Merge pull request sogou#402 from Barenboim/master

add MySQL SSL client

docs/en/tutorial-12-mysql_cli.md

@@ -16,6 +16,8 @@ After startup, you can directly enter MySQL command in the terminal to interact
 
 mysql://username:password@host:port/dbname?character\_set=charset&character\_set\_results=charset
 
+- set scheme to be **mysqls://** for accessing MySQL with SSL connnection (MySQL server 5.7 or above is required).
+
 - fill in the username and the password for the MySQL database;
 
 - the default port number is 3306;
@@ -34,6 +36,8 @@ mysql://root:password@127.0.0.1
 
 mysql://@test.mysql.com:3306/db1?character\_set=utf8&character_set_results=utf8
 
+mysqls://localhost/db1?character\_set=big5
+
 # Creating and starting a MySQL task
 
 You can use WFTaskFactory to create a MySQL task. The usage of creating interface and callback functions are similar to other tasks in workflow:

docs/tutorial-12-mysql_cli.md

@@ -15,6 +15,8 @@
 
 mysql://username:password@host:port/dbname?character_set=charset&character_set_results=charset
 
+- 如果以SSL连接访问MySQL，则scheme设为**mysqls://**。MySQL server 5.7及以上支持；
+
 - username和password按需填写；
 
 - port默认为3306；
@@ -33,6 +35,8 @@ mysql://root:password@127.0.0.1
 
 mysql://@test.mysql.com:3306/db1?character_set=utf8&character_set_results=utf8
 
+mysqls://localhost/db1?character\_set=big5
+
 # 创建并启动MySQL任务
 
 用户可以使用WFTaskFactory创建MySQL任务，创建接口与回调函数的用法都与workflow其他任务类似:

src/factory/HttpTaskImpl.cc

@@ -551,10 +551,7 @@ CommMessageOut *ComplexHttpProxyTask::message_out()
 	}
 
 	auto *msg = (ProtocolMessage *)this->ComplexHttpTask::message_out();
-	if (is_ssl_)
-		return get_ssl_wrapper(msg);
-
-	return msg;
+	return is_ssl_ ? get_ssl_wrapper(msg) : msg;
 }
 
 CommMessageIn *ComplexHttpProxyTask::message_in()