Add DatastoreIdentifier

This is a type-safe manifestation of RFC8342 datastore identity
for the purposes of yang-data-api. While this identifier not
immediately used in any contracts, it will be required for
RFC8525/RFC8528 interoperation where codecs are concerned.

JIRA: YANGTOOLS-1012
Change-Id: Ief45ed176d5751dc22249d3c40da2473f648bbc6
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>

diff --git a/yang/yang-data-api/src/main/java/org/opendaylight/yangtools/yang/data/api/DSIv1.java b/yang/yang-data-api/src/main/java/org/opendaylight/yangtools/yang/data/api/DSIv1.java
new file mode 100644 (file)
index 0000000..d2348e0
--- /dev/null
+++ b/yang/yang-data-api/src/main/java/org/opendaylight/yangtools/yang/data/api/DSIv1.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2019 PANTHEON.tech s.r.o. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.yangtools.yang.data.api;
+
+import static java.util.Objects.requireNonNull;
+
+import java.io.Externalizable;
+import java.io.IOException;
+import java.io.ObjectInput;
+import java.io.ObjectOutput;
+import org.eclipse.jdt.annotation.NonNull;
+import org.opendaylight.yangtools.yang.common.QName;
+
+final class DSIv1 implements Externalizable {
+    private static final long serialVersionUID = 1L;
+
+    private QName qname;
+
+    @SuppressWarnings("checkstyle:redundantModifier")
+    public DSIv1() {
+        // For Externalizable
+    }
+
+    DSIv1(final @NonNull QName qname) {
+        this.qname = requireNonNull(qname);
+    }
+
+    @Override
+    public void writeExternal(final ObjectOutput out) throws IOException {
+        qname.writeTo(out);
+    }
+
+    @Override
+    public void readExternal(final ObjectInput in) throws IOException {
+        qname = QName.readFrom(in);
+    }
+
+    private Object readResolve() {
+        return DatastoreIdentifier.create(qname);
+    }
+}

diff --git a/yang/yang-data-api/src/main/java/org/opendaylight/yangtools/yang/data/api/DatastoreIdentifier.java b/yang/yang-data-api/src/main/java/org/opendaylight/yangtools/yang/data/api/DatastoreIdentifier.java
new file mode 100644 (file)
index 0000000..3359025
--- /dev/null
+++ b/yang/yang-data-api/src/main/java/org/opendaylight/yangtools/yang/data/api/DatastoreIdentifier.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2019 PANTHEON.tech s.r.o. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.yangtools.yang.data.api;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.annotations.Beta;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.common.collect.ImmutableSet;
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+import java.net.URI;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.opendaylight.yangtools.concepts.WritableObject;
+import org.opendaylight.yangtools.util.AbstractIdentifier;
+import org.opendaylight.yangtools.yang.common.QName;
+
+/**
+ * Identifier of a RFC8342 (NMDA) datastore. This class is backed by the QName of the datastore, i.e.
+ * the {@code identity} which defines the datastore. This class does not allow creation of identifiers which are
+ * defined as abstract, that is "datastore", "conventional" and "dynamic" in the namespace of {@code ietf-datastores}.
+ */
+@Beta
+@NonNullByDefault
+public final class DatastoreIdentifier extends AbstractIdentifier<QName> implements WritableObject {
+    private static final long serialVersionUID = 1L;
+
+    private static final URI IETF_DATASTORES_NAMESPACE = URI.create("urn:ietf:params:xml:ns:yang:ietf-datastores");
+    private static final ImmutableSet<String> KNOWN_ABSTRACTS = ImmutableSet.of("datastore", "conventional", "dynamic");
+
+    private static final LoadingCache<QName, DatastoreIdentifier> CACHE = CacheBuilder.newBuilder().weakValues()
+            .build(new CacheLoader<QName, DatastoreIdentifier>() {
+                @Override
+                public DatastoreIdentifier load(final QName key) {
+                    return of(key);
+                }
+            });
+
+    private DatastoreIdentifier(final QName qname) {
+        super(qname);
+        if (IETF_DATASTORES_NAMESPACE.equals(qname.getNamespace())) {
+            checkArgument(!KNOWN_ABSTRACTS.contains(qname.getLocalName()), "%s refers to a known-abstract datastore",
+                qname);
+        }
+    }
+
+    public static DatastoreIdentifier of(final QName qname) {
+        return new DatastoreIdentifier(qname);
+    }
+
+    public static DatastoreIdentifier create(final QName qname) {
+        final DatastoreIdentifier existing = CACHE.getIfPresent(qname);
+        return existing != null ? existing : CACHE.getUnchecked(qname.intern());
+    }
+
+    public static DatastoreIdentifier readFrom(final DataInput in) throws IOException {
+        return create(QName.readFrom(in));
+    }
+
+    @Override
+    public void writeTo(final DataOutput out) throws IOException {
+        getValue().writeTo(out);
+    }
+
+    private Object writeReplace() {
+        return new DSIv1(getValue());
+    }
+}