codecgen

README

codecgen tool

Generate is given a list of *.go files to parse, and an output file (fout), codecgen will create an output file file.go which contains codec.Selfer implementations for the named types found in the files parsed.

Using codecgen is very straightforward.

Download and install the tool

go get -u github.com/hashicorp/go-msgpack/v2/codec/codecgen

Run the tool on your files

The command line format is:

codecgen [options] (-o outfile) (infile ...)

% codecgen -?
Usage of codecgen:
  -c="github.com/hashicorp/go-msgpack/v2/codec": codec path
  -o="": out file
  -r=".*": regex for type name to match
  -nr="": regex for type name to exclude
  -rt="": tags for go run
  -t="": build tag to put in file
  -u=false: Use unsafe, e.g. to avoid unnecessary allocation on []byte->string
  -x=false: keep temp file

% codecgen -o values_codecgen.go values.go values2.go moretypedefs.go

Please see the blog article for more information on how to use the tool.

Documentation

Overview

codecgen generates static implementations of the encoder and decoder functions for a given type, bypassing reflection, and giving some performance benefits in terms of wall and cpu time, and memory usage.

Benchmarks (as of Dec 2018) show that codecgen gives about

• for binary formats (cbor, etc): 25% on encoding and 30% on decoding to/from []byte
• for text formats (json, etc): 15% on encoding and 25% on decoding to/from []byte

Note that (as of Dec 2018) codecgen completely ignores

• MissingFielder interface (if you types implements it, codecgen ignores that)
• decode option PreferArrayOverSlice (we cannot dynamically create non-static arrays without reflection)

In explicit package terms: codecgen generates codec.Selfer implementations for a set of types.