Speeding up decimal (de)serialization.

[stebet]

Proposed Changes

Serializing the decimal datatype allocates 40 bytes every time and deserializing it is sub-optimal. This optimization removes that allocation and speeds up (de)serializing decimal values

Types of Changes

What types of changes does your code introduce to this project?
Put an x in the boxes that apply

• Bug fix (non-breaking change which fixes issue #NNNN)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause an observable behavior change in existing systems)
• Documentation improvements (corrections, new content, etc)
• Cosmetic change (whitespace, formatting, etc)

Checklist

• I have read the CONTRIBUTING.md document
• I have signed the CA (see https://cla.pivotal.io/sign/rabbitmq)
• All tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in related repositories

Results

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.20270
Intel Core i7-10700 CPU 2.90GHz, 1 CPU, 16 logical and 8 physical cores
.NET Core SDK=5.0.101
  [Host]        : .NET Core 3.1.10 (CoreCLR 4.700.20.51601, CoreFX 4.700.20.51901), X64 RyuJIT
  .NET 4.8      : .NET Framework 4.8 (4.8.4261.0), X64 RyuJIT
  .NET Core 3.1 : .NET Core 3.1.10 (CoreCLR 4.700.20.51601, CoreFX 4.700.20.51901), X64 RyuJIT

Before

Method	Job	Mean	Error	StdDev	Gen 0	Gen 1	Gen 2	Allocated	Code Size
DecimalRead	.NET 4.8	21.939 ns	0.1721 ns	0.1526 ns	-	-	-	-	781 B
DecimalWrite	.NET 4.8	29.016 ns	0.0880 ns	0.0735 ns	0.0063	-	-	40 B	686 B
DecimalRead	.NET Core 3.1	5.785 ns	0.0151 ns	0.0133 ns	-	-	-	-	449 B
DecimalWrite	.NET Core 3.1	14.726 ns	0.2515 ns	0.2353 ns	0.0048	-	-	40 B	300 B

After

Method	Job	Mean	Error	StdDev	Gen 0	Gen 1	Gen 2	Allocated	Code Size
DecimalRead	.NET 4.8	12.192 ns	0.0406 ns	0.0360 ns	-	-	-	-	592 B
DecimalWrite	.NET 4.8	13.177 ns	0.1229 ns	0.1089 ns	-	-	-	-	659 B
DecimalRead	.NET Core 3.1	2.439 ns	0.0136 ns	0.0121 ns	-	-	-	-	227 B
DecimalWrite	.NET Core 3.1	3.068 ns	0.0142 ns	0.0126 ns	-	-	-	-	284 B

[bollhals]

I assume decimals aren't used as often, but the improvement is substantial nonetheless. 👍

[stebet]

I assume decimals aren't used as often, but the improvement is substantial nonetheless. 👍

I figured since it's a user-provided field, it might be used considerably in some cases (financial apps come to mind), so better to have most primitives as fast as possible.

[michaelklishin]

@stebet can you please rebase this on top of the current master?

[stebet]

Will do. Might not happen until Monday though.

[michaelklishin]

Sure, no rush :)

[stebet]

Sure, no rush :)

Done :)

[michaelklishin]

I assume this can be backported all the way to 6.x?

[stebet]

I assume this can be backported all the way to 6.x?

Yup :)