From d446c44d5b0512a0f6b148cb89bf5bf923c03ef9 Mon Sep 17 00:00:00 2001
From: Joel Low <joel@joelsplace.sg>
Date: Fri, 1 Apr 2016 09:03:37 +0800
Subject: [PATCH] If an evaluation was allocated at the last attempt,
 immediately request for more.

This is so that when there is a queue of evaluations, the one minute cool down time is not used.
---
 lib/coursemology/evaluator/client.rb       | 34 +++++++++++++---------
 spec/coursemology/evaluator/client_spec.rb | 26 ++++++++++-------
 2 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/lib/coursemology/evaluator/client.rb b/lib/coursemology/evaluator/client.rb
index fef2dcb..3cfae63 100644
--- a/lib/coursemology/evaluator/client.rb
+++ b/lib/coursemology/evaluator/client.rb
@@ -17,30 +17,36 @@ def run
     Signal.trap('SIGTERM', method(:on_sig_term))
 
     loop do
-      allocate_evaluations
-      break if @terminate
+      evaluations = allocate_evaluations
+
+      if evaluations && !evaluations.empty?
+        on_allocate(evaluations)
+      else
+        # :nocov:
+        # This sleep might not be triggered in the specs, because interruptions to the thread is
+        # nondeterministically run by the OS scheduler.
+        sleep(1.minute)
+        # :nocov:
+      end
 
-      # :nocov:
-      # This sleep might not be triggered in the specs, because interruptions to the thread is
-      # nondeterministically run by the OS scheduler.
-      sleep(1.minute)
-      # :nocov:
+      break if @terminate
     end
   end
 
   private
 
   # Requests evaluations from the server.
+  #
+  # @return [Array<Coursemology::Evaluator::Models::ProgrammingEvaluation>] The evaluations
+  #   retrieved from the server.
   def allocate_evaluations
-    evaluations =
-      ActiveSupport::Notifications.instrument('allocate.client.evaluator.coursemology') do
-        languages = Coursemology::Polyglot::Language.concrete_languages.map(&:display_name)
-        Coursemology::Evaluator::Models::ProgrammingEvaluation.allocate(language: languages)
-      end
-
-    on_allocate(evaluations)
+    ActiveSupport::Notifications.instrument('allocate.client.evaluator.coursemology') do
+      languages = Coursemology::Polyglot::Language.concrete_languages.map(&:display_name)
+      Coursemology::Evaluator::Models::ProgrammingEvaluation.allocate(language: languages)
+    end
   rescue Flexirest::HTTPUnauthorisedClientException => e
     ActiveSupport::Notifications.publish('allocate_fail.client.evaluator.coursemology', e: e)
+    nil
   end
 
   # The callback for handling an array of allocated evaluations.
diff --git a/spec/coursemology/evaluator/client_spec.rb b/spec/coursemology/evaluator/client_spec.rb
index 6ca8895..895eb61 100644
--- a/spec/coursemology/evaluator/client_spec.rb
+++ b/spec/coursemology/evaluator/client_spec.rb
@@ -18,6 +18,8 @@
   end
 
   describe '#run' do
+    let(:dummy_evaluation) { build_stubbed(:programming_evaluation) }
+
     it 'loops until @terminate is set' do
       expect(subject).to receive(:allocate_evaluations).at_least(:once)
       allow(subject).to receive(:sleep) { sleep(0.1.seconds) }
@@ -25,22 +27,24 @@
       Thread.new { subject.instance_variable_set(:@terminate, true) }
       subject.run
     end
+
+    it 'calls #on_allocate with the evaluation' do
+      called = false
+      expect(subject).to receive(:allocate_evaluations) do
+        called ? [] : [dummy_evaluation]
+      end.at_least(:once)
+
+      expect(subject).to receive(:on_allocate).with([dummy_evaluation]).at_least(:once)
+      Thread.new { subject.send(:on_sig_term) }
+      subject.run
+    end
   end
 
   describe '#allocate_evaluations' do
     context 'when an evaluation is provided' do
-      let(:dummy_evaluation) { build_stubbed(:programming_evaluation) }
-      before do
-        expect(Coursemology::Evaluator::Models::ProgrammingEvaluation).to \
-          receive(:allocate).and_return([dummy_evaluation])
-      end
-
-      it 'calls #on_evaluation with the evaluation' do
-        expect(subject).to receive(:on_evaluation).with(dummy_evaluation)
-        subject.send(:allocate_evaluations)
-      end
-
       it 'instruments the allocation request' do
+        expect(Coursemology::Evaluator::Models::ProgrammingEvaluation).to \
+          receive(:allocate).and_return(nil)
         expect { subject.send(:allocate_evaluations) }.to \
           instrument_notification('allocate.client.evaluator.coursemology')
       end