From b2dce57abe0e860e0eaa758d3716d91b46196a0d Mon Sep 17 00:00:00 2001
From: Benoit Marty <benoit@matrix.org>
Date: Thu, 12 Dec 2024 11:40:53 +0100
Subject: [PATCH] Add a feature flag for the event cache.

---
 .../android/libraries/featureflag/api/FeatureFlags.kt      | 7 +++++++
 .../libraries/matrix/impl/RustMatrixClientFactory.kt       | 4 +---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt b/libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt
index 9add32499f..b028978c94 100644
--- a/libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt
+++ b/libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt
@@ -161,4 +161,11 @@ enum class FeatureFlags(
         defaultValue = { buildMeta -> buildMeta.buildType != BuildType.RELEASE },
         isFinished = false,
     ),
+    EventCache(
+        key = "feature.event_cache",
+        title = "Use SDK Event cache",
+        description = "Warning: you must kill and restart the app for the change to take effect.",
+        defaultValue = { false },
+        isFinished = false,
+    ),
 }
diff --git a/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/RustMatrixClientFactory.kt b/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/RustMatrixClientFactory.kt
index e688452510..d5af4ff67f 100644
--- a/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/RustMatrixClientFactory.kt
+++ b/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/RustMatrixClientFactory.kt
@@ -109,9 +109,7 @@ class RustMatrixClientFactory @Inject constructor(
             .addRootCertificates(userCertificatesProvider.provides())
             .autoEnableBackups(true)
             .autoEnableCrossSigning(true)
-            // TODO Add a feature flag to enable persistent storage
-            // See https://github.com/matrix-org/matrix-rust-sdk/pull/4396
-            .useEventCachePersistentStorage(false)
+            .useEventCachePersistentStorage(featureFlagService.isFeatureEnabled(FeatureFlags.EventCache))
             .roomKeyRecipientStrategy(
                 strategy = if (featureFlagService.isFeatureEnabled(FeatureFlags.OnlySignedDeviceIsolationMode)) {
                     CollectStrategy.IdentityBasedStrategy