go-bindings

README

Go bindings for UndoDB Live Recorder

The UndoDB Live Recorder allows recording of a running process for later playback in the Undo debugger.

There are two packages provided here: undolr and undoex.

undolr enables starting, stopping and saving recordings from directly within a Go program.

The undoex package allows insertion of annotations in to a recording, whether started via undolr or by running the program under Live Recorder. Note that the undoex package can be safely used when recording is not in use.

Delve support for Undo is current available in a fork of Delve. The intention is for support to eventually be merged in to the upstream project.

Building

Both packages use cgo to work with external libraries. These libraries (and the associated header files) can be obtained from Undo.

If the libraries and headers are not accessible via the standard paths then additional environment variables must be set to allow go to find them when building:

CGO_LDFLAGS=-L <path_to_undolr_libraries> -L <path_to_undoex_libraries>
CGO_CFLAGS=-I <path_to_undolr_headers> -I <path_to_undoex_headers>

In addition, the libraries will need to be on the library path:

LD_LIBRARY_PATH=<path_to_undolr_libraries>:<path_to_undoex_libraries>

The LD_LIBRARY_PATH will also need to be set when run, and the target system will need the relevant library.

Usage

The following snippet will start recording and insert an annotation. It then stops the recording and saves it in the background.

import (
	"github.com/undoio/go-bindings/undoex"
	"github.com/undoio/go-bindings/undolr"
	"time"
)

func Example_Annotation() {
	// Start a recording
	err := undolr.Start()
	if err != nil {
		panic(err)
	}

	// Add an annotation in the recording
	err = undoex.AnnotationAddInt("Example", "example annotation", 42)
	if err != nil {
		panic(err)
	}

	// Stop the recording process, defering Discard to clean up
	recContext, err := undolr.Stop()
	if err != nil {
		panic(err)
	}
	defer recContext.Discard()

	// We now have a recording context and we can save it as we please.
	// We save it via a goroutine here, so we could do other things while
	// the save continues in the background if we wanted.
	ch := make(chan error, 1)

	go recContext.SaveBackground("recording.undolr", ch)

	select {
	case err = <-ch:
		if err != nil {
			panic(err)
		}
	case <-time.After(time.Second * 30):
		panic("Save hadn't completed after 30 seconds")
	}
}

Further examples can be found within each package.