Fix inconsistent chunking

The chunking performed within RestorePlan#price and Cli#restore was
inconsistent. This did not show because of the memoization that existed
previously.

Author: bjorne

lib/tina/cli.rb

@@ -16,9 +16,9 @@ def restore(prefix_file)
 
       prefixes = File.readlines(prefix_file).map(&:chomp)
       objects = RestorePlan::ObjectCollection.new(s3_client.list_bucket_prefixes(prefixes))
-      restore_plan = RestorePlan.new(total_storage.to_i, objects)
-      price = restore_plan.price(duration_in_seconds)
-      chunks = objects.chunk(duration_in_seconds)
+      restore_plan = RestorePlan.new(total_storage.to_i, objects, duration_in_seconds)
+      price = restore_plan.price
+      chunks = restore_plan.object_chunks
       say
       say "Restores will be performed in the following chunks:"
       say "-" * 60

lib/tina/restore_plan.rb

@@ -5,31 +5,34 @@ class RestorePlan
     DAYS_PER_MONTH = 30
     PRICE_PER_GB_PER_HOUR = 0.011
 
-    def initialize(total_storage_size, objects, options = {})
+    def initialize(total_storage_size, objects, total_time, options = {})
       @total_storage_size = total_storage_size
       @objects = objects
+      @total_time = [total_time, 4 * 3600].max
       @price_per_gb_per_hour = options[:price_per_gb_per_hour] || PRICE_PER_GB_PER_HOUR
 
       @daily_allowance = @total_storage_size * MONTHLY_FREE_TIER_ALLOWANCE_FACTOR / DAYS_PER_MONTH
     end
 
-    def price(total_time)
-      total_time = [total_time, 4 * 3600].max
-      chunk_size = quadhourly_restore_rate(total_time)
-      chunks = @objects.chunk(chunk_size)
-      largest_chunk_object_size = chunks.map { |chunk| chunk.map(&:size).reduce(&:+) }.max
-      quadhours = chunks.size
+    def price
+      largest_chunk_object_size = object_chunks.map { |chunk| chunk.map(&:size).reduce(&:+) }.max
+      quadhours = object_chunks.size
       quadhourly_allowance = @daily_allowance / ( [(24 / 4), quadhours].min * 4)
 
       peak_retrieval_rate = largest_chunk_object_size / 4
       peak_billable_retrieval_rate = [0, peak_retrieval_rate - quadhourly_allowance].max
 
       peak_billable_retrieval_rate * (@price_per_gb_per_hour / 1024 ** 3) * 720
     end
+
+    def object_chunks
+      @object_chunks ||= @objects.chunk(quadhourly_restore_rate)
+    end
+
     private
 
-    def quadhourly_restore_rate(total_time)
-      @objects.total_size / (total_time / (4 * 3600))
+    def quadhourly_restore_rate
+      @objects.total_size / (@total_time / (4 * 3600))
     end
 
     class ObjectCollection

spec/tina/restore_plan_spec.rb

@@ -2,10 +2,6 @@
 
 module Tina
   describe RestorePlan do
-    subject do
-      described_class.new(total_storage_size, object_collection, options)
-    end
-
     let :total_storage_size do
       75 * (1024 ** 4)
     end
@@ -29,15 +25,15 @@ module Tina
         # http://aws.amazon.com/glacier/faqs/
         context 'with the examples given on the Amazon Glacier pricing FAQ' do
           it 'matches the the price for a restore with everything at once' do
-            expect(subject.price(4 * 3600)).to be_within(0.05).of(21.6)
+            expect(described_class.new(total_storage_size, object_collection, 4 * 3600, options).price).to be_within(0.05).of(21.6)
           end
 
           it 'matches the the price for a restore over 8 hours' do
-            expect(subject.price(8 * 3600)).to be_within(0.05).of(10.8)
+            expect(described_class.new(total_storage_size, object_collection, 8 * 3600, options).price).to be_within(0.05).of(10.8)
           end
 
           it 'matches the the price for a restore over 28 hours' do
-            expect(subject.price(28 * 3600)).to eq 0
+            expect(described_class.new(total_storage_size, object_collection, 28 * 3600, options).price).to eq 0
           end
         end
 
@@ -58,19 +54,19 @@ module Tina
           end
 
           it 'matches the price for a restore over a month' do
-            expect(subject.price(30 * 24 * 3600)).to be_within(0.05).of(4.16)
+            expect(described_class.new(total_storage_size, object_collection, 30 * 24 * 3600, options).price).to be_within(0.05).of(4.16)
           end
 
           it 'matches the price for a restore over a week' do
-            expect(subject.price(7 * 24 * 3600)).to be_within(0.05).of(437.87)
+            expect(described_class.new(total_storage_size, object_collection, 7 * 24 * 3600, options).price).to be_within(0.05).of(437.87)
           end
 
           it 'matches the price for a restore over a day' do
-            expect(subject.price(1 * 24 * 3600)).to be_within(0.05).of(3832.16)
+            expect(described_class.new(total_storage_size, object_collection, 1 * 24 * 3600, options).price).to be_within(0.05).of(3832.16)
           end
 
           it 'matches the price for a restore over a 4 hour period' do
-            expect(subject.price(4 * 3600)).to be_within(0.05).of(22992.93)
+            expect(described_class.new(total_storage_size, object_collection, 4 * 3600, options).price).to be_within(0.05).of(22992.93)
           end
         end
 
@@ -84,7 +80,7 @@ module Tina
           end
 
           it 'matches the price for a restore over 4 days' do
-            expect(subject.price(4 * 24 * 3600)).to be_within(20).of(768)
+            expect(described_class.new(total_storage_size, object_collection, 4 * 24 * 3600, options).price).to be_within(20).of(768)
           end
         end
       end