UserScopedService

Provides cached instances of a system service created with the context
of a specified user. This allows more natural interaction with APIs
which do not accept a direct UserId parameter.

Bug: 309960444
Bug: 300157408
Change-Id: Ib0abbd308a197b59c1d9ba37c7ce22d19d4dde9c

1 files changed, 46 insertions, 0 deletions

diff --git a/java/src/com/android/intentresolver/v2/data/repository/UserScopedService.kt b/java/src/com/android/intentresolver/v2/data/repository/UserScopedService.kt
new file mode 100644
index 00000000..7ee78d91
--- /dev/null
+++ b/java/src/com/android/intentresolver/v2/data/repository/UserScopedService.kt
@@ -0,0 +1,46 @@
+package com.android.intentresolver.v2.data.repository
+
+import android.content.Context
+import androidx.core.content.getSystemService
+import com.android.intentresolver.v2.data.model.User
+
+/**
+ * Provides cached instances of a [system service][Context.getSystemService] created with
+ * [the context of a specified user][Context.createContextAsUser].
+ *
+ * System services which have only `@UserHandleAware` APIs operate on the user id available from
+ * [Context.getUser], the context used to retrieve the service. This utility helps adapt a per-user
+ * API model to work in multi-user manner.
+ *
+ * Example usage:
+ * ```
+ * val usageStats = userScopedService<UsageStatsManager>(context)
+ *
+ * fun getStatsForUser(
+ *     user: User,
+ *     from: Long,
+ *     to: Long
+ * ): UsageStats {
+ *     return usageStats.forUser(user)
+ *        .queryUsageStats(INTERVAL_BEST, from, to)
+ * }
+ * ```
+ */
+interface UserScopedService<T> {
+    fun forUser(user: User): T
+}
+
+inline fun <reified T> userScopedService(context: Context): UserScopedService<T> {
+    return object : UserScopedService<T> {
+        private val map = mutableMapOf<User, T>()
+
+        override fun forUser(user: User): T {
+            return synchronized(this) {
+                map.getOrPut(user) {
+                    val userContext = context.createContextAsUser(user.handle, 0)
+                    requireNotNull(userContext.getSystemService())
+                }
+            }
+        }
+    }
+}