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Proof of concept for investigation of "Cannot recycle a resource whil…
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…e it is still acquired"
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TWiStErRob committed Oct 12, 2023
1 parent b1c6076 commit 70be029
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Showing 2 changed files with 82 additions and 3 deletions.
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ synchronized void recycle(Resource<?> resource, boolean forceNextFrame) {
// If a resource has sub-resources, releasing a sub resource can cause it's parent to be
// synchronously evicted which leads to a recycle loop when the parent releases it's children.
// Posting breaks this loop.
handler.obtainMessage(ResourceRecyclerCallback.RECYCLE_RESOURCE, resource).sendToTarget();
handler.obtainMessage(ResourceRecyclerCallback.RECYCLE_RESOURCE, new RecycleTask(resource, new Throwable("Async stack trace"))).sendToTarget();
} else {
isRecycling = true;
resource.recycle();
Expand All @@ -33,11 +33,37 @@ private static final class ResourceRecyclerCallback implements Handler.Callback
@Override
public boolean handleMessage(Message message) {
if (message.what == RECYCLE_RESOURCE) {
Resource<?> resource = (Resource<?>) message.obj;
resource.recycle();
RecycleTask task = (RecycleTask) message.obj;
try {
Resource<?> resource = task.resource;
resource.recycle();
} catch (RuntimeException | Error ex) {
task.rethrow(ex);
}
return true;
}
return false;
}
}

private static final class RecycleTask {
final Resource<?> resource;
final Throwable stacktrace;

RecycleTask(Resource<?> resource, Throwable stacktrace) {
this.resource = resource;
this.stacktrace = stacktrace;
}

void rethrow(Throwable original) {
Throwable rootCause = original;
while (rootCause.getCause() != null) {
rootCause = rootCause.getCause();
}
rootCause.initCause(stacktrace);
if (original instanceof Error) throw (Error) original;
if (original instanceof RuntimeException) throw (RuntimeException) original;
throw new IllegalStateException("Unknown exception: " + original, original);
}
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -2,11 +2,19 @@

import static com.bumptech.glide.RobolectricConstants.ROBOLECTRIC_SDK;
import static com.bumptech.glide.tests.Util.mockResource;
import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertSame;
import static org.junit.Assert.assertThrows;
import static org.mockito.Mockito.doAnswer;
import static org.mockito.Mockito.doThrow;
import static org.mockito.Mockito.never;
import static org.mockito.Mockito.verify;

import android.os.Looper;
import com.google.common.truth.Correspondence;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
Expand Down Expand Up @@ -71,4 +79,49 @@ public Void answer(InvocationOnMock invocationOnMock) throws Throwable {

verify(child).recycle();
}

@Test
public void recycle_withChild_asyncTraceable() {
final Resource<?> child = mockResource();
Throwable someCause = new Throwable("Some simulated cause.");
IllegalStateException testEx = new IllegalStateException("Simulated error for test.", someCause);
doThrow(testEx).when(child).recycle();
Resource<?> parent = mockResource();
class ChildRecycler implements Answer<Void> {
@Override
public Void answer(InvocationOnMock invocationOnMock) throws Throwable {
recycler.recycle(child, /* forceNextFrame= */ false);
return null;
}
}
doAnswer(new ChildRecycler()).when(parent).recycle();

Shadows.shadowOf(Looper.getMainLooper()).pause();
recycler.recycle(parent, /* forceNextFrame= */ false);
IllegalStateException ex = assertThrows(
IllegalStateException.class,
() -> Shadows.shadowOf(Looper.getMainLooper()).runOneTask()
);
assertSame("Original exception is thrown", testEx, ex);
assertSame("Cause is kept", someCause, ex.getCause());
assertThat(fullStackOf(ex))
.comparingElementsUsing(className())
.contains(ChildRecycler.class.getName());
}

private static Correspondence<StackTraceElement, String> className() {
return Correspondence.from(
(actual, expected) -> actual.getClassName().equals(expected),
"StackTraceElement.className"
);
}

private static List<StackTraceElement> fullStackOf(Throwable t) {
List<StackTraceElement> stack = new ArrayList<>();
do {
stack.addAll(Arrays.asList(t.getStackTrace()));
t = t.getCause();
} while (t != null);
return stack;
}
}

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