dimas-b commented on code in PR #490:
URL: https://github.com/apache/polaris/pull/490#discussion_r2033225171
##########
polaris-core/src/test/java/org/apache/polaris/core/persistence/cache/EntityCacheTest.java:
##########
@@ -478,4 +481,26 @@ void testRenameAndCacheDestinationBeforeLoadingSource() {
// now the loading by the old name should return null
Assertions.assertThat(cache.getOrLoadEntityByName(callCtx,
T4_name)).isNull();
}
+
+ /* Helper for `testEntityWeigher` */
+ private int getEntityWeight(PolarisEntity entity) {
+ return EntityWeigher.getInstance()
+ .weigh(-1L, new ResolvedPolarisEntity(diagServices, entity, List.of(),
1));
+ }
+
+ @Test
+ void testEntityWeigher() {
+ var smallEntity = new
IcebergTableLikeEntity.Builder(TableIdentifier.of("ns.t1"), "").build();
+ var mediumEntity =
+ new IcebergTableLikeEntity.Builder(TableIdentifier.of("ns.t1"), "")
+ .setMetadataLocation("a".repeat(10000))
+ .build();
+ var largeEntity =
+ new IcebergTableLikeEntity.Builder(TableIdentifier.of("ns.t1"), "")
+ .setMetadataLocation("a".repeat(1000 * 1000))
+ .build();
+
+
Assertions.assertThat(getEntityWeight(smallEntity)).isLessThan(getEntityWeight(mediumEntity));
+
Assertions.assertThat(getEntityWeight(mediumEntity)).isLessThan(getEntityWeight(largeEntity));
Review Comment:
IMHO this is not a very useful test. If we want to make sure the weigher
takes specific entity fields into account we should probably do that directly
in a weigher-specific unit test, and using exact comparisons (white-box test).
##########
polaris-core/src/main/java/org/apache/polaris/core/persistence/cache/EntityWeigher.java:
##########
@@ -0,0 +1,69 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.core.persistence.cache;
+
+import com.github.benmanes.caffeine.cache.Weigher;
+import org.apache.polaris.core.persistence.ResolvedPolarisEntity;
+import org.checkerframework.checker.index.qual.NonNegative;
+
+/**
+ * A {@link Weigher} implementation that weighs {@link ResolvedPolarisEntity}
objects by the
+ * approximate size of the entity object.
+ */
+public class EntityWeigher implements Weigher<Long, ResolvedPolarisEntity> {
+
+ /** The amount of weight that is expected to roughly equate to 1MB of memory
usage */
+ public static final long WEIGHT_PER_MB = 1024 * 1024;
Review Comment:
Do we need this constant anymore? Why not inline its value in the config
default?
##########
polaris-core/src/main/java/org/apache/polaris/core/config/FeatureConfiguration.java:
##########
@@ -183,4 +184,11 @@ protected FeatureConfiguration(
"How many times to retry refreshing metadata when the previous
error was retryable")
.defaultValue(2)
.buildFeatureConfiguration();
+
+ public static final FeatureConfiguration<Long> ENTITY_CACHE_WEIGHER_TARGET =
+ PolarisConfiguration.<Long>builder()
+ .key("ENTITY_CACHE_WEIGHER_TARGET")
+ .description("The target weight for the entity cache.")
Review Comment:
Given the current weigher impl., how about this message: `The maximum weight
for the entity cache. This is a heuristic value without any particular unit of
measurement. It roughly correlates with the total heap size of cached values.
Fine-tuning requires experimentation in the specific deployment environment`.
##########
polaris-core/src/main/java/org/apache/polaris/core/persistence/cache/EntityWeigher.java:
##########
@@ -0,0 +1,69 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.core.persistence.cache;
+
+import com.github.benmanes.caffeine.cache.Weigher;
+import org.apache.polaris.core.persistence.ResolvedPolarisEntity;
+import org.checkerframework.checker.index.qual.NonNegative;
+
+/**
+ * A {@link Weigher} implementation that weighs {@link ResolvedPolarisEntity}
objects by the
+ * approximate size of the entity object.
+ */
+public class EntityWeigher implements Weigher<Long, ResolvedPolarisEntity> {
+
+ /** The amount of weight that is expected to roughly equate to 1MB of memory
usage */
+ public static final long WEIGHT_PER_MB = 1024 * 1024;
+
+ /* Represents the approximate size of an entity beyond the properties */
+ private static final int APPROXIMATE_ENTITY_OVERHEAD = 1000;
+
+ /* Represents the amount of bytes that a character is expected to take up */
+ private static final int APPROXIMATE_BYTES_PER_CHAR = 3;
+
+ /** Singleton instance */
+ private static final EntityWeigher instance = new EntityWeigher();
+
+ private EntityWeigher() {}
+
+ /** Gets the singleton {@link EntityWeigher} */
+ public static EntityWeigher getInstance() {
+ return instance;
+ }
+
+ /**
+ * Computes the weight of a given entity. The unit here is not exactly
bytes, but it's close.
+ *
+ * @param key The entity's key; not used
+ * @param value The entity to be cached
+ * @return The weight of the entity
+ */
+ @Override
+ public @NonNegative int weigh(Long key, ResolvedPolarisEntity value) {
+ return APPROXIMATE_ENTITY_OVERHEAD
+ + (value.getEntity().getName().length() * APPROXIMATE_BYTES_PER_CHAR)
+ + (value.getEntity().getProperties().length() *
APPROXIMATE_BYTES_PER_CHAR)
+ + (value.getEntity().getInternalProperties().length() *
APPROXIMATE_BYTES_PER_CHAR);
Review Comment:
I think we can leave this "as is" for now. Putting a more general comment in
the main thread.
##########
polaris-core/src/main/java/org/apache/polaris/core/persistence/cache/EntityWeigher.java:
##########
@@ -0,0 +1,64 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.core.persistence.cache;
+
+import com.github.benmanes.caffeine.cache.Weigher;
+import org.checkerframework.checker.index.qual.NonNegative;
+
+/**
+ * A {@link Weigher} implementation that weighs {@link EntityCacheEntry}
objects by the approximate
+ * size of the entity object.
+ */
+public class EntityWeigher implements Weigher<Long, EntityCacheEntry> {
+
+ /** The amount of weight that is expected to roughly equate to 1MB of memory
usage */
+ public static final long WEIGHT_PER_MB = 1024 * 1024;
+
+ /* Represents the approximate size of an entity beyond the properties */
+ private static final int APPROXIMATE_ENTITY_OVERHEAD = 1000;
+
+ /** Singleton instance */
+ private static final EntityWeigher instance = new EntityWeigher();
+
+ private EntityWeigher() {}
+
+ /** Gets the singleton {@link EntityWeigher} */
+ public static EntityWeigher getInstance() {
+ return instance;
+ }
+
+ /**
+ * Computes the weight of a given entity
+ *
+ * @param key The entity's key; not used
+ * @param value The entity to be cached
+ * @return The weight of the entity
+ */
+ @Override
+ public @NonNegative int weigh(Long key, EntityCacheEntry value) {
+ return APPROXIMATE_ENTITY_OVERHEAD
+ + value.getEntity().getProperties().length()
+ + value.getEntity().getInternalProperties().length();
Review Comment:
I'd good to see a clear linear relationship between weight and heap usage
:+1:
Did you test include Grant Records inside cached entities? Do we expect
those to be prevalent in the cache at all?
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