capturedrefrace

README

gocapturedrefrace

An analyser that reports captured variable references in goroutine closures.

Goroutines that run function closures can capture reference variables from outer scopes which could lead to data races. This analyzer checks closures run by goroutines and reports uses of all variables declared in outer scopes, as well as arguments to the closure with a pointer type.

Example

Given the following program:

package main

func main() {}

type Record struct{}

func (r *Record) reticulateSplines() {}

type Spline struct {
	Curvature float64
}

func (r *Record) CapturedReference() {
	capturedReference := 0
	spline := &Spline{Curvature: 5.0}

	go func(s *Spline) {
		capturedReference += 1 // closure captures the variable
		// 'capturedReference' in a goroutine, which could
		// lead to data races

		if capturedReference > 0 {
			r.reticulateSplines() // goroutine closure captures 'r'
		}

		s.Curvature = 3.0 // 's' is a pointer type which could
		// lead to data races
	}(spline)
}

the analyser produces the following results:

$ gocapturedrefrace ./...
package_doc_example.go:17:10: reference s in goroutine closure
package_doc_example.go:18:3: captured reference capturedReference in goroutine closure
package_doc_example.go:22:6: captured reference capturedReference in goroutine closure
package_doc_example.go:23:4: captured reference r in goroutine closure

Install

$ go install gopkg.teddywing.com/capturedrefrace/cmd/gocapturedrefrace@latest

License

Copyright © 2023 Teddy Wing. Licensed under the GNU GPLv3+ (see the included COPYING file).

Documentation

Overview

Package capturedrefrace defines an Analyzer that checks for captured references in goroutine closures.

Analyzer capturedrefrace

capturedrefrace: report captured variable references in goroutine closures.

Goroutines that run function closures can capture reference variables from outer scopes which could lead to data races. This analyzer checks closures run by goroutines and reports uses of all variables declared in outer scopes, as well as arguments to the closure with a pointer type.

For example:

func (r *Record) CapturedReference() {
	capturedReference := 0
	spline := &Spline{Curvature: 5.0}

	go func(s *Spline) {
		capturedReference += 1 // closure captures the variable
			// 'capturedReference' in a goroutine, which could
			// lead to data races

		if capturedReference > 0 {
			r.reticulateSplines() // goroutine closure captures 'r'
		}

		s.Curvature = 3.0 // 's' is a pointer type which could
			// lead to data races
	}(spline)
}

Index

• Variables

Variables

var Analyzer = &analysis.Analyzer{
	Name:     "capturedrefrace",
	Doc:      "reports captured references in goroutine closures",
	Run:      run,
	Requires: []*analysis.Analyzer{inspect.Analyzer},
}