Watch your Manifest. Lin Wang | Android Efficiency Engineer | by Pinterest Engineering | Pinterest Engineering Weblog | Oct, 2022

Lin Wang | Android Efficiency Engineer

Black magnifying glass with “</” inside of the glass portion and “manifest >” to the right of the magnifying glass

It’s a widely known truth for Android builders that an app’s manifest (AndroidManifest.xml) holds essential software declarations. It’s hardly ever monitored after being arrange as a result of we assume it infrequently modifications. At Pinterest, nevertheless, we now have been actively monitoring the manifest after realizing it does change from time to time.

Whereas constructing an app, Gradle downloads all of the dependent libraries to compile and hyperlink them with the app. These dependent libraries every have their very own mini manifest. Throughout the construct course of, Android Gradle Plugin (AGP) merges them with the app’s principal manifest to kind the ultimate manifest. Due to this merging course of, the ultimate manifest usually seems fairly completely different from the unique one and comprises extra declarations. Generally, these additional declarations are needed for dependent libraries to perform. Nevertheless, typically they’ll have unintended behaviors.

It first caught our consideration throughout a chilly begin regression investigation. We discovered a third celebration Software program Improvement Equipment (SDK) declaring a particular ContentProvider in its manifest to heat up itself as early as attainable. It is because content material suppliers get initialized very early through the software startup, even earlier than the Utility’s onCreate() technique is invoked. Nevertheless, we need to management each third celebration libraries’ initialization and solely initialize them when it’s needed. Subsequently, we added the next declaration:

<provider android:name=”com.company.SdkEarlyInitializer” … other android properties … tools:node=”remove”/>

Including this declaration to the manifest will trigger the SdkEarlyInitializer to be faraway from the ultimate merged manifest. This alteration resulted in a chilly begin enchancment of 130ms.

From then on, we created the next course of to frequently monitor the merged manifest modifications earlier than touchdown a commit, beginning with taking a snapshot of the present merged manifest and conserving it within the codebase:

  1. As a part of the PR construct, we evaluate the merged manifest in opposition to the snapshot.
  2. If a distinction is detected, we fail the construct.
  3. The PR developer should then modify the snapshot manifest if the modifications are needed, or add the correct “take away” tags to maintain the brand new parts out of the ultimate manifest.

A small group of blocking reviewers will evaluate each manifest change.

  • Found the WorkManagerInitializer (ContentProvider), which was added by the work supervisor library. We firstly eliminated it and notified Google, who finally added assist for initializing the work supervisor with a custom configuration.
  • Discovered a brand new intent was added by upgrading of the exoplayer library to 2.15.0. We then contributed to the continuing issue discussion with Google to lastly have this pointless intent eliminated.
  • Detected the AD_ID permission was added by a library.
  • The common cshell diff is ample to check manifests
  • AGP does typically reorder the gadgets in manifest with out altering the content material, by which case the snapshot must be adjusted
  • Ignoring white areas and newlines is important
  • Incessantly modified gadgets within the manifest have to be explicitly ignored (e.g. UUIDs, model codes)

With this method, we might be alerted when any new part will get added to our app and really feel extra assured each time we add new dependencies.

Android Efficiency Crew: Arun Ok, Ernesto Duhart, Lin Wang, Sheng Liu, Tom Harman

Particular Thanks: Sha Sha Chu (She Her)

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