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

108 lines
2.8 KiB
Ruby

# --
# Copyright (C) 2008-2009 10gen Inc.
#
# 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/>.
# ++
require 'mutex_m'
require 'mongo/util/byte_buffer'
module XGen
module Mongo
module Driver
# Implementation of the Babble OID. Object ids are not required by
# Mongo, but they make certain operations more efficient.
#
# The driver does not automatically assign ids to records that are
# inserted. (An upcoming feature will allow you to give an id "factory"
# to a database and/or a collection.)
#
# 12 bytes
# ---
# 0 time
# 1
# 2
# 3
# 4 machine
# 5
# 6
# 7 pid
# 8
# 9 inc
# 10
# 11
class ObjectID
MACHINE = ( val = rand(0x1000000); [val & 0xff, (val >> 8) & 0xff, (val >> 16) & 0xff] )
PID = ( val = rand(0x10000); [val & 0xff, (val >> 8) & 0xff]; )
LOCK = Object.new
LOCK.extend Mutex_m
@@index_time = Time.new.to_i
@@index = 0
# +data+ is an array of bytes. If nil, a new id will be generated.
# The time +t+ is only used for testing; leave it nil.
def initialize(data=nil, t=nil)
@data = data || generate_id(t)
end
def eql?(other)
@data == other.to_a
end
alias_method :==, :eql?
def to_a
@data.dup
end
def to_s
@data.collect { |b| '%02x' % b }.join
end
# (Would normally be private, but isn't so we can test it.)
def generate_id(t=nil)
t ||= Time.new.to_i
buf = ByteBuffer.new
buf.put_int(t & 0xffffffff)
buf.put_array(MACHINE)
buf.put_array(PID)
i = index_for_time(t)
buf.put(i & 0xff)
buf.put((i >> 8) & 0xff)
buf.put((i >> 16) & 0xff)
buf.rewind
buf.to_a.dup
end
# (Would normally be private, but isn't so we can test it.)
def index_for_time(t)
LOCK.mu_synchronize {
if t != @@index_time
@@index = 0
@@index_time = t
end
retval = @@index
@@index += 1
retval
}
end
end
end
end
end