# EbisuConnection
[](http://badge.fury.io/rb/ebisu_connection) [](https://travis-ci.org/tsukasaoishi/ebisu_connection) [](https://codeclimate.com/github/tsukasaoishi/ebisu_connection)
EbisuConnection supports to connect with Mysql slave servers. It doesn't need Load Balancer.
You can assign a performance weight to each slave server. And slave config is reflected dynamic.
EbisuConnection uses FreshConnection (https://github.com/tsukasaoishi/fresh_connection).
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'ebisu_connection'
```
And then execute:
```
$ bundle
```
Or install it yourself as:
```
$ gem install ebisu_connection
```
## Config
config/database.yml
```yaml
production:
adapter: mysql2
encoding: utf8
reconnect: true
database: kaeru
pool: 5
username: master
password: master
host: localhost
socket: /var/run/mysqld/mysqld.sock
slave:
username: slave
password: slave
host: slave
```
```slave``` is base config to connect to slave servers.
Others will use the master setting. If you want to change, write in the slave.
Config of each slave server fill out config/slave.yaml
```yaml
production:
- "slave1, 10"
- "slave2, 20"
-
host: "slave3"
weight: 30
```
config/slave.yaml is checked by end of action. If config changed, it's reflected dynamic. Application doesn't need restart.
```yaml
"hostname, weight"
```
String format is it. You can write config with hash.
### use multiple slave servers group
If you may want to user multiple slave group, write multiple slave group to config/database.yml.
```yaml
production:
adapter: mysql2
encoding: utf8
reconnect: true
database: kaeru
pool: 5
username: master
password: master
host: localhost
socket: /var/run/mysqld/mysqld.sock
slave:
username: slave
password: slave
host: slave
admin_slave:
username: slave
password: slave
host: admin_slaves
```
Config of each slave server fill out config/slave.yaml
```yaml
production:
slave:
- "slave1, 10"
- "slave2, 20"
-
host: "slave3"
weight: 30
admin_slave:
- "slave3, 10"
- "slave4, 20"
```
And call establish_fresh_connection method in model that access to ```admin_slave``` slave group.
```ruby
class AdminUser < ActiveRecord::Base
establish_fresh_connection :admin_slave
end
```
The children is access to same slave group of parent.
```ruby
class Parent < ActiveRecord::Base
establish_fresh_connection :admin_slave
end
class AdminUser < Parent
end
class Benefit < Parent
end
```
AdminUser and Benefit access to ```admin_slave``` slave group.
### Declare model that doesn't use slave db
```ruby
class SomethingModel < ActiveRecord::Base
master_db_only!
end
```
If model that always access to master servers is exist, You may want to write ```master_db_only!``` in model.
The model that master_db_only model's child is always access to master db.
## Usage
Read query will be access to slave server.
```ruby
Article.where(:id => 1)
Article.count
```
If you want to access to the master server, use read_master.
```ruby
Article.where(:id => 1).read_master
```
It is possible to use readonly(false) instead of read_master, but it will be depricated at future version.
In transaction, Always will be access to master server.
```ruby
Article.transaction do
Article.where(:id => 1)
end
```
### for Unicorn
```ruby
before_fork do |server, worker|
...
ActiveRecord::Base.clear_all_slave_connections!
...
end
after_fork do |server, worker|
...
ActiveRecord::Base.establish_fresh_connection
...
end
```
## Contributing
1. Fork it
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Commit your changes (`git commit -am 'Add some feature'`)
4. Push to the branch (`git push origin my-new-feature`)
5. Create new Pull Request
## Test
I'm glad that you would do test!
To run the test suite, you need mysql installed.
How to setup your test environment.
```bash
bundle install --path .bundle
bundle exec appraisal install
```
This command run the spec suite for all rails versions supported.
```base
bundle exec appraisal rake test
```