Folly: Facebook Open-source Library
Folly (acronymed loosely after Facebook Open Source Library) is a library of C++11 components designed with practicality and efficiency in mind. Folly contains a variety of core library components used extensively at Facebook. In particular, it's often a dependency of Facebook's other open source C++ efforts and place where those projects can share code.
It complements (as opposed to competing against) offerings
such as Boost and of course
std. In fact, we embark on defining our
own component only when something we need is either not available, or
does not meet the needed performance profile. We endeavor to remove
things from folly if or when
std or Boost obsoletes them.
Performance concerns permeate much of Folly, sometimes leading to
designs that are more idiosyncratic than they would otherwise be (see
SmallLocks.h). Good performance at large
scale is a unifying theme in all of Folly.
Folly is a collection of relatively independent components, some as simple as a few symbols. There is no restriction on internal dependencies, meaning that a given folly module may use any other folly components.
All symbols are defined in the top-level namespace
folly, except of
course macros. Macro names are ALL_UPPERCASE and should be prefixed
folly defines other internal namespaces
detail. User code should not depend on symbols
in those namespaces.
Folly has an
experimental directory as well. This designation connotes
primarily that we feel the API may change heavily over time. This code,
typically, is still in heavy use and is well tested.
At the top level Folly uses the classic "stuttering" scheme
folly/folly used by Boost and others. The first directory serves as
an installation root of the library (with possible versioning a la
folly-1.0/), and the second is to distinguish the library when
including files, e.g.
The directory structure is flat (mimicking the namespace structure),
i.e. we don't have an elaborate directory hierarchy (it is possible
this will change in future versions). The subdirectory
contains files that are used inside folly and possibly at Facebook but
not considered stable enough for client use. Your code should not use
folly/experimental lest it may break when you update Folly.
folly/folly/test subdirectory includes the unittests for all
components, usually named
ComponentXyzTest.cpp for each
folly/folly/docs directory contains
What's in it?
Because of folly's fairly flat structure, the best way to see what's in it
is to look at the headers in top level
folly/ directory. You can also
docs folder for documentation, starting with the
Folly is published on Github at https://github.com/facebook/folly
folly requires gcc 4.8+ and a version of boost compiled with C++11 support.
Please download googletest from https://github.com/google/googletest/archive/release-1.7.0.zip and unzip it in the folly/test subdirectory.
This release is old, requiring many upgrades. However, since Travis CI runs
folly/build/deps_ubuntu_12.04.sh is provided, and upgrades all
the required packages.
The following packages are required (feel free to cut and paste the apt-get command below):
sudo apt-get install \ g++ \ automake \ autoconf \ autoconf-archive \ libtool \ libboost-all-dev \ libevent-dev \ libdouble-conversion-dev \ libgoogle-glog-dev \ libgflags-dev \ liblz4-dev \ liblzma-dev \ libsnappy-dev \ make \ zlib1g-dev \ binutils-dev \ libjemalloc-dev \ libssl-dev
If advanced debugging functionality is required
sudo apt-get install \ libunwind8-dev \ libelf-dev \ libdwarf-dev
Ubuntu 14.04 LTS
The packages listed above for Ubuntu 13.10 are required, as well as:
sudo apt-get install \ libiberty-dev
The above packages are sufficient for Ubuntu 13.10 and Ubuntu 14.04.
In the folly directory, run
autoreconf -ivf ./configure make make check sudo make install
OS X (Homebrew)
folly is available as a Formula and releases may be built via
brew install folly.
You may also use
folly/build/bootstrap-osx-homebrew.sh to build against
cd folly ./build/bootstrap-osx-homebrew.sh
OS X (MacPorts)
Install the required packages from MacPorts:
sudo port install \ autoconf \ automake \ boost \ gflags \ git \ google-glog \ libevent \ libtool \ lz4 \ lzma \ scons \ snappy \ zlib
Download and install double-conversion:
git clone https://github.com/google/double-conversion.git cd double-conversion cmake -DBUILD_SHARED_LIBS=ON . make sudo make install
Download and install folly with the parameters listed below:
git clone https://github.com/facebook/folly.git cd folly/folly autoreconf -ivf ./configure CPPFLAGS="-I/opt/local/include" LDFLAGS="-L/opt/local/lib" make sudo make install
Other Linux distributions
Download and build double-conversion. You may need to tell configure where to find it.
ln -s src double-conversion
./configure LDFLAGS=-L$DOUBLE_CONVERSION_HOME/ CPPFLAGS=-I$DOUBLE_CONVERSION_HOME/
additional platform specific dependencies:
Fedora 21 64-bit