Overview

mysql-pause

Description

mysql-pause is a proxy server to pause a query to MySQL.

Dependency

  • EventMachine
  • RExec

Install

gem install mysql-pause

Example

Start server

shell> mysql-pause start
Starting daemon...
Waiting for daemon to start...
Daemon status: running pid=56921
shell> mysql -h 127.0.0.1 -P 13306 -u scott -ptiger
mysql> select 1;
+---+
| 1 |
+---+
| 1 |
+---+
1 row in set (0.00 sec)

Pause

shell> mpctl pause
mysql> select 1;
(...no response...)

Resume

shell> mpctl resume
(...resume response...)
+---+
| 1 |
+---+
| 1 |
+---+
1 row in set (18.01 sec)

Extend MySQL adapter

Install

gem install mysql-pause-adapter-ext

Example code

require 'active_record'
require 'mysql-pause/adapter-ext'

ActiveRecord::Base.establish_connection(
  :adapter   => 'mysql2',
  :host      => '127.0.0.1',
  :port      => 13306,
  :username  => 'scott',
  :password  => 'tiger',
  :database  => 'employees',
  :reconnect => true,
)

class Employee < ActiveRecord::Base; end

loop do
  employee = Employee.new
  employee.first_name = 'Taro'
  employee.last_name = 'Yamada'
  employee.save!
  sleep 3
end

Behavior

log> DEBUG -- :    (0.6ms)  BEGIN
log> DEBUG -- :   SQL (0.7ms)  INSERT INTO `employees` (`first_name`, `last_name`) VALUES ('Taro', 'Yamada')
log> DEBUG -- :    (0.8ms)  COMMIT
log> DEBUG -- :    (0.6ms)  BEGIN
shell> mpctl pause
shell> service mysql restart
shell> mpctl resume
log> DEBUG -- :    (0.6ms)  BEGIN
(...handle error and reconnect...)
log> DEBUG -- : Mysql2::Error: %MYSQL_PAUSE%;;1000;;Aborted backend connection: BEGIN
log> WARN -- : ActiveRecord::StatementInvalid: Mysql2::Error: %MYSQL_PAUSE%;;1000;;Aborted backend connection: BEGIN
log> DEBUG -- :    (0.3ms)  BEGIN
log> DEBUG -- :   SQL (2.1ms)  INSERT INTO `employees` (`first_name`, `last_name`) VALUES ('Taro', 'Yamada')
log> DEBUG -- :    (0.8ms)  COMMIT