1 files changed, 46 insertions, 43 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index ebeac425d0..0493ab4e4b 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -191,30 +191,32 @@ module ActiveRecord
         type_casted_binds = type_casted_binds(binds)
 
         log(sql, name, binds, type_casted_binds) do
-          # Don't cache statements if they are not prepared
-          unless prepare
-            stmt    = @connection.prepare(sql)
-            begin
-              cols    = stmt.columns
-              unless without_prepared_statement?(binds)
-                stmt.bind_params(type_casted_binds)
+          ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
+            # Don't cache statements if they are not prepared
+            unless prepare
+              stmt = @connection.prepare(sql)
+              begin
+                cols = stmt.columns
+                unless without_prepared_statement?(binds)
+                  stmt.bind_params(type_casted_binds)
+                end
+                records = stmt.to_a
+              ensure
+                stmt.close
               end
+            else
+              cache = @statements[sql] ||= {
+                stmt: @connection.prepare(sql)
+              }
+              stmt = cache[:stmt]
+              cols = cache[:cols] ||= stmt.columns
+              stmt.reset!
+              stmt.bind_params(type_casted_binds)
               records = stmt.to_a
-            ensure
-              stmt.close
             end
-          else
-            cache = @statements[sql] ||= {
-              stmt: @connection.prepare(sql)
-            }
-            stmt = cache[:stmt]
-            cols = cache[:cols] ||= stmt.columns
-            stmt.reset!
-            stmt.bind_params(type_casted_binds)
-            records = stmt.to_a
-          end
 
-          ActiveRecord::Result.new(cols, records)
+            ActiveRecord::Result.new(cols, records)
+          end
         end
       end
 
@@ -229,19 +231,23 @@ module ActiveRecord
       end
 
       def execute(sql, name = nil) #:nodoc:
-        log(sql, name) { @connection.execute(sql) }
+        log(sql, name) do
+          ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
+            @connection.execute(sql)
+          end
+        end
       end
 
       def begin_db_transaction #:nodoc:
-        log("begin transaction",nil) { @connection.transaction }
+        log("begin transaction", nil) { @connection.transaction }
       end
 
       def commit_db_transaction #:nodoc:
-        log("commit transaction",nil) { @connection.commit }
+        log("commit transaction", nil) { @connection.commit }
       end
 
       def exec_rollback_db_transaction #:nodoc:
-        log("rollback transaction",nil) { @connection.rollback }
+        log("rollback transaction", nil) { @connection.rollback }
       end
 
       # SCHEMA STATEMENTS ========================================
@@ -298,24 +304,20 @@ module ActiveRecord
         select_values(sql, "SCHEMA").any?
       end
 
-      # Returns an array of +Column+ objects for the table specified by +table_name+.
-      def columns(table_name) # :nodoc:
-        table_name = table_name.to_s
-        table_structure(table_name).map do |field|
-          case field["dflt_value"]
-          when /^null$/i
-            field["dflt_value"] = nil
-          when /^'(.*)'$/m
-            field["dflt_value"] = $1.gsub("''", "'")
-          when /^"(.*)"$/m
-            field["dflt_value"] = $1.gsub('""', '"')
-          end
-
-          collation = field["collation"]
-          sql_type = field["type"]
-          type_metadata = fetch_type_metadata(sql_type)
-          new_column(field["name"], field["dflt_value"], type_metadata, field["notnull"].to_i == 0, table_name, nil, collation)
+      def new_column_from_field(table_name, field) # :nondoc:
+        case field["dflt_value"]
+        when /^null$/i
+          field["dflt_value"] = nil
+        when /^'(.*)'$/m
+          field["dflt_value"] = $1.gsub("''", "'")
+        when /^"(.*)"$/m
+          field["dflt_value"] = $1.gsub('""', '"')
         end
+
+        collation = field["collation"]
+        sql_type = field["type"]
+        type_metadata = fetch_type_metadata(sql_type)
+        new_column(field["name"], field["dflt_value"], type_metadata, field["notnull"].to_i == 0, table_name, nil, collation)
       end
 
       # Returns an array of indexes for the given table.
@@ -410,7 +412,7 @@ module ActiveRecord
             self.default = options[:default] if include_default
             self.null    = options[:null] if options.include?(:null)
             self.precision = options[:precision] if options.include?(:precision)
-            self.scale   = options[:scale] if options.include?(:scale)
+            self.scale = options[:scale] if options.include?(:scale)
             self.collation = options[:collation] if options.include?(:collation)
           end
         end
@@ -424,11 +426,12 @@ module ActiveRecord
 
       protected
 
-        def table_structure(table_name)
+        def table_structure(table_name) # :nodoc:
           structure = exec_query("PRAGMA table_info(#{quote_table_name(table_name)})", "SCHEMA")
           raise(ActiveRecord::StatementInvalid, "Could not find table '#{table_name}'") if structure.empty?
           table_structure_with_collation(table_name, structure)
         end
+        alias column_definitions table_structure
 
         def alter_table(table_name, options = {}) #:nodoc:
           altered_table_name = "a#{table_name}"