module Mongo::Networking

Constants

BINARY_ENCODING
RESPONSE_HEADER_SIZE
STANDARD_HEADER_SIZE

Public Instance Methods

receive_message(operation, message, log_message=nil, socket=nil, command=false, read=:primary, exhaust=false) click to toggle source

Sends a message to the database and waits for the response.

@param [Integer] operation a MongoDB opcode. @param [BSON::ByteBuffer] message a message to send to the database. @param [String] log_message this is currently a no-op and will be removed. @param [Socket] socket a socket to use in lieu of checking out a new one. @param [Boolean] command (false) indicate whether this is a command. If this is a command,

the message will be sent to the primary node.

@param [Boolean] command (false) indicate whether the cursor should be exhausted. Set

this to true only when the OP_QUERY_EXHAUST flag is set.

@return [Array]

An array whose indexes include [0] documents returned, [1] number of document received,
and [3] a cursor_id.
# File lib/mongo/networking.rb, line 116
def receive_message(operation, message, log_message=nil, socket=nil, command=false,
                    read=:primary, exhaust=false)
  request_id = add_message_headers(message, operation)
  packed_message = message.to_s

  result = ''
  sock   = nil
  begin
    if socket
      sock = socket
      should_checkin = false
    else
      if command || read == :primary
        sock = checkout_writer
      elsif read == :secondary
        sock = checkout_reader
      else
        sock = checkout_tagged(read)
      end
      should_checkin = true
    end

    send_message_on_socket(packed_message, sock)
    result = receive(sock, request_id, exhaust)
  rescue SystemStackError, NoMemoryError, SystemCallError => ex
    close
    raise ex
  rescue Exception => ex
    if defined?(IRB)
      close if ex.class == IRB::Abort
    end
    raise ex
  ensure
    if should_checkin
      if command || read == :primary
        checkin_writer(sock)
      elsif read == :secondary
        checkin_reader(sock)
      else
        # TODO: sock = checkout_tagged(read)
      end
    end
  end
  result
end
send_message(operation, message, opts={}) click to toggle source

Send a message to MongoDB, adding the necessary headers.

@param [Integer] operation a MongoDB opcode. @param [BSON::ByteBuffer] message a message to send to the database.

@option opts [Symbol] :connection (:writer) The connection to which

this message should be sent. Valid options are :writer and :reader.

@return [Integer] number of bytes sent

# File lib/mongo/networking.rb, line 19
def send_message(operation, message, opts={})
  if opts.is_a?(String)
    warn "Connection#send_message no longer takes a string log message. " +
      "Logging is now handled within the Collection and Cursor classes."
    opts = {}
  end

  connection = opts.fetch(:connection, :writer)

  add_message_headers(message, operation)
  packed_message = message.to_s

  sock = nil
  begin
    if connection == :writer
      sock = checkout_writer
    else
      sock = checkout_reader
    end

    send_message_on_socket(packed_message, sock)
  rescue SystemStackError, NoMemoryError, SystemCallError => ex
    close
    raise ex
  ensure
    if sock
      if connection == :writer
        checkin_writer(sock)
      else
        checkin_reader(sock)
      end
    end
  end
end
send_message_with_safe_check(operation, message, db_name, log_message=nil, last_error_params=false) click to toggle source

Sends a message to the database, waits for a response, and raises an exception if the operation has failed.

@param [Integer] operation a MongoDB opcode. @param [BSON::ByteBuffer] message a message to send to the database. @param [String] db_name the name of the database. used on call to get_last_error. @param [Hash] last_error_params parameters to be sent to getLastError. See DB#error for

available options.

@see Mongo::DB#get_last_error for valid last error params.

@return [Hash] The document returned by the call to getlasterror.

# File lib/mongo/networking.rb, line 66
def send_message_with_safe_check(operation, message, db_name, log_message=nil, last_error_params=false)
  docs = num_received = cursor_id = ''
  add_message_headers(message, operation)

  last_error_message = BSON::ByteBuffer.new
  build_last_error_message(last_error_message, db_name, last_error_params)
  last_error_id = add_message_headers(last_error_message, Mongo::Constants::OP_QUERY)

  packed_message = message.append!(last_error_message).to_s
  sock = nil
  begin
    sock = checkout_writer
    send_message_on_socket(packed_message, sock)
    docs, num_received, cursor_id = receive(sock, last_error_id)
    checkin_writer(sock)
  rescue ConnectionFailure, OperationFailure, OperationTimeout => ex
    checkin_writer(sock)
    raise ex
  rescue SystemStackError, NoMemoryError, SystemCallError => ex
    close
    raise ex
  end

  if num_received == 1 && (error = docs[0]['err'] || docs[0]['errmsg'])
    if error.include?("not master")
      close
      raise ConnectionFailure.new(docs[0]['code'].to_s + ': ' + error, docs[0]['code'], docs[0])
    else
      error = "wtimeout" if error == "timeout"
      raise OperationFailure.new(docs[0]['code'].to_s + ': ' + error, docs[0]['code'], docs[0])
    end
  end

  docs[0]
end

Private Instance Methods

add_message_headers(message, operation) click to toggle source

Prepares a message for transmission to MongoDB by constructing a valid message header.

Note: this method modifies message by reference.

@return [Integer] the request id used in the header

# File lib/mongo/networking.rb, line 271
def add_message_headers(message, operation)
  headers = [
    # Message size.
    16 + message.size,

    # Unique request id.
    request_id = get_request_id,

    # Response id.
    0,

    # Opcode.
    operation
  ].pack('VVVV')

  message.prepend!(headers)

  request_id
end
build_last_error_message(message, db_name, opts) click to toggle source

Constructs a getlasterror message. This method is used exclusively by #send_message_with_safe_check.

Because it modifies message by reference, we don't need to return it.

# File lib/mongo/networking.rb, line 250
def build_last_error_message(message, db_name, opts)
  message.put_int(0)
  BSON::BSON_RUBY.serialize_cstr(message, "#{db_name}.$cmd")
  message.put_int(0)
  message.put_int(-1)
  cmd = BSON::OrderedHash.new
  cmd[:getlasterror] = 1
  if opts.is_a?(Hash)
    opts.assert_valid_keys(:w, :wtimeout, :fsync, :j)
    cmd.merge!(opts)
  end
  message.put_binary(BSON::BSON_CODER.serialize(cmd, false).to_s)
  nil
end
check_response_flags(flags) click to toggle source
# File lib/mongo/networking.rb, line 224
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
get_request_id() click to toggle source

Increment and return the next available request id.

return [Integer]

# File lib/mongo/networking.rb, line 294
def get_request_id
  request_id = ''
  @id_lock.synchronize do
    request_id = @@current_request_id += 1
  end
  request_id
end
new_binary_string() click to toggle source
# File lib/mongo/networking.rb, line 360
def new_binary_string
  "".force_encoding(BINARY_ENCODING)
end
read_documents(number_received, sock) click to toggle source
# File lib/mongo/networking.rb, line 233
def read_documents(number_received, 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
    docs << BSON::BSON_CODER.deserialize(buf)
  end
  [docs, number_received]
end
receive(sock, cursor_id, exhaust=false) click to toggle source
# File lib/mongo/networking.rb, line 164
def receive(sock, cursor_id, exhaust=false)
  begin
    if exhaust
      docs = []
      num_received = 0

      while(cursor_id != 0) do
        receive_header(sock, cursor_id, exhaust)
        number_received, cursor_id = receive_response_header(sock)
        new_docs, n = read_documents(number_received, sock)
        docs += new_docs
        num_received += n
      end

      return [docs, num_received, cursor_id]
    else
      receive_header(sock, cursor_id, exhaust)
      number_received, cursor_id = receive_response_header(sock)
      docs, num_received = read_documents(number_received, sock)

      return [docs, num_received, cursor_id]
    end
  rescue Mongo::ConnectionFailure => ex
    close
    raise ex
  end
end
receive_data(length, socket) click to toggle source
# File lib/mongo/networking.rb, line 341
def receive_data(length, socket)
  message = new_binary_string
  socket.read(length, message)
 
  raise ConnectionFailure, "connection closed" unless message && 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
  end
  message
end
receive_header(sock, expected_response, exhaust=false) click to toggle source
# File lib/mongo/networking.rb, line 192
def receive_header(sock, expected_response, exhaust=false)
  header = receive_message_on_socket(16, sock)

  # unpacks to size, request_id, response_to
  response_to = header.unpack('VVV')[2]

  if !exhaust && expected_response != response_to
    raise Mongo::ConnectionFailure, "Expected response #{expected_response} but got #{response_to}"
  end

  unless header.size == STANDARD_HEADER_SIZE
    raise "Short read for DB response header: " +
      "expected #{STANDARD_HEADER_SIZE} bytes, saw #{header.size}"
  end
  nil
end
receive_message_on_socket(length, socket) click to toggle source

Low-level method for receiving data from socket. Requires length and an available socket.

# File lib/mongo/networking.rb, line 326
def receive_message_on_socket(length, socket)
  begin
      message = receive_data(length, socket)
  rescue OperationTimeout, ConnectionFailure => ex
    close

    if ex.class == OperationTimeout
      raise OperationTimeout, "Timed out waiting on socket read."
    else
      raise ConnectionFailure, "Operation failed with the following exception: #{ex}"
    end
  end
  message
end
receive_response_header(sock) click to toggle source
# File lib/mongo/networking.rb, line 209
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

  # unpacks to flags, cursor_id_a, cursor_id_b, starting_from, number_remaining
  flags, cursor_id_a, cursor_id_b, _, number_remaining = header_buf.unpack('VVVVV')
  
  check_response_flags(flags)
  cursor_id = (cursor_id_b << 32) + cursor_id_a
  [number_remaining, cursor_id]
end
send_message_on_socket(packed_message, socket) click to toggle source

Low-level method for sending a message on a socket. Requires a packed message and an available socket,

@return [Integer] number of bytes sent

# File lib/mongo/networking.rb, line 306
def send_message_on_socket(packed_message, socket)
  begin
  total_bytes_sent = socket.send(packed_message)
  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)
      total_bytes_sent += byte_sent
      packed_message.slice!(0, byte_sent)
    end
  end
  total_bytes_sent
  rescue => ex
    close
    raise ConnectionFailure, "Operation failed with the following exception: #{ex}:#{ex.message}"
  end
end