1)
latch_2 = Concurrent::CountDownLatch.new(1)
latch_3 = Concurrent::CountDownLatch.new(1)
write_flag = Concurrent::AtomicBoolean.new(false)
read_flag = Concurrent::AtomicBoolean.new(false)
thread_1 = in_thread do
latch_1.wait(1)
subject.acquire_write_lock
latch_2.count_down
latch_3.wait(1)
write_flag.make_true
subject.release_write_lock
end
thread_2 = in_thread do
latch_2.wait(1)
expect(write_flag.value).to be false
latch_3.count_down
subject.acquire_read_lock
expect(write_flag.value).to be true
read_flag.make_true
subject.release_read_lock
end
latch_1.count_down
[thread_1, thread_2].each(&:join)
expect(write_flag.value).to be true
expect(read_flag.value).to be true
end
it 'does not wait for any running readers' do
counter = Concurrent::AtomicFixnum.new(0)
allow(Concurrent::AtomicFixnum).to receive(:new).with(anything).and_return(counter)
latch_1 = Concurrent::CountDownLatch.new(1)
latch_2 = Concurrent::CountDownLatch.new(1)
latch_3 = Concurrent::CountDownLatch.new(1)
read_flag_1 = Concurrent::AtomicBoolean.new(false)
read_flag_2 = Concurrent::AtomicBoolean.new(false)
thread_1 = in_thread do
latch_1.wait(1)
subject.acquire_read_lock
expect(counter.value).to eq 1
latch_2.count_down
latch_3.wait(1)
read_flag_1.make_true
subject.release_read_lock
end
thread_2 = in_thread do
latch_2.wait(1)
expect(read_flag_1.value).to be false
subject.acquire_read_lock
expect(counter.value).to eq 2
latch_3.count_down
read_flag_2.make_true
subject.release_read_lock
end
latch_1.count_down
[thread_1, thread_2].each(&:join)
expect(read_flag_1.value).to be true
expect(read_flag_2.value).to be true
expect(counter.value).to eq 0
end
it 'raises an exception if maximum lock limit is exceeded' do
counter = Concurrent::AtomicFixnum.new(ReadWriteLock::MAX_WRITERS)
allow(Concurrent::AtomicFixnum).to receive(:new).with(anything).and_return(counter)
expect {
subject.acquire_write_lock { nil }
}.to raise_error(Concurrent::ResourceLimitError)
end
it 'returns true if the lock is acquired' do
expect(subject.acquire_read_lock).to be true
end
end
context '#release_read_lock' do
it 'decrements the counter' do
counter = Concurrent::AtomicFixnum.new(0)
allow(Concurrent::AtomicFixnum).to receive(:new).with(anything).and_return(counter)
subject.acquire_read_lock
expect(counter.value).to eq 1
subject.release_read_lock
expect(counter.value).to eq 0
end
it 'unblocks waiting writers' do
latch_1 = Concurrent::CountDownLatch.new(1)
latch_2 = Concurrent::CountDownLatch.new(1)
write_flag = Concurrent::AtomicBoolean.new(false)
thread = in_thread do
latch_1.wait(1)
latch_2.count_down
subject.acquire_write_lock
write_flag.make_true
subject.release_write_lock
end
subject.acquire_read_lock
latch_1.count_down
latch_2.wait(1)
expect(write_flag.value).to be false
subject.release_read_lock
thread.join
expect(write_flag.value).to be true
end
it 'returns true if the lock is released' do
subject.acquire_read_lock
expect(subject.release_read_lock).to be true
end
it 'returns true if the lock was never set' do
expect(subject.release_read_lock).to be true
end
end
context '#acquire_write_lock' do
it 'increments the lock count' do
counter = Concurrent::AtomicFixnum.new(0)
allow(Concurrent::AtomicFixnum).to receive(:new).with(anything).and_return(counter)
subject.acquire_write_lock
expect(counter.value).to be > 1
end
it 'waits for a running writer to finish' do
latch_1 = Concurrent::CountDownLatch.new(1)
latch_2 = Concurrent::CountDownLatch.new(1)
latch_3 = Concurrent::CountDownLatch.new(1)
write_flag_1 = Concurrent::AtomicBoolean.new(false)
write_flag_2 = Concurrent::AtomicBoolean.new(false)
thread_1 = in_thread do
latch_1.wait(1)
subject.acquire_write_lock
latch_2.count_down
latch_3.wait(1)
write_flag_1.make_true
subject.release_write_lock
end
thread_2 = in_thread do
latch_2.wait(1)
expect(write_flag_1.value).to be false
latch_3.count_down
subject.acquire_write_lock
expect(write_flag_1.value).to be true
write_flag_2.make_true
subject.release_write_lock
end
latch_1.count_down
[thread_1, thread_2].each(&:join)
expect(write_flag_1.value).to be true
expect(write_flag_2.value).to be true
end
it 'waits for a running reader to finish' do
latch_1 = Concurrent::CountDownLatch.new(1)
latch_2 = Concurrent::CountDownLatch.new(1)
latch_3 = Concurrent::CountDownLatch.new(1)
read_flag = Concurrent::AtomicBoolean.new(false)
write_flag = Concurrent::AtomicBoolean.new(false)
thread_1 = in_thread do
latch_1.wait(1)
subject.acquire_read_lock
latch_2.count_down
latch_3.wait(1)
read_flag.make_true
subject.release_read_lock
end
thread_2 = in_thread do
latch_2.wait(1)
expect(read_flag.value).to be false
latch_3.count_down
subject.acquire_write_lock
expect(read_flag.value).to be true
write_flag.make_true
subject.release_write_lock
end
latch_1.count_down
[thread_1, thread_2].each(&:join)
expect(read_flag.value).to be true
expect(write_flag.value).to be true
end
it 'raises an exception if maximum lock limit is exceeded' do
counter = Concurrent::AtomicFixnum.new(ReadWriteLock::MAX_WRITERS)
allow(Concurrent::AtomicFixnum).to receive(:new).with(anything).and_return(counter)
expect {
subject.acquire_write_lock { nil }
}.to raise_error(Concurrent::ResourceLimitError)
end
it 'returns true if the lock is acquired' do
expect(subject.acquire_write_lock).to be true
end
end
context '#release_write_lock' do
it 'decrements the counter' do
counter = Concurrent::AtomicFixnum.new(0)
allow(Concurrent::AtomicFixnum).to receive(:new).with(anything).and_return(counter)
subject.acquire_write_lock
expect(counter.value).to be > 1
subject.release_write_lock
expect(counter.value).to eq 0
end
it 'unblocks waiting readers' do
latch_1 = Concurrent::CountDownLatch.new(1)
latch_2 = Concurrent::CountDownLatch.new(1)
read_flag = Concurrent::AtomicBoolean.new(false)
thread = in_thread do
latch_1.wait(1)
latch_2.count_down
subject.acquire_read_lock
read_flag.make_true
subject.release_read_lock
end
subject.acquire_write_lock
latch_1.count_down
latch_2.wait(1)
expect(read_flag.value).to be false
subject.release_write_lock
thread.join
expect(read_flag.value).to be true
end
it 'unblocks waiting writers' do
latch_1 = Concurrent::CountDownLatch.new(1)
latch_2 = Concurrent::CountDownLatch.new(1)
write_flag = Concurrent::AtomicBoolean.new(false)
thread = in_thread do
latch_1.wait(1)
latch_2.count_down
subject.acquire_write_lock
write_flag.make_true
subject.release_write_lock
end
subject.acquire_write_lock
latch_1.count_down
latch_2.wait(1)
expect(write_flag.value).to be false
subject.release_write_lock
thread.join
expect(write_flag.value).to be true
end
it 'returns true if the lock is released' do
subject.acquire_write_lock
expect(subject.release_write_lock).to be true
end
it 'returns true if the lock was never set' do
expect(subject.release_write_lock).to be true
end
end
end
end
|
