From 0835f53e615350f432be9d7e759c7ec8327cf829 Mon Sep 17 00:00:00 2001
From: Adam McCrea <adam@adamlogic.com>
Date: Thu, 14 Dec 2023 12:10:47 -0500
Subject: [PATCH] perf: Skip reporting if there are no metrics (#191)

* Skip reporting if there are no metrics

We'll still report the first time through the loop. This lets Judoscale know the adapter is set up correctly.

* Fix test
---
 judoscale-ruby/lib/judoscale/reporter.rb |  9 +++++++++
 judoscale-ruby/test/reporter_test.rb     | 20 ++++++++++++++++----
 judoscale-ruby/test/test_helper.rb       |  6 ++++++
 3 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/judoscale-ruby/lib/judoscale/reporter.rb b/judoscale-ruby/lib/judoscale/reporter.rb
index 232dc6a0..ab4d1c81 100644
--- a/judoscale-ruby/lib/judoscale/reporter.rb
+++ b/judoscale-ruby/lib/judoscale/reporter.rb
@@ -74,17 +74,26 @@ def stop!
       @_thread&.terminate
       @_thread = nil
       @pid = nil
+      @reported = false
     end
 
     private
 
     def report(config, metrics)
+      # Make sure we report at least once, even if there are no metrics,
+      # so Judoscale knows the adapter is installed and running.
+      if @reported && metrics.empty?
+        logger.debug "No metrics to report - skipping"
+        return
+      end
+
       report = Report.new(Judoscale.adapters, config, metrics)
       logger.info "Reporting #{report.metrics.size} metrics"
       result = AdapterApi.new(config).report_metrics(report.as_json)
 
       case result
       when AdapterApi::SuccessResponse
+        @reported = true
         logger.debug "Reported successfully"
       when AdapterApi::FailureResponse
         logger.error "Reporter failed: #{result.failure_message}"
diff --git a/judoscale-ruby/test/reporter_test.rb b/judoscale-ruby/test/reporter_test.rb
index 28efef98..8aac54f6 100644
--- a/judoscale-ruby/test/reporter_test.rb
+++ b/judoscale-ruby/test/reporter_test.rb
@@ -10,9 +10,12 @@ module Judoscale
       Judoscale.configure do |config|
         config.current_runtime_container = Config::RuntimeContainer.new("web.1")
         config.api_base_url = "http://example.com/api/test-token"
+        config.test_job_config.enabled = true
       end
     }
 
+    after { Reporter.instance.stop! }
+
     describe ".start" do
       it "initializes the reporter with the current configuration and loaded adapters" do
         reporter_mock = Minitest::Mock.new
@@ -39,10 +42,6 @@ module Judoscale
     end
 
     describe "#start!" do
-      after {
-        Reporter.instance.stop!
-      }
-
       def run_reporter_start_thread
         stub_reporter_loop {
           reporter_thread = Reporter.instance.start!(Config.instance, Judoscale.adapters)
@@ -172,6 +171,19 @@ def stub_reporter_loop
         assert_requested stub
       end
 
+      it "only sends an empty (no metrics) report one time" do
+        metrics_collector = Test::TestEmptyMetricsCollector.new
+
+        expected_body = Report.new(Judoscale.adapters, Config.instance, metrics_collector.collect).as_json
+        stub = stub_request(:post, "http://example.com/api/test-token/v3/reports")
+          .with(body: JSON.generate(expected_body)).to_return({status: 200}).times(1)
+
+        Reporter.instance.run_metrics_collection Config.instance, [metrics_collector]
+        Reporter.instance.run_metrics_collection Config.instance, [metrics_collector]
+
+        assert_requested stub
+      end
+
       it "logs reporting failures" do
         metrics_collector = Test::TestWebMetricsCollector.new
 
diff --git a/judoscale-ruby/test/test_helper.rb b/judoscale-ruby/test/test_helper.rb
index 4d8346a2..2c771fc4 100644
--- a/judoscale-ruby/test/test_helper.rb
+++ b/judoscale-ruby/test/test_helper.rb
@@ -27,6 +27,12 @@ def collect
         [Metric.new(:qt, 1, Time.now)]
       end
     end
+
+    class TestEmptyMetricsCollector < Judoscale::WebMetricsCollector
+      def collect
+        []
+      end
+    end
   end
 
   add_adapter :test_web, {}, metrics_collector: Test::TestWebMetricsCollector