A Brief Overview of Go

Goals

• introduction to the go programming language (golang) for developers familiar with other languages
• from practitioners for practitioners
• a little bit of the history of go, comparison with other languages (chart)
• many tiny fully self-contained coding examples to exemplify common coding patterns and pitfalls in golang
• distilled version: save you time reading a thick textbook or watch hours of tutorials (maybe)
• focus on relevant features and examples

Resources

Golang Core

• Go Playground https://go.dev/play/
• A Tour Of Go https://go.dev/tour/list
• Go By Example https://gobyexample.com/
• How to write Go code https://go.dev/doc/code
• Effective Go https://go.dev/doc/effective_go
• Go Blog https://go.dev/blog/strings
• Downloads https://go.dev/dl/

Talks

• Rob Pike, Lexical Scanning in Go (channels) - https://www.youtube.com/watch?v=HxaD_trXwRE
• Liz Rice, Building a container from scratch in Go (unix system commands) - https://www.youtube.com/watch?v=Utf-A4rODH8

The Language - Syntax and Concepts

• simplicity - simple, concise and C-inspired syntax
• shadowing - shadowing variables based on scope
• interface - interface, type casts and type conversions, no generics
• pointers - pointers work very much like they do in C
• functional - functional programming
• variadic - introduction to variadic functions
• defer - use defer when you don't want to forget to clean up
• panic - recover from panics
• mapsandslices - basic operations with maps and slices
• safemap - a thread safe map implementation
• jsoninjsonout - parse and serialize json payloads
• duck - duck typing, no need to explicitly declare which interfaces are implemented
• composition - composition over inheritance
• oop - limitations regarding overriding functions, workaround using functional programming
• concurrency - use go routines for concurrent execution
• channel - creative use of goroutines and channels
• workerpool - combine go routines with go channels to send jobs to workers in a pool
• fanoutfanin - use worker pool to fan-out work and main thread to fan-in results
• producerconsumer / producer sends work to consumer via channel
• packages - importing and using packages, packages live inside a directory, everything uppercase is visible from outside the package
• module - manage package versions and dependencies

Patterns

• aws - use aws sdk to interact with amazon web services
• options - functional options
• context - use go context to manage lifecycle of long-running tasks with cancel and / or timeout
• errors - errors.As(), errors.Is()
• tinywebservice - a tiny web service using the http package from the standard library
• controlc - capture ctrl-c OS signal, then wait for all goroutines to finish
• shell execute shell command
• shellong execute long running shell command
• File I/O and HTTP
• init function
• Commandline parameters

Frameworks for Building RESTful Web Services

• webservice - building REST APIs using viper, cobra, gorilla mux, zerolog and other frameworks

Useful Libraries

• https://github.com/aws/aws-sdk-go-v2 - AWS SDK
• https://github.com/IBM/sarama - Kafka library
• https://github.com/rs/zerolog - structured logging
• https://github.com/gorilla/mux - http web services
• https://github.com/spf13/cobra - cli commands
• https://github.com/spf13/viper - configuration

Special Features

• embed - embed files in go binary with //go:embed
• cgo - use cgo to call C library functions

The Tool Chain

Packages, Modules and go mod

go mod init

go mod tidy

go get somedomain.com/somepackage

Go Build

go build

Cross-Compiling

GOOS=linux GOARCH=arm go build -o myprogram myprogram.go

Go Test

https://www.digitalocean.com/community/tutorials/how-to-write-unit-tests-in-go-using-go-test-and-the-testing-package

Unit Tests

unittest

go test -v

https://pkg.go.dev/testing

Benchmarks

go test -bench=.

Note: Runtime of benchmarked function must converge!

https://dave.cheney.net/2013/06/30/how-to-write-benchmarks-in-go

Race Conditions

go test -race

Golden Files

goldie - easy testing with golden files

https://github.com/sebdah/goldie

Mock Services

Table Driven Testing

Linter

linter

go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest

golangci-lint run

https://golangci-lint.run/usage/configuration/#config-file

Profiling

pprof - use pprof for heap profiling etc

Profile interactively for example with

go tool pprof http://localhost:8080/debug/pprof/heap

then use web command.

https://jvns.ca/blog/2017/09/24/profiling-go-with-pprof/

Go Releaser

Go Generate

Misc

• Core features
  • compiled
  • statically typed
  • garbage collected
  • statically linked
  • C-style pointers
  • no objects (structs and composition instead)
  • no generics
  • no method overloading
  • conventions (tests, exported functions, init function etc.)
• Strong support for concurrency built in (channels and concurrent execution as first class object, suited for multi-core architectures)
• History of golang and resources, Rob Pike et al.
• "Young" language
• Easy to transition, especially if you know a little about C (structs, pointers)
• Intellij Goland and debugging with https://github.com/go-delve/delve
• Semantic versioning