Add abstract utility class for working with GemFire/Geode cache instances (ClientCache & peer Cache) and Regions.

apache-geode-extensions/src/main/java/org/springframework/geode/util/CacheUtils.java

@@ -0,0 +1,171 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * 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 org.springframework.geode.util;
+
+import static org.springframework.geode.util.GeodeAssertions.assertThat;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+
+import org.apache.geode.cache.Cache;
+import org.apache.geode.cache.Region;
+import org.apache.geode.cache.RegionAttributes;
+import org.apache.geode.cache.RegionService;
+import org.apache.geode.cache.client.ClientCache;
+import org.apache.geode.internal.cache.GemFireCacheImpl;
+
+/**
+ * Abstract utility class for working with GemFire/Geode cache instances, such as {@link ClientCache}
+ * and {@literal peer} {@link Cache} instances.
+ *
+ * @author John Blum
+ * @see org.apache.geode.cache.Cache
+ * @see org.apache.geode.cache.Region
+ * @see org.apache.geode.cache.RegionService
+ * @see org.apache.geode.cache.client.ClientCache
+ * @since 1.3.0
+ */
+public abstract class CacheUtils {
+
+	/**
+	 * Collects all {@link Object values} from the given {@link Region}.
+	 *
+	 * This method is capable of pulling {@link Object values} from either {@literal client}
+	 * or {@literal peer} {@link Region Regions}.
+	 *
+	 * @param <T> {@link Class type} of the {@link Region} {@link Object values}.
+	 * @param region {@link Region} from which to collect the {@link Object values}.
+	 * @return a {@link Collection} of all {@link Object values} from the given {@link Region}.
+	 * @throws IllegalArgumentException if {@link Region} is {@literal null}.
+	 * @see org.apache.geode.cache.Region
+	 * @see java.util.Collection
+	 */
+	// TODO Add Predicate-based Filtering
+	public static <T> Collection<T> collectValues(Region<?, T> region) {
+
+		assertThat(region).isNotNull();
+
+		return isClientRegion(region)
+			? clientRegionValues(region)
+			: region.values();
+
+	}
+
+	private static <T> Collection<T> clientRegionValues(Region<?, T> region) {
+
+		Set<?> keys = nullSafeSet(region.keySetOnServer());
+
+		return !keys.isEmpty() ? getAll(keys, region) : Collections.emptySet();
+	}
+
+	private static <T> Collection<T> getAll(Set<?> keys, Region<?, T> region) {
+		return nullSafeMap(region.getAll(keys)).values();
+		// Fallback procedure if region.getAll(keys) is buggered
+		//return keys.stream().map(region::get).collect(Collectors.toSet());
+	}
+
+	private static boolean hasText(String value) {
+		return !(value == null || value.trim().isEmpty());
+	}
+
+	private static <K, V> Map<K, V> nullSafeMap(Map<K, V> map) {
+		return map != null ? map :Collections.emptyMap();
+	}
+
+	private static <T> Set<T> nullSafeSet(Set<T> set) {
+		return set != null ? set : Collections.emptySet();
+	}
+
+	/**
+	 * Null-safe method to determine whether the given {@link RegionService} is an instance of {@link ClientCache}.
+	 *
+	 * The problem is, {@link GemFireCacheImpl} implements both the (peer) {@link Cache}
+	 * and {@link ClientCache} interfaces. #sigh
+	 *
+	 * @param regionService {@link RegionService} to evaluate.
+	 * @return a boolean value indicating whether the {@link RegionService} an instance of {@link ClientCache}.
+	 * @see org.apache.geode.cache.client.ClientCache
+	 * @see org.apache.geode.cache.RegionService
+	 */
+	public static boolean isClientCache(RegionService regionService) {
+
+		boolean result = regionService instanceof ClientCache;
+
+		if (regionService instanceof GemFireCacheImpl) {
+			result &= ((GemFireCacheImpl) regionService).isClient();
+		}
+
+		return result;
+	}
+
+	/**
+	 * Null-safe method to determine whether the given {@link Region} is a {@literal client} {@link Region}
+	 * in a {@link ClientCache}.
+	 *
+	 * @param region {@link Region} to evaluate.
+	 * @return a boolean value indicating whether the given {@link Region} is a {@literal client} {@link Region}.
+	 * @see org.apache.geode.cache.Region
+	 * @see #isClientCache(RegionService)
+	 */
+	public static boolean isClientRegion(Region<?, ?> region) {
+
+		return region != null && (isClientCache(region.getRegionService())
+			|| Optional.ofNullable(region.getAttributes())
+				.map(RegionAttributes::getPoolName)
+				.filter(CacheUtils::hasText)
+				.isPresent());
+	}
+
+	/**
+	 * Null-safe method to determine whether the given {@link RegionService} is an instance of
+	 * a {@literal peer} {@link Cache}.
+	 *
+	 * The problem is, {@link GemFireCacheImpl} implements both the (peer) {@link Cache}
+	 * and {@link ClientCache} interfaces. #sigh
+	 *
+	 * @param regionService {@link RegionService} to evaluate.
+	 * @return a boolean value indicating whether the {@link RegionService} is an instance of
+	 * a {@literal peer} {@link Cache}.
+	 * @see org.apache.geode.cache.RegionService
+	 * @see org.apache.geode.cache.Cache
+	 */
+	public static boolean isPeerCache(RegionService regionService) {
+
+		boolean result = regionService instanceof Cache;
+
+		if (regionService instanceof GemFireCacheImpl) {
+			result &= !((GemFireCacheImpl) regionService).isClient();
+		}
+
+		return result;
+	}
+
+	/**
+	 * Null-safe method to determine whether the given {@link Region} is a {@literal peer} {@link Region}
+	 * in a {@literal peer} {@link Cache}.
+	 *
+	 * @param region {@link Region} to evaluate.
+	 * @return a boolean value indicating whether the given {@link Region} is a {@literal peer} {@link Region}.
+	 * @see org.apache.geode.cache.Region
+	 * @see #isPeerCache(RegionService)
+	 */
+	public static boolean isPeerRegion(Region<?, ?> region) {
+		return region != null && !isClientRegion(region);
+	}
+}