JT-78303: Add tests and config docs

entity-store/src/test/kotlin/jetbrains/exodus/entitystore/EntityIterableCacheAdapterTest.kt

@@ -0,0 +1,50 @@
+/*
+ * Copyright ${inceptionYear} - ${year} ${owner}
+ *
+ * Licensed 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
+ *
+ * https://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 jetbrains.exodus.entitystore
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+
+class EntityIterableCacheAdapterTest {
+
+    @Test
+    fun `should create weighted cache`() {
+        // Given
+        // Use default config values
+        val config = PersistentEntityStoreConfig()
+        val maxCacheWeight = config.entityIterableCacheWeight
+
+        // When
+        val adapter = EntityIterableCacheAdapter.create(config)
+
+        // Then
+        assertEquals(maxCacheWeight, adapter.cache.size())
+    }
+
+    @Test
+    fun `should create sized cache for backward compatibility`() {
+        // Given
+        System.setProperty(PersistentEntityStoreConfig.ENTITY_ITERABLE_CACHE_SIZE, "100")
+        val config = PersistentEntityStoreConfig()
+
+        // When
+        val adapter = EntityIterableCacheAdapter.create(config)
+
+        // Then
+        assertEquals(100, adapter.cache.size())
+    }
+}

openAPI/src/main/java/jetbrains/exodus/entitystore/PersistentEntityStoreConfig.java

@@ -232,7 +232,7 @@ public PersistentEntityStoreConfig setMutable(boolean isMutable) {
      * <p>Mutable at runtime: no
      *
      * @see #CACHING_DISABLED
-     * @deprecated use {@linkplain #ENTITY_ITERABLE_CACHE_MEMORY_PERCENTAGE} instead.
+     * @deprecated use weighted case in conjunction with {@linkplain #ENTITY_ITERABLE_CACHE_MEMORY_PERCENTAGE} instead.
      */
     public static final String ENTITY_ITERABLE_CACHE_SIZE = "exodus.entityStore.entityIterableCache.size";
 
@@ -243,14 +243,20 @@ public PersistentEntityStoreConfig setMutable(boolean isMutable) {
     public static final String ENTITY_ITERABLE_DEFERRED_CACHE_SIZE = "exodus.entityStore.entityIterableCache.deferred.size";
 
     /**
-     * Specifies the percentage (from 0 to 100) of heap memory used for cache.
+     * Specifies the percentage (from 0 to 100) of heap memory used for entity iterable cache.
+     * This value is used to calculate max cache weight.
+     * The final formula for maxCacheWeight is: maxMemory * memoryPercentage / 100 / entityWeight.
      * <p>Mutable at runtime: no
+     *
+     * @see #ENTITY_ITERABLE_CACHE_ENTITY_WEIGHT
      */
     public static final String ENTITY_ITERABLE_CACHE_MEMORY_PERCENTAGE = "exodus.entityStore.entityIterableCache.memoryPercentage";
 
     /**
      * Specifies the size of a single entity key stored in cached in bytes.
      * <p>Mutable at runtime: no
+     *
+     * @see #ENTITY_ITERABLE_CACHE_MEMORY_PERCENTAGE
      */
     public static final String ENTITY_ITERABLE_CACHE_ENTITY_WEIGHT = "exodus.entityStore.entityIterableCache.weightCoefficient";
 
@@ -703,7 +709,10 @@ public int getEntityIterableCacheEntityWeight() {
     }
 
     public long getEntityIterableCacheWeight() {
-        return (Runtime.getRuntime().maxMemory() * getEntityIterableCacheMemoryPercentage() / 100) / getEntityIterableCacheEntityWeight();
+        long maxMemory = Runtime.getRuntime().maxMemory();
+        long percentage = getEntityIterableCacheMemoryPercentage();
+        long entityWeight = getEntityIterableCacheEntityWeight();
+        return (maxMemory * percentage) / (100 * entityWeight);
     }
 
     public PersistentEntityStoreConfig setEntityIterableCacheSize(final int size) {

openAPI/src/test/kotlin/jetbrains/exodus/entitystore/PersistentEntityStoreCacheConfigTest.kt

@@ -0,0 +1,51 @@
+/*
+ * Copyright ${inceptionYear} - ${year} ${owner}
+ *
+ * Licensed 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
+ *
+ * https://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 jetbrains.exodus.entitystore
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class PersistentEntityStoreCacheConfigTest {
+
+    @Test
+    fun `should return default max cache weight`() {
+        // Given
+        val config = PersistentEntityStoreConfig()
+
+        // When
+        val maxCacheWeight = config.entityIterableCacheWeight
+
+        // Then
+        val maxMemory = Runtime.getRuntime().maxMemory()
+        assertTrue(maxCacheWeight in 1..<maxMemory)
+    }
+
+    @Test
+    fun `should calculate max cache weight from params`() {
+        // Given
+        System.setProperty(PersistentEntityStoreConfig.ENTITY_ITERABLE_CACHE_MEMORY_PERCENTAGE, "50")
+        System.setProperty(PersistentEntityStoreConfig.ENTITY_ITERABLE_CACHE_ENTITY_WEIGHT, "8")
+        val config = PersistentEntityStoreConfig()
+
+        // When
+        val maxCacheWeight = config.entityIterableCacheWeight
+
+        // Then
+        val maxMemory = Runtime.getRuntime().maxMemory()
+        assertEquals(maxCacheWeight, (maxMemory * 50) / (100 * 8))
+    }
+}