556 lines
18 KiB
Ruby
556 lines
18 KiB
Ruby
# --
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# Copyright (C) 2008-2009 10gen Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ++
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require 'set'
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require 'socket'
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require 'thread'
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module Mongo
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# Instantiates and manages connections to MongoDB.
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class Connection
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# Abort connections if a ConnectionError is raised.
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Thread.abort_on_exception = true
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DEFAULT_PORT = 27017
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STANDARD_HEADER_SIZE = 16
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RESPONSE_HEADER_SIZE = 20
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attr_reader :logger, :size, :host, :port, :nodes, :sockets, :checked_out
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# Counter for generating unique request ids.
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@@current_request_id = 0
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# Create a connection to MongoDB. Specify either one or a pair of servers,
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# along with a maximum connection pool size and timeout.
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#
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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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#
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# When specifying a pair, +pair_or_host+, is a hash with two keys: :left and :right. Each key maps to either
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# * a server name, in which case port is 27017,
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# * a port number, in which case the server is "localhost", or
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# * an array containing [server_name, port_number]
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#
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# Note that there are a few issues when using connection pooling with Ruby 1.9 on Windows. These
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# should be resolved in the next release.
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#
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# @param [String, Hash] pair_or_host See explanation above.
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# @param [Integer] port specify a port number here if only one host is being specified. Leave nil if
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# specifying a pair of servers in +pair_or_host+.
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#
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# @option options [Boolean] :slave_ok (false) Must be set to +true+ when connecting
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# to a single, slave node.
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# @option options [Logger, #debug] :logger (nil) Logger instance to receive driver operation log.
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# @option options [Boolean] :auto_reconnect DEPRECATED. See http://www.mongodb.org/display/DOCS/Replica+Pairs+in+Ruby
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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,
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# 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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#
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# @example localhost, 27017
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# Connection.new
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#
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# @example localhost, 27017
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# Connection.new("localhost")
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#
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# @example localhost, 3000, max 5 connections, with max 5 seconds of wait time.
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# Connection.new("localhost", 3000, :pool_size => 5, :timeout => 5)
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#
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# @example localhost, 3000, where this node may be a slave
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# Connection.new("localhost", 3000, :slave_ok => true)
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#
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# @example A pair of servers. The driver will always talk to master.
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# # On connection errors, Mongo::ConnectionFailure will be raised.
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# Connection.new({:left => ["db1.example.com", 27017],
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# :right => ["db2.example.com", 27017]})
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#
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# @example A pair of servers with connection pooling enabled. Note the nil param placeholder for port.
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# Connection.new({:left => ["db1.example.com", 27017],
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# :right => ["db2.example.com", 27017]}, nil,
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# :pool_size => 20, :timeout => 5)
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#
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# @see http://www.mongodb.org/display/DOCS/Replica+Pairs+in+Ruby Replica pairs in Ruby
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def initialize(pair_or_host=nil, port=nil, options={})
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@nodes = format_pair(pair_or_host, port)
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# Host and port of current master.
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@host = @port = nil
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# Lock for request ids.
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@id_lock = Mutex.new
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# Pool size and timeout.
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@size = options[:pool_size] || 1
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@timeout = options[:timeout] || 5.0
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# Mutex for synchronizing pool access
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@connection_mutex = Mutex.new
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@safe_mutex = Mutex.new
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# Condition variable for signal and wait
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@queue = ConditionVariable.new
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@sockets = []
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@checked_out = []
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if options[:auto_reconnect]
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warn(":auto_reconnect is deprecated. see http://www.mongodb.org/display/DOCS/Replica+Pairs+in+Ruby")
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end
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# slave_ok can be true only if one node is specified
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@slave_ok = options[:slave_ok] && @nodes.length == 1
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@logger = options[:logger] || nil
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@options = options
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should_connect = options[:connect].nil? ? true : options[:connect]
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connect_to_master if should_connect
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end
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# Return a hash with all database names
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# and their respective sizes on disk.
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#
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# @return [Hash]
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def database_info
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doc = self['admin'].command(:listDatabases => 1)
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returning({}) do |info|
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doc['databases'].each { |db| info[db['name']] = db['sizeOnDisk'].to_i }
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end
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end
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# Return an array of database names.
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#
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# @return [Array]
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def database_names
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database_info.keys
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end
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# Return a database with the given name.
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# See DB#new for valid options hash parameters.
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#
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# @param [String] db_name a valid database name.
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#
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# @return [Mongo::DB]
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def db(db_name, options={})
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DB.new(db_name, self, options.merge(:logger => @logger))
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end
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# Shortcut for returning a database. Use DB#db to accept options.
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#
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# @param [String] db_name a valid database name.
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#
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# @return [Mongo::DB]
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def [](db_name)
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DB.new(db_name, self, :logger => @logger)
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end
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# Drop a database.
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#
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# @param [String] name name of an existing database.
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def drop_database(name)
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self[name].command(:dropDatabase => 1)
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end
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# Copy the database +from+ on the local server to +to+ on the specified +host+.
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# +host+ defaults to 'localhost' if no value is provided.
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#
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# @param [String] from name of the database to copy from.
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# @param [String] to name of the database to copy to.
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# @param [String] from_host host of the 'from' database.
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def copy_database(from, to, from_host="localhost")
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oh = OrderedHash.new
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oh[:copydb] = 1
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oh[:fromhost] = from_host
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oh[:fromdb] = from
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oh[:todb] = to
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self["admin"].command(oh)
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end
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# Increment and return the next available request id.
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#
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# return [Integer]
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def get_request_id
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request_id = ''
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@id_lock.synchronize do
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request_id = @@current_request_id += 1
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end
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request_id
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end
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# Get the build information for the current connection.
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#
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# @return [Hash]
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def server_info
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db("admin").command({:buildinfo => 1}, {:admin => true, :check_response => true})
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end
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# Get the build version of the current server.
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#
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# @return [Mongo::ServerVersion]
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# object allowing easy comparability of version.
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def server_version
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ServerVersion.new(server_info["version"])
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end
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# Is it okay to connect to a slave?
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#
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# @return [Boolean]
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def slave_ok?
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@slave_ok
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end
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## Connections and pooling ##
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# Send a message to MongoDB, adding the necessary headers.
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#
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# @param [Integer] operation a MongoDB opcode.
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# @param [ByteBuffer] message a message to send to the database.
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# @param [String] log_message text version of +message+ for logging.
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#
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# @return [True]
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def send_message(operation, message, log_message=nil)
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@logger.debug(" MONGODB #{log_message || message}") if @logger
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begin
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packed_message = add_message_headers(operation, message).to_s
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socket = checkout
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send_message_on_socket(packed_message, socket)
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ensure
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checkin(socket)
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end
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end
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# 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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#
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# @param [Integer] operation a MongoDB opcode.
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# @param [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 [String] log_message text version of +message+ for logging.
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#
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# @return [Array]
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# An array whose indexes include [0] documents returned, [1] number of document received,
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# and [3] a cursor_id.
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def send_message_with_safe_check(operation, message, db_name, log_message=nil)
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message_with_headers = add_message_headers(operation, message)
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message_with_check = last_error_message(db_name)
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@logger.debug(" MONGODB #{log_message || message}") if @logger
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begin
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sock = checkout
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packed_message = message_with_headers.append!(message_with_check).to_s
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docs = num_received = cursor_id = ''
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@safe_mutex.synchronize do
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send_message_on_socket(packed_message, sock)
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docs, num_received, cursor_id = receive(sock)
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end
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ensure
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checkin(sock)
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end
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if num_received == 1 && error = docs[0]['err']
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raise Mongo::OperationFailure, error
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end
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[docs, num_received, cursor_id]
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end
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# Sends a message to the database and waits for the response.
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#
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# @param [Integer] operation a MongoDB opcode.
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# @param [ByteBuffer] message a message to send to the database.
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# @param [String] log_message text version of +message+ for logging.
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# @param [Socket] socket a socket to use in lieu of checking out a new one.
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#
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# @return [Array]
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# An array whose indexes include [0] documents returned, [1] number of document received,
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# and [3] a cursor_id.
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def receive_message(operation, message, log_message=nil, socket=nil)
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packed_message = add_message_headers(operation, message).to_s
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@logger.debug(" MONGODB #{log_message || message}") if @logger
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begin
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sock = socket || checkout
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result = ''
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@safe_mutex.synchronize do
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send_message_on_socket(packed_message, sock)
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result = receive(sock)
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end
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ensure
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checkin(sock)
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end
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result
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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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# @raise [ConnectionFailure] if unable to connect to any host or port.
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def connect_to_master
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close
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@host = @port = nil
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for node_pair in @nodes
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host, port = *node_pair
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begin
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socket = TCPSocket.new(host, port)
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socket.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
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# If we're connected to master, set the @host and @port
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result = self['admin'].command({:ismaster => 1}, false, false, socket)
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if result['ok'] == 1 && ((is_master = result['ismaster'] == 1) || @slave_ok)
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@host, @port = host, port
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end
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# Note: slave_ok can be true only when connecting to a single node.
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if @nodes.length == 1 && !is_master && !@slave_ok
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raise ConfigurationError, "Trying to connect directly to slave; " +
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"if this is what you want, specify :slave_ok => true."
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end
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break if is_master || @slave_ok
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rescue SocketError, SystemCallError, IOError => ex
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socket.close if socket
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false
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end
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end
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raise ConnectionFailure, "failed to connect to any given host:port" unless socket
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end
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# Are we connected to MongoDB? This is determined by checking whether
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# host and port have values, since they're set to nil on calls to #close.
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def connected?
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@host && @port
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end
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# Close the connection to the database.
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def close
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@sockets.each do |sock|
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sock.close
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end
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@host = @port = nil
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@sockets.clear
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@checked_out.clear
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end
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private
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# Return a socket to the pool.
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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
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end
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true
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end
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# Adds a new socket to the pool and checks it out.
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#
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# This method is called exclusively from #checkout;
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# therefore, it runs within a mutex.
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def checkout_new_socket
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begin
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socket = TCPSocket.new(@host, @port)
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socket.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
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rescue => ex
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raise ConnectionFailure, "Failed to connect socket: #{ex}"
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end
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@sockets << socket
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@checked_out << socket
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socket
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end
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# Checks out the first available socket from the pool.
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#
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# This method is called exclusively from #checkout;
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# therefore, it runs within a mutex.
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def checkout_existing_socket
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socket = (@sockets - @checked_out).first
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@checked_out << socket
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socket
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end
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# Check out an existing socket or create a new socket if the maximum
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# pool size has not been exceeded. Otherwise, wait for the next
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# available socket.
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def checkout
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connect_to_master if !connected?
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start_time = Time.now
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loop do
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if (Time.now - start_time) > @timeout
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raise ConnectionTimeoutError, "could not obtain connection within " +
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"#{@timeout} seconds. The max pool size is currently #{@size}; " +
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"consider increasing the pool size or timeout."
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end
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@connection_mutex.synchronize do
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socket = if @checked_out.size < @sockets.size
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checkout_existing_socket
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elsif @sockets.size < @size
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checkout_new_socket
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end
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return socket if socket
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# Otherwise, wait
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if @logger
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@logger.warn "Waiting for available connection; #{@checked_out.size} of #{@size} connections checked out."
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end
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@queue.wait(@connection_mutex)
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end
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end
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end
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def receive(sock)
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receive_header(sock)
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number_received, cursor_id = receive_response_header(sock)
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read_documents(number_received, cursor_id, sock)
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end
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def receive_header(sock)
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header = ByteBuffer.new
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header.put_array(receive_message_on_socket(16, sock).unpack("C*"))
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unless header.size == STANDARD_HEADER_SIZE
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raise "Short read for DB response header: " +
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"expected #{STANDARD_HEADER_SIZE} bytes, saw #{header.size}"
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end
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header.rewind
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size = header.get_int
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request_id = header.get_int
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response_to = header.get_int
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op = header.get_int
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end
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def receive_response_header(sock)
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header_buf = ByteBuffer.new
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header_buf.put_array(receive_message_on_socket(RESPONSE_HEADER_SIZE, sock).unpack("C*"))
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if header_buf.length != RESPONSE_HEADER_SIZE
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raise "Short read for DB response header; " +
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"expected #{RESPONSE_HEADER_SIZE} bytes, saw #{header_buf.length}"
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end
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header_buf.rewind
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result_flags = header_buf.get_int
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cursor_id = header_buf.get_long
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starting_from = header_buf.get_int
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number_remaining = header_buf.get_int
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[number_remaining, cursor_id]
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end
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def read_documents(number_received, cursor_id, sock)
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docs = []
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number_remaining = number_received
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while number_remaining > 0 do
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buf = ByteBuffer.new
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buf.put_array(receive_message_on_socket(4, sock).unpack("C*"))
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buf.rewind
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size = buf.get_int
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buf.put_array(receive_message_on_socket(size - 4, sock).unpack("C*"), 4)
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number_remaining -= 1
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buf.rewind
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docs << BSON.deserialize(buf)
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end
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[docs, number_received, cursor_id]
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end
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def last_error_message(db_name)
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message = ByteBuffer.new
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message.put_int(0)
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BSON_RUBY.serialize_cstr(message, "#{db_name}.$cmd")
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message.put_int(0)
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message.put_int(-1)
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message.put_array(BSON.serialize({:getlasterror => 1}, false).unpack("C*"))
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add_message_headers(Mongo::Constants::OP_QUERY, message)
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end
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# Prepares a message for transmission to MongoDB by
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# constructing a valid message header.
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def add_message_headers(operation, message)
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headers = ByteBuffer.new
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# Message size.
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headers.put_int(16 + message.size)
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# Unique request id.
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headers.put_int(get_request_id)
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# Response id.
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headers.put_int(0)
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# Opcode.
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headers.put_int(operation)
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message.prepend!(headers)
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end
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# Low-level method for sending a message on a socket.
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# Requires a packed message and an available socket,
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def send_message_on_socket(packed_message, socket)
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begin
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socket.send(packed_message, 0)
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rescue => ex
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close
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raise ConnectionFailure, "Operation failed with the following exception: #{ex}"
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end
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end
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# Low-level method for receiving data from socket.
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# Requires length and an available socket.
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def receive_message_on_socket(length, socket)
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message = ""
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begin
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while message.length < length do
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chunk = socket.recv(length - message.length)
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raise ConnectionFailure, "connection closed" unless chunk.length > 0
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message += chunk
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end
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rescue => ex
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raise ConnectionFailure, "Operation failed with the following exception: #{ex}"
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end
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message
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end
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## Private helper methods
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# Returns an array of host-port pairs.
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def format_pair(pair_or_host, port)
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case pair_or_host
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when String
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[[pair_or_host, port ? port.to_i : DEFAULT_PORT]]
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when Hash
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connections = []
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connections << pair_val_to_connection(pair_or_host[:left])
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connections << pair_val_to_connection(pair_or_host[:right])
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connections
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when nil
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[['localhost', DEFAULT_PORT]]
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end
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end
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# Turns an array containing a host name string and a
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# port number integer into a [host, port] pair array.
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def pair_val_to_connection(a)
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case a
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when nil
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['localhost', DEFAULT_PORT]
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when String
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[a, DEFAULT_PORT]
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when Integer
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['localhost', a]
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when Array
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a
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end
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end
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end
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end
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