Media/WebRTC/Legacy Updating Process

Process: rough, can use fleshing out

Get a copy of a stable branch from the webrtc.org repository

• Make a local clone of the webrtc.org repository:
  

     git clone https://chromium.googlesource.com/external/webrtc

• Move into the new repository.
• Edit the file .git/config. In the [remote "origin"] section, add the line:
  

     fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*

• Save the file
• Run "git fetch". This will add references to the individual release branches.
• Run "git branch -r" to list the available branch heads. (If new branches are later added to the origin repository you will not see them unless you run git fetch.)
• Check out one of the branches. For example, for branch 49 you could run:
  

     git checkout -b rel49 branch-heads/49

(To pick up later updates to this branch, run git pull.)
Replace the old webrtc.org code with the new version

• rm -rf media/webrtc/trunk/webrtc
• cp -r somewhere/40/webrtc media/webrtc/trunk
• copy over any files in somewhere/40 to media/webrtc/trunk that are needed (few if any - DEPS, OWNERS, etc)
• rm -rf media/webrtc/trunk/webrtc/examples/ media/webrtc/trunk/webrtc/libjingle
• hg addremove --similarity 70 --dry-run media/webrtc/trunk/webrtc 2>&1 >/tmp/addremove.out
• look for any false positives on renames and fix them (perhaps by adding them to an --exclude list when doing the real addremove)
  • near-empty files often result in false renames
  • For 40, I had to use "--exclude media/webrtc/trunk/webrtc/modules/desktop_capture/mac/osx_version.h --exclude media/webrtc/trunk/webrtc/test/testsupport/android/root_path_android.cc --exclude media/webrtc/trunk/webrtc/voice_engine/output_mixer_unittest.cc"
• look for any false negatives (typically fiddle the '70') or correct by hand after - less critical
• hg revert files removed from media/webrtc/trunk/webrtc/modules/video_capture/windows/
  • do this before the real addremove! (can be undone later if needed)
• hg addremove --exclude <whatever> --similarity 70 media/webrtc/trunk/webrtc 2>&1 >/tmp/addremove.out
  • or you can --exclude the directory if there are no renames, adds or removals there
  • These are files we added to avoid including/using DirectShow/etc files from Microsoft examples
• hg qnew webrtc_revXXX -m "Bug xxxxxx: Webrtc updated to branch N.MM rev XXXX; pull made <date_from_/tmp/date>"
• hg qref
  • Not sure why this is needed, but it is
• hg qpop
• find the last update changeset - there will be two, one for landing the upstream code, one for the rollup of any changes
  • We'll call these revs "upstream_changeset" and "rollup_changeset"
• hg diff -r upstream_changeset media/webrtc/trunk/webrtc >/tmp/rollup.patch
• hg qpush
• hg qimport /tmp/rollup.patch
• hg qpush 2>&1 >/tmp/apply.out
• Have much fun resolving conflicts!
  • Watch for renamed files, or removed files with the code merged into others
  • I use an Emacs keyboard macro to go to the next file in apply.out with an error and pull it and the .rej file into emacs: Media/WebRTC/Updating_Process/merge.macro
• hg qnew rollup_fixes
  • don't merge them in yet to rollup, since likely you'll need to revise this for a while and it helps to see what your merge-resolution was
• do builds, resolve any errors, hg qref
• submit Try builds
• Go back and fix any android/b2g-specific files where we didn't merge the diffs earlier
• Test in person-to-person calls
  

Now groom for release when ready

• hg qpop -a
• record the current changeset from hg log ("old_head")
• hg pull -u
• hg diff -r old_head media/webrtc/trunk/webrtc >/tmp/updates
  • If empty, jump ahead to land (unlikely)
• hg qpush (hopefully shouldn't get conflicts -- should be webrtc_revXXXX)
• hg qpush (should be rollup.patch)
• hg qfold rollup_fixes (merges into rollup.patch)
• hg qimport /tmp/updates
• hg qpush
• resolve any conflicts
• build
• test
• hg qpop
• hg qfold updates
• Verify that there are no changes to media/webrtc/trunk/webrtc since the diff that generated /tmp/apply (hg qpop -a; hg log ("new_head"); hg pull -u; hg diff -r new_head -> should yield nothing)
• land

(incomplete, WIP)