Support judgement expired schema cache dump.

activerecord/lib/active_record/connection_adapters/schema_cache.rb

 module ActiveRecord
   module ConnectionAdapters
     class SchemaCache
-      attr_reader :columns, :columns_hash, :primary_keys, :tables
+      attr_reader :columns, :columns_hash, :primary_keys, :tables, :version
       attr_accessor :connection
 
       def initialize(conn)
@@ -36,6 +36,7 @@ def clear!
         @columns_hash.clear
         @primary_keys.clear
         @tables.clear
+        @version = nil
       end
 
       # Clear out internal caches for table with +table_name+.
@@ -47,13 +48,15 @@ def clear_table_cache!(table_name)
       end
 
       def marshal_dump
-        [:@columns, :@columns_hash, :@primary_keys, :@tables].map do |val|
+        # if we get current version during initialization, it happens stack over flow.
+        @version = ActiveRecord::Migrator.current_version
+        [@version] + [:@columns, :@columns_hash, :@primary_keys, :@tables].map do |val|
           self.instance_variable_get(val).inject({}) { |h, v| h[v[0]] = v[1]; h }
         end
       end
 
       def marshal_load(array)
-        @columns, @columns_hash, @primary_keys, @tables = array
+        @version, @columns, @columns_hash, @primary_keys, @tables = array
         prepare_default_proc
       end
 

activerecord/lib/active_record/railtie.rb

@@ -121,7 +121,11 @@ class Railtie < Rails::Railtie
           filename = File.join(app.config.paths["db"].first, "schema_cache.dump")
           if File.file?(filename)
             cache = Marshal.load(open(filename, 'rb') { |f| f.read })
-            ActiveRecord::Base.connection.schema_cache = cache
+            if cache.version == ActiveRecord::Migrator.current_version
+              ActiveRecord::Base.connection.schema_cache = cache
+            else
+              warn "schema_cache.dump is expired. Current version is #{ActiveRecord::Migrator.current_version}, but cache version is #{cache.version}."
+            end
           end
         end
       end

railties/test/application/initializers/frameworks_test.rb

@@ -205,5 +205,19 @@ def from_bar_helper
       assert ActiveRecord::Base.connection.schema_cache.tables["posts"]
     end
 
+    test "expire schema cache dump" do
+      Dir.chdir(app_path) do
+        `rails generate model post title:string`
+        `bundle exec rake db:migrate`
+        `bundle exec rake db:schema:cache:dump`
+
+        `bundle exec rake db:rollback`
+      end
+      silence_warnings {
+        require "#{app_path}/config/environment"
+        assert !ActiveRecord::Base.connection.schema_cache.tables["posts"]
+      }
+    end
+
   end
 end