docs: Add guide on making a new SDK release

Also point the documentation to the latest release.

Change-Id: Iaa97401ea5456b55acbc9a17b551eb55a802207a

docs/contributing/sdk-releasing.md

diff --git a/docs/contributing/sdk-releasing.md b/docs/contributing/sdk-releasing.md
new file mode 100644
index 0000000..76e9ece
--- /dev/null
+++ b/docs/contributing/sdk-releasing.md
@@ -0,0 +1,111 @@
+# Making a new SDK release
+
+This guide shows how to make a new Perfetto SDK release.
+
+First, 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). In general minor
+updates should increment the minor version number (Y) while larger, more
+significant behavioral changes should be reflected in the major version
+number (X).
+
+Continue with the appropriate section below.
+
+## a) Creating a new major version
+
+Create a release branch for the new major version ("5.x" here) and merge in
+the code for the new release:
+
+```bash
+git fetch origin
+git push origin origin/master:refs/heads/releases/v5.x
+git fetch origin
+git checkout -b releases/v5.x -t origin/master
+git merge <sha1>
+```
+
+Continue with [building the release](#building-and-tagging-the-release).
+
+## b) Bumping the minor version
+
+Check out the existing release branch ("4.x" here) and merge in the desired
+revision for the new release, resolving any conflicts you may encounter.
+
+```bash
+git checkout -b releases/v4.x -t origin/releases/v4.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>
+```
+
+## 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](https://github.com/skyostil/perfetto-sdk-example) works with the new
+   release.
+
+```bash
+git clone https://github.com/skyostil/perfetto-sdk-example /tmp/perfetto-sdk-example
+cp -r sdk/ /tmp/perfetto-sdk-example/perfetto
+pushd /tmp/perfetto-sdk-example
+cmake -B build
+cmake --build build
+popd
+```
+
+3. Upload the new release for review.
+
+```bash
+git cl upload
+```
+
+4. Once the release has been reviewed and landed, create and push the tag for
+   it ("vX.Y" being the new version).
+
+```bash
+git tag -a -m "Perfetto vX.Y" vX.Y
+git push origin vX.Y
+```
+
+5. Roll the SDK example code to the new release.
+
+```bash
+pushd /tmp/perfetto-sdk-example
+rm -rf perfetto/sdk
+git submodule update --init --recursive
+cd perfetto
+git checkout vX.Y
+cd ..
+git add perfetto
+git commit -m "Roll to perfetto vX.Y"
+git push
+popd
+```
+
+6. Update [the documentation](../instrumentation/tracing-sdk.md) to point to the
+   latest release.
+
+Phew, you're done!

docs/instrumentation/tracing-sdk.md

diff --git a/docs/instrumentation/tracing-sdk.md b/docs/instrumentation/tracing-sdk.md
index 2efac8d..1c88946 100644
--- a/docs/instrumentation/tracing-sdk.md
+++ b/docs/instrumentation/tracing-sdk.md
@@ -30,7 +30,7 @@
 To start using the Client API, first check out the latest SDK release:
 
 ```sh
-git clone https://android.googlesource.com/platform/external/perfetto -b v3.1
+git clone https://android.googlesource.com/platform/external/perfetto -b v4.0
 ```
 
 The SDK consists of two files, `sdk/perfetto.h` and `sdk/perfetto.cc`. These are
@@ -391,4 +391,4 @@
 [ipc]: /docs/design-docs/api-and-abi.md#socket-protocol
 [atrace-ds]: /docs/data-sources/atrace.md
 [atrace-ndk]: https://developer.android.com/ndk/reference/group/tracing
-[atrace-sdk]: https://developer.android.com/reference/android/os/Trace
\ No newline at end of file
+[atrace-sdk]: https://developer.android.com/reference/android/os/Trace

docs/toc.md

diff --git a/docs/toc.md b/docs/toc.md
index f095fe4..03c2ad7 100644
--- a/docs/toc.md
+++ b/docs/toc.md
@@ -54,6 +54,7 @@
     * [Running tests](contributing/testing.md)
     * [Common tasks](contributing/common-tasks.md)
     * [Embedding Perfetto](contributing/embedding.md)
+    * [Releasing the SDK](contributing/sdk-releasing.md)
 
 * [Design documents](#)
     * [API and ABI surface](design-docs/api-and-abi.md)