make fewer trips to the db for report runners

we still don’t want to send a giant batch so this
will limit based off the number of ids being sent

refs CORE-2742

test plan
 - specs should pass

Change-Id: Ife00367d818a48a9934b4f224eb865c20292dd31
Reviewed-on: https://gerrit.instructure.com/188807
Tested-by: Jenkins
Reviewed-by: James Williams <jamesw@instructure.com>
QA-Review: James Williams <jamesw@instructure.com>
Product-Review: Rob Orton <rob@instructure.com>

app/models/account_report.rb

@@ -29,6 +29,24 @@ class AccountReport < ActiveRecord::Base
 
   serialize :parameters
 
+  attr_accessor :runners
+
+  def initialize(*)
+    @runners = []
+    super
+  end
+
+  def add_report_runner(batch)
+    @runners ||= []
+    runners << self.account_report_runners.new(batch_items: batch, created_at: Time.zone.now, updated_at: Time.zone.now)
+  end
+
+  def write_report_runners
+    return if runners.empty?
+    self.class.bulk_insert_objects(runners)
+    @runners = []
+  end
+
   workflow do
     state :created
     state :running

gems/plugins/account_reports/lib/account_reports/report_helper.rb

@@ -316,6 +316,19 @@ module AccountReports::ReportHelper
     [[item_count/100.to_f.round(0), min].max, max].min
   end
 
+  def create_report_runners(ids, total, min: 25, max: 1000)
+    ids_so_far = 0
+    ids.each_slice(number_of_items_per_runner(total, min: min, max: max)) do |batch|
+      @account_report.add_report_runner(batch)
+      ids_so_far += batch.length
+      if ids_so_far >= Setting.get("ids_per_report_runner_batch", 10_000).to_i
+        @account_report.write_report_runners
+        ids_so_far = 0
+      end
+    end
+    @account_report.write_report_runners
+  end
+
   def run_account_report_runner(report_runner, headers)
     return if report_runner.reload.workflow_state == 'aborted'
     @account_report = report_runner.account_report

gems/plugins/account_reports/spec_canvas/report_helper_spec.rb

@@ -42,6 +42,25 @@ describe "report helper" do
     expect(report.number_of_items_per_runner(109213081, max: 100)).to eq 100
   end
 
+  it 'should create report runners with a single trip' do
+    account_report.save!
+    expect(AccountReport).to receive(:bulk_insert_objects).once.and_call_original
+    report.create_report_runners((1..50).to_a, 50)
+    expect(account_report.account_report_runners.count).to eq 2
+  end
+
+  it 'should create report runners with few trips to the db' do
+    account_report.save!
+    # lower the setting so we can do more than one trip with less data
+    Setting.set("ids_per_report_runner_batch", 1_000)
+    # once with 1_008 ids and 84 runners and then once with 200 ids and the
+    # other runners
+    expect(AccountReport).to receive(:bulk_insert_objects).twice.and_call_original
+    # also got to pass min so that we get runners with 12 ids instead of 25
+    report.create_report_runners((1..1_200).to_a, 1_200, min: 10)
+    expect(account_report.account_report_runners.count).to eq 100
+  end
+
   describe "#send_report" do
     before do
       allow(AccountReports).to receive(:available_reports).and_return(account_report.report_type => {title: 'test_report'})