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README

go-callvis

go-callvis is a development tool to help visualize call graph of a Go program using interactive view.

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Introduction

The purpose of this tool is to provide developers with a visual overview of a Go program using data from call graph and its relations with packages and types. This is especially useful in larger projects where the complexity of the code much higher or when you are just simply trying to understand code of somebody else.

Features

• focus specific package in the program
• group functions by package and/or methods by type
• filter packages to specific import path prefixes
• omit various types of function calls
• 💥 interactive view using HTTP server that serves SVG images containing URLs on packages to change focused package dynamically

Output preview

Check out the source code for the above image.

How it works

It runs pointer analysis to construct the call graph of the program and uses the data to generate output in dot format, which can be rendered with Graphviz tools.

Reference guide

Here you can find descriptions for various types of output.

Packages / Types

Represents	Style
focused	blue color
stdlib	green color
other	yellow color

Functions / Methods

Represents	Style
exported	bold border
unexported	normal border
anonymous	dotted border

Calls

Represents	Style
internal	black color
external	brown color
static	solid line
dynamic	dashed line
regular	simple arrow
concurrent	arrow with circle
deferred	arrow with diamond

Quick start

Requirements

• Go 1.8+
• Graphviz

Installation

go get -u github.com/TrueFurby/go-callvis
cd $GOPATH/src/github.com/TrueFurby/go-callvis && make

Usage

go-callvis [flags] <main package>

This will start HTTP server listening at http://localhost:7878/. You can change it via -http flag.

Flags

-focus string
      Focus package with import path or name. (default: main)
-group string
    Grouping functions by packages and/or types. [pkg, type] (separated by comma)
-http string
	HTTP service address. (default ":7878")
-limit string
    Limit package paths to prefix. (separated by comma)
-ignore string
    Ignore package paths with prefix. (separated by comma)
-include string
   	Include package paths with given prefixes (separated by comma)
-nointer
	Omit calls to unexported functions.
-nostd
	Omit calls to/from packages in standard library.
-tags build tags
	a list of build tags to consider satisfied during the build.
-tests
	Include test code.

Run go-callvis -h to list all supported flags.

Examples

Here is an example for the project syncthing.

Check out more examples and used command options.

Community

Join #go-callvis channel at gophers.slack.com. (not a member yet? get invitation)

How to help

Did you find any bugs or have some suggestions?

• Feel free to open new issue or start discussion in the slack channel.

Do you want to contribute to the project?

• Fork the repository and open a pull request. Here you can find TODO features.

Known Issues

Each execution takes a lot of time, because currently:

• the call graph is always generated for the entire program
• there is yet no caching of call graph data

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Roadmap

The interactive tool described below has been published as a separate project called goexplorer!

Ideal goal of this project is to make web app that would locally store the call graph data and then provide quick access of the call graphs for any package of your dependency tree. At first it would show an interactive map of overall dependencies between packages and then by selecting particular package it would show the call graph and provide various options to alter the output dynamically.

Documentation

Overview

go-callvis: a tool to help visualize the call graph of a Go program.