dimas-b commented on code in PR #4474:
URL: https://github.com/apache/polaris/pull/4474#discussion_r3283418656
##########
persistence/nosql/persistence/impl/src/main/java/org/apache/polaris/persistence/nosql/impl/indexes/InternalIndexElement.java:
##########
@@ -47,5 +47,7 @@ interface InternalIndexElement<V> extends Index.Element<V> {
int contentSerializedSize(IndexValueSerializer<V> ser);
+ boolean hasNonNullValue();
Review Comment:
suggestion: `hasValue()` or `valuePresent()` (cf. `Optional.isPresent()`)
##########
persistence/nosql/persistence/impl/src/main/java/org/apache/polaris/persistence/nosql/impl/indexes/IndexImpl.java:
##########
@@ -802,10 +802,15 @@ private final class LazyIndexElement extends
AbstractIndexElement<V> {
/** The materialized key or {@code null}. */
private IndexKey key;
- /** The materialized content or {@code null}. */
- private V content;
+ /**
+ * Holds either one of the {@code VALUE_STATE_*} sentinels or a
materialized non-{@code null}
+ * content value.
+ */
+ private volatile Object contentState = VALUE_STATE_UNMATERIALIZED;
- private boolean hasContent;
+ private static final Object VALUE_STATE_UNMATERIALIZED = new Object();
+ private static final Object VALUE_STATE_NULL = new Object();
+ private static final Object VALUE_STATE_NON_NULL = new Object();
Review Comment:
suggestion: `VALUE_STATE_PRESENT`
##########
persistence/nosql/persistence/impl/src/main/java/org/apache/polaris/persistence/nosql/impl/indexes/IndexImpl.java:
##########
@@ -904,26 +909,43 @@ public IndexKey key() {
return k;
}
+ @Override
+ public boolean hasNonNullValue() {
+ var state = contentState;
+ if (state == VALUE_STATE_NULL) {
+ return false;
+ }
+ if (state != VALUE_STATE_UNMATERIALIZED) {
+ return true;
+ }
+ var nonNull =
+ !serializer.isNullSerialized(
+ serializedThreadSafe().limit(endOffset).position(valueOffset));
+ if (contentState == VALUE_STATE_UNMATERIALIZED) {
Review Comment:
Do we really need this `if`? It does not prevent races WRT line 941, but
adds confusion WRT line 918 🤔
##########
persistence/nosql/persistence/impl/src/main/java/org/apache/polaris/persistence/nosql/impl/indexes/IndexImpl.java:
##########
@@ -904,26 +909,43 @@ public IndexKey key() {
return k;
}
+ @Override
+ public boolean hasNonNullValue() {
+ var state = contentState;
+ if (state == VALUE_STATE_NULL) {
+ return false;
+ }
+ if (state != VALUE_STATE_UNMATERIALIZED) {
+ return true;
+ }
+ var nonNull =
+ !serializer.isNullSerialized(
+ serializedThreadSafe().limit(endOffset).position(valueOffset));
+ if (contentState == VALUE_STATE_UNMATERIALIZED) {
+ contentState = nonNull ? VALUE_STATE_NON_NULL : VALUE_STATE_NULL;
Review Comment:
WDYT about `AtomicReference.compareAndSet(VALUE_STATE_UNMATERIALIZED,
nonNull ? VALUE_STATE_NON_NULL : VALUE_STATE_NULL)`?
##########
persistence/nosql/persistence/impl/src/main/java/org/apache/polaris/persistence/nosql/impl/indexes/IndexImpl.java:
##########
@@ -904,26 +909,43 @@ public IndexKey key() {
return k;
}
+ @Override
+ public boolean hasNonNullValue() {
+ var state = contentState;
+ if (state == VALUE_STATE_NULL) {
+ return false;
+ }
+ if (state != VALUE_STATE_UNMATERIALIZED) {
+ return true;
+ }
+ var nonNull =
+ !serializer.isNullSerialized(
+ serializedThreadSafe().limit(endOffset).position(valueOffset));
+ if (contentState == VALUE_STATE_UNMATERIALIZED) {
+ contentState = nonNull ? VALUE_STATE_NON_NULL : VALUE_STATE_NULL;
+ }
+ return nonNull;
+ }
+
@Override
@Nullable
public V valueNullable() {
- var c = content;
- if (c == null) {
- if (!hasContent) {
- c =
- content =
- serializer.deserialize(
-
serializedThreadSafe().limit(endOffset).position(valueOffset));
- hasContent = true;
- }
+ var state = contentState;
+ if (state == VALUE_STATE_NULL) {
+ return null;
}
+ if (state != VALUE_STATE_UNMATERIALIZED && state !=
VALUE_STATE_NON_NULL) {
+ return materializedContent(state);
Review Comment:
the result of `materializedContent(state)` in this case is known to be
`state`... why use this indirection? 🤔
##########
persistence/nosql/persistence/impl/src/main/java/org/apache/polaris/persistence/nosql/impl/indexes/IndexImpl.java:
##########
@@ -943,6 +965,22 @@ public String toString() {
return sb.toString();
}
+
+ @Nullable
+ private V materializedContent() {
+ return materializedContent(contentState);
+ }
+
+ @SuppressWarnings("unchecked")
+ @Nullable
+ private V materializedContent(Object state) {
+ if (state == VALUE_STATE_UNMATERIALIZED
+ || state == VALUE_STATE_NULL
+ || state == VALUE_STATE_NON_NULL) {
+ return null;
Review Comment:
This actually returns something other that the materialized content (unless
it's `null`) despite the method name 🤔
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