libv8

A gem for distributing the v8 runtime libraries and headers in both source and binary form.

Why?

The goal of libv8 is two fold: provide a binary gem containing the a pre-compiled libv8.a for as many platforms as possible while at the same time supporting for an automated compilation for all others.

Not only does this drastically reduce gem install times, but it also reduces dependencies on the local machine receiving the gem. It also opens the door for supporting Windows.

Do I get a binary?

That depends on your platform. Right now, we support the following platforms.

• x86_64-darwin-16
• x86_64-darwin-15
• x86_64-darwin-14
• x86_64-linux
• x86-linux
• x86_64-freebsd-10
• x86_64-freebsd-11

If you don't see your platform on this list, first, make sure that it installs from source, and second talk to us about setting up a binary distro for you.

Note on OS X macOS binaries

If you're installing libv8 on a macOS system that is present in the list above, and despite that, RubyGems insists on downloading a source version and compiling it, check the output of ruby -e 'puts Gem::Platform.local'. If it does not reflect the current version of your OS, recompile Ruby.

The platform gets hardcoded in Ruby during compilation and if you've updated your OS since you've compiled Ruby, it does not represent correctly your current platform which leads to RubyGems trying to download a platform-specific gem for the older version of your OS.

Versioning

Versions of the libv8 gem track the version of V8 itself, adding its own point release after the main V8 version. So libv8 5.0.71.35.5 and 5.0.71.35.14 both correspond to V8 version 5.0.71.35. Another way to think about it would be that 5.0.71.35.14 is the 14th release of the libv8 rubygem based on V8 version 5.0.71.35

Source and Binary Releases

Starting with libv8 3.11.8.0, all even point releases contain only a source-based distribution, while odd point releases contain both a source-based distribution and binary distributions. However both point releases correspond to the exact underlying code. The only difference is the version number.

This way, the most recent version of the gem always has binary distributions, but if, for whatever reason, you have problems with the binaries, you can always "lock in" your dependency a single point version down, forcing it to compile from source.

So for example, 5.0.71.35.3 contains all the binary distributions, while 5.0.71.35.2 is the exact same code, but contain only a source-based distribution

This step release system is a workaround to carlhuda/bundler#1537

Use with different standard C libraries

The Linux binary versions of this gem are linked against the most used standard library - glibc. Currently rubygems has no mechanism to differentiate platform-specific gems by standard library so we have no way of distributing different binaries for different standard libraries.

What this means is that if you're running a distro that does not use glibc (like Alpine Linux), you'll have to use a source version of the gem.

Also, at the time of writing this, the Ruby version in Alpine's package repositories has been patched to not look to download binary versions of gems at all.

Requirements

Building the V8 library from source imposes the following requirements:

• A compiler that supports C++11 (such as GCC 4.8 and above or clang, preferably 3.5 and above)
• GNU Make
• Python 2

Using a git version

If you want to use the latest unstable version of the gem you can do so by specifying the git repo as a gem source. Just make sure you add the following to your Gemfile:

gem "libv8", github: "cowboyd/libv8", submodules: true

You can find more info on using a git repo as a gem source in Bundler's documentation.

What if I can't install from source?

If you can fix V8's build system so that it correctly compiles for your platform, we'll pull it right in!

To get the source, these commands will get you started:

git clone --recursive git://github.com/cowboyd/libv8.git
cd libv8
bundle install
bundle exec rake compile

Bring your own V8

This is a great way to ensure that the builds of all gems that depend on libv8 fail. Please see the Gotchas section below and use the follwing instructions only if you know what you're doing. If you're resorting to this because the build of the gem is failing on your system or because there's no platform-specific gem for your platform, please open up an issue.

Because libv8 is the interface for the V8 engine used by several gems, you may need to use libv8, even if you have V8 installed already. If you wish to use your own V8 installation, rather than have it built for you, use the --with-system-v8 option.

Using RubyGems:

gem install libv8 -- --with-system-v8

Using Bundler (in your Gemfile):

bundle config build.libv8 --with-system-v8

Gotchas

Please note that if you intend to run your own V8, you must install both V8 and its headers (found in libv8-dev for Debian-based distros).

Also, keep in mind that V8's API does not tend to be stable and in case you're using your local version of V8 you need to make sure that the the gems that depend on libv8 are compatible with the API of the version of V8 present on your system. Otherwise those gems' builds will fail. Ideally you want the same version of V8 as the one packaged in the installed version of the gem. See the Versioning section for more information.

Bring your own compiler

You can specify a compiler of your choice by either setting the CXX environment variable before compilation, or by adding the --with-cxx=<compiler> option to the bundle configuration:

bundle config build.libv8 --with-cxx=clang++

About

This project spun off of therubyracer which depends on having a specific version of V8 to compile and run against. However, actually delivering that version reliably to all the different platforms proved to be a challenge to say the least.

We got tired of waiting 5 minutes for V8 to compile every time we installed that gem.

Sponsored by

License

(The MIT License)

Copyright (c) 2009,2010 Charles Lowell

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.