require 'spec_helper' describe ReactiveCaching, :use_clean_rails_memory_store_caching do include ExclusiveLeaseHelpers include ReactiveCachingHelpers class CacheTest include ReactiveCaching self.reactive_cache_key = ->(thing) { ["foo", thing.id] } self.reactive_cache_lifetime = 5.minutes self.reactive_cache_refresh_interval = 15.seconds attr_reader :id def initialize(id, &blk) @id = id @calculator = blk end def calculate_reactive_cache @calculator.call end def result with_reactive_cache do |data| data / 2 end end end let(:calculation) { -> { 2 + 2 } } let(:cache_key) { "foo:666" } let(:instance) { CacheTest.new(666, &calculation) } describe '#with_reactive_cache' do before do stub_reactive_cache end subject(:go!) { instance.result } context 'when cache is empty' do it { is_expected.to be_nil } it 'enqueues a background worker to bootstrap the cache' do expect(ReactiveCachingWorker).to receive(:perform_async).with(CacheTest, 666) go! end it 'updates the cache lifespan' do expect(reactive_cache_alive?(instance)).to be_falsy go! expect(reactive_cache_alive?(instance)).to be_truthy end end context 'when the cache is full' do before do stub_reactive_cache(instance, 4) end it { is_expected.to eq(2) } it 'does not enqueue a background worker' do expect(ReactiveCachingWorker).not_to receive(:perform_async) go! end it 'updates the cache lifespan' do expect(Rails.cache).to receive(:write).with(alive_reactive_cache_key(instance), true, expires_in: anything) go! end context 'and expired' do before do invalidate_reactive_cache(instance) end it { is_expected.to be_nil } end end end describe '#clear_reactive_cache!' do before do stub_reactive_cache(instance, 4) instance.clear_reactive_cache! end it { expect(instance.result).to be_nil } it { expect(reactive_cache_alive?(instance)).to be_falsy } end describe '#exclusively_update_reactive_cache!' do subject(:go!) { instance.exclusively_update_reactive_cache! } context 'when the lease is free and lifetime is not exceeded' do before do stub_reactive_cache(instance, "preexisting") end it 'takes and releases the lease' do expect_to_obtain_exclusive_lease(cache_key, 'uuid') expect_to_cancel_exclusive_lease(cache_key, 'uuid') go! end it 'caches the result of #calculate_reactive_cache' do go! expect(read_reactive_cache(instance)).to eq(calculation.call) end it "enqueues a repeat worker" do expect_reactive_cache_update_queued(instance) go! end context 'and #calculate_reactive_cache raises an exception' do before do stub_reactive_cache(instance, "preexisting") end let(:calculation) { -> { raise "foo"} } it 'leaves the cache untouched' do expect { go! }.to raise_error("foo") expect(read_reactive_cache(instance)).to eq("preexisting") end it 'enqueues a repeat worker' do expect_reactive_cache_update_queued(instance) expect { go! }.to raise_error("foo") end end end context 'when lifetime is exceeded' do it 'skips the calculation' do expect(instance).to receive(:calculate_reactive_cache).never go! end end context 'when the lease is already taken' do it 'skips the calculation' do stub_exclusive_lease_taken(cache_key) expect(instance).to receive(:calculate_reactive_cache).never go! end end end end