Merge pull request #249 from ruby-concurrency/zero-interval

Fix ScheduledTask sometimes not accepting an interval of 0

Author: jdantonio

lib/concurrent/scheduled_task.rb

@@ -25,8 +25,9 @@ def initialize(intended_time, opts = {}, &block)
     # @since 0.5.0
     def execute
       if compare_and_set_state(:pending, :unscheduled)
-        @schedule_time = TimerSet.calculate_schedule_time(@intended_time)
-        Concurrent::timer(@schedule_time.to_f - Time.now.to_f) { @executor.post(&method(:process_task)) }
+        now = Time.now
+        @schedule_time = TimerSet.calculate_schedule_time(@intended_time, now)
+        Concurrent::timer(@schedule_time.to_f - now.to_f) { @executor.post(&method(:process_task)) }
         self
       end
     end

spec/concurrent/scheduled_task_spec.rb

@@ -130,6 +130,10 @@ def trigger_observable(observable)
         end
       end
 
+      it 'allows setting the execution interval to 0' do
+        expect { 1000.times { ScheduledTask.execute(0) { } } }.not_to raise_error
+      end
+
       it 'sets the sate to :pending' do
         task = ScheduledTask.new(1){ nil }
         task.execute