Merge pull request #9 from contentpass/CHORE-Improve-error-handling-in-SDK

Improve error handling in sdk

Author: slawomirzaba

README.md

@@ -14,7 +14,7 @@
 Our SDK is available on Maven Central.
 
 ```groovy
-implementation 'de.contentpass:contentpass-android:2.1.1'
+implementation 'de.contentpass:contentpass-android:2.2.1'
 ```
 
 Add this to your app's `build.gradle` file's `dependencies` element.
@@ -149,6 +149,19 @@ Any registered `Observer` will be called with the final authentication and subsc
 * We refresh these tokens automatically in the background before they're invalidated.
 * The subscription information gets validated as well on every token refresh.
 
+### Recovering from network errors
+
+Sometimes we encounter an error state while refreshing the tokens in the background due to bad or no internet connection.
+
+You will notice this because the `state` switched to `Error`. This state object contains a reference to the original exception that was thrown.
+
+Since we don't monitor the device's connection state you need to tell the SDK that the network connection has been reestablished / improved. We will then refresh and revalidate the user's authentication tokens.
+
+```kotlin
+contentPass.recoverFromError()
+```
+
+
 ### Counting an impression
 To count an impression, call either the suspending function `countImpressionSuspending(context: Context)` or
 the compatibility function `countImpression(context: Context, callback: CountImpressionCallback)`.

lib/build.gradle.kts

@@ -58,7 +58,7 @@ kapt {
 extra.apply{
     set("PUBLISH_GROUP_ID", "de.contentpass")
     set("PUBLISH_ARTIFACT_ID", "contentpass-android")
-    set("PUBLISH_VERSION", "2.1.1")
+    set("PUBLISH_VERSION", "2.2.1")
 }
 
 apply("${rootProject.projectDir}/scripts/publish-module.gradle")

lib/src/main/java/de/contentpass/lib/Authorizer.kt

@@ -51,7 +51,11 @@ internal class Authorizer(
     init {
         val context = Dispatchers.Default + Job()
         CoroutineScope(context).launch {
-            fetchConfig()
+            try {
+                fetchConfig()
+            } catch (e: Throwable) {
+                // this is allowed to fail
+            }
         }
     }
 

lib/src/main/java/de/contentpass/lib/ContentPass.kt

@@ -136,13 +136,23 @@ class ContentPass internal constructor(
      */
     sealed class State {
         /**
-         * The contentpass object was just created. Will switch to another state very soon.
+         * The contentpass object was just created or an error recovery is ongoing.
+         * Will switch to another state very soon.
          *
          * After the stored contentpass token information is validated and refreshed, this will
-         * switch to either [Unauthenticated] or [Authenticated]
+         * switch to one of [Error], [Unauthenticated] or [Authenticated]
          */
         object Initializing : State()
 
+        /**
+         * An error was encountered during token validation.
+         *
+         * This is probably due to a failing internet connection. You can check the exception and
+         * act accordingly. Once a stable network connection has been established, call [recoverFromError]
+         * to retry the token validation.
+         */
+        class Error(val exception: Throwable): State()
+
         /**
          * No user is currently authenticated.
          */
@@ -177,12 +187,15 @@ class ContentPass internal constructor(
 
     private val observers = mutableListOf<Observer>()
 
-    private val coroutineContext = Dispatchers.Default + Job()
+    private val coroutineContext = Dispatchers.Default + SupervisorJob()
 
     init {
+        initializeAuthState()
+    }
+
+    private fun initializeAuthState() {
         tokenStore.retrieveAuthState()?.let {
             authState = it
-
             CoroutineScope(coroutineContext).launch {
                 onNewAuthState(authState)
             }
@@ -348,6 +361,19 @@ class ContentPass internal constructor(
             countSampledImpression()
         }
     }
+    /**
+     * Reinitializes this object's state.
+     *
+     * Call this function when you encountered an error during token validation, the current [state]
+     * is set to [Error] and you want to try the validation again. Commonly used when network access
+     * has been reestablished.
+     */
+    fun recoverFromError() {
+        state = State.Initializing
+
+        initializeAuthState()
+    }
+
 
     private suspend fun countSampledImpression() {
         val generatedSample = Math.random()
@@ -405,8 +431,14 @@ class ContentPass internal constructor(
         state = if (authState.isAuthorized) {
             setupRefreshTimer(authState)?.let {
                 if (it) {
-                    val hasSubscription = authorizer.validateSubscription(authState.idToken!!)
-                    State.Authenticated(hasSubscription)
+                    authState.idToken?.let { idToken ->
+                        try {
+                            val hasSubscription = authorizer.validateSubscription(idToken)
+                            State.Authenticated(hasSubscription)
+                        } catch (e: Throwable) {
+                            State.Error(e)
+                        }
+                    } ?: State.Unauthenticated
                 } else {
                     state
                 }