NetSerializer - A fast, simple serializer for .Net

NetSerializer is a simple and very fast serializer for .Net languages. It is
the fastest serializer I have found for my use cases.

The main pros of NetSerializer are:

- Excellent for network serialization
- Supports classes, structs, enums, interfaces, abstract classes
- No versioning or other extra information is serialized, only pure data
- No type IDs for primitive types, structs or sealed classes, so less data to
  be sent
- No dynamic type lookup for primitive types, structs or sealed classes, so
  deserialization is faster
- No extra attributes needed (like DataContract/Member), just add the standard
  [Serializable]
- Thread safe without locks
- The data is written to the stream and read from the stream directly, without
  the need for temporary buffers or large buffers

The simpleness of NetSerializer has a drawback which must be considered by the
user: no versioning or other meta information is sent, which means that the
sender and the receiver have to have the same versions of the types being
serialized.  This means that it's a bad idea to save the serialized data for
longer periods of time, as a version upgrade could make the data
non-deserializable.  For this reason I think the best (and perhaps only) use
for NetSerializer is for sending data over network, between a client and a
server which have verified version compatibility when the connection is made.

Supported Types

NetSerializer supports serializing the following types:

- All primitive types (Boolean, Byte, SByte, Int16, UInt16, Int32, UInt32,
  Int64, UInt64, IntPtr, UIntPtr, Char, Double, and Single)
- Strings
- Enums
- Single dimensional arrays
- Structs and classes marked as [Serializable]. Note that NetSerializer does
  _not_ support ISerializable, so not all classes marked with [Serializable]
  are supported.  However, NetSerializer has special support for the following
  ISerializable classes:
- Dictionary<K,V>
- DateTime

NetSerializer also supports creating custom serializers. Custom serializers can
be used to serialize types not directly supported by NetSerializer.

Usage

Usage is simple. The types to be serialized need to be marked with the standard
[Serializable].  You can also use [NonSerialized] for fields you don't want to
serialize. Nothing else needs to be done for the types to be serialized.

Then you need to initialize NetSerializer by giving it a list of types you will
be serializing. NetSerializer will scan through the given types, and
recursively add all the types used by the given types, and create
(de)serialization code.

Initialization:

	var ser = new Serializer(types);

Serializing:

	ser.Serialize(stream, ob);

Deserializing:

	(YourType)ser.Deserialize(stream);


Performance

Below is a performance comparison between NetSerializer and protobuf-net.
Protobuf-net is a fast Protocol Buffers compatible serializer, which was the
best serializer I could find out there when I considered the serializer for
my use case.


The table lists the time it takes run the test, the number of GC collections
(per generation) that happened during the test, and the size of the
outputted serialized data (when available).


There are three tests:

- MemStream Serialize - serializes an array of objects to a memory stream.

- MemStream Deserialize - deserializes the stream created with MemStream
  Serialize test.

- NetTest - uses two threads, of which the first one serializes objects and
  sends them over a local socket, and the second one receive the data and
  deserialize the objects. Note that the size is not available for NetTest, as
  tracking the sent data is not trivial. However, the dataset is the same as
  with MemStream, an so is the size of the data.

The tests are ran for different kinds of datasets. These datasets are composed
of objects of the same type. However, each object is initialized with random
data. The types used in the datasets are:

- U8NullMessage - contains a single byte field, initialized always to 0
- S16Message - contains a single short field
- S32Message - contains a single int field
- U32Message - contains a single uint field
- S64Message - contains a single long field
- PrimitivesMessage - contains multiple fields of primitive types
- ComplexMessage - contains fields with interface and abstract references
- StringMessage - contains random length string
- ByteArrayMessage - contains random length byte array
- IntArrayMessage - contains random length int array

The details of the tests can be found from the source code. The tests were run
on a 32bit Windows XP laptop.


                                      |  time (ms) |    GC coll. |   size (B) |
== 2000000 U8NullMessage ==
NetSerializer | MemStream Serialize   |        320 |   0   0   0 |    4000000 |
NetSerializer | MemStream Deserialize |        872 |   4   2   0 |            |
protobuf-net  | MemStream Serialize   |       1068 | 137   0   0 |    6000000 |
protobuf-net  | MemStream Deserialize |       1892 |  42  16   0 |            |
NetSerializer | NetTest               |        495 |   4   2   0 |            |
protobuf-net  | NetTest               |      10801 | 222  66   1 |            |

== 2000000 S16Message ==
NetSerializer | MemStream Serialize   |        244 |   0   0   0 |    7496110 |
NetSerializer | MemStream Deserialize |        609 |   6   4   1 |            |
protobuf-net  | MemStream Serialize   |        853 | 138   1   1 |   20492059 |
protobuf-net  | MemStream Deserialize |       2701 |  43  11   1 |            |
NetSerializer | NetTest               |        730 |   5   4   0 |            |
protobuf-net  | NetTest               |      11143 | 217  51   1 |            |

== 2000000 S32Message ==
NetSerializer | MemStream Serialize   |        420 |   0   0   0 |   11874526 |
NetSerializer | MemStream Deserialize |        795 |   4   3   0 |            |
protobuf-net  | MemStream Serialize   |        928 | 138   1   1 |   17748783 |
protobuf-net  | MemStream Deserialize |       2477 |  43  11   1 |            |
NetSerializer | NetTest               |        803 |   4   3   0 |            |
protobuf-net  | NetTest               |      10917 | 216  47   1 |            |

== 2000000 U32Message ==
NetSerializer | MemStream Serialize   |        382 |   0   0   0 |   11748852 |
NetSerializer | MemStream Deserialize |        633 |   4   3   0 |            |
protobuf-net  | MemStream Serialize   |       1182 | 138   1   1 |   17748852 |
protobuf-net  | MemStream Deserialize |       2526 |  43  11   1 |            |
NetSerializer | NetTest               |        726 |   4   3   0 |            |
protobuf-net  | NetTest               |      11198 | 216  47   1 |            |

== 2000000 S64Message ==
NetSerializer | MemStream Serialize   |        393 |   1   1   1 |   20992943 |
NetSerializer | MemStream Deserialize |        647 |   5   4   0 |            |
protobuf-net  | MemStream Serialize   |       1229 | 138   1   1 |   26992398 |
protobuf-net  | MemStream Deserialize |       2493 |  44  16   1 |            |
NetSerializer | NetTest               |        932 |   6   3   0 |            |
protobuf-net  | NetTest               |      11649 |  81  30   1 |            |

== 1000000 PrimitivesMessage ==
NetSerializer | MemStream Serialize   |        986 |   1   1   1 |   45867626 |
NetSerializer | MemStream Deserialize |       1055 |  10   6   0 |            |
protobuf-net  | MemStream Serialize   |       1160 |  70   2   2 |   65223933 |
protobuf-net  | MemStream Deserialize |       1997 |  29  21   1 |            |
NetSerializer | NetTest               |        990 |  10   5   0 |            |
protobuf-net  | NetTest               |       6621 |  75  31   1 |            |

== 300000 ComplexMessage ==
NetSerializer | MemStream Serialize   |        401 |   0   0   0 |   22147415 |
NetSerializer | MemStream Deserialize |        788 |  15   9   0 |            |
protobuf-net  | MemStream Serialize   |        897 |  21   1   1 |   43046672 |
protobuf-net  | MemStream Deserialize |       2285 |  58  44   1 |            |
NetSerializer | NetTest               |       1110 |  16  13   0 |            |
protobuf-net  | NetTest               |       3853 |  65  27   2 |            |

== 200000 StringMessage ==
NetSerializer | MemStream Serialize   |        487 |  73   1   1 |  100256848 |
NetSerializer | MemStream Deserialize |        744 |  70  44   1 |            |
protobuf-net  | MemStream Serialize   |        479 |  14   1   1 |  101206237 |
protobuf-net  | MemStream Deserialize |        909 |  44  24   1 |            |
NetSerializer | NetTest               |       1101 | 120  65   1 |            |
protobuf-net  | NetTest               |       2283 |  47  27   1 |            |

== 5000 ByteArrayMessage ==
NetSerializer | MemStream Serialize   |        387 |   1   1   1 |  253320407 |
NetSerializer | MemStream Deserialize |        356 |  33  20   1 |            |
protobuf-net  | MemStream Serialize   |        789 | 170   5   3 |  253353761 |
protobuf-net  | MemStream Deserialize |        441 |  33  24   1 |            |
NetSerializer | NetTest               |       1300 |  34  22   1 |            |
protobuf-net  | NetTest               |       1285 |  83  34   3 |            |

== 800 IntArrayMessage ==
NetSerializer | MemStream Serialize   |       2040 |   1   1   1 |  198093146 |
NetSerializer | MemStream Deserialize |       1464 |   2   1   1 |            |
protobuf-net  | MemStream Serialize   |       2212 |  65   3   3 |  235691847 |
protobuf-net  | MemStream Deserialize |       1862 |  20   3   1 |            |
NetSerializer | NetTest               |       2220 |   3   2   1 |            |
protobuf-net  | NetTest               |       2906 |  76   6   3 |            |

As can be seen from the tests, NetSerializer is clearly faster and has smaller
memory footprint in about all of the cases. For example, the tests with
ComplexMessages show NetSerializer's MemStream Serialize cause zero garbage
collections, even though 22MB of data is being serialized.

The speed of the serializer depends, of course, very much on the data being
serialized. For some particular payloads it may well be that protobuf-net is
faster than NetSerializer. However, I believe that those cases can always be
optimized and in the end NetSerializer will be faster, due to the minimalistic
design of NetSerializer.