Improved timeout pattern

ankane · Feb 27, 2023 · b9a23a7 · b9a23a7
1 parent ccb1751
commit b9a23a7
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Showing 4 changed files with 21 additions and 20 deletions.
diff --git a/app/controllers/pg_hero/home_controller.rb b/app/controllers/pg_hero/home_controller.rb
@@ -46,16 +46,18 @@ def index
 
       @transaction_id_danger = @database.transaction_id_danger(threshold: 1500000000)
 
-      sequences = rescue_lock_timeout { @database.sequences } || []
+      sequences, @sequences_timeout = rescue_timeout([]) { @database.sequences }
       @readable_sequences, @unreadable_sequences = sequences.partition { |s| s[:readable] }
 
       @sequence_danger = @database.sequence_danger(threshold: (params[:sequence_threshold] || 0.9).to_f, sequences: @readable_sequences)
 
-      # TODO improve rescue_lock_timeout pattern
-      @sequence_timeout = @lock_timeout
-      @lock_timeout = false
-
-      @indexes = rescue_lock_timeout { @database.indexes } || []
+      @indexes, @indexes_timeout =
+        if @sequences_timeout
+          # skip indexes for faster loading
+          [[], true]
+        else
+          rescue_timeout([]) { @database.indexes }
+        end
       @invalid_indexes = @database.invalid_indexes(indexes: @indexes)
       @invalid_constraints = @database.invalid_constraints
       @duplicate_indexes = @database.duplicate_indexes(indexes: @indexes)
@@ -85,7 +87,7 @@ def space
       @days = (params[:days] || 7).to_i
       @database_size = @database.database_size
       @only_tables = params[:tables].present?
-      @relation_sizes = rescue_lock_timeout { @only_tables ? @database.table_sizes : @database.relation_sizes } || []
+      @relation_sizes, @sizes_timeout = rescue_timeout([]) { @only_tables ? @database.table_sizes : @database.relation_sizes }
       @space_stats_enabled = @database.space_stats_enabled? && !@only_tables
       if @space_stats_enabled
         space_growth = @database.space_growth(days: @days, relation_sizes: @relation_sizes)
@@ -199,7 +201,7 @@ def show_query
 
         if @tables.any?
           @row_counts = @database.table_stats(table: @tables).to_h { |i| [i[:table], i[:estimated_rows]] }
-          indexes = rescue_lock_timeout { @database.indexes } || []
+          indexes, @indexes_timeout = rescue_timeout([]) { @database.indexes }
           @indexes_by_table = indexes.group_by { |i| i[:table] }
         end
       else
@@ -448,18 +450,18 @@ def set_query_stats_enabled
     end
 
     def set_suggested_indexes(min_average_time = 0, min_calls = 0)
-      if @database.suggested_indexes_enabled?
-        @indexes ||= rescue_lock_timeout { @database.indexes } || []
+      if @database.suggested_indexes_enabled? && !@indexes
+        @indexes, @indexes_timeout = rescue_timeout([]) { @database.indexes }
       end
 
       @suggested_indexes_by_query =
-        if !@lock_timeout && @database.suggested_indexes_enabled?
+        if !@indexes_timeout && @database.suggested_indexes_enabled?
           @database.suggested_indexes_by_query(query_stats: @query_stats.select { |qs| qs[:average_time] >= min_average_time && qs[:calls] >= min_calls }, indexes: @indexes)
         else
           {}
         end
 
-      @suggested_indexes = @lock_timeout ? {} : @database.suggested_indexes(suggested_indexes_by_query: @suggested_indexes_by_query)
+      @suggested_indexes = @database.suggested_indexes(suggested_indexes_by_query: @suggested_indexes_by_query)
       @query_stats_by_query = @query_stats.index_by { |q| q[:query] }
       @debug = params[:debug].present?
     end
@@ -510,11 +512,10 @@ def ensure_query_stats
 
     # rescue QueryCanceled for case when
     # statement timeout is less than lock timeout
-    def rescue_lock_timeout
-      yield
+    def rescue_timeout(default)
+      [yield, false]
     rescue ActiveRecord::LockWaitTimeout, ActiveRecord::QueryCanceled
-      @lock_timeout = true
-      nil
+      [default, true]
     end
   end
 end
diff --git a/app/views/pg_hero/home/index.html.erb b/app/views/pg_hero/home/index.html.erb
@@ -55,10 +55,10 @@
       Vacuuming healthy
     <% end %>
   </div>
-  <div class="alert alert-<%= @sequence_danger && @sequence_danger.empty? && !@sequence_timeout ? "success" : "warning" %>">
+  <div class="alert alert-<%= @sequence_danger && @sequence_danger.empty? && !@sequences_timeout ? "success" : "warning" %>">
     <% if @sequence_danger.any? %>
       <%= pluralize(@sequence_danger.size, "column") %> approaching overflow
-    <% elsif @sequence_timeout %>
+    <% elsif @sequences_timeout %>
       Sequences not available (system catalog locked)
     <% else %>
       No columns near integer overflow

diff --git a/app/views/pg_hero/home/show_query.html.erb b/app/views/pg_hero/home/show_query.html.erb
@@ -88,7 +88,7 @@
             <td><%= table %></td>
             <td><%= @row_counts[table] %></td>
             <td>
-              <% if @lock_timeout %>
+              <% if @indexes_timeout %>
                 Not available
               <% else %>
                 <ul>

diff --git a/app/views/pg_hero/home/space.html.erb b/app/views/pg_hero/home/space.html.erb
@@ -37,7 +37,7 @@
     </div>
   <% end %>
 
-  <% if @lock_timeout %>
+  <% if @sizes_timeout %>
     <p>Breakdown not available (system catalog locked)</p>
   <% else %>
     <table class="table space-table">