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

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# encoding: UTF-8
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# --
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# Copyright (C) 2008-2010 10gen Inc.
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#
# 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
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#
# http://www.apache.org/licenses/LICENSE-2.0
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#
# 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.
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# ++
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require 'set'
require 'socket'
require 'thread'
module Mongo
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# Instantiates and manages connections to MongoDB.
class Connection
TCPSocket = ::TCPSocket
Mutex = ::Mutex
ConditionVariable = ::ConditionVariable
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# Abort connections if a ConnectionError is raised.
Thread.abort_on_exception = true
DEFAULT_PORT = 27017
STANDARD_HEADER_SIZE = 16
RESPONSE_HEADER_SIZE = 20
MONGODB_URI_MATCHER = /(([-_.\w\d]+):([-_\w\d]+)@)?([-.\w\d]+)(:([\w\d]+))?(\/([-\d\w]+))?/
MONGODB_URI_SPEC = "mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/database]"
attr_reader :logger, :size, :host, :port, :nodes, :auths, :sockets, :checked_out, :primary, :secondaries, :arbiters
# Counter for generating unique request ids.
@@current_request_id = 0
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# Create a connection to MongoDB.
#
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# If connecting to just one server, you may specify whether connection to slave is permitted.
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# In all cases, the default host is "localhost" and the default port is 27017.
#
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# To specify more than one host pair to be used as seeds in a replica set
# or replica pair, use Connection.multi. If you're only specifying one node in the
# replica set, you can use Connection.new, as any other host known to the set will be
# cached.
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#
# Once connected to a replica set, you can find out which nodes are primary, secondary, and
# arbiters with the corresponding accessors: Connection#primary, Connection#secondaries, and
# Connection#arbiters. This is useful if your application needs to connect manually to nodes other
# than the primary.
#
# @param [String, Hash] host.
# @param [Integer] port specify a port number here if only one host is being specified.
#
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# @option options [Boolean] :slave_ok (false) Must be set to +true+ when connecting
# to a single, slave node.
# @option options [Logger, #debug] :logger (nil) Logger instance to receive driver operation log.
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# @option options [Integer] :pool_size (1) The maximum number of socket connections that can be
# opened to the database.
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# @option options [Float] :timeout (5.0) When all of the connections to the pool are checked out,
# this is the number of seconds to wait for a new connection to be released before throwing an exception.
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#
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# @example localhost, 27017
# Connection.new
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#
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# @example localhost, 27017
# Connection.new("localhost")
#
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# @example localhost, 3000, max 5 connections, with max 5 seconds of wait time.
# Connection.new("localhost", 3000, :pool_size => 5, :timeout => 5)
#
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# @example localhost, 3000, where this node may be a slave
# Connection.new("localhost", 3000, :slave_ok => true)
#
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# @see http://www.mongodb.org/display/DOCS/Replica+Pairs+in+Ruby Replica pairs in Ruby
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#
# @core connections
def initialize(host=nil, port=nil, options={})
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@auths = []
if block_given?
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@nodes = yield self
else
@nodes = format_pair(host, port)
end
# Host and port of current master.
@host = @port = nil
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# Lock for request ids.
@id_lock = Mutex.new
# Pool size and timeout.
@size = options[:pool_size] || 1
@timeout = options[:timeout] || 5.0
# Mutex for synchronizing pool access
@connection_mutex = Mutex.new
# Create a mutex when a new key, in this case a socket,
# is added to the hash.
@safe_mutexes = Hash.new { |h, k| h[k] = Mutex.new }
# Condition variable for signal and wait
@queue = ConditionVariable.new
@sockets = []
@checked_out = []
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# slave_ok can be true only if one node is specified
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if @nodes.length > 1 && options[:slave_ok]
raise MongoArgumentError, "Can't specify more than one node when :slave_ok is true."
else
@slave_ok = options[:slave_ok]
end
# Cache the various node types
# when connecting to a replica set.
@primary = nil
@secondaries = []
@arbiters = []
@logger = options[:logger] || nil
@options = options
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should_connect = options.fetch(:connect, true)
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connect if should_connect
end
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# Initialize a connection to a MongoDB replica set using an array of seed nodes.
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#
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# Note that, even when connecting to a replica set, you can use Connection.new specifying
# just a single node. If the replica set is up, the remaining nodes in the set will be cached
# for failover.
#
# @param nodes [Array] An array of arrays, each of which specifies a host and port.
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# @param opts Takes the same options as Connection.new
#
# @example
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# Connection.multi([["db1.example.com", 27017],
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# ["db2.example.com", 27017]])
#
# @example
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# Connection.multi([["db1.example.com", 27017], ["db2.example.com", 27017], ["db3.example.com", 27017]],
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# :pool_size => 20, :timeout => 5)
#
# @return [Mongo::Connection]
def self.multi(nodes, opts={})
unless nodes.length > 0 && nodes.all? {|n| n.is_a? Array}
raise MongoArgumentError, "Connection.multi requires at least one node to be specified."
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end
# Block returns an array, the first element being an array of nodes and the second an array
# of authorizations for the database.
new(nil, nil, opts) do |con|
nodes.map do |node|
con.pair_val_to_connection(node)
end
end
end
# Initialize a connection to MongoDB using the MongoDB URI spec:
#
# @param uri [String]
# A string of the format mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/database]
#
# @param opts Any of the options available for Connection.new
#
# @return [Mongo::Connection]
def self.from_uri(uri, opts={})
new(nil, nil, opts) do |con|
con.parse_uri(uri)
end
end
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# Fsync, then lock the mongod process against writes. Use this to get
# the datafiles in a state safe for snapshotting, backing up, etc.
#
# @return [BSON::OrderedHash] the command response
def lock!
cmd = BSON::OrderedHash.new
cmd[:fsync] = 1
cmd[:lock] = true
self['admin'].command(cmd)
end
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# Is this database locked against writes?
#
# @return [Boolean]
def locked?
self['admin']['$cmd.sys.inprog'].find_one['fsyncLock'] == 1
end
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# Unlock a previously fsync-locked mongod process.
#
# @return [BSON::OrderedHash] command response
def unlock!
self['admin']['$cmd.sys.unlock'].find_one
end
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# Apply each of the saved database authentications.
#
# @return [Boolean] returns true if authentications exist and succeeed, false
# if none exists.
#
# @raise [AuthenticationError] raises an exception if any one
# authentication fails.
def apply_saved_authentication
return false if @auths.empty?
@auths.each do |auth|
self[auth['db_name']].authenticate(auth['username'], auth['password'], false)
end
true
end
# Save an authentication to this connection. When connecting,
# the connection will attempt to re-authenticate on every db
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# specificed in the list of auths. This method is called automatically
# by DB#authenticate.
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#
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# Note: this method will not actually issue an authentication command. To do that,
# either run Connection#apply_saved_authentication or DB#authenticate.
#
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# @param [String] db_name
# @param [String] username
# @param [String] password
#
# @return [Hash] a hash representing the authentication just added.
def add_auth(db_name, username, password)
remove_auth(db_name)
auth = {}
auth['db_name'] = db_name
auth['username'] = username
auth['password'] = password
@auths << auth
auth
end
# Remove a saved authentication for this connection.
#
# @param [String] db_name
#
# @return [Boolean]
def remove_auth(db_name)
return unless @auths
if @auths.reject! { |a| a['db_name'] == db_name }
true
else
false
end
end
# Remove all authenication information stored in this connection.
#
# @return [true] this operation return true because it always succeeds.
def clear_auths
@auths = []
true
end
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# Return a hash with all database names
# and their respective sizes on disk.
#
# @return [Hash]
def database_info
doc = self['admin'].command({:listDatabases => 1})
doc['databases'].each_with_object({}) do |db, info|
info[db['name']] = db['sizeOnDisk'].to_i
end
end
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# Return an array of database names.
#
# @return [Array]
def database_names
database_info.keys
end
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# Return a database with the given name.
# See DB#new for valid options hash parameters.
#
# @param [String] db_name a valid database name.
#
# @return [Mongo::DB]
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#
# @core databases db-instance_method
def db(db_name, options={})
DB.new(db_name, self, options)
end
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# Shortcut for returning a database. Use DB#db to accept options.
#
# @param [String] db_name a valid database name.
#
# @return [Mongo::DB]
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#
# @core databases []-instance_method
def [](db_name)
DB.new(db_name, self)
end
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# Drop a database.
#
# @param [String] name name of an existing database.
def drop_database(name)
self[name].command(:dropDatabase => 1)
end
# Copy the database +from+ to +to+ on localhost. The +from+ database is
# assumed to be on localhost, but an alternate host can be specified.
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#
# @param [String] from name of the database to copy from.
# @param [String] to name of the database to copy to.
# @param [String] from_host host of the 'from' database.
# @param [String] username username for authentication against from_db (>=1.3.x).
# @param [String] password password for authentication against from_db (>=1.3.x).
def copy_database(from, to, from_host="localhost", username=nil, password=nil)
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oh = BSON::OrderedHash.new
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oh[:copydb] = 1
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oh[:fromhost] = from_host
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oh[:fromdb] = from
oh[:todb] = to
if username || password
unless username && password
raise MongoArgumentError, "Both username and password must be supplied for authentication."
end
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nonce_cmd = BSON::OrderedHash.new
nonce_cmd[:copydbgetnonce] = 1
nonce_cmd[:fromhost] = from_host
result = self["admin"].command(nonce_cmd)
oh[:nonce] = result["nonce"]
oh[:username] = username
oh[:key] = Mongo::Support.auth_key(username, password, oh[:nonce])
end
self["admin"].command(oh)
end
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# Increment and return the next available request id.
#
# return [Integer]
def get_request_id
request_id = ''
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@id_lock.synchronize do
request_id = @@current_request_id += 1
end
request_id
end
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# Get the build information for the current connection.
#
# @return [Hash]
def server_info
self["admin"].command({:buildinfo => 1})
end
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# Get the build version of the current server.
#
# @return [Mongo::ServerVersion]
# object allowing easy comparability of version.
def server_version
ServerVersion.new(server_info["version"])
end
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# Is it okay to connect to a slave?
#
# @return [Boolean]
def slave_ok?
@slave_ok
end
## Connections and pooling ##
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# Send a message to MongoDB, adding the necessary headers.
#
# @param [Integer] operation a MongoDB opcode.
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# @param [BSON::ByteBuffer] message a message to send to the database.
#
# @return [Integer] number of bytes sent
def send_message(operation, message, log_message=nil)
begin
packed_message = add_message_headers(operation, message).to_s
socket = checkout
send_message_on_socket(packed_message, socket)
ensure
checkin(socket)
end
end
# Sends a message to the database, waits for a response, and raises
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# an exception if the operation has failed.
#
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# @param [Integer] operation a MongoDB opcode.
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# @param [BSON::ByteBuffer] message a message to send to the database.
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# @param [String] db_name the name of the database. used on call to get_last_error.
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# @param [Hash] last_error_params parameters to be sent to getLastError. See DB#error for
# available options.
#
# @see DB#get_last_error for valid last error params.
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#
# @return [Array]
# An array whose indexes include [0] documents returned, [1] number of document received,
# and [3] a cursor_id.
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def send_message_with_safe_check(operation, message, db_name, log_message=nil, last_error_params=false)
message_with_headers = add_message_headers(operation, message)
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message_with_check = last_error_message(db_name, last_error_params)
begin
sock = checkout
packed_message = message_with_headers.append!(message_with_check).to_s
docs = num_received = cursor_id = ''
@safe_mutexes[sock].synchronize do
send_message_on_socket(packed_message, sock)
docs, num_received, cursor_id = receive(sock)
end
ensure
checkin(sock)
end
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if num_received == 1 && (error = docs[0]['err'] || docs[0]['errmsg'])
raise Mongo::OperationFailure, error
end
[docs, num_received, cursor_id]
end
# Sends a message to the database and waits for the response.
#
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# @param [Integer] operation a MongoDB opcode.
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# @param [BSON::ByteBuffer] message a message to send to the database.
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# @param [Socket] socket a socket to use in lieu of checking out a new one.
#
# @return [Array]
# An array whose indexes include [0] documents returned, [1] number of document received,
# and [3] a cursor_id.
def receive_message(operation, message, log_message=nil, socket=nil)
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packed_message = add_message_headers(operation, message).to_s
begin
sock = socket || checkout
result = ''
@safe_mutexes[sock].synchronize do
send_message_on_socket(packed_message, sock)
result = receive(sock)
end
ensure
checkin(sock)
end
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result
end
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# Create a new socket and attempt to connect to master.
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# If successful, sets host and port to master and returns the socket.
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#
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# If connecting to a replica set, this method will update the
# initially-provided seed list with any nodes known to the set.
#
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# @raise [ConnectionFailure] if unable to connect to any host or port.
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def connect
reset_connection
while !connected? && !(nodes_to_try = @nodes - @nodes_tried).empty?
nodes_to_try.each do |node|
config = check_is_master(node)
if is_primary?(config)
set_primary(node)
else
set_auxillary(node, config)
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end
end
end
raise ConnectionFailure, "failed to connect to any given host:port" unless connected?
end
def connected?
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@host && @port
end
# Close the connection to the database.
def close
@sockets.each do |sock|
sock.close
end
@host = @port = nil
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@sockets.clear
@checked_out.clear
end
## Configuration helper methods
# Returns an array of host-port pairs.
#
# @private
def format_pair(pair_or_host, port)
case pair_or_host
when String
[[pair_or_host, port ? port.to_i : DEFAULT_PORT]]
when nil
[['localhost', DEFAULT_PORT]]
end
end
# Convert an argument containing a host name string and a
# port number integer into a [host, port] pair array.
#
# @private
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
# Parse a MongoDB URI. This method is used by Connection.from_uri.
# Returns an array of nodes and an array of db authorizations, if applicable.
#
# @private
def parse_uri(string)
if string =~ /^mongodb:\/\//
string = string[10..-1]
else
raise MongoArgumentError, "MongoDB URI must match this spec: #{MONGODB_URI_SPEC}"
end
nodes = []
auths = []
specs = string.split(',')
specs.each do |spec|
matches = MONGODB_URI_MATCHER.match(spec)
if !matches
raise MongoArgumentError, "MongoDB URI must match this spec: #{MONGODB_URI_SPEC}"
end
uname = matches[2]
pwd = matches[3]
host = matches[4]
port = matches[6] || DEFAULT_PORT
if !(port.to_s =~ /^\d+$/)
raise MongoArgumentError, "Invalid port #{port}; port must be specified as digits."
end
port = port.to_i
db = matches[8]
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if uname && pwd && db
add_auth(db, uname, pwd)
elsif uname || pwd || db
raise MongoArgumentError, "MongoDB URI must include all three of username, password, " +
"and db if any one of these is specified."
end
nodes << [host, port]
end
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nodes
end
private
# If a ConnectionFailure is raised, this method will be called
# to close the connection and reset connection values.
def reset_connection
close
@host = nil
@port = nil
@primary = nil
@secondaries = []
@arbiters = []
@nodes_tried = []
end
# Primary is defined as either a master node or a slave if
# :slave_ok has been set to +true+.
#
# If a primary node is discovered, we set the the @host and @port and
# apply any saved authentication.
#
# TODO: use the 'primary', and 'seconday' fields if we're in a replica set
def is_primary?(config)
config && (config['ismaster'] == 1 || config['ismaster'] == true) || @slave_ok
end
def check_is_master(node)
begin
host, port = *node
socket = TCPSocket.new(host, port)
socket.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
config = self['admin'].command({:ismaster => 1}, :sock => socket)
rescue OperationFailure, SocketError, SystemCallError, IOError => ex
close
ensure
@nodes_tried << node
if config
update_node_list(config['hosts']) if config['hosts']
if @logger
@logger.warn("MONGODB #{config['msg']}") if config['msg']
end
end
socket.close if socket
end
config
end
# Set the specified node as primary, and
# apply any saved authentication credentials.
def set_primary(node)
@host, @port = *node
@primary = [@host, @port]
apply_saved_authentication
end
# Determines what kind of node we have and caches its host
# and port so that users can easily connect manually.
def set_auxillary(node, config)
if config
if config['secondary']
@secondaries << node unless @secondaries.include?(node)
elsif config['arbiterOnly']
@arbiters << node unless @arbiters.include?(node)
end
end
end
# Update the list of known nodes. Only applies to replica sets,
# where the response to the ismaster command will return a list
# of known hosts.
#
# @param hosts [Array] a list of hosts, specified as string-encoded
# host-port values. Example: ["myserver-1.org:27017", "myserver-1.org:27017"]
#
# @return [Array] the updated list of nodes
def update_node_list(hosts)
new_nodes = hosts.map do |host|
if !host.respond_to?(:split)
warn "Could not parse host #{host.inspect}."
next
end
host, port = host.split(':')
[host, port.to_i]
end
@nodes |= new_nodes
end
# Return a socket to the pool.
def checkin(socket)
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@connection_mutex.synchronize do
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@checked_out.delete(socket)
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@queue.signal
end
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true
end
# Adds a new socket to the pool and checks it out.
#
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# This method is called exclusively from #checkout;
# therefore, it runs within a mutex.
def checkout_new_socket
begin
socket = TCPSocket.new(@host, @port)
socket.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
rescue => ex
raise ConnectionFailure, "Failed to connect socket: #{ex}"
end
@sockets << socket
@checked_out << socket
socket
end
# Checks out the first available socket from the pool.
#
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# This method is called exclusively from #checkout;
# therefore, it runs within a mutex.
def checkout_existing_socket
socket = (@sockets - @checked_out).first
@checked_out << socket
socket
end
# Check out an existing socket or create a new socket if the maximum
# pool size has not been exceeded. Otherwise, wait for the next
# available socket.
def checkout
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connect if !connected?
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start_time = Time.now
loop do
if (Time.now - start_time) > @timeout
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raise ConnectionTimeoutError, "could not obtain connection within " +
"#{@timeout} seconds. The max pool size is currently #{@size}; " +
"consider increasing the pool size or timeout."
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end
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@connection_mutex.synchronize do
socket = if @checked_out.size < @sockets.size
checkout_existing_socket
elsif @sockets.size < @size
checkout_new_socket
end
return socket if socket
# Otherwise, wait
if @logger
@logger.warn "MONGODB Waiting for available connection; #{@checked_out.size} of #{@size} connections checked out."
end
@queue.wait(@connection_mutex)
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end
end
end
def receive(sock)
receive_and_discard_header(sock)
number_received, cursor_id = receive_response_header(sock)
read_documents(number_received, cursor_id, sock)
end
def receive_header(sock)
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header = BSON::ByteBuffer.new
header.put_binary(receive_message_on_socket(16, sock))
unless header.size == STANDARD_HEADER_SIZE
raise "Short read for DB response header: " +
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"expected #{STANDARD_HEADER_SIZE} bytes, saw #{header.size}"
end
header.rewind
size = header.get_int
request_id = header.get_int
response_to = header.get_int
op = header.get_int
end
def receive_and_discard_header(sock)
bytes_read = receive_and_discard_message_on_socket(16, sock)
unless bytes_read == STANDARD_HEADER_SIZE
raise "Short read for DB response header: " +
"expected #{STANDARD_HEADER_SIZE} bytes, saw #{bytes_read}"
end
nil
end
def receive_response_header(sock)
header_buf = receive_message_on_socket(RESPONSE_HEADER_SIZE, sock)
if header_buf.length != RESPONSE_HEADER_SIZE
raise "Short read for DB response header; " +
"expected #{RESPONSE_HEADER_SIZE} bytes, saw #{header_buf.length}"
end
flags, cursor_id_a, cursor_id_b, starting_from, number_remaining = header_buf.unpack('VVVVV')
check_response_flags(flags)
cursor_id = (cursor_id_b << 32) + cursor_id_a
[number_remaining, cursor_id]
end
def check_response_flags(flags)
if flags & Mongo::Constants::REPLY_CURSOR_NOT_FOUND != 0
raise Mongo::OperationFailure, "Query response returned CURSOR_NOT_FOUND. " +
"Either an invalid cursor was specified, or the cursor may have timed out on the server."
elsif flags & Mongo::Constants::REPLY_QUERY_FAILURE != 0
# Getting odd failures when a exception is raised here.
end
end
def read_documents(number_received, cursor_id, sock)
docs = []
number_remaining = number_received
while number_remaining > 0 do
buf = receive_message_on_socket(4, sock)
size = buf.unpack('V')[0]
buf << receive_message_on_socket(size - 4, sock)
number_remaining -= 1
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docs << BSON::BSON_CODER.deserialize(buf)
end
[docs, number_received, cursor_id]
end
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# Constructs a getlasterror message. This method is used exclusively by
# Connection#send_message_with_safe_check.
def last_error_message(db_name, opts)
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message = BSON::ByteBuffer.new
message.put_int(0)
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BSON::BSON_RUBY.serialize_cstr(message, "#{db_name}.$cmd")
message.put_int(0)
message.put_int(-1)
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cmd = BSON::OrderedHash.new
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cmd[:getlasterror] = 1
if opts.is_a?(Hash)
opts.assert_valid_keys(:w, :wtimeout, :fsync)
cmd.merge!(opts)
end
message.put_binary(BSON::BSON_CODER.serialize(cmd, false).to_s)
add_message_headers(Mongo::Constants::OP_QUERY, message)
end
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# Prepares a message for transmission to MongoDB by
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# constructing a valid message header.
def add_message_headers(operation, message)
headers = [
# Message size.
16 + message.size,
# Unique request id.
get_request_id,
# Response id.
0,
# Opcode.
operation
].pack('VVVV')
message.prepend!(headers)
end
# Low-level method for sending a message on a socket.
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# Requires a packed message and an available socket,
#
# @return [Integer] number of bytes sent
def send_message_on_socket(packed_message, socket)
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begin
total_bytes_sent = socket.send(packed_message, 0)
if total_bytes_sent != packed_message.size
packed_message.slice!(0, total_bytes_sent)
while packed_message.size > 0
byte_sent = socket.send(packed_message, 0)
total_bytes_sent += byte_sent
packed_message.slice!(0, byte_sent)
end
end
total_bytes_sent
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rescue => ex
close
raise ConnectionFailure, "Operation failed with the following exception: #{ex}"
end
end
# Low-level method for receiving data from socket.
# Requires length and an available socket.
def receive_message_on_socket(length, socket)
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begin
message = socket.read(length)
raise ConnectionFailure, "connection closed" unless message.length > 0
if message.length < length
chunk = new_binary_string
while message.length < length
socket.read(length - message.length, chunk)
raise ConnectionFailure, "connection closed" unless chunk.length > 0
message << chunk
end
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end
rescue => ex
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close
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raise ConnectionFailure, "Operation failed with the following exception: #{ex}"
end
message
end
# Low-level data for receiving data from socket.
# Unlike #receive_message_on_socket, this method immediately discards the data
# and only returns the number of bytes read.
def receive_and_discard_message_on_socket(length, socket)
bytes_read = 0
begin
chunk = socket.read(length)
bytes_read = chunk.length
raise ConnectionFailure, "connection closed" unless bytes_read > 0
if bytes_read < length
while bytes_read < length
socket.read(length - bytes_read, chunk)
raise ConnectionFailure, "connection closed" unless chunk.length > 0
bytes_read += chunk.length
end
end
rescue => ex
close
raise ConnectionFailure, "Operation failed with the following exception: #{ex}"
end
bytes_read
end
if defined?(Encoding)
BINARY_ENCODING = Encoding.find("binary")
def new_binary_string
"".force_encoding(BINARY_ENCODING)
end
else
def new_binary_string
""
end
end
end
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end