Preserve exception cause in LockBasedStorageManager

2013-12-24 19:01:17 +04:00
parent d00b17c621
commit 5f20450053
1 changed files with 12 additions and 1 deletions
@@ -324,14 +324,25 @@ public class LockBasedStorageManager implements StorageManager {
                value = cache.get(input);
                if (value != null) return WrappedValues.unescapeExceptionOrNull(value);

+                AssertionError error = null;
                try {
                    V typedValue = compute.invoke(input);
                    Object oldValue = cache.put(input, WrappedValues.escapeNull(typedValue));
-                    assert oldValue == null : "Race condition or recursion detected. Old value is " + oldValue;
+
+                    // This code effectively asserts that oldValue is null
+                    // The trickery is here because below we catch all exceptions thrown here, and this is the only exception that shouldn't be stored
+                    // A seemingly obvious way to come about this case would be to declare a special exception class, but the problem is that
+                    // one memoized function is likely to (indirectly) call another, and if this second one throws this exception, we are screwed
+                    if (oldValue != null) {
+                        error = new AssertionError("Race condition or recursion detected. Old value is " + oldValue);
+                        throw error;
+                    }

                    return typedValue;
                }
                catch (Throwable throwable) {
+                    if (throwable == error) throw error;
+
                    Object oldValue = cache.put(input, WrappedValues.escapeThrowable(throwable));
                    assert oldValue == null : "Race condition or recursion detected. Old value is " + oldValue;