Replace retry with exponential backoff with arrow schedule

Also clean up the code related to play purchase verification

8 files changed, 43 insertions, 64 deletions

diff --git a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/constant/PaymentConstant.kt b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/constant/PaymentConstant.kt
index 1cf1c32b2c..ba2413d4fc 100644
--- a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/constant/PaymentConstant.kt
+++ b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/constant/PaymentConstant.kt
@@ -1,5 +1,7 @@
 package net.mullvad.mullvadvpn.constant
 
+import kotlin.time.Duration.Companion.seconds
+
 const val VERIFICATION_MAX_ATTEMPTS = 4
-const val VERIFICATION_INITIAL_BACK_OFF_MILLISECONDS = 3000L
-const val VERIFICATION_BACK_OFF_FACTOR = 3L
+val VERIFICATION_INITIAL_BACK_OFF_DURATION = 3.seconds
+const val VERIFICATION_BACK_OFF_FACTOR = 3.toDouble()
diff --git a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/usecase/PaymentUseCase.kt b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/usecase/PaymentUseCase.kt
index fbd662f95e..23f6c797b0 100644
--- a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/usecase/PaymentUseCase.kt
+++ b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/usecase/PaymentUseCase.kt
@@ -1,20 +1,24 @@
 package net.mullvad.mullvadvpn.usecase
 
 import android.app.Activity
+import arrow.core.Either
+import arrow.core.right
+import arrow.resilience.Schedule
+import arrow.resilience.retryEither
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.transform
 import net.mullvad.mullvadvpn.constant.VERIFICATION_BACK_OFF_FACTOR
-import net.mullvad.mullvadvpn.constant.VERIFICATION_INITIAL_BACK_OFF_MILLISECONDS
+import net.mullvad.mullvadvpn.constant.VERIFICATION_INITIAL_BACK_OFF_DURATION
 import net.mullvad.mullvadvpn.constant.VERIFICATION_MAX_ATTEMPTS
 import net.mullvad.mullvadvpn.lib.payment.PaymentRepository
 import net.mullvad.mullvadvpn.lib.payment.model.PaymentAvailability
 import net.mullvad.mullvadvpn.lib.payment.model.ProductId
 import net.mullvad.mullvadvpn.lib.payment.model.PurchaseResult
+import net.mullvad.mullvadvpn.lib.payment.model.VerificationError
 import net.mullvad.mullvadvpn.lib.payment.model.VerificationResult
-import net.mullvad.mullvadvpn.util.retryWithExponentialBackOff
 
 interface PaymentUseCase {
     val paymentAvailability: Flow<PaymentAvailability?>
@@ -26,7 +30,7 @@ interface PaymentUseCase {
 
     suspend fun resetPurchaseResult()
 
-    suspend fun verifyPurchases(onSuccessfulVerification: () -> Unit = {})
+    suspend fun verifyPurchases(): Either<VerificationError, VerificationResult>
 }
 
 class PlayPaymentUseCase(private val paymentRepository: PaymentRepository) : PaymentUseCase {
@@ -60,24 +64,19 @@ class PlayPaymentUseCase(private val paymentRepository: PaymentRepository) : Pay
     }
 
     @Suppress("ensure every public functions method is named 'invoke' with operator modifier")
-    override suspend fun verifyPurchases(onSuccessfulVerification: () -> Unit) {
-        paymentRepository
-            .verifyPurchases()
-            .retryWithExponentialBackOff(
-                maxAttempts = VERIFICATION_MAX_ATTEMPTS,
-                initialBackOffDelay = VERIFICATION_INITIAL_BACK_OFF_MILLISECONDS,
-                backOffDelayFactor = VERIFICATION_BACK_OFF_FACTOR
-            ) {
-                it is VerificationResult.Error
-            }
-            .collect {
+    override suspend fun verifyPurchases() =
+        Schedule.exponential<VerificationError>(
+                VERIFICATION_INITIAL_BACK_OFF_DURATION,
+                VERIFICATION_BACK_OFF_FACTOR
+            )
+            .and(Schedule.recurs(VERIFICATION_MAX_ATTEMPTS.toLong()))
+            .retryEither { paymentRepository.verifyPurchases() }
+            .onRight {
                 if (it == VerificationResult.Success) {
                     // Update the payment availability after a successful verification.
                     queryPaymentAvailability()
-                    onSuccessfulVerification()
                 }
             }
-    }
 
     private fun PurchaseResult?.shouldDelayLoading() =
         this is PurchaseResult.FetchingProducts || this is PurchaseResult.VerificationStarted
@@ -107,7 +106,5 @@ class EmptyPaymentUseCase : PaymentUseCase {
     }
 
     @Suppress("ensure every public functions method is named 'invoke' with operator modifier")
-    override suspend fun verifyPurchases(onSuccessfulVerification: () -> Unit) {
-        // No op
-    }
+    override suspend fun verifyPurchases() = VerificationResult.NothingToVerify.right()
 }
diff --git a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/util/FlowUtils.kt b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/util/FlowUtils.kt
index fbe44a5fea..13561aa7f8 100644
--- a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/util/FlowUtils.kt
+++ b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/util/FlowUtils.kt
@@ -3,11 +3,7 @@
 package net.mullvad.mullvadvpn.util
 
 import kotlinx.coroutines.Deferred
-import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.catch
-import kotlinx.coroutines.flow.map
-import kotlinx.coroutines.flow.retryWhen
 
 inline fun <T1, T2, T3, T4, T5, T6, R> combine(
     flow: Flow<T1>,
@@ -90,34 +86,3 @@ fun <T> Deferred<T>.getOrDefault(default: T) =
     } catch (e: IllegalStateException) {
         default
     }
-
-@Suppress("UNCHECKED_CAST")
-suspend inline fun <T> Flow<T>.retryWithExponentialBackOff(
-    maxAttempts: Int,
-    initialBackOffDelay: Long,
-    backOffDelayFactor: Long,
-    crossinline predicate: (T) -> Boolean,
-): Flow<T> =
-    map {
-            if (predicate(it)) {
-                throw ExceptionWrapper(it as Any)
-            }
-            it
-        }
-        .retryWhen { _, attempt ->
-            if (attempt >= maxAttempts) {
-                return@retryWhen false
-            }
-            val backOffDelay = initialBackOffDelay * backOffDelayFactor.pow(attempt.toInt())
-            delay(backOffDelay)
-            true
-        }
-        .catch {
-            if (it is ExceptionWrapper) {
-                this.emit(it.item as T)
-            } else {
-                throw it
-            }
-        }
-
-class ExceptionWrapper(val item: Any) : Throwable()
diff --git a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/util/VerificationResultExtensions.kt b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/util/VerificationResultExtensions.kt
new file mode 100644
index 0000000000..d4484d50e6
--- /dev/null
+++ b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/util/VerificationResultExtensions.kt
@@ -0,0 +1,8 @@
+package net.mullvad.mullvadvpn.util
+
+import arrow.core.Either
+import net.mullvad.mullvadvpn.lib.payment.model.VerificationError
+import net.mullvad.mullvadvpn.lib.payment.model.VerificationResult
+
+fun Either<VerificationError, VerificationResult>.isSuccess() =
+    getOrNull() == VerificationResult.Success
diff --git a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/AccountViewModel.kt b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/AccountViewModel.kt
index a42003d6e2..7c2635b63a 100644
--- a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/AccountViewModel.kt
+++ b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/AccountViewModel.kt
@@ -24,6 +24,7 @@ import net.mullvad.mullvadvpn.lib.payment.model.ProductId
 import net.mullvad.mullvadvpn.lib.shared.AccountRepository
 import net.mullvad.mullvadvpn.lib.shared.DeviceRepository
 import net.mullvad.mullvadvpn.usecase.PaymentUseCase
+import net.mullvad.mullvadvpn.util.isSuccess
 import net.mullvad.mullvadvpn.util.toPaymentState
 import org.joda.time.DateTime
 
@@ -90,8 +91,9 @@ class AccountViewModel(
 
     private fun verifyPurchases() {
         viewModelScope.launch {
-            paymentUseCase.verifyPurchases()
-            updateAccountExpiry()
+            if (paymentUseCase.verifyPurchases().isSuccess()) {
+                updateAccountExpiry()
+            }
         }
     }
 
diff --git a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/ConnectViewModel.kt b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/ConnectViewModel.kt
index b41a175dad..037c3243ab 100644
--- a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/ConnectViewModel.kt
+++ b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/ConnectViewModel.kt
@@ -32,6 +32,7 @@ import net.mullvad.mullvadvpn.usecase.PaymentUseCase
 import net.mullvad.mullvadvpn.usecase.SelectedLocationTitleUseCase
 import net.mullvad.mullvadvpn.util.combine
 import net.mullvad.mullvadvpn.util.daysFromNow
+import net.mullvad.mullvadvpn.util.isSuccess
 import net.mullvad.mullvadvpn.util.toInAddress
 import net.mullvad.mullvadvpn.util.toOutAddress
 
@@ -114,8 +115,8 @@ class ConnectViewModel(
 
     init {
         viewModelScope.launch {
-            paymentUseCase.verifyPurchases {
-                viewModelScope.launch { accountRepository.getAccountData() }
+            if (paymentUseCase.verifyPurchases().isSuccess()) {
+                accountRepository.getAccountData()
             }
         }
         viewModelScope.launch { deviceRepository.updateDevice() }
diff --git a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/OutOfTimeViewModel.kt b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/OutOfTimeViewModel.kt
index 7784181466..d279792853 100644
--- a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/OutOfTimeViewModel.kt
+++ b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/OutOfTimeViewModel.kt
@@ -20,6 +20,7 @@ import net.mullvad.mullvadvpn.lib.shared.ConnectionProxy
 import net.mullvad.mullvadvpn.lib.shared.DeviceRepository
 import net.mullvad.mullvadvpn.usecase.OutOfTimeUseCase
 import net.mullvad.mullvadvpn.usecase.PaymentUseCase
+import net.mullvad.mullvadvpn.util.isSuccess
 import net.mullvad.mullvadvpn.util.toPaymentState
 
 class OutOfTimeViewModel(
@@ -76,8 +77,9 @@ class OutOfTimeViewModel(
 
     private fun verifyPurchases() {
         viewModelScope.launch {
-            paymentUseCase.verifyPurchases()
-            updateAccountExpiry()
+            if (paymentUseCase.verifyPurchases().isSuccess()) {
+                updateAccountExpiry()
+            }
         }
     }
 
diff --git a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/WelcomeViewModel.kt b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/WelcomeViewModel.kt
index 4b61468f8e..9322ef9ce4 100644
--- a/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/WelcomeViewModel.kt
+++ b/android/app/src/main/kotlin/net/mullvad/mullvadvpn/viewmodel/WelcomeViewModel.kt
@@ -21,6 +21,7 @@ import net.mullvad.mullvadvpn.lib.shared.AccountRepository
 import net.mullvad.mullvadvpn.lib.shared.ConnectionProxy
 import net.mullvad.mullvadvpn.lib.shared.DeviceRepository
 import net.mullvad.mullvadvpn.usecase.PaymentUseCase
+import net.mullvad.mullvadvpn.util.isSuccess
 import net.mullvad.mullvadvpn.util.toPaymentState
 
 class WelcomeViewModel(
@@ -79,8 +80,9 @@ class WelcomeViewModel(
 
     private fun verifyPurchases() {
         viewModelScope.launch {
-            paymentUseCase.verifyPurchases()
-            updateAccountExpiry()
+            if (paymentUseCase.verifyPurchases().isSuccess()) {
+                updateAccountExpiry()
+            }
         }
     }