Created adapter interface

lib/blazer.rb

@@ -5,6 +5,7 @@ require "safely/core"
 require "blazer/version"
 require "blazer/data_source"
 require "blazer/result"
+require "blazer/adapters/active_record_adapter"
 require "blazer/engine"
 
 module Blazer

lib/blazer/adapters/active_record_adapter.rb

@@ -0,0 +1,119 @@
+module Blazer
+  module Adapters
+    class ActiveRecordAdapter
+      attr_reader :data_source, :connection_model
+
+      def initialize(data_source)
+        @data_source = data_source
+
+        @connection_model =
+          Class.new(Blazer::Connection) do
+            def self.name
+              "Blazer::Connection::#{object_id}"
+            end
+            establish_connection(data_source.settings["url"]) if data_source.settings["url"]
+          end
+      end
+
+      def schemas
+        default_schema = (postgresql? || redshift?) ? "public" : connection_model.connection_config[:database]
+        settings["schemas"] || [connection_model.connection_config[:schema] || default_schema]
+      end
+
+      def tables
+        result = data_source.run_statement(connection_model.send(:sanitize_sql_array, ["SELECT table_name FROM information_schema.tables WHERE table_schema IN (?) ORDER BY table_name", schemas]))
+        result.rows.map(&:first)
+      end
+
+      def run_statement(statement, comment)
+        columns = []
+        rows = []
+        error = nil
+        start_time = Time.now
+
+        begin
+          in_transaction do
+            set_timeout(data_source.timeout) if data_source.timeout
+
+            result = connection_model.connection.select_all("#{statement} /*#{comment}*/")
+            columns = result.columns
+            cast_method = Rails::VERSION::MAJOR < 5 ? :type_cast : :cast_value
+            result.rows.each do |untyped_row|
+              rows << (result.column_types.empty? ? untyped_row : columns.each_with_index.map { |c, i| untyped_row[i] ? result.column_types[c].send(cast_method, untyped_row[i]) : nil })
+            end
+          end
+        rescue ActiveRecord::StatementInvalid => e
+          error = e.message.sub(/.+ERROR: /, "")
+          error = Blazer::TIMEOUT_MESSAGE if Blazer::TIMEOUT_ERRORS.any? { |e| error.include?(e) }
+        end
+
+        [columns, rows, error]
+      end
+
+      def reconnect
+        connection_model.establish_connection(settings["url"])
+      end
+
+      def cost(statement)
+        result = explain(statement)
+        match = /cost=\d+\.\d+..(\d+\.\d+) /.match(result)
+        match[1] if match
+      end
+
+      def explain(statement)
+        if postgresql? || redshift?
+          connection_model.connection.select_all("EXPLAIN #{statement}").rows.first.first
+        end
+      rescue
+        nil
+      end
+
+      private
+
+      def postgresql?
+        ["PostgreSQL", "PostGIS"].include?(adapter_name)
+      end
+
+      def redshift?
+        ["Redshift"].include?(adapter_name)
+      end
+
+      def mysql?
+        ["MySQL", "Mysql2", "Mysql2Spatial"].include?(adapter_name)
+      end
+
+      def adapter_name
+        connection_model.connection.adapter_name
+      end
+
+      def set_timeout(timeout)
+        if postgresql? || redshift?
+          connection_model.connection.execute("SET statement_timeout = #{timeout.to_i * 1000}")
+        elsif mysql?
+          connection_model.connection.execute("SET max_execution_time = #{timeout.to_i * 1000}")
+        else
+          raise Blazer::TimeoutNotSupported, "Timeout not supported for #{adapter_name} adapter"
+        end
+      end
+
+      def use_transaction?
+        settings.key?("use_transaction") ? settings["use_transaction"] : true
+      end
+
+      def in_transaction
+        if use_transaction?
+          connection_model.transaction do
+            yield
+            raise ActiveRecord::Rollback
+          end
+        else
+          yield
+        end
+      end
+
+      def settings
+        @data_source.settings
+      end
+    end
+  end
+end

lib/blazer/data_source.rb

@@ -2,7 +2,11 @@ require "digest/md5"
 
 module Blazer
   class DataSource
-    attr_reader :id, :settings, :connection_model
+    extend Forwardable
+
+    attr_reader :id, :settings, :adapter
+
+    def_delegators :adapter, :schema, :tables, :reconnect, :cost, :explain
 
     def initialize(id, settings)
       @id = id
@@ -12,13 +16,7 @@ module Blazer
         raise Blazer::Error, "Empty url"
       end
 
-      @connection_model =
-        Class.new(Blazer::Connection) do
-          def self.name
-            "Blazer::Connection::#{object_id}"
-          end
-          establish_connection(settings["url"]) if settings["url"]
-        end
+      @adapter = Blazer::Adapters::ActiveRecordAdapter.new(self)
     end
 
     def name
@@ -78,24 +76,6 @@ module Blazer
       @local_time_suffix ||= Array(settings["local_time_suffix"])
     end
 
-    def use_transaction?
-      settings.key?("use_transaction") ? settings["use_transaction"] : true
-    end
-
-    def cost(statement)
-      result = explain(statement)
-      match = /cost=\d+\.\d+..(\d+\.\d+) /.match(result)
-      match[1] if match
-    end
-
-    def explain(statement)
-      if postgresql? || redshift?
-        connection_model.connection.select_all("EXPLAIN #{statement}").rows.first.first
-      end
-    rescue
-      nil
-    end
-
     def run_main_statement(statement, options = {})
       query = options[:query]
       Blazer.transform_statement.call(self, statement) if Blazer.transform_statement
@@ -192,70 +172,13 @@ module Blazer
       cache_key(["run", run_id])
     end
 
-    def schemas
-      default_schema = (postgresql? || redshift?) ? "public" : connection_model.connection_config[:database]
-      settings["schemas"] || [connection_model.connection_config[:schema] || default_schema]
-    end
-
-    def tables
-      result = run_statement(connection_model.send(:sanitize_sql_array, ["SELECT table_name FROM information_schema.tables WHERE table_schema IN (?) ORDER BY table_name", schemas]))
-      result.rows.map(&:first)
-    end
-
-    def postgresql?
-      ["PostgreSQL", "PostGIS"].include?(adapter_name)
-    end
-
-    def redshift?
-      ["Redshift"].include?(adapter_name)
-    end
-
-    def mysql?
-      ["MySQL", "Mysql2", "Mysql2Spatial"].include?(adapter_name)
-    end
-
-    def reconnect
-      connection_model.establish_connection(settings["url"])
-    end
-
     protected
 
     def run_statement_helper(statement, comment, run_id)
-      columns = []
-      rows = []
-      error = nil
       start_time = Time.now
-      result = nil
-
-      begin
-        in_transaction do
-          if timeout
-            if postgresql? || redshift?
-              connection_model.connection.execute("SET statement_timeout = #{timeout.to_i * 1000}")
-            elsif mysql?
-              connection_model.connection.execute("SET max_execution_time = #{timeout.to_i * 1000}")
-            else
-              raise Blazer::TimeoutNotSupported, "Timeout not supported for #{adapter_name} adapter"
-            end
-          end
-
-          result = connection_model.connection.select_all("#{statement} /*#{comment}*/")
-        end
-      rescue ActiveRecord::StatementInvalid => e
-        error = e.message.sub(/.+ERROR: /, "")
-        error = Blazer::TIMEOUT_MESSAGE if Blazer::TIMEOUT_ERRORS.any? { |e| error.include?(e) }
-      end
-
+      columns, rows, error = @adapter.run_statement(statement, comment)
       duration = Time.now - start_time
 
-      if result
-        columns = result.columns
-        cast_method = Rails::VERSION::MAJOR < 5 ? :type_cast : :cast_value
-        result.rows.each do |untyped_row|
-          rows << (result.column_types.empty? ? untyped_row : columns.each_with_index.map { |c, i| untyped_row[i] ? result.column_types[c].send(cast_method, untyped_row[i]) : nil })
-        end
-      end
-
       cache_data = nil
       cache = !error && (cache_mode == "all" || (cache_mode == "slow" && duration >= cache_slow_threshold))
       if cache || run_id
@@ -276,20 +199,5 @@ module Blazer
 
       Blazer::Result.new(self, columns, rows, error, nil, cache && !cache_data.nil?)
     end
-
-    def adapter_name
-      connection_model.connection.adapter_name
-    end
-
-    def in_transaction
-      if use_transaction?
-        connection_model.transaction do
-          yield
-          raise ActiveRecord::Rollback
-        end
-      else
-        yield
-      end
-    end
   end
 end