feat(AssetsController): Measure intial fetch duration by Kriys94 · Pull Request #7871 · MetaMask/core

Kriys94 · 2026-02-09T13:05:34Z

Explanation

Current state / why change: AssetsController runs an initial asset fetch when the user unlocks the wallet or when the app opens. There is no way to report how long that first fetch takes to our analytics. We need to measure this (InitMetrics) so we can track performance in MetaMetrics and spot regressions or improvements in the assets pipeline.
Solution / how it works: An optional trackMetaMetricsEvent callback was added to the AssetsController constructor. When the first init/fetch completes (after unlock or app open), the controller invokes this callback once per session with a payload: durationMs (wall-clock duration in ms), chainIds (requested chains, e.g. ['eip155:1', 'eip155:137']), and durationByDataSource (exclusive latency per data source, same order as the middleware chain). A new type AssetsControllerFirstInitFetchMetaMetricsPayload was added and exported so consumers can type the callback. The callback is only fired once per “session”; the internal “reported” flag is reset in #stop() (e.g. on lock), so the next unlock can trigger the event again. Consumers (e.g. the extension) can pass a callback that forwards this payload to MetaMetricsController; the controller does not depend on MetaMetrics directly.
Non-obvious changes: durationByDataSource is exclusive latency per data source (sum approximates durationMs). This allows downstream analytics to see which data sources contribute most to init time.
Other packages / dependency upgrades: None; changes are confined to @metamask/assets-controller.

References

(Add issue numbers or related PRs if applicable; e.g. Fixes #XXXX, or link to extension/mobile PR that wires up trackMetaMetricsEvent.)

Checklist

I've updated the test suite for new or updated code as appropriate
I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
I've communicated my changes to consumers by updating changelogs for packages I've changed
I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

Note

Medium Risk
Touches the core asset fetch pipeline and start/stop lifecycle by refactoring middleware execution and adding new timing/analytics hooks, which could affect initial fetch behavior and ordering if incorrect.

Overview
Adds an optional trackMetaMetricsEvent callback to AssetsController that fires once per unlock/app-open session after the first getAssets({ forceUpdate: true }) completes, reporting total duration, requested chainIds, and a per-source durationByDataSource breakdown.

To support this, middleware execution is refactored to accept sources with getName() and to measure/return exclusive timings per data source/middleware; TokenDataSource, DetectionMiddleware, and PriceDataSource now expose getName() (and PriceDataSource no longer relies on an instance name field). Tests and exports are updated, and the “first init reported” flag resets on #stop() (lock) so the metric can be emitted again next session.

^{Written by Cursor Bugbot for commit 01f41a9. This will update automatically on new commits. Configure here.}

cursor · 2026-02-13T08:33:54Z

packages/assets-controller/src/AssetsController.ts

      hasPriceSubscription: this.#activeSubscriptions.has('ds:PriceDataSource'),
    });

+    this.#firstInitFetchReported = false;


Session metric resets on preference toggle

Medium Severity

#firstInitFetchReported is reset inside #stop(), but #stop() is also called by handleBasicFunctionalityChange(). That allows trackMetaMetricsEvent to fire again without a lock/unlock cycle, so the “first init fetch once per session” guarantee in AssetsController can be violated.

Additional Locations (1)

packages/assets-controller/src/AssetsController.ts#L1459-L1460

This is not a problem

packages/assets-controller/src/AssetsController.ts

salimtb · 2026-02-13T10:07:29Z

packages/assets-controller/src/AssetsController.ts

+ */
+export type AssetsControllerFirstInitFetchMetaMetricsPayload = {
+  /** Duration of the first init fetch in milliseconds (wall-clock). */
+  durationMs: number;


is this a duration for all fetch we do ?

salimtb · 2026-02-13T10:07:40Z

packages/assets-controller/src/AssetsController.ts

+   * Exclusive latency in ms per data source (time spent in that source only).
+   * Sum of values approximates durationMs. Order: same as middleware chain.
+   */
+  durationByDataSource: Record<string, number>;


and i guess this is duration per data source

salimtb · 2026-02-13T10:08:27Z

packages/assets-controller/src/AssetsController.ts

+  ) => void;
+
+  /** Whether we have already reported first init fetch for this session (reset on #stop). */
+  #firstInitFetchReported = false;


what this means ? is this reset after each open/close of the app or when the background stop and restart ?

salimtb

approving this PR , but it will be great if you can create a preview build and test it on the UI

Prithpal-Sooriya · 2026-02-13T10:14:53Z

packages/assets-controller/src/data-sources/PriceDataSource.ts

  readonly name = CONTROLLER_NAME;

+  getName(): string {
+    return this.name;
+  }


nit - thoughts on.

Making the name a static property, we never override this so it can remain static.

We can then remove the method since we can grab the name from the static class.

export class PriceDataSource { static readonly controllerName = CONTROLLER_NAME } // Elsewhere const foo = PriceDataSource.controllerName

Or... technically you don't need a name right? Since the class prototype already takes the name of the class?

// The class prototype already has a name of 'PriceDataSource' export class PriceDataSource { } // Elsewhere const foo = PriceDataSource.name

Okay, I see the implementation below, we want instances to grab the name. Still we can clean this method up by making it point to the static fields (instead of creating a name for every instantiation?)

getName(): string { return PriceDataSource.controllerName } // or use Class name prototype getName(): string { return PriceDataSource.name }

Done thanks :)

Kriys94 · 2026-02-13T12:17:08Z

approving this PR , but it will be great if you can create a preview build and test it on the UI

Yeah I've tested it with MetaMask/metamask-extension#40087

cursor

Cursor Bugbot has reviewed your changes and found 1 potential issue.

cursor · 2026-02-13T15:08:25Z

packages/assets-controller/src/AssetsController.ts

+          durationMs,
+          chainIds,
+          durationByDataSource,
+        });


Stale fetch can misreport session metric

Medium Severity

trackMetaMetricsEvent is emitted based only on #firstInitFetchReported, with no guard that the fetch still belongs to the active session. If #stop() runs while a prior getAssets(..., forceUpdate) is still in flight, that stale fetch can report after stop and set the flag, skewing session attribution and suppressing the next real init metric.

Additional Locations (1)

packages/assets-controller/src/AssetsController.ts#L1436-L1437

## Explanation  * **Current state / why change:** AssetsController runs an initial asset fetch when the user unlocks the wallet or when the app opens. There is no way to report how long that first fetch takes to our analytics. We need to measure this (InitMetrics) so we can track performance in MetaMetrics and spot regressions or improvements in the assets pipeline. * **Solution / how it works:** An optional `trackMetaMetricsEvent` callback was added to the AssetsController constructor. When the **first** init/fetch completes (after unlock or app open), the controller invokes this callback once per session with a payload: `durationMs` (wall-clock duration in ms), `chainIds` (requested chains, e.g. `['eip155:1', 'eip155:137']`), and `durationByDataSource` (exclusive latency per data source, same order as the middleware chain). A new type `AssetsControllerFirstInitFetchMetaMetricsPayload` was added and exported so consumers can type the callback. The callback is only fired once per “session”; the internal “reported” flag is reset in `#stop()` (e.g. on lock), so the next unlock can trigger the event again. Consumers (e.g. the extension) can pass a callback that forwards this payload to MetaMetricsController; the controller does not depend on MetaMetrics directly. * **Non-obvious changes:** `durationByDataSource` is exclusive latency per data source (sum approximates `durationMs`). This allows downstream analytics to see which data sources contribute most to init time. * **Other packages / dependency upgrades:** None; changes are confined to `@metamask/assets-controller`. ## References  * (Add issue numbers or related PRs if applicable; e.g. Fixes #XXXX, or link to extension/mobile PR that wires up `trackMetaMetricsEvent`.) ## Checklist - [ ] I've updated the test suite for new or updated code as appropriate - [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate - [ ] I've communicated my changes to consumers by [updating changelogs for packages I've changed](https://github.com/MetaMask/core/tree/main/docs/processes/updating-changelogs.md) - [ ] I've introduced [breaking changes](https://github.com/MetaMask/core/tree/main/docs/processes/breaking-changes.md) in this PR and have prepared draft pull requests for clients and consumer packages to resolve them  --- > [!NOTE] > **Medium Risk** > Touches the core asset fetch pipeline and start/stop lifecycle by refactoring middleware execution and adding new timing/analytics hooks, which could affect initial fetch behavior and ordering if incorrect. > > **Overview** > Adds an optional `trackMetaMetricsEvent` callback to `AssetsController` that fires **once per unlock/app-open session** after the first `getAssets({ forceUpdate: true })` completes, reporting total duration, requested `chainIds`, and a per-source `durationByDataSource` breakdown. > > To support this, middleware execution is refactored to accept sources with `getName()` and to measure/return exclusive timings per data source/middleware; `TokenDataSource`, `DetectionMiddleware`, and `PriceDataSource` now expose `getName()` (and `PriceDataSource` no longer relies on an instance `name` field). Tests and exports are updated, and the “first init reported” flag resets on `#stop()` (lock) so the metric can be emitted again next session. > > <sup>Written by [Cursor Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit 01f41a9. This will update automatically on new commits. Configure [here](https://cursor.com/dashboard?tab=bugbot).</sup>

Kriys94 force-pushed the feature/InitMetrics branch 2 times, most recently from 6ce09f9 to ddf7448 Compare February 13, 2026 08:22

Kriys94 marked this pull request as ready for review February 13, 2026 08:31

Kriys94 requested review from a team as code owners February 13, 2026 08:31

cursor bot reviewed Feb 13, 2026

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salimtb reviewed Feb 13, 2026

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salimtb previously approved these changes Feb 13, 2026

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Prithpal-Sooriya reviewed Feb 13, 2026

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feat(AssetsController): Measure intial fetch duration

06eb670

Kriys94 dismissed salimtb’s stale review via 06eb670 February 13, 2026 12:16

Kriys94 force-pushed the feature/InitMetrics branch from ddf7448 to 06eb670 Compare February 13, 2026 12:16

salimtb previously approved these changes Feb 13, 2026

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Merge branch 'main' into feature/InitMetrics

01f41a9

Kriys94 dismissed salimtb’s stale review via 01f41a9 February 13, 2026 15:05

salimtb approved these changes Feb 13, 2026

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Kriys94 added this pull request to the merge queue Feb 13, 2026

Merged via the queue into main with commit 731cd2c Feb 13, 2026
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Kriys94 deleted the feature/InitMetrics branch February 13, 2026 15:11

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Kriys94 commented Feb 9, 2026 • edited by cursor bot Loading Uh oh! There was an error while loading. Please reload this page.

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Explanation

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Session metric resets on preference toggle

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Prithpal-Sooriya Feb 13, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Kriys94 commented Feb 13, 2026

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Stale fetch can misreport session metric

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Kriys94 commented Feb 9, 2026 •

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