v8js

V8Js on GNU/Linux

Installation of V8Js on GNU/Linux is pretty much straight forward.

The biggest hurdle actually is that you need a rather new V8 library. However many distributions still ship the rusty version 3.14, published years ago.

This means that you usually need to compile V8 on your own before you can start to compile & install V8Js itself.

It is recommended to install the V8 version for V8Js off your system's load path, so it doesn't interfere with the V8 library shipped with your system's distribution.

Snapshots

V8 has (optional) support for so-called snapshots which speed up startup performance drastically. Hence they are generally recommended for use.

There are two flavours of snapshots: internal & external.

Internal snapshots are built right into the V8 library (libv8.so file), so there's no need to handle them specially.

Besides there are external snapshots (which are enabled unless configured otherwise). If V8 is compiled with these, then V8Js needs to provide two "binary blobs" to V8, named natives_blob.bin and snapshot_blob.bin. In that case copy those two files to the same directory libv8.so was installed to.

Pointer Compression

V8 versions 8.0 and higher enable pointer compression by default. See the design document for details.

Hence if you use one of the recent version (which you really should), then you

a) either need to manually disable pointer compression during

the build of the library by passing the
`v8_enable_pointer_compression=false` flag to `v8gen.py`

b) or compile php-v8js with pointer compression as well, by adding

`CPPFLAGS="-DV8_COMPRESS_POINTERS"` to the `./configure` call.

Compile V8 5.6 and newer (using GN)

# Install required dependencies
sudo apt-get install build-essential curl git python libglib2.0-dev

cd /tmp

# Install depot_tools first (needed for source checkout)
git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
export PATH=`pwd`/depot_tools:"$PATH"

# Download v8
fetch v8
cd v8

# (optional) If you'd like to build a certain version:
git checkout 8.0.426.30
gclient sync

# Setup GN
tools/dev/v8gen.py -vv x64.release -- is_component_build=true use_custom_libcxx=false

# Build
ninja -C out.gn/x64.release/

# Install to /opt/v8/
sudo mkdir -p /opt/v8/{lib,include}
sudo cp out.gn/x64.release/lib*.so out.gn/x64.release/*_blob.bin \
  out.gn/x64.release/icudtl.dat /opt/v8/lib/
sudo cp -R include/* /opt/v8/include/

On Debian Stretch you need to set RPATH on the installed libraries, so the library loader finds the dependencies:

sudo apt-get install patchelf
for A in /opt/v8/lib/*.so; do sudo patchelf --set-rpath '$ORIGIN' $A; done

Compile php-v8js itself

cd /tmp
git clone https://github.com/phpv8/v8js.git
cd v8js
phpize
./configure --with-v8js=/opt/v8 LDFLAGS="-lstdc++" CPPFLAGS="-DV8_COMPRESS_POINTERS"
make
make test
sudo make install

Then add extension=v8js.so to your php.ini file. If you have a separate configuration for CLI, add it there also.

V8Js' build system assumes that the icudtl.dat file is located next to the libv8.so library file and compiles the path into the library itself. If for whatever reason the icudtl.dat file is stored at a different place during runtime, you need to set the php.ini variable v8js.icudtl_dat_path to point to the file. Otherwise locale-aware features of V8 will not work as expected.