The openscreen library implements the Open Screen Protocol. Information about the protocol and its specification can be found on GitHub.
openscreen library dependencies are managed using
gclient, from the depot_tools repo.
To get gclient, run the following command in your terminal:
git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
Then add the
depot_tools folder to your
PATH environment variable.
Note that openscreen does not use other features of
drover. However, some
git-cl functions do work, like
git cl try,
git cl lint and
git cl upload.
From the parent directory of where you want the openscreen checkout, configure
gclient and check out openscreen with the following commands:
gclient config https://chromium.googlesource.com/openscreen gclient sync
Now, you should have
openscreen/ repository checked out, with all dependencies checked out to their appropriate revisions.
To update your local checkout from the openscreen master repository, just run
git pull gclient sync
This will rebase any local commits on the remote top-of-tree, and update any dependencies that have changed.
./tools/install-build-tools.sh from the root source directory to obtain a copy of the following build tools:
ninja will be installed in the repository root, which must be included in your
$PATH or the build will fail.
You also need to ensure that you have the compiler toolchain dependencies. Currently, both Linux and Mac OS X build configurations use clang by default.
On Linux, the build will automatically download the Clang compiler from the Google storage cache, the same way that Chromium does it.
Ensure that libstdc++ 8 is installed, as clang depends on the system instance of it. On Debian flavors, you can run:
sudo apt-get install libstdc++-8-dev
On Mac OS X, the build will use the clang provided by XCode, which must be installed.
gn argument “is_gcc=true” on Linux enables building using gcc instead. Note that g++ must be installed.
gn gen out/Default --args="is_gcc=true"
gn argument “is_debug=true” enables debug build.
gn gen out/Default --args="is_debug=true"
To install debug information for libstdc++ 8 on Debian flavors, you can run:
sudo apt-get install libstdc++6-8-dbg
gn args opens an editor that allows to create a list of arguments passed to every invocation of
gn args out/Default
The following commands will build a sample executable and run it.
mkdir out/Default gn gen out/Default # Creates the build directory and necessary ninja files ninja -C out/Default demo # Builds the executable with ninja ./out/Default/demo # Runs the executable
-C argument to
ninja works just like it does for GNU Make: it specifies the working directory for the build. So the same could be done as follows:
./gn gen out/Default cd out/Default ninja ./demo
After editing a file, only
ninja needs to be rerun, not
gn. If you have edited a
ninja will re-run
gn for you.
For details on running
demo, see its README.md.
ninja -C out/Default gn_all will build all non-test targets in the repository.
gn ls --type=executable out/Default/ will list all of the executable targets that can be built.
If you want to customize the build further, you can run
gn args out/Default to pull up an editor for build flags.
gn args --list out/Default prints all of the build flags available.
ninja -C out/Default unittests ./out/Default/unittests
openscreen uses LUCI builders to monitor the build and test health of the library. Current builders include:
|linux_debug||x86-64||Linux Ubuntu 16.04||clang||debug||ASAN enabled|
|linux_debug_gcc||x86-64||Linux Ubuntu 16.04||gcc||debug||ASAN enabled|
|mac_debug||x86-64||Mac OS X/Xcode||clang||debug|
You can run a patch through the try job queue (which tests it on all builders) using
git cl try, or through Gerrit (details below).
openscreen library code should follow the Open Screen Library Style Guide.
openscreen uses Chromium Gerrit for patch management and code review (for better or worse).
The following sections contain some tips about dealing with Gerrit for code reviews, specifically when pushing patches for review, getting patches reviewed, and committing patches.
git cl tool handles details of interacting with Gerrit (the Chromium code review tool) and is recommended for pushing patches for review. Once you have committed changes locally, simply run:
git cl upload
This will run our
PRESUBMIT.sh script to check style, and if it passes, a new code review will be posted on
If you make additional commits to your local branch, then running
git cl upload again in the same branch will merge those commits into the ongoing review as a new patchset.
It's simplest to create a local git branch for each patch you want reviewed separately.
git cl keeps track of review status separately for each local branch.
If conflicting commits have been landed in the repository for a patch in review, Gerrit will flag the patch as having a merge conflict. In that case, use the instructions above to rebase your commits on top-of-tree and upload a new patchset with the merge conflicts resolved.
CQ DRY RUN button (also, confusingly, labeled
COMMIT QUEUE +1) will run the current patchset through all LUCI builders and report the results. It is always a good idea get a green tryjob on a patch before sending it for review to avoid extra back-and-forth.
You can also run
git cl try from the commandline to submit a tryjob.
Send your patch to one or more committers in the COMMITTERS file for code review. All patches must receive at least one LGTM by a committer before it can be submitted.
After your patch has received one or more LGTM commit it by clicking the
SUBMIT button (or, confusingly,
COMMIT QUEUE +2) in Gerrit. This will run your patch through the builders again before committing to the main openscreen repository.
Currently, openscreen is also built in Chromium, with some build differences. The files that are built are determined by the following build variables:
truewhen building as part of a Chromium checkout,
falseotherwise. Set by
true. Controls whether the default mDNSResponder mDNS implementation is used. Set by
true. Controls whether the Chromium QUIC implementation clone is used. Set by