Ignore callbacks from cancelled or otherwise invalid requests in SourceGenerator.

PiperOrigin-RevId: 277765705

Author: sjudd

library/src/main/java/com/bumptech/glide/load/engine/SourceGenerator.java

@@ -2,13 +2,16 @@
 
 import android.util.Log;
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import com.bumptech.glide.load.DataSource;
 import com.bumptech.glide.load.Encoder;
 import com.bumptech.glide.load.Key;
 import com.bumptech.glide.load.data.DataFetcher;
+import com.bumptech.glide.load.data.DataFetcher.DataCallback;
 import com.bumptech.glide.load.model.ModelLoader;
 import com.bumptech.glide.load.model.ModelLoader.LoadData;
 import com.bumptech.glide.util.LogTime;
+import com.bumptech.glide.util.Synthetic;
 import java.util.Collections;
 
 /**
@@ -19,10 +22,7 @@
  * <p>Depending on the disk cache strategy, source data may first be written to disk and then loaded
  * from the cache file rather than returned directly.
  */
-class SourceGenerator
-    implements DataFetcherGenerator,
-        DataFetcher.DataCallback<Object>,
-        DataFetcherGenerator.FetcherReadyCallback {
+class SourceGenerator implements DataFetcherGenerator, DataFetcherGenerator.FetcherReadyCallback {
   private static final String TAG = "SourceGenerator";
 
   private final DecodeHelper<?> helper;
@@ -60,12 +60,40 @@ public boolean startNext() {
           && (helper.getDiskCacheStrategy().isDataCacheable(loadData.fetcher.getDataSource())
               || helper.hasLoadPath(loadData.fetcher.getDataClass()))) {
         started = true;
-        loadData.fetcher.loadData(helper.getPriority(), this);
+        startNextLoad(loadData);
       }
     }
     return started;
   }
 
+  private void startNextLoad(final LoadData<?> toStart) {
+    loadData.fetcher.loadData(
+        helper.getPriority(),
+        new DataCallback<Object>() {
+          @Override
+          public void onDataReady(@Nullable Object data) {
+            if (isCurrentRequest(toStart)) {
+              onDataReadyInternal(toStart, data);
+            }
+          }
+
+          @Override
+          public void onLoadFailed(@NonNull Exception e) {
+            if (isCurrentRequest(toStart)) {
+              onLoadFailedInternal(toStart, e);
+            }
+          }
+        });
+  }
+
+  // We want reference equality explicitly to make sure we ignore results from old requests.
+  @SuppressWarnings({"PMD.CompareObjectsWithEquals", "WeakerAccess"})
+  @Synthetic
+  boolean isCurrentRequest(LoadData<?> requestLoadData) {
+    LoadData<?> currentLoadData = loadData;
+    return currentLoadData != null && currentLoadData == requestLoadData;
+  }
+
   private boolean hasNextModelLoader() {
     return loadDataListIndex < helper.getLoadData().size();
   }
@@ -107,8 +135,9 @@ public void cancel() {
     }
   }
 
-  @Override
-  public void onDataReady(Object data) {
+  @SuppressWarnings("WeakerAccess")
+  @Synthetic
+  void onDataReadyInternal(LoadData<?> loadData, Object data) {
     DiskCacheStrategy diskCacheStrategy = helper.getDiskCacheStrategy();
     if (data != null && diskCacheStrategy.isDataCacheable(loadData.fetcher.getDataSource())) {
       dataToCache = data;
@@ -125,8 +154,9 @@ public void onDataReady(Object data) {
     }
   }
 
-  @Override
-  public void onLoadFailed(@NonNull Exception e) {
+  @SuppressWarnings("WeakerAccess")
+  @Synthetic
+  void onLoadFailedInternal(LoadData<?> loadData, @NonNull Exception e) {
     cb.onDataFetcherFailed(originalKey, e, loadData.fetcher, loadData.fetcher.getDataSource());
   }