MBL-2144 Fix concurrency crash when preloading images (#2241)

* Patch to fix concurrency crash

* Match BackingFragment

* ktlint

* Make copy of list so that we don't reference mutable list that could be cleared

Author: ycheng-kickstarter

app/src/main/java/com/kickstarter/ui/activities/compose/projectpage/AddOnsScreen.kt

@@ -1,5 +1,6 @@
 package com.kickstarter.ui.activities.compose.projectpage
 
+import android.content.Context
 import android.content.res.Configuration
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Box
@@ -26,7 +27,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.tooling.preview.Preview
-import coil.ImageLoader
+import coil.Coil
 import coil.request.ImageRequest
 import com.kickstarter.R
 import com.kickstarter.libs.Environment
@@ -115,18 +116,7 @@ fun AddOnsScreen(
         ).toString()
     } ?: ""
 
-    // Preload add ons images asynchronously
-    val imageLoader = ImageLoader.Builder(context)
-        .crossfade(true)
-        .build()
-    for (reward in addOns) {
-        reward.image()?.let {
-            val request = ImageRequest.Builder(context)
-                .data(reward.image()?.full())
-                .build()
-            imageLoader.enqueue(request)
-        }
-    }
+    preloadImages(context, addOns)
 
     Box(
         modifier = Modifier.fillMaxSize(),
@@ -337,3 +327,16 @@ fun AddOnsScreen(
         }
     }
 }
+
+private fun preloadImages(context: Context, rewards: List<Reward>) {
+    val rewardsIterator = rewards.iterator()
+    while (rewardsIterator.hasNext()) {
+        val reward = rewardsIterator.next()
+        reward.image()?.let {
+            val request = ImageRequest.Builder(context)
+                .data(reward.image()?.full())
+                .build()
+            Coil.imageLoader(context).enqueue(request)
+        }
+    }
+}

app/src/main/java/com/kickstarter/ui/fragments/BackingFragment.kt

@@ -23,7 +23,7 @@ import androidx.fragment.app.Fragment
 import androidx.fragment.app.viewModels
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
-import coil.ImageLoader
+import coil.Coil
 import coil.request.ImageRequest
 import com.kickstarter.R
 import com.kickstarter.databinding.FragmentBackingBinding
@@ -580,16 +580,14 @@ class BackingFragment : Fragment() {
     }
 
     private fun preloadImages(rewards: List<Reward>) {
-        // Preload reward images asynchronously
-        val imageLoader = ImageLoader.Builder(requireContext())
-            .crossfade(true)
-            .build()
-        for (reward in rewards) {
+        val rewardsIterator = rewards.iterator()
+        while (rewardsIterator.hasNext()) {
+            val reward = rewardsIterator.next()
             reward.image()?.let {
                 val request = ImageRequest.Builder(requireContext())
                     .data(reward.image()?.full())
                     .build()
-                imageLoader.enqueue(request)
+                Coil.imageLoader(requireContext()).enqueue(request)
             }
         }
     }

app/src/main/java/com/kickstarter/ui/fragments/RewardsFragment.kt

@@ -1,5 +1,6 @@
 package com.kickstarter.ui.fragments
 
+import android.content.Context
 import android.os.Bundle
 import android.util.Pair
 import android.view.LayoutInflater
@@ -9,17 +10,19 @@ import androidx.appcompat.app.AlertDialog
 import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.ViewCompositionStrategy
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.viewModels
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
-import coil.ImageLoader
+import coil.Coil
 import coil.request.ImageRequest
 import com.kickstarter.R
 import com.kickstarter.databinding.FragmentRewardsBinding
 import com.kickstarter.libs.Environment
 import com.kickstarter.libs.utils.extensions.getEnvironment
 import com.kickstarter.libs.utils.extensions.reduce
+import com.kickstarter.models.Reward
 import com.kickstarter.ui.activities.compose.projectpage.RewardCarouselScreen
 import com.kickstarter.ui.compose.designsystem.KSTheme
 import com.kickstarter.ui.compose.designsystem.KickstarterApp
@@ -71,18 +74,7 @@ class RewardsFragment : Fragment() {
                         val indexOfBackedReward = rewardSelectionUIState.initialRewardIndex
                         val rewards = shippingUIState.filteredRw
 
-                        // Preload reward images asynchronously
-                        val imageLoader = ImageLoader.Builder(context)
-                            .crossfade(true)
-                            .build()
-                        for (reward in rewards) {
-                            reward.image()?.let {
-                                val request = ImageRequest.Builder(context)
-                                    .data(reward.image()?.full())
-                                    .build()
-                                imageLoader.enqueue(request)
-                            }
-                        }
+                        preloadImages(LocalContext.current, rewards)
 
                         val project = projectData.project()
                         val backing = projectData.backing()
@@ -128,6 +120,19 @@ class RewardsFragment : Fragment() {
         }
     }
 
+    private fun preloadImages(context: Context, rewards: List<Reward>) {
+        val rewardsIterator = rewards.iterator()
+        while (rewardsIterator.hasNext()) {
+            val reward = rewardsIterator.next()
+            reward.image()?.let {
+                val request = ImageRequest.Builder(context)
+                    .data(reward.image()?.full())
+                    .build()
+                Coil.imageLoader(context).enqueue(request)
+            }
+        }
+    }
+
     private fun createDialog() {
         context?.let { context ->
             dialog = AlertDialog.Builder(context, R.style.AlertDialog)

app/src/main/java/com/kickstarter/viewmodels/usecases/GetShippingRulesUseCase.kt

@@ -148,7 +148,7 @@ class GetShippingRulesUseCase(
                 loading = isLoading,
                 selectedShippingRule = defaultShippingRule,
                 error = errorMessage,
-                filteredRw = filteredRewards
+                filteredRw = filteredRewards.toList()
             )
         )
     }