Merge pull request QueueClassic#29 from jasoncodes/transaction

Add `transaction` helper method for batch queueing.

lib/queue_classic/database.rb

@@ -54,6 +54,21 @@ def wait_for_notify(t)
       log("done waiting for notify")
     end
 
+    def transaction
+      begin
+        execute 'BEGIN'
+        yield
+        execute 'COMMIT'
+      rescue Exception
+        execute 'ROLLBACK'
+        raise
+      end
+    end
+
+    def transaction_idle?
+      connection.transaction_status == PGconn::PQTRANS_IDLE
+    end
+
     def execute(sql, *params)
       log("executing #{sql.inspect}, #{params.inspect}")
       begin

test/database_test.rb

@@ -41,4 +41,33 @@
     assert_equal [{"a"=>"123", "b"=>"456", "c"=>"579"}], result.to_a
   end
 
+  def job_count
+    @database.execute('SELECT COUNT(*) FROM queue_classic_jobs')[0].values.first.to_i
+  end
+
+  test "transaction should commit" do
+    assert_equal true, @database.transaction_idle?
+    assert_equal 0, job_count
+    @database.transaction do
+      assert_equal false, @database.transaction_idle?
+      assert_equal 0, job_count
+      @database.execute "INSERT INTO queue_classic_jobs (details) VALUES ('test');"
+      assert_equal false, @database.transaction_idle?
+      assert_equal 1, job_count
+    end
+    assert_equal true, @database.transaction_idle?
+    assert_equal 1, job_count
+  end
+
+  test "transaction should rollback if there's an error" do
+    assert_raises RuntimeError do
+      @database.transaction do
+        @database.execute "INSERT INTO queue_classic_jobs (details) VALUES ('test');"
+        assert_equal 1, job_count
+        raise "force rollback"
+      end
+    end
+    assert_equal 0, job_count
+  end
+
 end