1 files changed, 156 insertions, 0 deletions
diff --git a/catalog-be/src/main/java/org/openecomp/sdc/be/tosca/ComponentCache.java b/catalog-be/src/main/java/org/openecomp/sdc/be/tosca/ComponentCache.java
new file mode 100644
index 0000000000..7871176dab
--- /dev/null
+++ b/catalog-be/src/main/java/org/openecomp/sdc/be/tosca/ComponentCache.java
@@ -0,0 +1,156 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * SDC
+ * ================================================================================
+ * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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
+ *
+ *      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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.openecomp.sdc.be.tosca;
+
+import static org.openecomp.sdc.be.utils.CommonBeUtils.compareAsdcComponentVersions;
+
+import io.vavr.collection.HashMap;
+import io.vavr.collection.Map;
+import io.vavr.collection.Stream;
+import java.util.function.BiConsumer;
+import java.util.function.BinaryOperator;
+import lombok.EqualsAndHashCode;
+import org.apache.commons.lang3.tuple.ImmutableTriple;
+import org.openecomp.sdc.be.model.Component;
+
+/**
+ * Provides caching abilities for components
+ */
+public final class ComponentCache {
+
+    // TODO: Make this final whenever possible. The current code using the class
+    // does not allow this.
+    private Map<String, CacheEntry> entries = HashMap.empty();
+    private final BinaryOperator<CacheEntry> merge;
+
+    private ComponentCache(BinaryOperator<CacheEntry> merge) {
+        this.merge = merge;
+    }
+
+    /**
+     * Creates an overwritable cache based on a merging strategy
+     * @param merge The strategy used to merge two values which keys are the same
+     */
+    public static ComponentCache overwritable(BinaryOperator<CacheEntry> merge) {
+        return new ComponentCache(merge);
+    }
+
+    /**
+     * Creates a cached entry
+     * @param id The id of the entry
+     * @param fileName the filename of the entry
+     * @param component the cached component
+     */
+    public static CacheEntry entry(String id, String fileName, Component component) {
+        return new CacheEntry(id, fileName, component);
+    }
+
+    /**
+     * Decorate the cache with a listener called whenever a value is merged
+     * @param bc the consumer called when a value is merged
+     */
+    public ComponentCache onMerge(BiConsumer<CacheEntry, CacheEntry> bc) {
+        return new ComponentCache((oldValue, newValue) -> {
+            CacheEntry value = merge.apply(oldValue, newValue);
+            if(value.equals(newValue)) {
+                bc.accept(oldValue, newValue);
+            }
+            return value;
+        });
+    }
+
+    public interface MergeStrategy {
+
+        /**
+         * A strategy designed to favour the latest component version when merging two cached entries
+         */
+        static BinaryOperator<CacheEntry> overwriteIfSameVersions() {
+            return (oldValue, newValue) ->
+                compareAsdcComponentVersions(newValue.getComponentVersion(), oldValue.getComponentVersion()) ?
+                    newValue : oldValue;
+        }
+    }
+
+    /**
+     * Entry stored by the cache
+     */
+    @EqualsAndHashCode
+    public static final class CacheEntry {
+        final String id;
+
+        final String fileName;
+
+        final Component component;
+        CacheEntry(String id, String fileName, Component component) {
+            this.id = id;
+            this.fileName = fileName;
+            this.component = component;
+        }
+
+        public String getComponentVersion() {
+            return component.getVersion();
+        }
+    }
+
+    // TODO: Encapsulate the cache and expose functions to interact with it
+    // For now we'll keep this as is, to prevent the refactoring to be too big
+    public Iterable<ImmutableTriple<String, String, Component>> iterable() {
+        return all().map(e ->
+            new ImmutableTriple<>(e.id, e.fileName, e.component)
+        );
+    }
+
+    /**
+     * Streams all the entries stored in the cache
+     */
+    public Stream<CacheEntry> all() {
+        return entries.values().toStream();
+    }
+
+    /**
+     * Tells if an entry has been cached for a specific key
+     * @param key The key used to index the entry
+     */
+    public boolean notCached(String key) {
+        return !entries.get(key).isDefined();
+    }
+
+    /**
+     * Store an entry in the cache. Keep in mind that currently this mutates the cache and does not work in a
+     * referentially transparent way (This should be fixed whenever possible).
+     *
+     * @param id The id of the entry
+     * @param fileName the filename of the entry
+     * @param component the cached component
+     */
+    public ComponentCache put(
+        String id,
+        String fileName,
+        Component component
+    ) {
+        String uuid = component.getInvariantUUID();
+        CacheEntry entry = new CacheEntry(id, fileName, component);
+        // TODO: Make the entries final whenever possible. The current code using the class does not allow this
+        entries = entries.put(uuid, entry, merge);
+
+        return this;
+    }
+}