Merge 8d0d53a into 0d23948

app/models/metric.rb

@@ -3,7 +3,20 @@ class Metric < ApplicationRecord
 
   include Metric::Common
 
-  def self.reindex_table_name
-    "metrics_#{Time.now.utc.hour + 1}"
+  def self.table_name
+    Thread.current[:targeted_metric_subtable_name] || super
+  end
+
+  def self.with_table_for_time(hour = Time.now.utc.hour)
+    Thread.current[:targeted_metric_subtable_name] = reindex_table_name(hour)
+    yield
+  ensure
+    Thread.current[:targeted_metric_subtable_name] = nil
+  end
+
+  # @param hour the hour to run (default: now)
+  # @return the table for the given hour
+  def self.reindex_table_name(hour = Time.now.utc.hour)
+    "metrics_%02d" % hour
   end
 end

app/models/metric/purging.rb

@@ -61,6 +61,8 @@ def self.purge_count(older_than, interval)
     purge_scope(older_than, interval).count
   end
 
+  # TODO: delete these using the same created_at queries by date
+  # rather than by joining to metrics - then hourly could be truncated vs deleted
   def self.purge_associated_records(metric_type, ids)
     # Since VimPerformanceTagValues are 6 * number of tags per performance
     # record, we need to batch in smaller trips.
@@ -85,9 +87,32 @@ def self.purge_hourly(older_than, window = nil, total_limit = nil, &block)
   end
 
   def self.purge_realtime(older_than, window = nil, total_limit = nil, &block)
-    purge_by_date(older_than, "realtime", window, total_limit, &block)
+    truncate_child_tables(older_than)
   end
 
+  def self.truncate_child_tables(older_than)
+    target_hours = determine_target_hours(older_than, Time.now.utc)
+    return if target_hours.blank?
+
+    target_hours.each do |hour|
+      Metric.with_table_for_time(hour) do
+        Metric.truncate
+      end
+    end
+  end
+
+  def self.determine_target_hours(older_than, end_date)
+    return [] if (end_date - older_than) > 24.hours
+
+    start_hour = older_than.utc.hour
+    end_hour = end_date.utc.hour
+    end_hour += 24 if start_hour > end_hour
+
+    good_hours = (start_hour..end_hour).map { |h| h % 24 }
+    (0..23).to_a - good_hours.to_a
+  end
+  private_class_method :determine_target_hours
+
   def self.purge(older_than, interval, window = nil, total_limit = nil, &block)
     purge_by_date(older_than, interval, window, total_limit, &block)
   end

spec/models/metric/purging_spec.rb

@@ -82,4 +82,24 @@
       end
     end
   end
+
+  context "#purge_realtime" do
+    let(:vm1) { FactoryGirl.create(:vm_vmware) }
+
+    it "deletes old, keeps new" do
+      EvmSpecHelper.create_guid_miq_server_zone
+
+      Timecop.freeze('2018-02-01T02:12:00Z') do
+        # this is overkill. since we prune every 21 minutes, there will only be ~1 table with data
+        (0..16).each do |hours|
+          FactoryGirl.create(:metric_vm_rt, :resource_id => vm1.id, :timestamp => hours.hours.ago)
+        end
+        expect(Metric.count).to eq(17)
+        # keep metric for 02:12 - 22:12 (down to 22:00)
+        described_class.purge_realtime(4.hours.ago)
+        expect(Metric.all.map { |metric| metric.timestamp.hour }.sort).to eq [0, 1, 2, 22, 23]
+        expect(Metric.count).to eq(5)
+      end
+    end
+  end
 end