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# Copyright (C) 2017 MongoDB, 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 'zlib'
module Mongo
module Protocol
# MongoDB Wire protocol Compressed message.
#
# This is a bi-directional message that compresses another opcode.
#
# @api semipublic
#
# @since 2.5.0
class Compressed < Message
# The byte signaling that the message has been compressed with Zlib.
#
# @since 2.5.0
ZLIB_BYTE = 2.chr.force_encoding(BSON::BINARY).freeze
# The Zlib compressor identifier.
#
# @since 2.5.0
ZLIB = 'zlib'.freeze
# The compressor identifier to byte map.
#
# @since 2.5.0
COMPRESSOR_ID_MAP = { ZLIB => ZLIB_BYTE }.freeze
# Creates a new OP_COMPRESSED message.
#
# @example Create an OP_COMPRESSED message.
# Compressed.new(original_message, 'zlib')
#
# @param [ Mongo::Protocol::Message ] message The original message.
# @param [ String, Symbol ] compressor The compression algorithm to use.
# @param [ Integer ] zlib_compression_level The zlib compression level to use.
# -1 and nil imply default.
#
# @since 2.5.0
def initialize(message, compressor, zlib_compression_level = nil)
@original_message = message
@original_op_code = message.op_code
@uncompressed_size = 0
@compressor_id = COMPRESSOR_ID_MAP[compressor]
@compressed_message = ''
@zlib_compression_level = zlib_compression_level if zlib_compression_level && zlib_compression_level != -1
@request_id = message.set_request_id
end
# Inflate an OP_COMRESSED message and return the original message.
#
# @example Inflate a compressed message.
# message.inflate!
#
# @return [ Protocol::Message ] The inflated message.
#
# @since 2.5.0
def inflate!
message = Registry.get(@original_op_code).allocate
uncompressed_message = Zlib::Inflate.inflate(@compressed_message)
buf = BSON::ByteBuffer.new(uncompressed_message)
message.send(:fields).each do |field|
if field[:multi]
Message.deserialize_array(message, buf, field)
else
Message.deserialize_field(message, buf, field)
end
end
message
end
# Whether the message expects a reply from the database.
#
# @example Does the message require a reply?
# message.replyable?
#
# @return [ true, false ] If the message expects a reply.
#
# @since 2.5.0
def replyable?
@original_message.replyable?
end
private
# The operation code for a +Compressed+ message.
# @return [ Fixnum ] the operation code.
#
# @since 2.5.0
OP_CODE = 2012
# @!attribute
# Field representing the original message's op code as an Int32.
field :original_op_code, Int32
# @!attribute
# @return [ Fixnum ] The size of the original message, excluding header as an Int32.
field :uncompressed_size, Int32
# @!attribute
# @return [ String ] The id of the compressor as a single byte.
field :compressor_id, Byte
# @!attribute
# @return [ String ] The actual compressed message bytes.
field :compressed_message, Bytes
def serialize_fields(buffer, max_bson_size)
buf = BSON::ByteBuffer.new
@original_message.send(:serialize_fields, buf, max_bson_size)
@uncompressed_size = buf.length
@compressed_message = Zlib::Deflate.deflate(buf.to_s, @zlib_compression_level).force_encoding(BSON::BINARY)
super
end
Registry.register(OP_CODE, self)
end
end
end
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