Class: ActiveRecord::ConnectionAdapters::ConnectionHandler

### Home Classes Methods

### In Files

- lib/active_record/connection_adapters/abstract/connection_pool.rb

### Parent

Object

### Methods

- ::new
- #active_connections?
- #clear_active_connections!
- #clear_all_connections!
- #clear_reloadable_connections!
- #connected?
- #establish_connection
- #remove_connection
- #retrieve_connection_pool

### Files

- README.rdoc

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# ActiveRecord::ConnectionAdapters::ConnectionHandler

ConnectionHandler is a collection of ConnectionPool objects. It is used for keeping separate connection pools for Active Record models that connect to different databases.

For example, suppose that you have 5 models, with the following hierarchy:

    |
    +-- Book
    |    |
    |    +-- ScaryBook
    |    +-- GoodBook
    +-- Author
    +-- BankAccount

Suppose that Book is to connect to a separate database (i.e. one other than the default database). Then Book, ScaryBook and GoodBook will all use the same connection pool. Likewise, Author and BankAccount will use the same connection pool. However, the connection pool used by Author/BankAccount is not the same as the one used by Book/ScaryBook/GoodBook.

Normally there is only a single ConnectionHandler instance, accessible via ActiveRecord::Base.connection_handler. Active Record models use this to determine that connection pool that they should use.

### Attributes

connection_pools[R]

### Public Class Methods

new(pools = {}) click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_pool.rb, line 369
    def initialize(pools = {})
      @connection_pools = pools
      @class_to_pool    = {}
    end

### Public Instance Methods

active_connections?() click to toggle source

Returns true if there are any active connections among the connection pools that the ConnectionHandler is managing.

    # File lib/active_record/connection_adapters/abstract/connection_pool.rb, line 381
    def active_connections?
      connection_pools.values.any? { |pool| pool.active_connection? }
    end

clear_active_connections!() click to toggle source

Returns any connections in use by the current thread back to the pool.

    # File lib/active_record/connection_adapters/abstract/connection_pool.rb, line 386
    def clear_active_connections!
      @connection_pools.each_value {|pool| pool.release_connection }
    end

clear_all_connections!() click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_pool.rb, line 395
    def clear_all_connections!
      @connection_pools.each_value {|pool| pool.disconnect! }
    end

clear_reloadable_connections!() click to toggle source

Clears the cache which maps classes.

    # File lib/active_record/connection_adapters/abstract/connection_pool.rb, line 391
    def clear_reloadable_connections!
      @connection_pools.each_value {|pool| pool.clear_reloadable_connections! }
    end

connected?(klass) click to toggle source

Returns true if a connection that's accessible to this class has already been opened.

    # File lib/active_record/connection_adapters/abstract/connection_pool.rb, line 415
    def connected?(klass)
      conn = retrieve_connection_pool(klass)
      conn && conn.connected?
    end

establish_connection(name, spec) click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_pool.rb, line 374
    def establish_connection(name, spec)
      @connection_pools[spec] ||= ConnectionAdapters::ConnectionPool.new(spec)
      @class_to_pool[name] = @connection_pools[spec]
    end

remove_connection(klass) click to toggle source

Remove the connection for this class. This will close the active connection and the defined connection (if they exist). The result can be used as an argument for establish_connection, for easily re-establishing the connection.

    # File lib/active_record/connection_adapters/abstract/connection_pool.rb, line 424
    def remove_connection(klass)
      pool = @class_to_pool.delete(klass.name)
      return nil unless pool

      @connection_pools.delete pool.spec
      pool.automatic_reconnect = false
      pool.disconnect!
      pool.spec.config
    end

retrieve_connection_pool(klass) click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_pool.rb, line 434
    def retrieve_connection_pool(klass)
      pool = @class_to_pool[klass.name]
      return pool if pool
      return nil if ActiveRecord::Base == klass
      retrieve_connection_pool klass.superclass
    end

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