📰 Tweak the suggestion ranks for UMA to handle fetchMore

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SectionList.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.ntp.cards;
 
 import org.chromium.base.Log;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.browser.ntp.NewTabPageView.NewTabPageManager;
 import org.chromium.chrome.browser.ntp.snippets.CategoryInt;
@@ skipping 14 matching lines @@
  * suggestions source and updates the corresponding sections.
  */
 public class SectionList
         extends InnerNode implements SuggestionsSource.Observer, SuggestionsSection.Delegate {
     private static final String TAG = "Ntp";
 
     /** Maps suggestion categories to sections, with stable iteration ordering. */
     private final Map<Integer, SuggestionsSection> mSections = new LinkedHashMap<>();
     private final NewTabPageManager mNewTabPageManager;
     private final OfflinePageBridge mOfflinePageBridge;
+    private final SuggestionRanker mSuggestionRanker;
 
     public SectionList(NewTabPageManager newTabPageManager, OfflinePageBridge offlinePageBridge) {
+        mSuggestionRanker = new SuggestionRanker();
         mNewTabPageManager = newTabPageManager;
         mNewTabPageManager.getSuggestionsSource().setObserver(this);
         mOfflinePageBridge = offlinePageBridge;
         resetSections(/* alwaysAllowEmptySections = */ false);
     }
 
     /**
      * Resets the sections, reloading the whole new tab page content.
      * @param alwaysAllowEmptySections Whether sections are always allowed to be displayed when
      *     they are empty, even when they are normally not.
      */
     public void resetSections(boolean alwaysAllowEmptySections) {
         removeAllSections();
 
         SuggestionsSource suggestionsSource = mNewTabPageManager.getSuggestionsSource();
         int[] categories = suggestionsSource.getCategories();
         int[] suggestionsPerCategory = new int[categories.length];
         int i = 0;
         for (int category : categories) {
             int categoryStatus = suggestionsSource.getCategoryStatus(category);
             if (categoryStatus == CategoryStatus.LOADING_ERROR
                     || categoryStatus == CategoryStatus.NOT_PROVIDED
                     || categoryStatus == CategoryStatus.CATEGORY_EXPLICITLY_DISABLED)
                 continue;
 
             suggestionsPerCategory[i++] =
                     resetSection(category, categoryStatus, alwaysAllowEmptySections);
         }
 
-        mNewTabPageManager.trackSnippetsPageImpression(categories, suggestionsPerCategory);
+        mNewTabPageManager.getSuggestionsMetricsReporter().onPageShown(
+                categories, suggestionsPerCategory);
     }
 
     /**
      * Resets the section for {@code category}. Removes the section if there are no suggestions for
      * it and it is not allowed to be empty. Otherwise, creates the section if it is not present
      * yet. Sets the available suggestions on the section.
      * @param category The category for which the section must be reset.
      * @param categoryStatus The category status.
      * @param alwaysAllowEmptySections Whether sections are always allowed to be displayed when
      *     they are empty, even when they are normally not.
      * @return The number of suggestions for the section.
      */
     private int resetSection(@CategoryInt int category, @CategoryStatusEnum int categoryStatus,
             boolean alwaysAllowEmptySections) {
         SuggestionsSource suggestionsSource = mNewTabPageManager.getSuggestionsSource();
         List<SnippetArticle> suggestions = suggestionsSource.getSuggestionsForCategory(category);
         SuggestionsCategoryInfo info = suggestionsSource.getCategoryInfo(category);
 
         SuggestionsSection section = mSections.get(category);
 
         // Do not show an empty section if not allowed.
         if (suggestions.isEmpty() && !info.showIfEmpty() && !alwaysAllowEmptySections) {
             if (section != null) removeSection(section);
             return 0;
         }
 
         // Create the section if needed.
         if (section == null) {
-            section = new SuggestionsSection(this, mNewTabPageManager, mOfflinePageBridge, info);
+            section = new SuggestionsSection(
+                    this, mNewTabPageManager, mSuggestionRanker, mOfflinePageBridge, info);
             mSections.put(category, section);
+            mSuggestionRanker.registerCategory(category);
             addChild(section);
         }
 
         // Set the new suggestions.
         setSuggestions(category, suggestions, categoryStatus, /* replaceExisting = */ true);
 
         return suggestions.size();
     }
 
     @Override
@@ skipping 69 matching lines @@
      * may have no or only partial effect if changing the list of suggestions is not allowed (e.g.
      * because the user has already seen the suggestions).
      * @param category The category for which the suggestions should be set.
      * @param suggestions The new list of suggestions for the given category.
      * @param status The new category status.
      * @param replaceExisting If true, {@code suggestions} replace the current list of suggestions.
      * If false, {@code suggestions} are appended to current list of suggestions.
      */
     private void setSuggestions(@CategoryInt int category, List<SnippetArticle> suggestions,
             @CategoryStatusEnum int status, boolean replaceExisting) {
-        // Count the number of suggestions before this category.
-        int globalPositionOffset = 0;
-        for (Map.Entry<Integer, SuggestionsSection> entry : mSections.entrySet()) {
-            if (entry.getKey() == category) break;
-            globalPositionOffset += entry.getValue().getSuggestionsCount();
-        }
-        // Assign global indices to the new suggestions.
-        for (SnippetArticle suggestion : suggestions) {
-            suggestion.mGlobalPosition = globalPositionOffset + suggestion.mPosition;
-        }
-
         mSections.get(category).setSuggestions(suggestions, status, replaceExisting);
     }
 
     private boolean canLoadSuggestions(@CategoryInt int category, @CategoryStatusEnum int status) {
         // We never want to add suggestions from unknown categories.
         if (!mSections.containsKey(category)) return false;
 
         // The status may have changed while the suggestions were loading, perhaps they should not
         // be displayed any more.
         if (!SnippetsBridge.isCategoryEnabled(status)) {
@@ skipping 40 matching lines @@
     /**
      * @return Whether the list of sections is empty.
      */
     public boolean isEmpty() {
         return mSections.isEmpty();
     }
 
     SuggestionsSection getSectionForTesting(@CategoryInt int categoryId) {
         return mSections.get(categoryId);
     }
+
+    /**
+     * Attributes ranks to suggestions and related elements.
+     *
+     * Ranks here are 0-based scores attributed based on the position or loading order of the
+     * elements. See implementation for more details.
+     */
+    public static class SuggestionRanker {

[Bernhard Bauer, 2017/01/17 17:42:31]

Can we move this to a separate class? There isn't much here that requires it to
be in SectionList.

[dgn, 2017/01/17 18:46:24]

Done.

+        private final Map<Integer, Integer> mSuggestionsAddedPerSection = new LinkedHashMap<>();
+        private int mTotalAddedSuggestions;
+
+        /**
+         * Attributes a per section rank to the provided action item.
+         * @see ActionItem#getPerSectionRank()
+         */
+        public void rankItem(ActionItem actionItem, SuggestionsSection section) {

[Bernhard Bauer, 2017/01/17 17:42:31]

Can we rename these methods to rankActionItem() and rankSuggestion()?

[dgn, 2017/01/17 18:46:24]

Done.

+            if (actionItem.getPerSectionRank() != -1) return; // Item was already ranked.
+            actionItem.setRank(section.getSuggestionsCount());
+        }
+
+        /**
+         * Attributes global and per section rank to the provided suggestion.
+         * @see SnippetArticle#getPerSectionRank()
+         * @see SnippetArticle#getGlobalRank()
+         */
+        public void rankItem(SnippetArticle suggestion) {
+            int globalRank = mTotalAddedSuggestions++;
+            int perSectionRank = mSuggestionsAddedPerSection.get(suggestion.mCategory);
+            mSuggestionsAddedPerSection.put(suggestion.mCategory, perSectionRank + 1);
+
+            suggestion.setRank(perSectionRank, globalRank);
+        }
+
+        public void registerCategory(@CategoryInt int category) {
+            mSuggestionsAddedPerSection.put(category, 0);
+        }
+    }
 }