Caching main index views

This commit adds caching for the main index views (without filters) to
speed up the "typical" use case where many users are viewing the latest
topics.

To still support logged in user / team features (icons/badges), all of
these features were extracted into an eager loaded turbo frame, so that
even if we generate the cache with a logged in user, we do not include
any user specific details in the display.

Author: dutow

app/assets/stylesheets/components/topics.css

@@ -193,6 +193,10 @@
   }
 }
 
+.is-hidden {
+  display: none !important;
+}
+
 .topic-row {
   &:hover {
     background: var(--color-bg-hover);

app/controllers/topics_controller.rb

@@ -8,15 +8,18 @@ def index
 
     apply_cursor_pagination(base_query)
     @new_topics_count = 0
+    @page_cache_key = topics_page_cache_key
 
-    preload_topic_states if user_signed_in?
-    preload_note_counts if user_signed_in?
     load_visible_tags if user_signed_in?
-    preload_participation_flags if user_signed_in?
 
     respond_to do |format|
       format.html
-      format.turbo_stream
+      format.turbo_stream do
+        body = topics_turbo_stream_cache_fetch do
+          render_to_string(:index, formats: [:turbo_stream])
+        end
+        render body:, content_type: "text/vnd.turbo-stream.html"
+      end
     end
   end
 
@@ -106,6 +109,61 @@ def search
     end
   end
 
+  def user_state
+    topic_ids = params[:topic_ids].is_a?(Array) ? params[:topic_ids].map(&:to_i).uniq : []
+    return render json: { topics: {} } unless user_signed_in? && topic_ids.any?
+
+    @topics = Topic.where(id: topic_ids)
+    preload_topic_states
+    preload_note_counts
+    preload_participation_flags
+
+    payload = topic_ids.index_with do |tid|
+      state = @topic_states[tid] || {}
+      readers = Array(state[:team_readers]).map do |entry|
+        {
+          status: entry[:status],
+          user_id: entry[:user]&.id,
+          team_ids: entry[:team_ids]
+        }
+      end
+      participation = @participation_flags&.dig(tid) || { mine: false, team: false, aliases: [] }
+      participation_payload = {
+        mine: participation[:mine],
+        team: participation[:team],
+        aliases_count: Array(participation[:aliases]).size
+      }
+      {
+        status: state[:status],
+        progress: state[:progress],
+        read_count: state[:read_count],
+        last_id: state[:last_id],
+        aware_until: state[:aware_until],
+        team_readers: readers,
+        note_count: @topic_note_counts&.dig(tid).to_i,
+        participation: participation_payload
+      }
+    end
+
+    render json: { topics: payload }
+  end
+
+  def user_state_frame
+    topic_ids = params[:topic_ids].is_a?(Array) ? params[:topic_ids].map(&:to_i).uniq : []
+    return head :unauthorized unless user_signed_in?
+    return head :ok if topic_ids.empty?
+
+    @topics = Topic.includes(:creator).where(id: topic_ids)
+    preload_topic_states
+    preload_note_counts
+    preload_participation_flags
+
+    respond_to do |format|
+      format.turbo_stream
+      format.html { head :not_acceptable }
+    end
+  end
+
   private
 
   def set_topic
@@ -671,4 +729,32 @@ def hydrate_topics_from_entries(entries)
       topic
     end
   end
+
+  def topics_page_cache_key
+    return nil unless @topics&.last
+    return nil if params[:filter].present? || params[:team_id].present?
+
+    last_topic = @topics.last
+    watermark = "#{last_topic.last_activity.to_i}_#{last_topic.id}"
+    ["topics-index", watermark]
+  end
+
+  def topics_turbo_stream_cache_key
+    [
+      "topics-index-turbo",
+      params[:filter],
+      params[:team_id],
+      params[:cursor].presence || "root"
+    ]
+  end
+
+  def topics_turbo_stream_cache_read
+    Rails.cache.read(topics_turbo_stream_cache_key)
+  end
+
+  def topics_turbo_stream_cache_fetch
+    Rails.cache.fetch(topics_turbo_stream_cache_key, expires_in: 10.minutes) do
+      yield
+    end
+  end
 end

app/services/search_result_cache.rb

@@ -57,9 +57,6 @@ def cache_key(watermarks)
       "wm", watermark_part,
       "lp", @longpage
     ].join(":")
-    File.open("cachelog.txt", 'a') do |f|
-      f.puts "CACHE KEY: #{key}"
-    end
     key
   end
 

app/views/topics/_note_icon.html.slim

@@ -0,0 +1,7 @@
+- count = count.to_i
+- classes = ["topic-icon", "activity-note"]
+- classes << "is-hidden" unless count.positive?
+div class=classes.join(" ") id=dom_id(topic, "notes") data-controller="hover-popover" data-hover-popover-delay-value="200" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
+  i.fa-solid.fa-note-sticky
+  - if count.positive?
+    span.topic-icon-badge = count

app/views/topics/_participation_icon.html.slim

@@ -0,0 +1,14 @@
+- classes = ["topic-icon", "activity-team"]
+- classes << "is-mine" if participation[:mine]
+- classes << "is-hidden" unless participation[:mine] || participation[:team]
+- aliases = participation[:aliases] || []
+- count = aliases.size
+div class=classes.join(" ") id=dom_id(topic, "participation") data-controller="hover-popover" data-hover-popover-delay-value="200" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
+  i.fa-solid.fa-user-group
+  - if count > 1
+    span.topic-icon-badge = count
+  - if aliases.any?
+    .topic-icon-hover data-hover-popover-target="popover" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
+      - aliases.each do |alias_record|
+        - participant_stub = { alias: alias_record }
+        = render partial: "participant_row", locals: { participant: participant_stub, avatar_size: 32, tooltip: alias_record.name }

app/views/topics/_status_cell.html.slim

@@ -0,0 +1,17 @@
+- status = state[:status] || "new"
+- status_class = "status-#{status}"
+td.topic-title.status-border class=status_class id=dom_id(topic, "status_cell") data-label="Topic"
+  - if status.to_s == "reading"
+    - read_count = state[:read_count].to_i
+    - total_count = topic.messages.count
+    - unread_count = [total_count - read_count, 0].max
+    .topic-icon.topic-icon-reading
+      i.fa-solid.fa-envelope
+      - if unread_count.positive?
+        span.topic-icon-badge.topic-icon-badge-sup = unread_count
+  = render partial: "topics/note_icon", locals: { topic: topic, count: note_count.to_i }
+  = render partial: "topics/team_readers_icon", locals: { topic: topic, readers: team_readers }
+  - if topic.attachments.exists?
+    .topic-icon
+      i.fa-solid.fa-paperclip
+  = link_to topic.title, topic_path(topic), class: "topic-link"

app/views/topics/_team_readers_icon.html.slim

@@ -0,0 +1,13 @@
+- count = readers&.size.to_i
+- classes = ["topic-icon", "activity-team-read"]
+- classes << "is-hidden" if count.zero?
+div class=classes.join(" ") id=dom_id(topic, "team_readers") data-controller="hover-popover" data-hover-popover-delay-value="200" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
+  i.fa-solid.fa-users
+  - if count.positive?
+    span.topic-icon-badge = count
+    .topic-icon-hover data-hover-popover-target="popover" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
+      - readers.each do |reader|
+        - alias_record = reader[:user]&.primary_alias || reader[:user]&.aliases&.first
+        - next unless alias_record
+        - participant_stub = { alias: alias_record }
+        = render partial: "participant_row", locals: { participant: participant_stub, avatar_size: 32, tooltip: "#{alias_record.name} (#{reader[:status]})" }

app/views/topics/_topics.html.slim

@@ -1,40 +1,6 @@
 - topics.each do |topic|
-  - state = @topic_states&.dig(topic.id) || {}
-  - team_readers = state[:team_readers] || []
-  - filtered_readers = team_readers
-  - if params[:team_id].present?
-    - filtered_readers = team_readers.select { |r| r[:team_ids]&.include?(params[:team_id].to_i) }
-  - other_team_readers = filtered_readers.reject { |r| r[:user].id == current_user&.id }.uniq { |r| r[:user].id }
-  tr class="topic-row topic-#{state[:status]}" data-topic-id=topic.id data-last-message-id=topic.messages.maximum(:id)
-    td class="topic-title status-border status-#{state[:status] || 'new'}" data-label="Topic"
-      - if state[:status] == :reading
-        - unread_count = [topic.messages.count - state[:read_count], 0].max
-        .topic-icon.topic-icon-reading
-          i.fa-solid.fa-envelope
-          - if unread_count.positive?
-            span.topic-icon-badge.topic-icon-badge-sup = unread_count
-      - if user_signed_in? && other_team_readers.any?
-        - reader_count = other_team_readers.size
-        div class="topic-icon activity-team-read" data-controller="hover-popover" data-hover-popover-delay-value="200" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
-          i.fa-solid.fa-users
-          - if reader_count.positive?
-            span.topic-icon-badge = reader_count
-          .topic-icon-hover data-hover-popover-target="popover" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
-            - other_team_readers.each do |reader|
-              - alias_record = reader[:user].primary_alias || reader[:user].aliases.first
-              - next unless alias_record
-              - participant_stub = { alias: alias_record }
-              = render partial: "participant_row", locals: { participant: participant_stub, avatar_size: 32, tooltip: "#{alias_record.name} (#{reader[:status]})" }
-      - if user_signed_in?
-        - note_count = @topic_note_counts&.dig(topic.id).to_i
-        - if note_count.positive?
-          div class="topic-icon activity-note" data-controller="hover-popover" data-hover-popover-delay-value="200" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
-            i.fa-solid.fa-note-sticky
-            span.topic-icon-badge = note_count
-      - if topic.attachments.exists?
-        .topic-icon
-          i.fa-solid.fa-paperclip
-      = link_to topic.title, topic_path(topic), class: "topic-link"
+  tr class="topic-row" data-topic-id=topic.id data-last-message-id=topic.messages.maximum(:id)
+    = render partial: "topics/status_cell", locals: { topic: topic, state: {}, note_count: 0, team_readers: [] }
     td.topic-activity data-label="Activity"
       - last_message = topic.messages.order(:created_at).last
       - replies_count = [topic.messages.count - 1, 0].max
@@ -56,19 +22,4 @@
             .topic-icon-hover data-hover-popover-target="popover" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
               - contributor_participants.each do |participant|
                 = render partial: "participant_row", locals: { participant: participant, avatar_size: 32 }
-      - if user_signed_in?
-        - participation = @participation_flags&.dig(topic.id)
-        - show_team_icon = participation && (participation[:team] || participation[:mine])
-        - if show_team_icon
-          - icon_classes = ["topic-icon", "activity-team"]
-          - icon_classes << "is-mine" if participation[:mine]
-          - aliases = participation[:aliases] || []
-          div class=icon_classes.join(" ") data-controller="hover-popover" data-hover-popover-delay-value="200" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
-            i.fa-solid.fa-user-group
-            - if aliases.size > 1
-              span.topic-icon-badge = aliases.size
-            - if aliases.any?
-              .topic-icon-hover data-hover-popover-target="popover" data-action="mouseenter->hover-popover#show mouseleave->hover-popover#scheduleHide"
-                - aliases.each do |alias_record|
-                  - participant_stub = { alias: alias_record }
-                  = render partial: "participant_row", locals: { participant: participant_stub, avatar_size: 32, tooltip: alias_record.name }
+      = render partial: "topics/participation_icon", locals: { topic: topic, participation: {} }

app/views/topics/index.html.slim

@@ -1,32 +1,45 @@
 - content_for :title, "PostgreSQL Hackers Archive"
 
-= render partial: "sidebar", locals: { available_note_tags: @available_note_tags, search_query: @search_query }
+- cache_block = lambda do
+  #new-topics-banner data-controller="new-topics-banner" data-new-topics-banner-url-value=new_topics_count_topics_path(viewing_since: @viewing_since.iso8601, filter: params[:filter], team_id: params[:team_id]) data-new-topics-banner-interval-ms-value="180000"
+    = render partial: "new_topics_banner", locals: { count: @new_topics_count, viewing_since: @viewing_since }
 
-#new-topics-banner data-controller="new-topics-banner" data-new-topics-banner-url-value=new_topics_count_topics_path(viewing_since: @viewing_since.iso8601, filter: params[:filter], team_id: params[:team_id]) data-new-topics-banner-interval-ms-value="180000"
-  = render partial: "new_topics_banner", locals: { count: @new_topics_count, viewing_since: @viewing_since }
+  - if @active_note_tag.present?
+    .tag-filter-banner
+      span Filtering by ##{@active_note_tag}
+      = link_to "Clear", topics_path, class: "clear-tag-filter"
 
-- if @active_note_tag.present?
-  .tag-filter-banner
-    span Filtering by ##{@active_note_tag}
-    = link_to "Clear", topics_path, class: "clear-tag-filter"
-
-.topics-table
   - if user_signed_in?
-    .topics-actions data-controller="topics-aware" data-topics-aware-aware-url-value=aware_bulk_topics_path data-topics-aware-aware-all-url-value=aware_all_topics_path
-      button.mark-aware-button data-action="click->topics-aware#markVisibleAware" Mark displayed threads aware
-      button.mark-aware-button.secondary data-action="click->topics-aware#markAllAware" Mark everything up to now aware
+    #user-state-requests
+      = turbo_frame_tag "user-state-root", src: user_state_frame_topics_path(topic_ids: @topics.map(&:id), format: :turbo_stream), loading: :eager
+
+  .topics-table
+    - if user_signed_in?
+      .topics-actions data-controller="topics-aware" data-topics-aware-aware-url-value=aware_bulk_topics_path data-topics-aware-aware-all-url-value=aware_all_topics_path
+        button.mark-aware-button data-action="click->topics-aware#markVisibleAware" Mark displayed threads aware
+        button.mark-aware-button.secondary data-action="click->topics-aware#markAllAware" Mark everything up to now aware
+
+    table
+      thead
+        tr
+          th.topic-title Topic
+          th.activity-header Activity
+          th.participants-header Participants
+      tbody#topics
+        = render partial: "topics", locals: { topics: @topics }
 
-  table
-    thead
-      tr
-        th.topic-title Topic
-        th.activity-header Activity
-        th.participants-header Participants
-    tbody#topics
-      = render partial: "topics", locals: { topics: @topics }
+    - if @topics.size == 25
+      - last_topic = @topics.last
+      - cursor = "#{last_topic.last_activity.iso8601}_#{last_topic.id}"
+      = turbo_frame_tag "pagination", src: topics_path(cursor: cursor, viewing_since: @viewing_since.iso8601, format: :turbo_stream), loading: :lazy do
+        .loading-indicator Loading more topics...
+    - else
+      = turbo_frame_tag "pagination"
 
-  - if @topics.size == 25
-    - last_topic = @topics.last
-    - cursor = "#{last_topic.last_activity.iso8601}_#{last_topic.id}"
-    = turbo_frame_tag "pagination", src: topics_path(cursor: cursor, viewing_since: @viewing_since.iso8601, format: :turbo_stream), loading: :lazy do
-      .loading-indicator Loading more topics...
+- if @page_cache_key
+  = render partial: "sidebar", locals: { available_note_tags: @available_note_tags, search_query: @search_query }
+  - cache(@page_cache_key) do
+    - cache_block.call
+- else
+  = render partial: "sidebar", locals: { available_note_tags: @available_note_tags, search_query: @search_query }
+  - cache_block.call

app/views/topics/index.turbo_stream.slim

@@ -1,9 +1,16 @@
 = turbo_stream.append "topics" do
   = render partial: "topics", locals: { topics: @topics }
 
+- if user_signed_in?
+  - frame_id = params[:cursor].present? ? "user-state-#{params[:cursor]}" : "user-state-root"
+  = turbo_stream.append "user-state-requests" do
+    = turbo_frame_tag frame_id, src: user_state_frame_topics_path(topic_ids: @topics.map(&:id), format: :turbo_stream), loading: :eager
+
 - if @topics.size == 25
   - last_topic = @topics.last
   - cursor = "#{last_topic.last_activity.iso8601}_#{last_topic.id}"
   = turbo_stream.replace "pagination" do
     = turbo_frame_tag "pagination", src: topics_path(cursor: cursor, viewing_since: @viewing_since.iso8601, format: :turbo_stream), loading: :lazy do
       .loading-indicator Loading more topics...
+- elsif params[:cursor].present?
+  = turbo_stream.remove "pagination"