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

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# --
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# Copyright (C) 2008-2009 10gen Inc.
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#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License, version 3, as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License
# for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
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# ++
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require 'mongo/db'
module XGen
module Mongo
module Driver
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# Represents a Mongo database server.
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class Mongo
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 either 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+.
#
# Since that's so confusing, here are a few examples:
#
# Mongo.new # localhost, DEFAULT_PORT, !slave
# Mongo.new("localhost") # localhost, DEFAULT_PORT, !slave
# Mongo.new("localhost", 3000) # localhost, 3000, slave not ok
# # localhost, 3000, slave ok
# Mongo.new("localhost", 3000, :slave_ok => true)
# # localhost, DEFAULT_PORT, auto reconnect
# Mongo.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.
# Mongo.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.
# Mongo.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 || 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
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end
# Return the XGen::Mongo::Driver::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={})
XGen::Mongo::Driver::DB.new(db_name, @pair, @options.merge(options))
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end
# Returns a hash containing database names as keys and disk space for
# each as values.
def database_info
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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
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# Not implemented.
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def clone_database(from)
raise "not implemented"
end
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# Not implemented.
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def copy_database(from_host, from_db, to_db)
raise "not implemented"
end
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# Drops the database +name+.
def drop_database(name)
single_db_command(name, :dropDatabase => 1)
end
protected
# Turns an array containing an optional host name string and an
# optional 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
connection = ['localhost', DEFAULT_PORT]
connection[0] = a[0] if a[0].kind_of?(String)
connection[0] = a[1] if a[1].kind_of?(String)
connection[1] = a[0] if a[0].kind_of?(Integer)
connection[1] = a[1] if a[1].kind_of?(Integer)
connection
end
end
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# 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)
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raise "error retrieving database info: #{doc.inspect}" unless db.ok?(doc)
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doc
ensure
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db.close if db
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end
end
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end
end
end
end