REFACTOR: Simplify sentiment classification (#977)

This change adds a simpler class for sentiment classification, replacing the soon-to-be removed `Classificator` hierarchy. Additionally, it adds a method for classifying concurrently, speeding up the backfill rake task.

app/jobs/regular/post_sentiment_analysis.rb

@@ -9,9 +9,7 @@ module ::Jobs
       post = Post.find_by(id: post_id, post_type: Post.types[:regular])
       return if post&.raw.blank?
 
-      DiscourseAi::PostClassificator.new(
-        DiscourseAi::Sentiment::SentimentClassification.new,
-      ).classify!(post)
+      DiscourseAi::Sentiment::PostClassification.new.classify!(post)
     end
   end
 end

lib/inference/hugging_face_text_embeddings.rb

@@ -64,8 +64,8 @@ module ::DiscourseAi
           JSON.parse(response.body, symbolize_names: true)
         end
 
-        def classify(content, model_config)
-          headers = { "Referer" => Discourse.base_url, "Content-Type" => "application/json" }
+        def classify(content, model_config, base_url = Discourse.base_url)
+          headers = { "Referer" => base_url, "Content-Type" => "application/json" }
           headers["X-API-KEY"] = model_config.api_key
           headers["Authorization"] = "Bearer #{model_config.api_key}"
 

lib/sentiment/post_classification.rb

@@ -0,0 +1,111 @@
+# frozen_string_literal: true
+
+module DiscourseAi
+  module Sentiment
+    class PostClassification
+      def bulk_classify!(relation)
+        http_pool_size = 100
+        pool =
+          Concurrent::CachedThreadPool.new(
+            min_threads: 0,
+            max_threads: http_pool_size,
+            idletime: 30,
+          )
+
+        available_classifiers = classifiers
+        base_url = Discourse.base_url
+
+        promised_classifications =
+          relation
+            .map do |record|
+              text = prepare_text(record)
+              next if text.blank?
+
+              Concurrent::Promises
+                .fulfilled_future({ target: record, text: text }, pool)
+                .then_on(pool) do |w_text|
+                  results = Concurrent::Hash.new
+
+                  promised_target_results =
+                    available_classifiers.map do |c|
+                      Concurrent::Promises.future_on(pool) do
+                        results[c.model_name] = request_with(w_text[:text], c, base_url)
+                      end
+                    end
+
+                  Concurrent::Promises
+                    .zip(*promised_target_results)
+                    .then_on(pool) { |_| w_text.merge(classification: results) }
+                end
+                .flat(1)
+            end
+            .compact
+
+        Concurrent::Promises
+          .zip(*promised_classifications)
+          .value!
+          .each { |r| store_classification(r[:target], r[:classification]) }
+
+        pool.shutdown
+        pool.wait_for_termination
+      end
+
+      def classify!(target)
+        return if target.blank?
+
+        to_classify = prepare_text(target)
+        return if to_classify.blank?
+
+        results =
+          classifiers.reduce({}) do |memo, model|
+            memo[model.model_name] = request_with(to_classify, model)
+            memo
+          end
+
+        store_classification(target, results)
+      end
+
+      private
+
+      def prepare_text(target)
+        content =
+          if target.post_number == 1
+            "#{target.topic.title}\n#{target.raw}"
+          else
+            target.raw
+          end
+
+        Tokenizer::BertTokenizer.truncate(content, 512)
+      end
+
+      def classifiers
+        DiscourseAi::Sentiment::SentimentSiteSettingJsonSchema.values
+      end
+
+      def request_with(content, config, base_url = Discourse.base_url)
+        DiscourseAi::Inference::HuggingFaceTextEmbeddings.classify(content, config, base_url)
+      end
+
+      def store_classification(target, classification)
+        attrs =
+          classification.map do |model_name, classifications|
+            {
+              model_used: model_name,
+              target_id: target.id,
+              target_type: target.class.sti_name,
+              classification_type: :sentiment,
+              classification: classifications,
+              updated_at: DateTime.now,
+              created_at: DateTime.now,
+            }
+          end
+
+        ClassificationResult.upsert_all(
+          attrs,
+          unique_by: %i[target_id target_type model_used],
+          update_only: %i[classification],
+        )
+      end
+    end
+  end
+end

lib/tasks/modules/sentiment/backfill.rake

@@ -14,11 +14,8 @@ task "ai:sentiment:backfill", [:start_post] => [:environment] do |_, args|
     .where("category_id IN (?)", public_categories)
     .where(posts: { deleted_at: nil })
     .where(topics: { deleted_at: nil })
-    .order("posts.id ASC")
-    .find_each do |post|
+    .find_in_batches do |batch|
       print "."
-      DiscourseAi::PostClassificator.new(
-        DiscourseAi::Sentiment::SentimentClassification.new,
-      ).classify!(post)
+      DiscourseAi::Sentiment::PostClassification.new.bulk_classify!(batch)
     end
 end

spec/lib/modules/sentiment/post_classification_spec.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+require_relative "../../../support/sentiment_inference_stubs"
+
+RSpec.describe DiscourseAi::Sentiment::PostClassification do
+  fab!(:post_1) { Fabricate(:post, post_number: 2) }
+
+  before do
+    SiteSetting.ai_sentiment_enabled = true
+    SiteSetting.ai_sentiment_model_configs =
+      "[{\"model_name\":\"SamLowe/roberta-base-go_emotions\",\"endpoint\":\"http://samlowe-emotion.com\",\"api_key\":\"123\"},{\"model_name\":\"j-hartmann/emotion-english-distilroberta-base\",\"endpoint\":\"http://jhartmann-emotion.com\",\"api_key\":\"123\"},{\"model_name\":\"cardiffnlp/twitter-roberta-base-sentiment-latest\",\"endpoint\":\"http://cardiffnlp-sentiment.com\",\"api_key\":\"123\"}]"
+  end
+
+  describe "#classify!" do
+    it "does nothing if the post content is blank" do
+      post_1.update_columns(raw: "")
+
+      subject.classify!(post_1)
+
+      expect(ClassificationResult.where(target: post_1).count).to be_zero
+    end
+
+    it "successfully classifies the post" do
+      expected_analysis = DiscourseAi::Sentiment::SentimentSiteSettingJsonSchema.values.length
+      SentimentInferenceStubs.stub_classification(post_1)
+
+      subject.classify!(post_1)
+
+      expect(ClassificationResult.where(target: post_1).count).to eq(expected_analysis)
+    end
+  end
+
+  describe "#classify_bulk!" do
+    fab!(:post_2) { Fabricate(:post, post_number: 2) }
+
+    it "classifies all given posts" do
+      expected_analysis = DiscourseAi::Sentiment::SentimentSiteSettingJsonSchema.values.length
+      SentimentInferenceStubs.stub_classification(post_1)
+      SentimentInferenceStubs.stub_classification(post_2)
+
+      subject.bulk_classify!(Post.where(id: [post_1.id, post_2.id]))
+
+      expect(ClassificationResult.where(target: post_1).count).to eq(expected_analysis)
+      expect(ClassificationResult.where(target: post_2).count).to eq(expected_analysis)
+    end
+  end
+end