fabric

Package errors

The errors package is an enhancement of Go’s standard errors package. It augments the standard error to capture and print stack traces. For this purpose, it overrides the standard errors.New method and adds a new errors.Newf (in lieu of fmt.Errorf).

import "github.com/microbus-io/errors"

err := errors.New("my error") // err is augmented with the stack trace of this line
err = errors.Newf("error in process '%s'", processName) // err is augmented with the stack trace of this line

Note how it seamlessly replaces the standard import "errors" with import "github.com/microbus-io/errors". That is made possible because github.com/microbus-io/errors redefines all the constructs in errors.

If a standard error was created by an unaware function, errors.Trace is used to augment it with the stack trace

import "github.com/microbus-io/errors"

body, err := io.ReadAll("non/existent.file") // err is a standard Go error
err = errors.Trace(err) // err is now augmented with the stack trace of this line

HTTP status codes can be attached to errors by using errors.Newc, or by converting the error to the underlying *TracedError manually, or with errors.Convert. The status code is returned to upstream clients.

notFound := errors.Newc(http.StatusNotFound, "nothing to see here")

body, err := io.ReadAll("non/existent.file") // err is a standard Go error
err = errors.Trace(err) // err is now augmented with the stack trace of this line
errors.Convert(err).StatusCode = http.StatusNotFound
// or
err.(*errors.TracedError).StatusCode = http.StatusNotFound

The fmt verb %v is equivalent to err.Error() and prints the error message. The extended verb %+v is equivalent to errors.Convert(err).String() and also print the stack trace.

strconv.ParseInt: parsing "nan": invalid syntax
[400]

- calculator.(*Service).Square
  /src/github.com/microbus-io/fabric/examples/calculator/service.go:75
- connector.(*Connector).onRequest
  /src/github.com/microbus-io/fabric/connector/messaging.go:225
- connector.(*Connector).Publish
  /src/github.com/microbus-io/fabric/connector/messaging.go:94
- httpingress.(*Service).ServeHTTP
  /src/github.com/microbus-io/fabric/coreservices/httpingress/service.go:124

CatchPanic is a utility function that converts panics into standard errors. It is used to wrap callbacks to user code.

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