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module ActiveRecord
class Base
class ConnectionSpecification #:nodoc:
attr_reader :config, :adapter_method
def initialize (config, adapter_method)
@config, @adapter_method = config, adapter_method
end
end
# The class -> [adapter_method, config] map
@@defined_connections = {}
# The class -> thread id -> adapter cache.
@@connection_cache = Hash.new { |h, k| h[k] = Hash.new }
# Returns the connection currently associated with the class. This can
# also be used to "borrow" the connection to do database work unrelated
# to any of the specific Active Records.
def self.connection
@@connection_cache[Thread.current.object_id][name] ||= retrieve_connection
end
# Clears the cache which maps classes to connections.
def self.clear_connection_cache!
@@connection_cache.clear
end
# Returns the connection currently associated with the class. This can
# also be used to "borrow" the connection to do database work that isn't
# easily done without going straight to SQL.
def connection
self.class.connection
end
# Establishes the connection to the database. Accepts a hash as input where
# the :adapter key must be specified with the name of a database adapter (in lower-case)
# example for regular databases (MySQL, Postgresql, etc):
#
# ActiveRecord::Base.establish_connection(
# :adapter => "mysql",
# :host => "localhost",
# :username => "myuser",
# :password => "mypass",
# :database => "somedatabase"
# )
#
# Example for SQLite database:
#
# ActiveRecord::Base.establish_connection(
# :adapter => "sqlite",
# :database => "path/to/dbfile"
# )
#
# Also accepts keys as strings (for parsing from yaml for example):
# ActiveRecord::Base.establish_connection(
# "adapter" => "sqlite",
# "database" => "path/to/dbfile"
# )
#
# The exceptions AdapterNotSpecified, AdapterNotFound and ArgumentError
# may be returned on an error.
def self.establish_connection(spec = nil)
case spec
when nil
raise AdapterNotSpecified unless defined? RAILS_ENV
establish_connection(RAILS_ENV)
when ConnectionSpecification
@@defined_connections[name] = spec
when Symbol, String
if configuration = configurations[spec.to_s]
establish_connection(configuration)
else
raise AdapterNotSpecified, "#{spec} database is not configured"
end
else
spec = spec.symbolize_keys
unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end
adapter_method = "#{spec[:adapter]}_connection"
unless respond_to?(adapter_method) then raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter" end
remove_connection
establish_connection(ConnectionSpecification.new(spec, adapter_method))
end
end
def self.active_connections #:nodoc:
if allow_concurrency
Thread.current['active_connections'] ||= {}
else
@@active_connections ||= {}
end
end
# Locate the connection of the nearest super class. This can be an
# active or defined connections: if it is the latter, it will be
# opened and set as the active connection for the class it was defined
# for (not necessarily the current class).
def self.retrieve_connection #:nodoc:
klass = self
ar_super = ActiveRecord::Base.superclass
until klass == ar_super
if conn = active_connections[klass.name]
# Reconnect if the connection is inactive.
conn.reconnect! unless conn.active?
return conn
elsif conn = @@defined_connections[klass.name]
# Activate this connection specification.
klass.connection = conn
return self.connection
end
klass = klass.superclass
end
raise ConnectionNotEstablished
end
# Returns true if a connection that's accessible to this class have already been opened.
def self.connected?
klass = self
until klass == ActiveRecord::Base.superclass
if active_connections[klass.name]
return true
else
klass = klass.superclass
end
end
return false
end
# 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 argument for establish_connection, for easy
# re-establishing of the connection.
def self.remove_connection(klass=self)
conn = @@defined_connections[klass.name]
@@defined_connections.delete(klass.name)
@@connection_cache[Thread.current.object_id].delete(klass.name)
active_connections.delete(klass.name)
@connection = nil
conn.config if conn
end
# Set the connection for the class.
def self.connection=(spec)
if spec.kind_of?(ActiveRecord::ConnectionAdapters::AbstractAdapter)
active_connections[name] = spec
elsif spec.kind_of?(ConnectionSpecification)
self.connection = self.send(spec.adapter_method, spec.config)
elsif spec.nil?
raise ConnectionNotEstablished
else
establish_connection spec
end
end
end
end
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