Add networking module.
This commit is contained in:
Kyle Banker
parent
a5373ddb83
commit
3e7c28e1ef
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module Mongo
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module Networking
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STANDARD_HEADER_SIZE = 16
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RESPONSE_HEADER_SIZE = 20
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# Counter for generating unique request ids.
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@@current_request_id = 0
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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 [BSON::ByteBuffer] message a message to send to the database.
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#
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# @option opts [Symbol] :connection (:writer) The connection to which
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# this message should be sent. Valid options are :writer and :reader.
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#
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# @return [Integer] number of bytes sent
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def send_message(operation, message, opts={})
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if opts.is_a?(String)
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warn "Connection#send_message no longer takes a string log message. " +
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"Logging is now handled within the Collection and Cursor classes."
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opts = {}
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end
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connection = opts.fetch(:connection, :writer)
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begin
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add_message_headers(message, operation)
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packed_message = message.to_s
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if connection == :writer
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socket = checkout_writer
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else
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socket = checkout_reader
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end
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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 [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
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# available options.
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#
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# @see DB#get_last_error for valid last error params.
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#
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# @return [Hash] The document returned by the call to getlasterror.
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def send_message_with_safe_check(operation, message, db_name, log_message=nil, last_error_params=false)
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docs = num_received = cursor_id = ''
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add_message_headers(message, operation)
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last_error_message = BSON::ByteBuffer.new
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build_last_error_message(last_error_message, db_name, last_error_params)
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last_error_id = add_message_headers(last_error_message, Mongo::Constants::OP_QUERY)
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packed_message = message.append!(last_error_message).to_s
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begin
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sock = checkout_writer
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send_message_on_socket(packed_message, sock)
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docs, num_received, cursor_id = receive(sock, last_error_id)
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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'] || docs[0]['errmsg'])
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close if error == "not master"
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error = "wtimeout" if error == "timeout"
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raise OperationFailure.new(docs[0]['code'].to_s + ': ' + error, docs[0]['code'], docs[0])
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end
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docs[0]
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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 [BSON::ByteBuffer] message a message to send to the database.
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# @param [String] log_message this is currently a no-op and will be removed.
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# @param [Socket] socket a socket to use in lieu of checking out a new one.
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# @param [Boolean] command (false) indicate whether this is a command. If this is a command,
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# the message will be sent to the primary node.
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# @param [Boolean] command (false) indicate whether the cursor should be exhausted. Set
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# this to true only when the OP_QUERY_EXHAUST flag is set.
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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, command=false,
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read=:primary, exhaust=false)
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request_id = add_message_headers(message, operation)
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packed_message = message.to_s
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begin
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if socket
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sock = socket
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should_checkin = false
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else
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if command
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sock = checkout_writer
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elsif read == :primary
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sock = checkout_writer
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elsif read == :secondary
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sock = checkout_reader
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else
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sock = checkout_tagged(read)
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end
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should_checkin = true
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end
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result = ''
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@safe_mutexes[sock].synchronize do
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send_message_on_socket(packed_message, sock)
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result = receive(sock, request_id, exhaust)
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end
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ensure
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if should_checkin
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checkin(sock)
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end
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end
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result
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end
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private
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def receive(sock, cursor_id, exhaust=false)
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begin
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if exhaust
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docs = []
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num_received = 0
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while(cursor_id != 0) do
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receive_header(sock, cursor_id, exhaust)
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number_received, cursor_id = receive_response_header(sock)
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new_docs, n = read_documents(number_received, sock)
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docs += new_docs
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num_received += n
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end
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return [docs, num_received, cursor_id]
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else
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receive_header(sock, cursor_id, exhaust)
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number_received, cursor_id = receive_response_header(sock)
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docs, num_received = read_documents(number_received, sock)
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return [docs, num_received, cursor_id]
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end
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rescue Mongo::ConnectionFailure => ex
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close
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raise ex
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end
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end
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def receive_header(sock, expected_response, exhaust=false)
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header = receive_message_on_socket(16, sock)
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size, request_id, response_to = header.unpack('VVV')
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if !exhaust && expected_response != response_to
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raise Mongo::ConnectionFailure, "Expected response #{expected_response} but got #{response_to}"
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end
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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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nil
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end
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def receive_response_header(sock)
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header_buf = receive_message_on_socket(RESPONSE_HEADER_SIZE, sock)
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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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flags, cursor_id_a, cursor_id_b, starting_from, number_remaining = header_buf.unpack('VVVVV')
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check_response_flags(flags)
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cursor_id = (cursor_id_b << 32) + cursor_id_a
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[number_remaining, cursor_id]
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end
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def check_response_flags(flags)
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if flags & Mongo::Constants::REPLY_CURSOR_NOT_FOUND != 0
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raise Mongo::OperationFailure, "Query response returned CURSOR_NOT_FOUND. " +
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"Either an invalid cursor was specified, or the cursor may have timed out on the server."
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elsif flags & Mongo::Constants::REPLY_QUERY_FAILURE != 0
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# Getting odd failures when a exception is raised here.
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end
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end
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def read_documents(number_received, 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 = receive_message_on_socket(4, sock)
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size = buf.unpack('V')[0]
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buf << receive_message_on_socket(size - 4, sock)
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number_remaining -= 1
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docs << BSON::BSON_CODER.deserialize(buf)
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end
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[docs, number_received]
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end
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# Constructs a getlasterror message. This method is used exclusively by
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# Connection#send_message_with_safe_check.
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#
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# Because it modifies message by reference, we don't need to return it.
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def build_last_error_message(message, db_name, opts)
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message.put_int(0)
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BSON::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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cmd = BSON::OrderedHash.new
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cmd[:getlasterror] = 1
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if opts.is_a?(Hash)
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opts.assert_valid_keys(:w, :wtimeout, :fsync)
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cmd.merge!(opts)
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end
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message.put_binary(BSON::BSON_CODER.serialize(cmd, false).to_s)
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nil
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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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#
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# Note: this method modifies message by reference.
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#
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# @return [Integer] the request id used in the header
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def add_message_headers(message, operation)
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headers = [
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# Message size.
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16 + message.size,
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# Unique request id.
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request_id = get_request_id,
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# Response id.
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0,
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# Opcode.
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operation
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].pack('VVVV')
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message.prepend!(headers)
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request_id
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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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# 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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#
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# @return [Integer] number of bytes sent
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def send_message_on_socket(packed_message, socket)
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begin
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total_bytes_sent = socket.send(packed_message, 0)
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if total_bytes_sent != packed_message.size
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packed_message.slice!(0, total_bytes_sent)
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while packed_message.size > 0
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byte_sent = socket.send(packed_message, 0)
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total_bytes_sent += byte_sent
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packed_message.slice!(0, byte_sent)
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end
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end
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total_bytes_sent
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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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begin
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if @op_timeout
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message = nil
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Mongo::TimeoutHandler.timeout(@op_timeout, OperationTimeout) do
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message = receive_data(length, socket)
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end
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else
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message = receive_data(length, socket)
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end
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rescue => ex
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close
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if ex.class == OperationTimeout
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raise OperationTimeout, "Timed out waiting on socket read."
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else
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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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message
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end
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def receive_data(length, socket)
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message = new_binary_string
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socket.read(length, message)
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raise ConnectionFailure, "connection closed" unless message && message.length > 0
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if message.length < length
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chunk = new_binary_string
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while message.length < length
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socket.read(length - message.length, chunk)
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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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end
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message
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end
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if defined?(Encoding)
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BINARY_ENCODING = Encoding.find("binary")
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def new_binary_string
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"".force_encoding(BINARY_ENCODING)
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end
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else
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def new_binary_string
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""
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end
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end
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end
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end
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