Raise nicely when data dictionary is needed but missing

lib/innodb/data_dictionary.rb

@@ -235,7 +235,14 @@ def data_dictionary_indexes
       system_space.data_dictionary_page.data_dictionary_header[:indexes]
     end
 
+    # Check if the data dictionary indexes are all available.
+    def found?
+      data_dictionary_indexes.values.map(&:values).flatten.none?(&:zero?)
+    end
+
     def data_dictionary_index_ids
+      raise "Data Dictionary not found; is the MySQL version supported?" unless found?
+
       return @data_dictionary_index_ids if @data_dictionary_index_ids
 
       # TODO: This could probably be done a lot more Ruby-like.
@@ -275,6 +282,8 @@ def data_dictionary_index_describer(table_name, index_name)
     # internal data dictionary index with an appropriate
     # record describer so that records can be recursed.
     def data_dictionary_index(table_name, index_name)
+      raise "Data Dictionary not found; is the MySQL version supported?" unless found?
+
       table_entry = data_dictionary_indexes[table_name]
       raise "Unknown data dictionary table #{table_name}" unless table_entry
 

lib/innodb/page/index.rb

@@ -546,7 +546,7 @@ def supremum
       end
 
       def make_record_describer
-        if space&.innodb_system && index_id
+        if space&.innodb_system&.data_dictionary&.found? && index_id && !ibuf_index?
           @record_describer = space.innodb_system.data_dictionary.record_describer_by_index_id(index_id)
         elsif space
           @record_describer = space.record_describer
@@ -1096,17 +1096,23 @@ def dump
         pp supremum.record
         puts
 
-        puts "garbage records:"
-        each_garbage_record do |rec|
-          pp rec.record
+        if ibuf_index?
+          puts "(records not dumped due to this being an insert buffer index)"
+        elsif !record_describer
+          puts "(records not dumped due to missing record describer or data dictionary)"
+        else
+          puts "garbage records:"
+          each_garbage_record do |rec|
+            pp rec.record
+            puts
+          end
           puts
-        end
-        puts
 
-        puts "records:"
-        each_record do |rec|
-          pp rec.record
-          puts
+          puts "records:"
+          each_record do |rec|
+            pp rec.record
+            puts
+          end
         end
         puts
       end

lib/innodb/space.rb

@@ -276,14 +276,22 @@ def space_id
       fsp[:space_id]
     end
 
+    def checked_page_class!(page, expected_class)
+      return page if page.instance_of?(expected_class)
+
+      raise "Page #{page.offset} is not the correct type, found: #{page.class}, expected: #{expected_class}"
+    end
+
     # Return the page number for the space's TRX_SYS page.
     def page_trx_sys
       5
     end
 
     # Get the Innodb::Page::TrxSys page for a system space.
     def trx_sys
-      page(page_trx_sys) if system_space?
+      raise "Transaction System is only available in system spaces" unless system_space?
+
+      checked_page_class!(page(page_trx_sys), Innodb::Page::TrxSys)
     end
 
     def rseg_page?(page_number)
@@ -299,7 +307,9 @@ def page_sys_data_dictionary
 
     # Get the Innodb::Page::SysDataDictionaryHeader page for a system space.
     def data_dictionary_page
-      page(page_sys_data_dictionary) if system_space?
+      raise "Data Dictionary is only available in system spaces" unless system_space?
+
+      checked_page_class!(page(page_sys_data_dictionary), Innodb::Page::SysDataDictionaryHeader)
     end
 
     # Get an Innodb::List object for a specific list by list name.

spec/innodb/space_spec.rb

@@ -108,7 +108,7 @@
     end
 
     it "should return nil for a non-system space" do
-      @space_ibd.trx_sys.should eql nil
+      expect { @space_ibd.trx_sys }.to raise_error(RuntimeError)
     end
   end
 
@@ -118,7 +118,7 @@
     end
 
     it "should return nil for a non-system space" do
-      @space_ibd.data_dictionary_page.should eql nil
+      expect { @space_ibd.data_dictionary_page }.to raise_error(RuntimeError)
     end
   end