From e42bf0b626c57ea194be93678025c6fa11674ecc Mon Sep 17 00:00:00 2001
From: Dhruv Kapadia <git@dkapadia.com>
Date: Wed, 21 Apr 2010 19:22:08 -0400
Subject: [PATCH] Setting up redis based prompt_queue to speed up catchup algorithm

---
 app/models/choice.rb         |  3 +--
 app/models/question.rb       | 21 +++++++++++++++++++++
 config/initializers/redis.rb |  2 ++
 spec/models/question_spec.rb | 43 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 67 insertions(+), 2 deletions(-)
 create mode 100644 config/initializers/redis.rb

diff --git a/app/models/choice.rb b/app/models/choice.rb
index ce96cf2..361884d 100644
--- a/app/models/choice.rb
+++ b/app/models/choice.rb
@@ -108,7 +108,7 @@ class Choice < ActiveRecord::Base
   
   def generate_prompts
     #once a choice is added, we need to generate the new prompts (possible combinations of choices)
-    #do this in a new process (via delayed jobs)
+    #do this in a new process (via delayed jobs)? Maybe just for uploaded ideas
     previous_choices = (self.question.choices - [self])
     return if previous_choices.empty?
     inserts = []
@@ -127,7 +127,6 @@ class Choice < ActiveRecord::Base
 
     Question.update_counters(self.question_id, :prompts_count => 2*previous_choices.size)
 
-    logger.info("The sql is:::: #{sql}")
 
     ActiveRecord::Base.connection.execute(sql)
 
diff --git a/app/models/question.rb b/app/models/question.rb
index 20b8174..f45ce02 100644
--- a/app/models/question.rb
+++ b/app/models/question.rb
@@ -298,6 +298,27 @@ class Question < ActiveRecord::Base
 	  end
   end
 
+  def pq_key
+	  @pq_key ||= "#{self.id}_prompt_queue"
+  end
+
+  def clear_prompt_queue
+	  $redis.del(self.pq_key)
+  end
+
+  def add_prompt_to_queue
+	  prompt = self.catchup_choose_prompt
+	  $redis.rpush(self.pq_key, prompt.id)
+	  prompt
+  end
+
+  def pop_prompt_queue
+	  prompt_id = $redis.lpop(self.pq_key)
+	  prompt = prompt_id.nil? ? nil : Prompt.find(prompt_id.to_i)
+  end
+
+
+
 
 
 end
diff --git a/config/initializers/redis.rb b/config/initializers/redis.rb
new file mode 100644
index 0000000..bf03bc0
--- /dev/null
+++ b/config/initializers/redis.rb
@@ -0,0 +1,2 @@
+require 'redis'
+$redis = Redis.new
diff --git a/spec/models/question_spec.rb b/spec/models/question_spec.rb
index 537e7d9..2168db5 100644
--- a/spec/models/question_spec.rb
+++ b/spec/models/question_spec.rb
@@ -84,6 +84,49 @@ describe Question do
 		  (sum - 1.0).abs.should < 0.000001
 	  end
 
+	  it "should allow the prompt queue to be cleared" do
+		  @catchup_q.add_prompt_to_queue
+		  @catchup_q.clear_prompt_queue
+
+		  @catchup_q.pop_prompt_queue.should == nil
+	  end
+	  it "should allow a prompt to be added to the prompt queue" do
+		  @catchup_q.clear_prompt_queue
+		  @catchup_q.pop_prompt_queue.should == nil
+
+		  @catchup_q.add_prompt_to_queue
+
+		  prompt = @catchup_q.pop_prompt_queue
+
+		  prompt.should_not == nil
+		  prompt.active?.should == true
+	  end
+	  it "should return prompts from the queue in FIFO order" do
+		  @catchup_q.clear_prompt_queue
+		  @catchup_q.pop_prompt_queue.should == nil
+		  
+		  prompt1 = @catchup_q.add_prompt_to_queue
+		  prompt2 = @catchup_q.add_prompt_to_queue
+		  prompt3 = @catchup_q.add_prompt_to_queue
+
+		  prompt_1 = @catchup_q.pop_prompt_queue
+		  prompt_2 = @catchup_q.pop_prompt_queue
+		  prompt_3 = @catchup_q.pop_prompt_queue
+
+
+		  prompt_1.should == prompt1
+		  prompt_2.should == prompt2
+		  prompt_3.should == prompt3
+
+		  # there is a small probability that the catchup algorithm
+		  # choose two prompts that are indeed equal
+		  prompt_1.should_not == prompt_2
+		  prompt_1.should_not == prompt_3
+		  prompt_2.should_not == prompt_3
+
+
+		  @catchup_q.pop_prompt_queue.should == nil
+	  end
 
 
   end
--
libgit2 0.21.2