tracer

Simple error handling and stack traces for fast debugging. Error handling in go does not provide any tracing functionality out of the box. This makes error masking necessary so that you can comprehend what went wrong and why some problem occured. When you do not have any way to understand where along the code execution of your business logic an error occurred then debugging and fixing the root cause of a problem takes an unnecessary big amount of time. Therefore, using tracer errors can be masked and stack traces can be printed.

Errors And Matchers

A typical error.go in any package might look like the following example. Note a couple of best practices to align with for simplicity and consistency reasons.

• Keep error types private so that nobody outside your package can mess with it.
• Keep error matchers public so that anyone can match against your package errors.
• Keep the variable name and Kind consistent for easy tracking during debugging.
• Keep error matcher implementations simple by using errors.Is(a, b).
• Keep the order of errors and matchers alphabetical for easier navigation.

package foo

import (
	"errors"

	"github.com/xh3b4sd/tracer"
)

var invalidConfigError = &tracer.Error{
	Kind: "invalidConfigError",
}

func IsInvalidConfig(err error) bool {
	return errors.Is(err, invalidConfigError)
}

var notFoundError = &tracer.Error{
	Kind: "notFoundError",
}

func IsNotFound(err error) bool {
	return errors.Is(err, notFoundError)
}

Matching In Code

Below is a bad example to illustrate how not to do error handling.

return err

Below is a good example to illustrate how to do error handling.

return tracer.Mask(err)

Stack Trace Printing

Type *tracer.Error implements GoString() string so that fmt printing yields the JSON repesentation of the error instance at hand like the example shown below.

{
	"anno": "some useful annotation",
	"kind": "testError",
	"stck": [
		"--REPLACED--/json_test.go:111",
		"--REPLACED--/json_test.go:112"
	]
}

Use tracer.Panic(tracer.Mask(err)) in program entry points of command line tools in order to conveniently produce consistent error messages upon unexpected program failure.

func main() {
    err := mainE(context.Background())
    if err != nil {
        tracer.Panic(tracer.Mask(err))
    }
}

program panic at 2022-06-10 18:37:41.90837 +0000 UTC

    {
        "anno": "rpc error: code = Unavailable desc = connection error: desc = \"transport: Error while dialing dial tcp :7777: connect: connection refused\"",
        "stck": [
            "--REPLACED--/main.go:59",
            "--REPLACED--/main.go:23"
        ]
    }

exit status 1