Select blob source by priority and weighted random by tonidero · Pull Request #3458 · RevenueCat/purchases-android

tonidero · 2026-05-08T14:13:40Z

Motivation

RemoteConfigManager.refresh was hardcoded to pick blobSources.firstOrNull() with a WIP: comment. The backend already returns priority and weight on each source, so this PR wires up the real selection logic.

Description

Highest priority value wins.

Among sources tied at the top priority, pick one with weighted random using weight:

total = sum(weights)
r = random(0, total)
cumulative = 0
for source in candidates:
    cumulative += source.weight
    if r < cumulative: return source

Fallback to uniform random when all top-priority weights are zero (or any of them are negative, defensively).
Selection extracted into a WeightedSource interface + List<T>.selectWeighted(Random) extension so the same algorithm can later be reused for ApiSource (which has the same priority/weight shape).
RemoteConfigManager now takes an injectable Random (defaulted to Random.Default) for deterministic unit tests.

Test plan

New WeightedSourceSelectionTest covers: empty list, single source with zero weight, priority dominance, weighted-pick boundary cases (r=0, r=29, r=30, r=99 for weights [30, 70]), zero-weight uniform fallback, negative-weight uniform fallback.
RemoteConfigManagerTest updated: existing multi-source test relaxed to assert delegation; new test asserts the highest-priority source is selected through the manager.
./gradlew :purchases:testDefaultsBc8DebugUnitTest --tests "com.revenuecat.purchases.common.remoteconfig.*" passes.
./gradlew detektAll passes.

Note

Medium Risk
Changes remote-config blob source selection from deterministic first-item to priority/weight-based randomness, which can affect which CDN/source is used in production. Risk is moderate but bounded to remote config fetching and covered by new unit tests and injectable RNG for determinism.

Overview
Remote config blob fetching now selects a BlobSource by highest priority, and breaks ties with weighted random using weight (with a uniform-random fallback for zero/negative weights) rather than always using blobSources.firstOrNull().

This extracts the algorithm into a reusable WeightedSource + selectWeighted(...) helper, updates ApiSource/BlobSource to implement it, injects Random into RemoteConfigManager for deterministic tests, and expands unit coverage for priority/weight edge cases.

^{Reviewed by Cursor Bugbot for commit 98ba254. Bugbot is set up for automated code reviews on this repo. Configure here.}

tonidero · 2026-05-08T14:14:05Z

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codecov · 2026-05-08T14:31:56Z

Codecov Report

❌ Patch coverage is 83.33333% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.53%. Comparing base (03c6f6f) to head (c125314).

Files with missing lines	Patch %	Lines
...at/purchases/common/remoteconfig/WeightedSource.kt	75.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@                                   Coverage Diff                                    @@
##           toniricodiez/use-topic-file-for-offline-entitlements    #3458      +/-   ##
========================================================================================
- Coverage                                                 79.53%   79.53%   -0.01%     
========================================================================================
  Files                                                       369      370       +1     
  Lines                                                     14885    14898      +13     
  Branches                                                   2042     2048       +6     
========================================================================================
+ Hits                                                      11839    11849      +10     
- Misses                                                     2224     2226       +2     
- Partials                                                    822      823       +1

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ajpallares

Some initial comments on the weight-based randomization logic. Will keep looking 👀

ajpallares

I think it looks good! I have some doubts though, mostly about whether the lower-priority blob sources not being picked at all for now.
Great job btw!

ajpallares · 2026-05-13T13:03:44Z

+    override val priority: Int,
+    override val weight: Int,
+) : WeightedSource


NABD, but I believe in this PR we're not actually using the conformance of ApiSource to WeightedSource

Correct! The idea is that we can reuse the same logic to select the ApiSource, but that's not implemented yet (will be in future PRs)

ajpallares · 2026-05-13T13:06:51Z

        }
-        // WIP: We should have some logic to pick the correct source for this. Right now, hardcoded to the first source.
-        val source = response.blobSources.firstOrNull()
+        val source = response.blobSources.selectWeighted(random)


I'm guessing this will be tackled in follow-up PRs, but, with the current implementation of this PR, we only ever use the highest priority blobSources, right? lower-priority sources aren't fallback candidates.

That's indeed correct! That's tackled in this follow-up PR: #3466

ajpallares · 2026-05-13T13:10:01Z

+    val totalWeight = candidates.sumOf { it.weight }
+    val anyNegativeWeights = candidates.any { it.weight < 0 }
+    return if (totalWeight <= 0 || anyNegativeWeights) {
+        candidates[random.nextInt(candidates.size)]


Cursor highlighted some concerns about thread safety in random. Seems like the default Random.Default is thread safe, so this would only really affect tests I guess. Just wanted to highlight here as well

Hmm can you elaborate? I think for tests as well, we create new instances on each test. It's true we don't test with the "actual" Random.Default, but this is to make the tests deterministic.

You're right, yes. With the uses we have for it now, it's not a problem. Please ignore me

ajpallares

I think this looks great!

@RCGitBot

**This is an automatic release.** ## RevenueCat SDK ### 📦 Dependency Updates * [RENOVATE] Update dependency gradle to v8.14.5 (#3459) via RevenueCat Git Bot (@RCGitBot) ## RevenueCatUI SDK ### ✨ New Features * Pre-warm image cache for workflow step states (#3447) via Cesar de la Vega (@vegaro) ### Paywallv2 #### ✨ New Features * Add `close_workflow` button action (#3453) via Cesar de la Vega (@vegaro) #### 🐞 Bugfixes * Fix preload VideoComponent fallback override images (#3449) via Cesar de la Vega (@vegaro) ### 🔄 Other Changes * Select blob source by priority and weighted random (#3458) via Toni Rico (@tonidero) * [AUTOMATIC] Update golden test files for backend integration tests (#3473) via RevenueCat Git Bot (@RCGitBot) * Clean up unreferenced topic files after successful remote-config refresh (#3439) via Toni Rico (@tonidero) * Cache remote config response in memory with TTL and persist to disk (#3457) via Toni Rico (@tonidero) * build(deps): bump fastlane from 2.233.1 to 2.234.0 (#3463) via dependabot[bot] (@dependabot[bot]) * Update codelabs links (#3460) via Jaewoong Eum (@skydoves) * Add RemoteConfigManager and TopicFetcher (#3437) via Toni Rico (@tonidero) * Add exit offers support to workflows (#3452) via Cesar de la Vega (@vegaro) * Update baseline profiles (#3461) via RevenueCat Git Bot (@RCGitBot) * Add network scaffolding for remote config endpoint (#3435) via Toni Rico (@tonidero) * test: cover singleStepFallbackId == initialStepId edge case (#3445) via Facundo Menzella (@facumenzella)  --- > [!NOTE] > **Low Risk** > Low risk: this is a release/versioning update (SNAPSHOT -> final) plus docs deployment path changes, with no functional code changes beyond version constants. > > **Overview** > Finalizes the `10.6.0` release by switching all version references from `10.6.0-SNAPSHOT` to `10.6.0` (root `.version`, `gradle.properties`, `Config.frameworkVersion`, and sample/test app `libs.versions.toml` files). > > Updates documentation publishing to point at the `10.6.0` docs path (CircleCI S3 sync target and `docs/index.html` redirect), and prepends the `10.6.0` section to `CHANGELOG.md`/`CHANGELOG.latest.md`. > > <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit 4da1697. Bugbot is set up for automated code reviews on this repo. Configure [here](https://www.cursor.com/dashboard/bugbot).</sup>

tonidero mentioned this pull request May 8, 2026

Cache remote config response in memory with TTL and persist to disk #3457

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tonidero added the pr:other label May 8, 2026

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch from 4f3da1a to a820471 Compare May 11, 2026 08:40

tonidero force-pushed the toniricodiez/use-topic-file-for-offline-entitlements branch from 475500e to 5d17b34 Compare May 11, 2026 08:40

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch from a820471 to c125314 Compare May 11, 2026 11:37

tonidero force-pushed the toniricodiez/use-topic-file-for-offline-entitlements branch 2 times, most recently from 03c6f6f to d128c04 Compare May 11, 2026 13:16

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch from c125314 to 5b5596f Compare May 11, 2026 13:16

tonidero changed the base branch from toniricodiez/use-topic-file-for-offline-entitlements to graphite-base/3458 May 11, 2026 13:22

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch from 5b5596f to 78ea29f Compare May 11, 2026 13:23

tonidero force-pushed the graphite-base/3458 branch from d128c04 to 6d89f70 Compare May 11, 2026 13:23

tonidero changed the base branch from graphite-base/3458 to toniricodiez/add-remote-config-topic-cleanup May 11, 2026 13:23

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch from 78ea29f to 48367fa Compare May 11, 2026 13:30

tonidero force-pushed the toniricodiez/add-remote-config-topic-cleanup branch from 6d89f70 to 32ba5ab Compare May 11, 2026 13:30

tonidero marked this pull request as ready for review May 11, 2026 13:36

tonidero requested a review from a team as a code owner May 11, 2026 13:36

tonidero force-pushed the toniricodiez/add-remote-config-topic-cleanup branch from 32ba5ab to 85b8714 Compare May 11, 2026 13:52

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch 2 times, most recently from 4e64b90 to ae9921c Compare May 11, 2026 14:05

tonidero force-pushed the toniricodiez/add-remote-config-topic-cleanup branch 2 times, most recently from 3985e09 to 74eedab Compare May 12, 2026 09:47

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch from ae9921c to 6eda732 Compare May 12, 2026 09:47

tonidero force-pushed the toniricodiez/add-remote-config-topic-cleanup branch from 74eedab to e1dac4b Compare May 12, 2026 11:56

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch 2 times, most recently from 6eda732 to 4cd0810 Compare May 12, 2026 11:56

tonidero force-pushed the toniricodiez/add-remote-config-topic-cleanup branch from 74eedab to e1dac4b Compare May 12, 2026 11:56

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch from 4cd0810 to a29029f Compare May 12, 2026 12:52

tonidero mentioned this pull request May 12, 2026

Fall back across blob sources when topic downloads fail #3466

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tonidero changed the base branch from toniricodiez/add-remote-config-topic-cleanup to graphite-base/3458 May 12, 2026 14:06

tonidero force-pushed the graphite-base/3458 branch from 9503c36 to e9b0f74 Compare May 13, 2026 08:49

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tonidero changed the base branch from graphite-base/3458 to main May 13, 2026 08:49

ajpallares reviewed May 13, 2026

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Comment thread purchases/src/main/kotlin/com/revenuecat/purchases/common/remoteconfig/WeightedSource.kt Outdated

Comment thread purchases/src/main/kotlin/com/revenuecat/purchases/common/remoteconfig/WeightedSource.kt Outdated

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch from 337c191 to ff1124a Compare May 13, 2026 11:09

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tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch from ff1124a to 9d28ec1 Compare May 13, 2026 13:23

ajpallares approved these changes May 13, 2026

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98ba254

tonidero force-pushed the toniricodiez/select-blob-source-by-priority-and-weight branch from 9d28ec1 to 98ba254 Compare May 13, 2026 15:19

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Merged via the queue into main with commit 1631b1f May 13, 2026
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tonidero deleted the toniricodiez/select-blob-source-by-priority-and-weight branch May 13, 2026 16:03

RCGitBot mentioned this pull request May 13, 2026

[AUTOMATIC] Release/10.6.0 #3476

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