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

# encoding: UTF-8

# --
# Copyright (C) 2008-2011 10gen Inc.
#
# 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
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# 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.
# ++

require 'set'
require 'socket'
require 'thread'
module Mongo

  # Instantiates and manages self.connections to MongoDB.
  class Connection
    include Mongo::Logging
    include Mongo::Networking

    TCPSocket = Mongo::TCPSocket
    Mutex = ::Mutex
    ConditionVariable = ::ConditionVariable

    Thread.abort_on_exception = true

    DEFAULT_HOST = 'localhost'
    DEFAULT_PORT = 27017
    GENERIC_OPTS = [:ssl, :auths, :pool_size, :pool_timeout, :timeout, :op_timeout, :connect_timeout, :safe, :logger, :connect]
    CONNECTION_OPTS = [:slave_ok]

    mongo_thread_local_accessor :connections

    attr_reader :logger, :size, :auths, :primary, :safe, :host_to_try,
      :pool_size, :connect_timeout, :pool_timeout,
      :primary_pool, :socket_class, :op_timeout

    # Create a connection to single MongoDB instance.
    #
    # If no args are provided, it will check <code>ENV["MONGODB_URI"]</code>.
    #
    # You may specify whether connection to slave is permitted.
    # In all cases, the default host is "localhost" and the default port is 27017.
    #
    # If you're connecting to a replica set, you'll need to use ReplSetConnection.new instead.
    #
    # 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.
    #
    # @option opts [Boolean, Hash] :safe (false) Set the default safe-mode options
    #   propogated to DB objects instantiated off of this Connection. This
    #   default can be overridden upon instantiation of any DB by explicity setting a :safe value
    #   on initialization.
    # @option opts [Boolean] :slave_ok (false) Must be set to +true+ when connecting
    #   to a single, slave node.
    # @option opts [Logger, #debug] :logger (nil) A Logger instance for debugging driver ops. Note that
    #   logging negatively impacts performance; therefore, it should not be used for high-performance apps.
    # @option opts [Integer] :pool_size (1) The maximum number of socket self.connections allowed per
    #   connection pool. Note: this setting is relevant only for multi-threaded applications.
    # @option opts [Float] :timeout (5.0) When all of the self.connections a pool are checked out,
    #   this is the number of seconds to wait for a new connection to be released before throwing an exception.
    #   Note: this setting is relevant only for multi-threaded applications (which in Ruby are rare).
    # @option opts [Float] :op_timeout (nil) The number of seconds to wait for a read operation to time out.
    #   Disabled by default.
    # @option opts [Float] :connect_timeout (nil) The number of seconds to wait before timing out a
    #   connection attempt.
    # @option opts [Boolean] :ssl (false) If true, create the connection to the server using SSL.
    #
    # @example localhost, 27017 (or <code>ENV["MONGODB_URI"]</code> if available)
    #   Mongo::Connection.new
    #
    # @example localhost, 27017
    #   Mongo::Connection.new("localhost")
    #
    # @example localhost, 3000, max 5 self.connections, with max 5 seconds of wait time.
    #   Mongo::Connection.new("localhost", 3000, :pool_size => 5, :timeout => 5)
    #
    # @example localhost, 3000, where this node may be a slave
    #   Mongo::Connection.new("localhost", 3000, :slave_ok => true)
    #
    # @see http://api.mongodb.org/ruby/current/file.REPLICA_SETS.html Replica sets in Ruby
    #
    # @raise [ReplicaSetConnectionError] This is raised if a replica set name is specified and the
    #   driver fails to connect to a replica set with that name.
    #
    # @raise [MongoArgumentError] If called with no arguments and <code>ENV["MONGODB_URI"]</code> implies a replica set.
    #
    # @core self.connections
    def initialize(host=nil, port=nil, opts={})
      if host.nil? and ENV.has_key?('MONGODB_URI')
        parser = URIParser.new ENV['MONGODB_URI'], opts
        if parser.replicaset?
          raise MongoArgumentError, "Mongo::Connection.new called with no arguments, but ENV['MONGODB_URI'] implies a replica set."
        end
        opts = parser.connection_options
        @host_to_try = [parser.host, parser.port]
      elsif host.is_a?(String)
        @host_to_try = [host, (port || DEFAULT_PORT).to_i]
      else
        @host_to_try = [DEFAULT_HOST, DEFAULT_PORT]
      end

      # Host and port of current master.
      @host = @port = nil
      
      # Default maximum BSON object size
      @max_bson_size = Mongo::DEFAULT_MAX_BSON_SIZE
      
      # Lock for request ids.
      @id_lock = Mutex.new
      
      # Connection pool for primay node
      @primary      = nil
      @primary_pool = nil

      check_opts(opts)
      setup(opts)
    end

    # DEPRECATED
    #
    # Initialize a connection to a MongoDB replica set using an array of seed nodes.
    #
    # The seed nodes specified will be used on the initial connection to the replica set, but note
    # that this list of nodes will be replced by the list of canonical nodes returned by running the
    # is_master command on the replica set.
    #
    # @param nodes [Array] An array of arrays, each of which specifies a host and port.
    # @param opts [Hash] Any of the available options that can be passed to Connection.new.
    #
    # @option opts [String] :rs_name (nil) The name of the replica set to connect to. An exception will be
    #   raised if unable to connect to a replica set with this name.
    # @option opts [Boolean] :read_secondary (false) When true, this connection object will pick a random slave
    #   to send reads to.
    #
    # @example
    #   Mongo::Connection.multi([["db1.example.com", 27017], ["db2.example.com", 27017]])
    #
    # @example This connection will read from a random secondary node.
    #   Mongo::Connection.multi([["db1.example.com", 27017], ["db2.example.com", 27017], ["db3.example.com", 27017]],
    #                   :read_secondary => true)
    #
    # @return [Mongo::Connection]
    #
    # @deprecated
    def self.multi(nodes, opts={})
      warn "Connection.multi is now deprecated and will be removed in v2.0. Please use ReplSetConnection.new instead."

      ReplSetConnection.new(*(nodes+[opts]))
    end

    # Initialize a connection to MongoDB using the MongoDB URI spec.
    #
    # Since Connection.new cannot be used with any <code>ENV["MONGODB_URI"]</code> that has multiple hosts (implying a replicaset), you may use this when the type of your connection varies by environment and should be determined solely from <code>ENV["MONGODB_URI"]</code>.
    #
    # @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, Mongo::ReplSetConnection]
    def self.from_uri(uri = ENV['MONGODB_URI'], extra_opts={})
      parser = URIParser.new uri, extra_opts
      parser.connection
    end

    # The host name used for this connection.
    #
    # @return [String]
    def host
      @primary_pool.host
    end

    # The port used for this connection.
    #
    # @return [Integer]
    def port
      @primary_pool.port
    end

    # 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

    # Is this database locked against writes?
    #
    # @return [Boolean]
    def locked?
      self['admin']['$cmd.sys.inprog'].find_one['fsyncLock'] == 1
    end

    # Unlock a previously fsync-locked mongod process.
    #
    # @return [BSON::OrderedHash] command response
    def unlock!
      self['admin']['$cmd.sys.unlock'].find_one
    end

    # 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(opts={})
      return false if @auths.empty?
      @auths.each do |auth|
        self[auth['db_name']].issue_authentication(auth['username'], auth['password'], false,
          :socket => opts[:socket])
      end
      true
    end

    # Save an authentication to this connection. When connecting,
    # the connection will attempt to re-authenticate on every db
    # specificed in the list of auths. This method is called automatically
    # by DB#authenticate.
    #
    # Note: this method will not actually issue an authentication command. To do that,
    # either run Connection#apply_saved_authentication or DB#authenticate.
    #
    # @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

    def authenticate_pools
      @primary_pool.authenticate_existing
    end

    def logout_pools(db)
      @primary_pool.logout_existing(db)
    end

    # 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

    # Return an array of database names.
    #
    # @return [Array]
    def database_names
      database_info.keys
    end

    # Return a database with the given name.
    # See DB#new for valid options hash parameters.
    #
    # @param [String] db_name a valid database name.
    # @param [Hash] opts options to be passed to the DB constructor.
    #
    # @return [Mongo::DB]
    #
    # @core databases db-instance_method
    def db(db_name, opts={})
      DB.new(db_name, self, opts)
    end

    # Shortcut for returning a database. Use DB#db to accept options.
    #
    # @param [String] db_name a valid database name.
    #
    # @return [Mongo::DB]
    #
    # @core databases []-instance_method
    def [](db_name)
      DB.new(db_name, self)
    end

    # 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.
    #
    # @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=DEFAULT_HOST, username=nil, password=nil)
      oh = BSON::OrderedHash.new
      oh[:copydb]   = 1
      oh[:fromhost] = from_host
      oh[:fromdb]   = from
      oh[:todb]     = to
      if username || password
        unless username && password
          raise MongoArgumentError, "Both username and password must be supplied for authentication."
        end
        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

    # Checks if a server is alive. This command will return immediately
    # even if the server is in a lock.
    #
    # @return [Hash]
    def ping
      self["admin"].command({:ping => 1})
    end

    # Get the build information for the current connection.
    #
    # @return [Hash]
    def server_info
      self["admin"].command({:buildinfo => 1})
    end


    # 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

    # Is it okay to connect to a slave?
    #
    # @return [Boolean]
    def slave_ok?
      @slave_ok
    end

    # Create a new socket and attempt to connect to master.
    # If successful, sets host and port to master and returns the socket.
    #
    # If connecting to a replica set, this method will replace the
    # initially-provided seed list with any nodes known to the set.
    #
    # @raise [ConnectionFailure] if unable to connect to any host or port.
    def connect
      close

      config = check_is_master(@host_to_try)
      if config
        if config['ismaster'] == 1 || config['ismaster'] == true
          @read_primary = true
        elsif @slave_ok
          @read_primary = false
        end

        @max_bson_size = config['maxBsonObjectSize'] || Mongo::DEFAULT_MAX_BSON_SIZE
        set_primary(@host_to_try)
      end

      if !connected?
        raise ConnectionFailure, "Failed to connect to a master node at #{@host_to_try[0]}:#{@host_to_try[1]}"
      end
    end
    alias :reconnect :connect

    # It's possible that we defined connected as all nodes being connected???
    # NOTE: Do check if this needs to be more stringent.
    # Probably not since if any node raises a connection failure, all nodes will be closed.
    def connected?
      @primary_pool && !@primary_pool.closed?
    end

    # Determine if the connection is active. In a normal case the *server_info* operation
    # will be performed without issues, but if the connection was dropped by the server or
    # for some reason the sockets are unsynchronized, a ConnectionFailure will be raised and
    # the return will be false.
    #
    # @return [Boolean]
    def active?
      return false unless connected?

      ping
      true

      rescue ConnectionFailure
      false
    end

    # Determine whether we're reading from a primary node. If false,
    # this connection connects to a secondary node and @slave_ok is true.
    #
    # @return [Boolean]
    def read_primary?
      @read_primary
    end
    alias :primary? :read_primary?

    # The socket pool that this connection reads from.
    #
    # @return [Mongo::Pool]
    def read_pool
      @primary_pool
    end

    # The value of the read preference.
    def read_preference
      if slave_ok?
        :secondary
      else
        :primary
      end
    end

    # Close the connection to the database.
    def close
      @primary_pool.close if @primary_pool
      @primary_pool = nil
      @primary = nil
    end

    # Returns the maximum BSON object size as returned by the core server.
    # Use the 4MB default when the server doesn't report this.
    #
    # @return [Integer]
    def max_bson_size
      @max_bson_size
    end

    # Prefer primary pool but fall back to secondary
    def checkout_best
      connect unless connected?
      @primary_pool.checkout
    end

    # Checkout a socket for reading (i.e., a secondary node).
    # Note: this is overridden in ReplSetConnection.
    def checkout_reader
      connect unless connected?
      @primary_pool.checkout
    end

    # Checkout a socket for writing (i.e., a primary node).
    # Note: this is overridden in ReplSetConnection.
    def checkout_writer
      connect unless connected?
      @primary_pool.checkout
    end

    # Checkin a socket used for reading.
    # Note: this is overridden in ReplSetConnection.
    def checkin_reader(socket)
      checkin(socket)
    end

    # Checkin a socket used for writing.
    # Note: this is overridden in ReplSetConnection.
    def checkin_writer(socket)
      checkin(socket)
    end

    # Check a socket back into its pool.
    def checkin(socket)
      if @primary_pool && socket
        socket.pool.checkin(socket)
      end
    end

    # Excecutes block with the best available socket
    def best_available_socket
      socket = nil
      begin
        socket = checkout_best
        yield socket
      ensure
        if socket
          socket.pool.checkin(socket)
        end
      end
    end

    protected

    def valid_opts
      GENERIC_OPTS + CONNECTION_OPTS
    end

    def check_opts(opts)
      bad_opts = opts.keys.reject { |opt| valid_opts.include?(opt) }

      unless bad_opts.empty?
        bad_opts.each {|opt| warn "#{opt} is not a valid option for #{self.class}"}
      end
    end

    # Parse option hash
    def setup(opts)
      # slave_ok can be true only if one node is specified
      @slave_ok = opts[:slave_ok]
      
      # Determine whether to use SSL.
      @ssl = opts.fetch(:ssl, false)
      if @ssl
        @socket_class = Mongo::SSLSocket
      else
        @socket_class = Mongo::TCPSocket
      end

      # Authentication objects
      @auths = opts.fetch(:auths, [])

      # Pool size and timeout.
      @pool_size = opts[:pool_size] || 1
      if opts[:timeout]
        warn "The :timeout option has been deprecated " +
          "and will be removed in the 2.0 release. Use :pool_timeout instead."
      end
      @pool_timeout = opts[:pool_timeout] || opts[:timeout] || 5.0

      # Timeout on socket read operation.
      @op_timeout = opts[:op_timeout] || nil

      # Timeout on socket connect.
      @connect_timeout = opts[:connect_timeout] || nil

      # Global safe option. This is false by default.
      @safe = opts[:safe] || false

      @logger = opts.fetch(:logger, nil)

      if @logger
        write_logging_startup_message
      end

      if opts.fetch(:connect, true)
        connect
      end
    end

    private

    ## Methods for establishing a connection:

    # If a ConnectionFailure is raised, this method will be called
    # to close the connection and reset connection values.
    # TODO: evaluate whether this method is actually necessary
    def reset_connection
      close
    end

    def check_is_master(node)
      begin
        host, port = *node
        socket = nil
        config = nil

        socket = @socket_class.new(host, port, @op_timeout, @connect_timeout) 
        config = self['admin'].command({:ismaster => 1}, :socket => socket)
      rescue OperationFailure, SocketError, SystemCallError, IOError
        close
      ensure
        if socket
          socket.close unless socket.closed?
        end
      end

      config
    end

    # Set the specified node as primary.
    def set_primary(node)
      host, port = *node
      @primary = [host, port]
      @primary_pool = Pool.new(self, host, port, :size => @pool_size, :timeout => @pool_timeout)
    end
  end
end