mongo-ruby-driver/lib/mongo/connection.rb

152 lines
5.2 KiB
Ruby

# --
# Copyright (C) 2008-2009 10gen Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ++
require 'mongo/db'
module Mongo
# A connection to MongoDB.
class Connection
DEFAULT_PORT = 27017
# Create a Mongo database server instance. You specify either one or a
# pair of servers. If one, you also say if connecting to a slave is
# OK. In either case, the host default is "localhost" and port default
# is DEFAULT_PORT.
#
# If you specify a pair, pair_or_host is a hash with two keys :left
# and :right. Each key maps to either
# * a server name, in which case port is DEFAULT_PORT
# * a port number, in which case server is "localhost"
# * an array containing a server name and a port number in that order
#
# +options+ are passed on to each DB instance:
#
# :slave_ok :: Only used if one host is specified. If false, when
# connecting to that host/port a DB object will check to
# see if the server is the master. If it is not, an error
# is thrown.
#
# :auto_reconnect :: If a DB connection gets closed (for example, we
# have a server pair and saw the "not master"
# error, which closes the connection), then
# automatically try to reconnect to the master or
# to the single server we have been given. Defaults
# to +false+.
# :logger :: Optional Logger instance to which driver usage information
# will be logged.
#
# Since that's so confusing, here are a few examples:
#
# Connection.new # localhost, DEFAULT_PORT, !slave
# Connection.new("localhost") # localhost, DEFAULT_PORT, !slave
# Connection.new("localhost", 3000) # localhost, 3000, slave not ok
# # localhost, 3000, slave ok
# Connection.new("localhost", 3000, :slave_ok => true)
# # localhost, DEFAULT_PORT, auto reconnect
# Connection.new(nil, nil, :auto_reconnect => true)
#
# # A pair of servers. DB will always talk to the master. On socket
# # error or "not master" error, we will auto-reconnect to the
# # current master.
# Connection.new({:left => ["db1.example.com", 3000],
# :right => "db2.example.com"}, # DEFAULT_PORT
# nil, :auto_reconnect => true)
#
# # Here, :right is localhost/DEFAULT_PORT. No auto-reconnect.
# Connection.new({:left => ["db1.example.com", 3000]})
#
# When a DB object first connects to a pair, it will find the master
# instance and connect to that one.
def initialize(pair_or_host=nil, port=nil, options={})
@pair = case pair_or_host
when String
[[pair_or_host, port ? port.to_i : DEFAULT_PORT]]
when Hash
connections = []
connections << pair_val_to_connection(pair_or_host[:left])
connections << pair_val_to_connection(pair_or_host[:right])
connections
when nil
[['localhost', DEFAULT_PORT]]
end
@options = options
end
# Return the Mongo::DB named +db_name+. The slave_ok and
# auto_reconnect options passed in via #new may be overridden here.
# See DB#new for other options you can pass in.
def db(db_name, options={})
DB.new(db_name, @pair, @options.merge(options))
end
# Returns a hash containing database names as keys and disk space for
# each as values.
def database_info
doc = single_db_command('admin', :listDatabases => 1)
h = {}
doc['databases'].each { |db|
h[db['name']] = db['sizeOnDisk'].to_i
}
h
end
# Returns an array of database names.
def database_names
database_info.keys
end
# Drops the database +name+.
def drop_database(name)
single_db_command(name, :dropDatabase => 1)
end
protected
# Turns an array containing a host name string and a
# port number integer into a [host, port] pair array.
def pair_val_to_connection(a)
case a
when nil
['localhost', DEFAULT_PORT]
when String
[a, DEFAULT_PORT]
when Integer
['localhost', a]
when Array
a
end
end
# Send cmd (a hash, possibly ordered) to the admin database and return
# the answer. Raises an error unless the return is "ok" (DB#ok?
# returns +true+).
def single_db_command(db_name, cmd)
db = nil
begin
db = db(db_name)
doc = db.db_command(cmd)
raise "error retrieving database info: #{doc.inspect}" unless db.ok?(doc)
doc
ensure
db.close if db
end
end
end
end