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require 'set'
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
# Check for activity after at least +verification_timeout+ seconds.
# Defaults to 0 (always check.)
cattr_accessor :verification_timeout, :instance_writer => false
@@verification_timeout = 0
# The class -> [adapter_method, config] map
@@defined_connections = {}
# The class -> thread id -> adapter cache. (class -> adapter if not allow_concurrency)
@@active_connections = {}
class << self
# Retrieve the connection cache.
def thread_safe_active_connections #:nodoc:
@@active_connections[Thread.current.object_id] ||= {}
end
def single_threaded_active_connections #:nodoc:
@@active_connections
end
# pick up the right active_connection method from @@allow_concurrency
if @@allow_concurrency
alias_method :active_connections, :thread_safe_active_connections
else
alias_method :active_connections, :single_threaded_active_connections
end
# set concurrency support flag (not thread safe, like most of the methods in this file)
def allow_concurrency=(threaded) #:nodoc:
logger.debug "allow_concurrency=#{threaded}" if logger
return if @@allow_concurrency == threaded
clear_all_cached_connections!
@@allow_concurrency = threaded
method_prefix = threaded ? "thread_safe" : "single_threaded"
sing = (class << self; self; end)
[:active_connections, :scoped_methods].each do |method|
sing.send(:alias_method, method, "#{method_prefix}_#{method}")
end
log_connections if logger
end
def active_connection_name #:nodoc:
@active_connection_name ||=
if active_connections[name] || @@defined_connections[name]
name
elsif self == ActiveRecord::Base
nil
else
superclass.active_connection_name
end
end
def clear_active_connection_name #:nodoc:
@active_connection_name = nil
subclasses.each { |klass| klass.clear_active_connection_name }
end
# 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 connection
if defined?(@active_connection_name) && (conn = active_connections[@active_connection_name])
conn
else
# retrieve_connection sets the cache key.
conn = retrieve_connection
active_connections[@active_connection_name] = conn
end
end
# Clears the cache which maps classes to connections.
def clear_active_connections!
clear_cache!(@@active_connections) do |name, conn|
conn.disconnect!
end
end
# Clears the cache which maps classes
def clear_reloadable_connections!
if @@allow_concurrency
# With concurrent connections @@active_connections is
# a hash keyed by thread id.
@@active_connections.each do |thread_id, conns|
conns.each do |name, conn|
if conn.requires_reloading?
conn.disconnect!
@@active_connections[thread_id].delete(name)
end
end
end
else
@@active_connections.each do |name, conn|
if conn.requires_reloading?
conn.disconnect!
@@active_connections.delete(name)
end
end
end
end
# Verify active connections.
def verify_active_connections! #:nodoc:
if @@allow_concurrency
remove_stale_cached_threads!(@@active_connections) do |name, conn|
conn.disconnect!
end
end
active_connections.each_value do |connection|
connection.verify!(@@verification_timeout)
end
end
private
def clear_cache!(cache, thread_id = nil, &block)
if cache
if @@allow_concurrency
thread_id ||= Thread.current.object_id
thread_cache, cache = cache, cache[thread_id]
return unless cache
end
cache.each(&block) if block_given?
cache.clear
end
ensure
if thread_cache && @@allow_concurrency
thread_cache.delete(thread_id)
end
end
# Remove stale threads from the cache.
def remove_stale_cached_threads!(cache, &block)
stale = Set.new(cache.keys)
Thread.list.each do |thread|
stale.delete(thread.object_id) if thread.alive?
end
stale.each do |thread_id|
clear_cache!(cache, thread_id, &block)
end
end
def clear_all_cached_connections!
if @@allow_concurrency
@@active_connections.each_value do |connection_hash_for_thread|
connection_hash_for_thread.each_value {|conn| conn.disconnect! }
connection_hash_for_thread.clear
end
else
@@active_connections.each_value {|conn| conn.disconnect! }
end
@@active_connections.clear
end
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 <tt>:adapter</tt> 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
clear_active_connection_name
@active_connection_name = name
@@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
begin
require 'rubygems'
gem "activerecord-#{spec[:adapter]}-adapter"
require "active_record/connection_adapters/#{spec[:adapter]}_adapter"
rescue LoadError
begin
require "active_record/connection_adapters/#{spec[:adapter]}_adapter"
rescue LoadError
raise "Please install the #{spec[:adapter]} adapter: `gem install activerecord-#{spec[:adapter]}-adapter` (#{$!})"
end
end
adapter_method = "#{spec[:adapter]}_connection"
if !respond_to?(adapter_method)
raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter"
end
remove_connection
establish_connection(ConnectionSpecification.new(spec, adapter_method))
end
end
# Locate the connection of the nearest super class. This can be an
# active or defined connection: 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:
# Name is nil if establish_connection hasn't been called for
# some class along the inheritance chain up to AR::Base yet.
if name = active_connection_name
if conn = active_connections[name]
# Verify the connection.
conn.verify!(@@verification_timeout)
elsif spec = @@defined_connections[name]
# Activate this connection specification.
klass = name.constantize
klass.connection = spec
conn = active_connections[name]
end
end
conn or raise ConnectionNotEstablished
end
# Returns true if a connection that's accessible to this class has already been opened.
def self.connected?
active_connections[active_connection_name] ? true : 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 an argument for establish_connection, for easily
# re-establishing the connection.
def self.remove_connection(klass=self)
spec = @@defined_connections[klass.name]
konn = active_connections[klass.name]
@@defined_connections.delete_if { |key, value| value == spec }
active_connections.delete_if { |key, value| value == konn }
konn.disconnect! if konn
spec.config if spec
end
# Set the connection for the class.
def self.connection=(spec) #:nodoc:
if spec.kind_of?(ActiveRecord::ConnectionAdapters::AbstractAdapter)
active_connections[name] = spec
elsif spec.kind_of?(ConnectionSpecification)
config = spec.config.reverse_merge(:allow_concurrency => @@allow_concurrency)
self.connection = self.send(spec.adapter_method, config)
elsif spec.nil?
raise ConnectionNotEstablished
else
establish_connection spec
end
end
# connection state logging
def self.log_connections #:nodoc:
if logger
logger.info "Defined connections: #{@@defined_connections.inspect}"
logger.info "Active connections: #{active_connections.inspect}"
logger.info "Active connection name: #{@active_connection_name}"
end
end
end
end
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