Class: Mongo::Protocol::Compressed

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain: self, `Message`
Instance Chain: self, `Message`, `Serializers`, `::Mongo::Id`
Inherits:	Mongo::Protocol::Message Object Mongo::Protocol::Message Mongo::Protocol::Compressed
Defined in:	lib/mongo/protocol/compressed.rb

Overview

MongoDB Wire protocol Compressed message.

This is a bi-directional message that compresses another opcode. See github.com/mongodb/specifications/blob/master/source/compression/OP_COMPRESSED.rst

Since:

2.5.0

Constant Summary

COMPRESSOR_ID_MAP =

The compressor identifier to byte map.
Since:
- 2.5.0
# File 'lib/mongo/protocol/compressed.rb', line 62
```
{
  SNAPPY => SNAPPY_BYTE,
  ZSTD => ZSTD_BYTE,
  ZLIB => ZLIB_BYTE
}.freeze
```
NOOP =

The noop compressor identifier.
Since:
- 2.5.0
# File 'lib/mongo/protocol/compressed.rb', line 32
```
'noop'.freeze
```
NOOP_BYTE =

The byte signaling that the message has not been compressed (test mode).
Since:
- 2.5.0
# File 'lib/mongo/protocol/compressed.rb', line 35
```
0.chr.force_encoding(BSON::BINARY).freeze
```
OP_CODE =

The operation code for a Compressed message.
Returns:
- (Fixnum) —
  
  the operation code.
Since:
- 2.5.0
# File 'lib/mongo/protocol/compressed.rb', line 130
```
2012
```
SNAPPY =

The snappy compressor identifier.
Since:
- 2.5.0
# File 'lib/mongo/protocol/compressed.rb', line 38
```
'snappy'.freeze
```
SNAPPY_BYTE =

The byte signaling that the message has been compressed with snappy.
Since:
- 2.5.0
# File 'lib/mongo/protocol/compressed.rb', line 41
```
1.chr.force_encoding(BSON::BINARY).freeze
```
ZLIB =

The Zlib compressor identifier.
Since:
- 2.5.0
# File 'lib/mongo/protocol/compressed.rb', line 51
```
'zlib'.freeze
```
ZLIB_BYTE =

The byte signaling that the message has been compressed with Zlib.
Since:
- 2.5.0
# File 'lib/mongo/protocol/compressed.rb', line 46
```
2.chr.force_encoding(BSON::BINARY).freeze
```
ZSTD =

The zstd compressor identifier.
Since:
- 2.5.0
# File 'lib/mongo/protocol/compressed.rb', line 54
```
'zstd'.freeze
```
ZSTD_BYTE =

The byte signaling that the message has been compressed with zstd.
Since:
- 2.5.0
# File 'lib/mongo/protocol/compressed.rb', line 57
```
3.chr.force_encoding(BSON::BINARY).freeze
```

`Serializers` - Included

HEADER_PACK, INT32_PACK, INT64_PACK, NULL, ZERO

`Message` - Inherited

BATCH_SIZE, COLLECTION, LIMIT, MAX_MESSAGE_SIZE, ORDERED, Q

Class Method Summary

.new(message, compressor, zlib_compression_level = nil) ⇒ Compressed constructor

Creates a new OP_COMPRESSED message.

`Message` - Inherited

.deserialize	Deserializes messages from an IO stream.
.new	:nodoc:
.deserialize_array	Deserializes an array of fields in a message.
.deserialize_field	Deserializes a single field in a message.
.deserialize_header	Deserializes the header of the message.
.field	A method for declaring a message field.
.fields	A class method for getting the fields for a message class.

Instance Attribute Summary

#replyable? ⇒ true, false readonly

Whether the message expects a reply from the database.
#compressed_message ⇒ String rw private
#compressor_id ⇒ String rw private
#original_op_code rw private

Field representing the original message’s op code as an Int32.
#uncompressed_size ⇒ Fixnum rw private

`Message` - Inherited

#replyable?	The default for messages is not to require a reply after sending a message to the server.
#request_id	Returns the request id for the message.

Instance Method Summary

#maybe_inflate ⇒ Protocol::Message Internal use only Internal use only

Inflates an OP_COMRESSED message and returns the original message.
#compress(buffer) private
#decompress(compressed_message) private
#serialize_fields(buffer, max_bson_size) private

`Message` - Inherited

#==	Tests for equality between two wire protocol messages by comparing class and field values.
#eql?	Alias for Message#==.
#hash	Creates a hash from the values of the fields of a message.
#maybe_add_server_api,
#maybe_compress	Compress the message, if supported by the wire protocol used and if the command being sent permits compression.
#maybe_decrypt	Possibly decrypt this message with libmongocrypt.
#maybe_encrypt	Possibly encrypt this message with libmongocrypt.
#maybe_inflate	Inflate a message if it is compressed.
#number_returned	Default number returned value for protocol messages.
#serialize	Serializes message into bytes that can be sent on the wire.
#set_request_id	Generates a request id for a message.
#to_s	Alias for Message#serialize.
#compress_if_possible	Compress the message, if the command being sent permits compression.
#fields	A method for getting the fields for a message class.
#merge_sections,
#serialize_fields	Serializes message fields into a buffer.
#serialize_header	Serializes the header of the message consisting of 4 32bit integers.

Constructor Details

.new(message, compressor, zlib_compression_level = nil) ⇒ `Compressed`

Creates a new OP_COMPRESSED message.

Examples:

Create an OP_COMPRESSED message.

Compressed.new(original_message, 'zlib')

Parameters:

message (Mongo::Protocol::Message) —

The original message.
compressor (String, Symbol) —

The compression algorithm to use.
zlib_compression_level (Integer) (defaults to: nil) —

The zlib compression level to use. -1 and nil imply default.

Since:

2.5.0

[ GitHub ]

# File 'lib/mongo/protocol/compressed.rb', line 79


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.request_id
end

Instance Attribute Details

#compressed_message ⇒ `String` (rw, private)

Returns:

(String) —

The actual compressed message bytes.

[ GitHub ]

# File 'lib/mongo/protocol/compressed.rb', line 146


field :compressed_message, Bytes

#compressor_id ⇒ `String` (rw, private)

Returns:

(String) —

The id of the compressor as a single byte.

[ GitHub ]

# File 'lib/mongo/protocol/compressed.rb', line 142


field :compressor_id, Byte

#original_op_code (rw, private)

Field representing the original message’s op code as an Int32.

[ GitHub ]

# File 'lib/mongo/protocol/compressed.rb', line 134


field :original_op_code, Int32

#replyable? ⇒ `true`, `false` (readonly)

Whether the message expects a reply from the database.

Examples:

Does the message require a reply?

message.replyable?

Returns:

(true, false) —

If the message expects a reply.

Since:

2.5.0

[ GitHub ]

# File 'lib/mongo/protocol/compressed.rb', line 120


def replyable?
  @original_message.replyable?
end

#uncompressed_size ⇒ `Fixnum` (rw, private)

Returns:

(Fixnum) —

The size of the original message, excluding header as an Int32.

[ GitHub ]

# File 'lib/mongo/protocol/compressed.rb', line 138


field :uncompressed_size, Int32

Instance Method Details

#compress(buffer) (private)

Since:

2.5.0

[ GitHub ]

# File 'lib/mongo/protocol/compressed.rb', line 156


def compress(buffer)
  if @compressor_id == NOOP_BYTE
    buffer.to_s.force_encoding(BSON::BINARY)
  elsif @compressor_id == ZLIB_BYTE
    Zlib::Deflate.deflate(buffer.to_s, @zlib_compression_level).force_encoding(BSON::BINARY)
  elsif @compressor_id == SNAPPY_BYTE
    Snappy.deflate(buffer.to_s).force_encoding(BSON::BINARY)
  elsif @compressor_id == ZSTD_BYTE
    # DRIVERS-600 will allow this to be configurable in the future
    Zstd.compress(buffer.to_s).force_encoding(BSON::BINARY)
  end
end

#decompress(compressed_message) (private)

Since:

2.5.0

[ GitHub ]

# File 'lib/mongo/protocol/compressed.rb', line 169


def decompress(compressed_message)
  if @compressor_id == NOOP_BYTE
    BSON::ByteBuffer.new(compressed_message)
  elsif @compressor_id == ZLIB_BYTE
    BSON::ByteBuffer.new(Zlib::Inflate.inflate(compressed_message))
  elsif @compressor_id == SNAPPY_BYTE
    BSON::ByteBuffer.new(Snappy.inflate(compressed_message))
  elsif @compressor_id == ZSTD_BYTE
    BSON::ByteBuffer.new(Zstd.decompress(compressed_message))
  end
end

#maybe_inflate ⇒ Protocol::Message

This method is for internal use only.

Inflates an OP_COMRESSED message and returns the original message.

Returns:

(Protocol::Message) —

The inflated message.

Since:

2.5.0

[ GitHub ]

# File 'lib/mongo/protocol/compressed.rb', line 95


def maybe_inflate
  message = Registry.get(@original_op_code).allocate
  buf = decompress(@compressed_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
  if message.is_a?(Msg)
    message.fix_after_deserialization
  end
  message
end

#serialize_fields(buffer, max_bson_size) (private)

Since:

2.5.0

[ GitHub ]

# File 'lib/mongo/protocol/compressed.rb', line 148


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 = compress(buf)
  super
end

Class: Mongo::Protocol::Compressed

Overview

Constant Summary

Serializers - Included

Message - Inherited

Class Method Summary

Message - Inherited

Instance Attribute Summary

Message - Inherited

Instance Method Summary

Message - Inherited

Constructor Details

.new(message, compressor, zlib_compression_level = nil) ⇒ Compressed

Instance Attribute Details

#compressed_message ⇒ String (rw, private)

#compressor_id ⇒ String (rw, private)

#original_op_code (rw, private)

#replyable? ⇒ true, false (readonly)

#uncompressed_size ⇒ Fixnum (rw, private)

Instance Method Details

#compress(buffer) (private)

#decompress(compressed_message) (private)

#maybe_inflate ⇒ Protocol::Message

#serialize_fields(buffer, max_bson_size) (private)

`Serializers` - Included

`Message` - Inherited

`Message` - Inherited

`Message` - Inherited

`Message` - Inherited

.new(message, compressor, zlib_compression_level = nil) ⇒ `Compressed`

#compressed_message ⇒ `String` (rw, private)

#compressor_id ⇒ `String` (rw, private)

#replyable? ⇒ `true`, `false` (readonly)

#uncompressed_size ⇒ `Fixnum` (rw, private)