檢查mysql連接到遠程主機

我有模型來存儲數據庫連接參數（主機，數據庫名稱，用戶名，密碼）並填寫它的形式。在創建或更新之前，我需要檢查連接是否適合輸入的參數。我創建validate :check_connection驗證：檢查mysql連接到遠程主機

# don`t change primary connection 
class Remote < ActiveRecord::Base; end 

def check_connection 
    return if errors.any? || (!new_record? && password.empty?) 
    begin 
    Remote.establish_connection(
     adapter: 'mysql2', 
     host: host, 
     username: username, 
     password: password, 
     database: database, 
     connect_timeout: 5, 
     reconnect: false 
    ) 
    # maybe need to make some sql request? did try it 
    rescue Exception => e 
    errors.add :connection, 'Could not connect to database' 
    end 
end

當我試圖進入訪問主機（localhost），像上面的代碼工作良好。但如果主機像192.168.1.1（無法訪問）頁面凍結後提交表單。我看到每秒連接的嘗試，並且它在瀏覽器（停止加載頁面）後不停止（我在網絡接口上看到tcpdump的嘗試）。並嘗試不停止。

那麼，我該如何驗證連接到數據庫？而如果連接不能建立，頁面必須不會加載很長時間。

來源

2012-08-30 Yuriy Kolodovskyy

我嘗試在軌控制檯'Mysql2 :: Client.new（主持人： '192.168.1.1'，數據庫： 'test'，用戶名：'user'，密碼：'pass'，connect_timeout：1，read_timeout：1，write_timeout：1）'並且永久嘗試連接。超時不起作用。哪裏不對？ –

我確實使用gem 'mysql2'和捆綁安裝0.3.11版本。此版本忽略connect_timeout並修正了較新版本的錯誤。在我嘗試0.3.12b4（gem 'mysql2', '~> 0.3.12b4'）之後，一切正常。

來源

2012-08-30 11:04:58

phew，一年後，0.3.12還沒有發佈還是:( – Kevin

變量connect_timeout是一個全局變量。因此，mysql2可能會忽略它。

上mysql5.6：

mysql[(none)]> set connect_timeout = 123; 
ERROR 1229 (HY000): Variable 'connect_timeout' is a GLOBAL variable and should be set with SET GLOBAL

我設置timeout變量初始化mysql2時，但它沒有體現出來。 mysql2自述文件說，你可以設置*超時選項，但我認爲自述文件已過時或損壞。

上mysql2 0.3.14（GEM）：

client = Mysql2::Client.new(
    host: 'localhost', 
    database: 'test', 
    username: 'root', 
    password: '', 
    connect_timeout: 3, 
    read_timeout: 3, 
    write_timeout: 3, 
    wait_timeout: 3); 

client.query('show variables like "%timeout%"').map{|r| [r["Variable_name"], r["Value"]] } 

=> [["connect_timeout", "10"], 
["delayed_insert_timeout", "300"], 
["innodb_lock_wait_timeout", "50"], 
["innodb_rollback_on_timeout", "OFF"], 
["interactive_timeout", "28800"], 
["lock_wait_timeout", "31536000"], 
["net_read_timeout", "30"], # Maybe older mysql has read_timeout? 
["net_write_timeout", "60"], # Maybe older mysql has write_timeout? 
["slave_net_timeout", "3600"], 
["wait_timeout", "28800"]]

如果使用ActiveRecord，您可以通過設置database.yml僅wait_timeout變量。

在database.yml中

：

development: 
    adapter: mysql2 
    encoding: utf8 
    charset: utf8 
    database: test 
    pool: 5 
    username: root 
    password: 
    host: localhost 
    connect_timeout: 3 
    read_timeout: 3 
    write_timeout: 3 
    wait_timeout: 3

的ActiveRecord 4.0.1的結果：

> ActiveRecord::Base.connection.execute('show variables like "%timeout%"').to_a 
=> [["connect_timeout", "10"], 
["delayed_insert_timeout", "300"], 
["innodb_flush_log_at_timeout", "1"], 
["innodb_lock_wait_timeout", "50"], 
["innodb_rollback_on_timeout", "OFF"], 
["interactive_timeout", "28800"], 
["lock_wait_timeout", "31536000"], 
["net_read_timeout", "30"], 
["net_write_timeout", "60"], 
["rpl_stop_slave_timeout", "31536000"], 
["slave_net_timeout", "3600"], 
["wait_timeout", "3"]]

ActiveRecord的設置wait_timeout變量abstract_mysql_adapter.rb。

看到：

abstract_mysql_adapter.rb https://github.com/rails/rails/blob/master/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

mysql2_adapter.rb https://github.com/rails/rails/blob/master/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb

來源

2014-09-13 11:52:38

檢查mysql連接到遠程主機

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