mongo-ruby-driver/lib/mongo/db.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 'socket'
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require 'mutex_m'
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require 'mongo/collection'
require 'mongo/message'
require 'mongo/query'
require 'mongo/util/ordered_hash.rb'
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require 'mongo/admin'
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module XGen
module Mongo
module Driver
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# A Mongo database.
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class DB
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SYSTEM_NAMESPACE_COLLECTION = "system.namespaces"
SYSTEM_INDEX_COLLECTION = "system.indexes"
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SYSTEM_PROFILE_COLLECTION = "system.profile"
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SYSTEM_COMMAND_COLLECTION = "$cmd"
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# Strict mode enforces collection existence checks. When +true+,
# asking for a collection that does not exist or trying to create a
# collection that already exists raises an error.
#
# Strict mode is off (+false+) by default. Its value can be changed at
# any time.
attr_writer :strict
# Returns the value of the +strict+ flag.
def strict?; @strict; end
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# The name of the database.
attr_reader :name
# Host to which we are currently connected.
attr_reader :host
# Port to which we are currently connected.
attr_reader :port
# An array of [host, port] pairs.
attr_reader :nodes
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# The database's socket. For internal (and Cursor) use only.
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attr_reader :socket
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# db_name :: The database name
#
# nodes :: An array of [host, port] pairs.
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#
# When a DB object first connects, it tries the first node. If that
# fails, it keeps trying to connect to the remaining nodes until it
# sucessfully connects.
def initialize(db_name, nodes)
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raise "Invalid DB name" if !db_name || (db_name && db_name.length > 0 && db_name.include?("."))
@name, @nodes = db_name, nodes
@strict = false
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@semaphore = Object.new
@semaphore.extend Mutex_m
connect_to_first_available_host
end
def connect_to_first_available_host
close if @socket
@host = @port = nil
@nodes.detect { |hp|
@host, @port = *hp
begin
@socket = TCPSocket.new(@host, @port)
break if ok?(db_command(:ismaster => 1)) # success
rescue => ex
close if @socket
end
@socket
}
raise "error: failed to connect to any given host:port" unless @socket
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end
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# Returns an array of collection names. Each name is of the form
# "database_name.collection_name".
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def collection_names
names = collections_info.collect { |doc| doc['name'] || '' }
names.delete('')
names
end
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# Returns a cursor over query result hashes. Each hash contains a
# 'name' string and optionally an 'options' hash. If +coll_name+ is
# specified, an array of length 1 is returned.
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def collections_info(coll_name=nil)
selector = {}
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selector[:name] = full_coll_name(coll_name) if coll_name
query(Collection.new(self, SYSTEM_NAMESPACE_COLLECTION), Query.new(selector))
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end
# Create a collection. If +strict+ is false, will return existing or
# new collection. If +strict+ is true, will raise an error if
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# collection +name+ already exists.
#
# Options is an optional hash:
#
# :capped :: Boolean. If not specified, capped is +false+.
#
# :size :: If +capped+ is +true+, specifies the maximum number of
# bytes. If +false+, specifies the initial extent of the
# collection.
#
# :max :: Max number of records in a capped collection. Optional.
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def create_collection(name, options={})
# First check existence
if collection_names.include?(full_coll_name(name))
if strict?
raise "Collection #{name} already exists. Currently in strict mode."
else
return Collection.new(self, name)
end
end
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# Create new collection
oh = OrderedHash.new
oh[:create] = name
doc = db_command(oh.merge(options || {}))
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ok = doc['ok']
return Collection.new(self, name) if ok.kind_of?(Numeric) && (ok.to_i == 1 || ok.to_i == 0)
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raise "Error creating collection: #{doc.inspect}"
end
def admin
Admin.new(self)
end
# Return a collection. If +strict+ is false, will return existing or
# new collection. If +strict+ is true, will raise an error if
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# collection +name+ does not already exists.
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def collection(name)
return Collection.new(self, name) if collection_names.include?(full_coll_name(name))
if strict?
raise "Collection #{name} doesn't exist. Currently in strict mode."
else
create_collection(name)
end
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end
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# Drop collection +name+. Returns +true+ on success or if the
# collection does not exist, +false+ otherwise.
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def drop_collection(name)
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return true unless collection_names.include?(full_coll_name(name))
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coll = collection(name)
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coll.drop_indexes # Mongo requires that we drop indexes manually
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ok?(db_command(:drop => name))
end
# Returns true if this database is a master (or is not paired with any
# other database), false if it is a slave.
def master?
doc = db_command(:ismaster => 1)
is_master = doc['ismaster']
ok?(doc) && is_master.kind_of?(Numeric) && is_master.to_i == 1
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end
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# Returns a string of the form "host:port" that points to the master
# database. Works even if this is the master database.
def master
doc = db_command(:ismaster => 1)
is_master = doc['ismaster']
raise "Error retrieving master database" unless ok?(doc) && is_master.kind_of?(Numeric)
case is_master.to_i
when 1
"#@host:#@port"
else
doc['remote']
end
end
# Switches our socket to the master database. If we are already the
# master, no change is made.
def switch_to_master
master_str = master()
unless master_str == "#@host:#@port"
@semaphore.synchronize {
master_str =~ /(.+):(\d+)/
@host, @port = $1, $2
close()
@socket = TCPSocket.new(@host, @port)
}
end
end
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# Close the connection to the database.
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def close
@socket.close if @socket
@socket = nil
end
def connected?
@socket != nil
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end
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# Send a MsgMessage to the database.
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def send_message(msg)
send_to_db(MsgMessage.new(msg))
end
# Returns a Cursor over the query results.
#
# Note that the query gets sent lazily; the cursor calls
# #send_query_message when needed. If the caller never requests an
# object from the cursor, the query never gets sent.
def query(collection, query)
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Cursor.new(self, collection, query)
end
# Used by a Cursor to lazily send the query to the database.
def send_query_message(query_message)
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@semaphore.synchronize {
send_to_db(query_message)
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}
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end
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# Remove the records that match +selector+ from +collection_name+.
# Normally called by Collection#remove or Collection#clear.
def remove_from_db(collection_name, selector)
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@semaphore.synchronize {
send_to_db(RemoveMessage.new(@name, collection_name, selector))
}
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end
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# Update records in +collection_name+ that match +selector+ by
# applying +obj+ as an update. Normally called by Collection#replace.
def replace_in_db(collection_name, selector, obj)
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@semaphore.synchronize {
send_to_db(UpdateMessage.new(@name, collection_name, selector, obj, false))
}
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end
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# Alias for #replace_in_db. Normally called by Collection.modify.
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alias_method :modify_in_db, :replace_in_db
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# Update records in +collection_name+ that match +selector+ by
# applying +obj+ as an update. If no match, inserts (???). Normally
# called by Collection#repsert.
def repsert_in_db(collection_name, selector, obj)
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# TODO if PKInjector, inject
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@semaphore.synchronize {
send_to_db(UpdateMessage.new(@name, collection_name, selector, obj, true))
obj
}
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end
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# Return the number of records in +collection_name+ that match
# +selector+. If +selector+ is +nil+ or an empty hash, returns the
# count of all records. Normally called by Collection#count.
def count(collection_name, selector={})
oh = OrderedHash.new
oh[:count] = collection_name
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oh[:query] = selector || {}
doc = db_command(oh)
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return doc['n'].to_i if ok?(doc)
raise "Error with count command: #{doc.inspect}"
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end
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# Drop index +name+ from +collection_name+. Normally called from
# Collection#drop_index or Collection#drop_indexes.
def drop_index(collection_name, name)
oh = OrderedHash.new
oh[:deleteIndexes] = collection_name
oh[:index] = name
doc = db_command(oh)
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raise "Error with drop_index command: #{doc.inspect}" unless ok?(doc)
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end
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# Return an array of hashes, one for each index on +collection_name+.
# Normally called by Collection#index_information. Each hash contains:
#
# :name :: Index name
#
# :keys :: Hash whose keys are the names of the fields that make up
# the key and values are integers.
#
# :ns :: Namespace; same as +collection_name+.
def index_information(collection_name)
sel = {:ns => full_coll_name(collection_name)}
query(Collection.new(self, SYSTEM_INDEX_COLLECTION), Query.new(sel)).collect { |row|
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h = {:name => row['name']}
raise "Name of index on return from db was nil. Coll = #{full_coll_name(collection_name)}" unless h[:name]
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h[:keys] = row['key']
raise "Keys for index on return from db was nil. Coll = #{full_coll_name(collection_name)}" unless h[:keys]
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h[:ns] = row['ns']
raise "Namespace for index on return from db was nil. Coll = #{full_coll_name(collection_name)}" unless h[:ns]
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h[:ns].sub!(/.*\./, '')
raise "Error: ns != collection" unless h[:ns] == collection_name
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h
}
end
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# Create a new index on +collection_name+ named +index_name+. +fields+
# should be an array of field names. Normally called by
# Collection#create_index.
def create_index(collection_name, index_name, fields)
sel = {:name => index_name, :ns => full_coll_name(collection_name)}
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field_h = {}
fields.each { |f| field_h[f] = 1 }
sel[:key] = field_h
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@semaphore.synchronize {
send_to_db(InsertMessage.new(@name, SYSTEM_INDEX_COLLECTION, sel))
}
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end
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# Insert +objects+ into +collection_name+. Normally called by
# Collection#insert.
def insert_into_db(collection_name, objects)
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@semaphore.synchronize {
objects.each { |o| send_to_db(InsertMessage.new(@name, collection_name, o)) }
}
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end
def send_to_db(message)
@socket.print(message.buf.to_s)
end
def full_coll_name(collection_name)
"#{@name}.#{collection_name}"
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end
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# Return +true+ if +doc+ contains an 'ok' field with the value 1.
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def ok?(doc)
ok = doc['ok']
ok.kind_of?(Numeric) && ok.to_i == 1
end
# DB commands need to be ordered, so selector must be an OrderedHash
# (or a Hash with only one element). What DB commands really need is
# that the "command" key be first.
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#
# Do not call this. Intended for driver use only.
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def db_command(selector)
if !selector.kind_of?(OrderedHash)
if !selector.kind_of?(Hash) || selector.keys.length > 1
raise "db_command must be given an OrderedHash when there is more than one key"
end
end
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q = Query.new(selector)
q.number_to_return = 1
query(Collection.new(self, SYSTEM_COMMAND_COLLECTION), q).next_object
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end
end
end
end
end