# Making a new SDK release

This guide shows how to make a new Perfetto SDK release.

Before snapshotting a release, check that no [release-blockers](http://b/savedsearches/5776355) are
open.

Check out the code:

```bash
git clone https://android.googlesource.com/platform/external/perfetto
cd perfetto
```

Next, decide the version number for the new release (vX.Y).
The major version number (X) is incremented on every release (monthly).
The minor version number is incremented only for minor changes / fixes on top of the monthly
release (cherry-picks on the releases/vN.x branch).

Continue with the appropriate section below.

## a) Creating a new major version

Make sure that the current master branch builds on
[LUCI](https://luci-scheduler.appspot.com/jobs/perfetto) by triggering all the
builds and waiting for their success. If any of the builds fail, fix the failure
on master before proceeding.

Create an entry in CHANGELOG with the new major version: this usually involves
renaming the "Unreleased" entry to the version number you chose earlier
([example](https://r.android.com/2417175)).

Test that the perfetto build tools can parse the CHANGELOG: after building,
running `perfetto --version` should show your new version number.

Upload the CHANGELOG change and submit it on the master branch.

Create a release branch for the new major version ("v16.x" here):

```bash
git fetch origin
git push origin origin/master:refs/heads/releases/v16.x
git fetch origin
git checkout -b releases/v16.x -t origin/releases/v16.x
```

Continue with [building the release](#building-and-tagging-the-release).

## b) Bumping the minor version

Check out the existing release branch ("5.x" here) and merge in the desired
revision for the new release, resolving any conflicts you may encounter.

```bash
git checkout -b releases/v16.x -t origin/releases/v16.x
```

If you only want to introduce one or two patches in the new release, consider
cherry-picking them individually:

```bash
git cherry-pick <sha1>
```

Otherwise, you can do a full merge:

```bash
git merge <sha1>
```

Update the CHANGELOG with a dedicated entry for the new minor version.
This is important because the
[write_version_header.py](/tools/write_version_header.py) script, which is
invoked by the build system, looks at the CHANGELOG to work out the latest
v${maj}.${min} version.

For an example see [r.android.com/1730332](https://r.android.com/1730332)

```txt
v16.1 - 2021-06-08:
  Tracing service and probes:
    * Cherry-pick of r.android.com/1716718 which missed the v16 branch ... .


v16.0 - 2021-06-01:
  ...
```

## Building and tagging the release

1. Generate and commit the amalgamated source files.

```bash
tools/gen_amalgamated --output sdk/perfetto
git add sdk/perfetto.{cc,h}
git commit -m "Amalgamated source for vX.Y"
```

2. Check that the SDK example code works with the new release.

```bash
cd examples/sdk
cmake -B build
cmake --build build
```

3. Upload the new release for review.

```bash
git cl upload --no-squash
```

If you get an error about a missing Change-Id field (`remote: ERROR: commit
a7c7c4c: missing Change-Id in message footer`), install the commit-msg hook
script and amend the change to make sure that field is present:

```bash
curl -Lo .git/hooks/commit-msg http://android-review.googlesource.com/tools/hooks/commit-msg
chmod u+x .git/hooks/commit-msg
git commit --amend
```

4. Once the release has been reviewed and landed, create and push the tag for
   it ("vX.Y" being the new version).

```bash
# This brings the branch up to date with the CL landed in the step above.
git pull

git status
# Should print: Your branch is up to date with 'origin/releases/v16.x'.
# Do NOT proceed if your branch has diverged from origin/releases/vX.X

git tag -a -m "Perfetto vX.Y" vX.Y
git push origin vX.Y
```

5. Update the documentation to point to the latest release.

   - [docs/instrumentation/tracing-sdk.md](/docs/instrumentation/tracing-sdk.md)
   - [examples/sdk/README.md](/examples/sdk/README.md)

6. Send an email with the CHANGELOG to perfetto-dev@ (internal) and to the
   [public perfetto-dev](https://groups.google.com/forum/#!forum/perfetto-dev).

## Creating a GitHub release with prebuilts

7. Within few mins the LUCI scheduler will trigger builds of prebuilt binaries
   on https://luci-scheduler.appspot.com/jobs/perfetto . Wait for all the bots
   to have completed successfully and be back into the WAITING state.

8. Run `tools/package-prebuilts-for-github-release vX.Y`. It will pull the
   prebuilts under `/tmp/perfetto-prebuilts-vX.Y`.
  - There must be 10 zips in total: linux-{arm,arm64,amd64},
    android-{arm,arm64,x86,x64}, mac-{amd64,arm64}, win-amd64.
  - If one or more are missing it means that one of the LUCI bots failed,
    check the logs (follow the "Task URL: " link) from the invocation log.
  - If this happens you'll need to respin a vX.(Y+1) release with the fix
    (look at the history v20.1, where a Windows failure required a respin).

9. Open https://github.com/google/perfetto/releases/new and
  - Select "Choose Tag" -> vX.Y
  - "Release title" -> "Perfetto vX.Y"
  - "Describe release" -> Copy the CHANGELOG, wrapping it in triple backticks.
  - "Attach binaries" -> Attach the ten .zip files from the previous step.

10. Run `tools/roll-prebuilts vX.Y`. It will update the SHA256 into the various
   scripts under `tools/`. Upload a CL with the changes.

11. Phew, you're done!