use versionable model ids in partition precreator

closes #CORE-3256

Change-Id: I88a21eb9c0b404ba843149d20cdd3e13b48bc313
Reviewed-on: https://gerrit.instructure.com/204647
Tested-by: Jenkins
Reviewed-by: Rob Orton <rob@instructure.com>
QA-Review: Rob Orton <rob@instructure.com>
Product-Review: Rob Orton <rob@instructure.com>

gems/canvas_partman/lib/canvas_partman/partition_manager/by_id.rb

@@ -59,11 +59,6 @@ SQL
       def ensure_or_check_partitions(advance, create_partitions)
         empties = 0
         partitions = partition_tables
-        partitions.reverse_each do |partition|
-          break if empties >= advance
-          break if base_class.from(base_class.connection.quote_table_name(partition)).exists?
-          empties += 1
-        end
 
         if partitions.empty?
           current = -1
@@ -71,6 +66,19 @@ SQL
           current = partitions.last[base_class.table_name.length + 1..-1].to_i
         end
 
+        if self.partition_on_primary_key?
+          partitions.reverse_each do |partition|
+            break if empties >= advance
+            break if base_class.from(base_class.connection.quote_table_name(partition)).exists?
+            empties += 1
+          end
+        else
+          id = self.maximum_foreign_id
+          last_needed = id ? (id / base_class.partition_size) : -1
+          # yes `empties` could be negative but that just means we'll make even more partitions to catch up
+          empties = current - last_needed
+        end
+
         while empties < advance
           current += 1
           if create_partitions
@@ -89,6 +97,27 @@ SQL
 
       protected
 
+      def partition_on_primary_key?
+        base_class.partitioning_field.to_s == base_class.primary_key.to_s
+      end
+
+      def maximum_foreign_id
+        reflection = base_class.reflections.detect { |_, r| r.belongs_to? && base_class.partitioning_field.to_s }.last
+        klasses =
+          if reflection.polymorphic?
+            reflection.options[:polymorphic].map do |type|
+              if type.is_a?(Hash)
+                type.values.map{|v| v.constantize rescue nil}
+              else
+                type.to_s.classify.constantize rescue nil
+              end
+            end.flatten.compact
+          else
+            [reflection.klass]
+          end
+        klasses.map{|klass| klass.maximum(klass.primary_key)}.compact.max
+      end
+
       def table_regex
         @table_regex ||= /^#{Regexp.escape(base_class.table_name)}_(?<index>\d+)$/.freeze
       end

gems/canvas_partman/spec/canvas_partman/partition_manager_spec.rb

@@ -161,6 +161,7 @@ describe CanvasPartman::PartitionManager do
     describe "#ensure_partitions" do
       it "creates the proper number of partitions" do
         expect(subject).to receive(:partition_tables).and_return([])
+        expect(Zoo).to receive(:maximum).and_return(nil)
         expect(subject).to receive(:create_partition).with(0)
         expect(subject).to receive(:create_partition).with(5)
 
@@ -169,11 +170,23 @@ describe CanvasPartman::PartitionManager do
 
       it "detects when enough partitions already exist" do
         expect(subject).to receive(:partition_tables).and_return(['partman_trails_0', 'partman_trails_1'])
-        expect(subject.base_class).to receive(:from).twice.and_return(Trail.none)
+        expect(Zoo).to receive(:maximum).and_return(nil)
         expect(subject).to receive(:create_partition).never
 
         subject.ensure_partitions(2)
       end
+
+      it "detects how many partitions are needed based on the foreign key table" do
+        expect(subject).to receive(:partition_tables).and_return([])
+        expect(Zoo).to receive(:maximum).and_return(7)
+
+        expect(subject).to receive(:create_partition).with(0)
+        expect(subject).to receive(:create_partition).with(5) # catches up
+        expect(subject).to receive(:create_partition).with(10)
+        expect(subject).to receive(:create_partition).with(15) # and adds two more
+
+        subject.ensure_partitions(2)
+      end
     end
   end
 end

spec/controllers/info_controller_spec.rb

@@ -63,9 +63,9 @@ describe InfoController do
       # stick a Version into last partition
       last_partition = CanvasPartman::PartitionManager.create(Version).partition_tables.last
       v_id = (last_partition.sub("versions_", "").to_i * Version.partition_size) + 1
-      Version.suspend_callbacks(:initialize_number) do
-        Version.create!(:versionable_id => v_id, :versionable_type => "Assignment")
-      end
+
+      # don't have to make a real version anymore, just an object that _could_ make a version
+      Course.create.wiki_pages.create!(:id => v_id, :title => "t")
 
       Timecop.freeze(4.years.from_now) do # and jump forward a ways
         get "health_prognosis"