perf: Remove costly reduce operation for generating Engine context

[MajorLift]

Overview

Optimizes an expensive operation from the Engine initialization process.

A custom span for measuring this process was added in #11579.

Motivation

Currently, the Engine's context object is created using a Array.prototype.reduce() operation on a large controllers array. This reduce call is also written to create a temporary object on every iteration.

Benchmarks show that this particular implementation of reduce runs significantly slower than other means of creating an object, and compared to reduce calls that are written to re-use the output object the difference is in four orders of magnitude (1555.6 Ops/sec vs. 0.2 Ops/sec).

https://www.measurethat.net/Benchmarks/Show/21554/0/objectfromentries-vs-reduce-vs-assign

A simple fix would be to refactor the reduce operation so it doesn't rely on temporary objects and spreading:

diff --git a/app/core/Engine.ts b/app/core/Engine.ts
index decf28da51..1ba63ed106 100644
--- a/app/core/Engine.ts
+++ b/app/core/Engine.ts
@@ -1738,10 +1738,10 @@ export class Engine {
       this.controllerMessenger,
     );
     this.context = controllers.reduce<Partial<typeof this.context>>(
-      (context, controller) => ({
-        ...context,
-        [controller.name]: controller,
-      }),
+      (context, controller) => {
+        context[controller.name] = controller;
+        return context;
+      },
       {},
     ) as typeof this.context;

However, we can also avoid the cost of running reduce altogether simply by creating a controller name-keyed object to assign to the Engine's context field. This is also the approach taken in the Extension MetamaskController.

Description

• Replaces controllers array in the Engine class with a corresponding object that is directly assigned to context.
• Optimize Object.values for deriving ComposableController input with Object.keys and reduce (re-uses object).

  https://www.measurethat.net/Benchmarks/Show/7173/0/objectvalues-vs-reduce

• Removes for-loop that sets initial state for V1 controllers now that all mobile controllers have been updated to V2.

Related issues

• Contributes to https://github.com/MetaMask/mobile-planning/issues/1095
• Related https://www.notion.so/metamask-consensys/Refactor-Engine-Init-to-only-include-minimum-controllers-for-logging-in-on-startup-23ee10636dcc44d480a93a63361abb5b

Manual testing steps

Screenshots/Recordings

Pre-merge author checklist

• I’ve followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• I've completed the PR template to the best of my ability
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

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[github-actions]

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[github-actions]

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✅✅✅ pr_smoke_e2e_pipeline passed on Bitrise! ✅✅✅

Commit hash: 0c662ae
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Note

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.

Project coverage is 56.46%. Comparing base (22a4989) to head (0c662ae).
Report is 29 commits behind head on main.

Files with missing lines	Patch %	Lines
app/core/Engine.ts	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12374      +/-   ##
==========================================
+ Coverage   56.41%   56.46%   +0.04%     
==========================================
  Files        1797     1808      +11     
  Lines       40586    40724     +138     
  Branches     5097     5131      +34     
==========================================
+ Hits        22896    22993      +97     
- Misses      16134    16159      +25     
- Partials     1556     1572      +16     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

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[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
87.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[tommasini]

LOVE IT! LGTM! So cool that we now only have base controllers v2 controllers!

[tommasini]

LOVE IT! LGTM! So cool that we now only have base controllers v2 controllers!

[Cal-L]

Left a comment

[Cal-L]

LGTM