Fixing speed issue on spans option

Unecessarily setting the start time search back to the start of the schedule for a spanned search, when in fact it simply needs to step back a duration.

Author: jopotts

lib/ice_cube/schedule.rb

@@ -411,7 +411,7 @@ def enumerate_occurrences(opening_time, closing_time = nil, spans = false, &bloc
       opening_time = start_time if opening_time < start_time
       Enumerator.new do |yielder|
         reset
-        t1 = full_required? || spans ? start_time : realign(opening_time)
+        t1 = full_required? ? start_time : realign((spans ? opening_time - duration : opening_time))
         loop do
           break unless (t0 = next_time(t1, closing_time))
           break if closing_time && t0 > closing_time

spec/examples/schedule_spec.rb

@@ -1,4 +1,5 @@
 require File.dirname(__FILE__) + '/../spec_helper'
+require 'benchmark'
 
 describe IceCube::Schedule do
 
@@ -504,6 +505,19 @@
       schedule = IceCube::Schedule.new(t0, :duration => IceCube::ONE_HOUR)
       schedule.occurs_between?(t0 + IceCube::ONE_HOUR, t0 + 2 * IceCube::ONE_HOUR, true).should be_true
     end
+    
+    it 'should quickly fetch a future time from a recurring schedule' do
+      t0 = Time.utc(2000, 10, 1, 00, 00)
+      t1 = Time.utc(2015, 10, 1, 12, 00)
+      schedule = IceCube::Schedule.new(t0, :duration => IceCube::ONE_HOUR - 1)
+      schedule.add_recurrence_rule IceCube::Rule.hourly
+      occ = nil
+      timing = Benchmark.realtime do
+        occ = schedule.remaining_occurrences_enumerator(t1, true).take(1)
+      end
+      timing.should < 0.1
+      occ.should == [t1]
+    end
 
   end