Add common entity ownership interfaces

[mdsal.git] / common / mdsal-common-api / src / main / java / org / opendaylight / mdsal / common / api / clustering / EntityOwnershipChangeState.java

diff --git a/common/mdsal-common-api/src/main/java/org/opendaylight/mdsal/common/api/clustering/EntityOwnershipChangeState.java b/common/mdsal-common-api/src/main/java/org/opendaylight/mdsal/common/api/clustering/EntityOwnershipChangeState.java
new file mode 100644 (file)
index 0000000..4dbb629
--- /dev/null
+++ b/common/mdsal-common-api/src/main/java/org/opendaylight/mdsal/common/api/clustering/EntityOwnershipChangeState.java
@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 2015 Brocade Communications Systems, Inc. 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.mdsal.common.api.clustering;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableMap.Builder;
+import java.util.Map;
+
+/**
+ * Enumerates the ownership change states for an entity.
+ *
+ * @author Thomas Pantelis
+ */
+public enum EntityOwnershipChangeState {
+    /**
+     * The local process instance has been granted ownership.
+     */
+    LOCAL_OWNERSHIP_GRANTED(false, true, true),
+
+    /**
+     * The local process instance has lost ownership and another process instance is now the owner.
+     */
+    LOCAL_OWNERSHIP_LOST_NEW_OWNER(true, false, true),
+
+    /**
+     * The local process instance has lost ownership and there are no longer any candidates for the entity and
+     * thus has no owner.
+     */
+    LOCAL_OWNERSHIP_LOST_NO_OWNER(true, false, false),
+
+    /**
+     * Entity ownership has transitioned to another process instance and this instance was not the previous owner.
+     */
+    REMOTE_OWNERSHIP_CHANGED(false, false, true),
+
+    /**
+     * A remote process instance has lost ownership and there are no longer any candidates for the entity and
+     * thus has no owner.
+     */
+    REMOTE_OWNERSHIP_LOST_NO_OWNER(false, false, false);
+
+    private static final Map<Key, EntityOwnershipChangeState> BY_KEY;
+    static {
+        Builder<Key, EntityOwnershipChangeState> builder = ImmutableMap.<Key, EntityOwnershipChangeState>builder();
+        for(EntityOwnershipChangeState e: values()) {
+            builder.put(new Key(e.wasOwner, e.isOwner, e.hasOwner), e);
+        }
+
+        BY_KEY = builder.build();
+    }
+
+    private final boolean wasOwner;
+    private final boolean isOwner;
+    private final boolean hasOwner;
+
+    private EntityOwnershipChangeState(boolean wasOwner, boolean isOwner, boolean hasOwner) {
+        this.wasOwner = wasOwner;
+        this.isOwner = isOwner;
+        this.hasOwner = hasOwner;
+    }
+
+    /**
+     * Returns the previous ownership status of the entity for this process instance.
+     * @return true if this process was the owner of the entity at the time this notification was generated
+     */
+    public boolean wasOwner() {
+        return wasOwner;
+    }
+
+    /**
+     * Returns the current ownership status of the entity for this process instance.
+     * @return true if this process is now the owner of the entity
+     */
+    public boolean isOwner() {
+        return isOwner;
+    }
+
+    /**
+     * Returns the current ownership status of the entity across all process instances.
+     * @return true if the entity has an owner which may or may not be this process. If false, then
+     *         the entity has no candidates and thus no owner.
+     */
+    public boolean hasOwner() {
+        return hasOwner;
+    }
+
+    @Override
+    public String toString() {
+        return name() + " [wasOwner=" + wasOwner + ", isOwner=" + isOwner + ", hasOwner=" + hasOwner + "]";
+    }
+
+    public static EntityOwnershipChangeState from(boolean wasOwner, boolean isOwner, boolean hasOwner) {
+        EntityOwnershipChangeState state = BY_KEY.get(new Key(wasOwner, isOwner, hasOwner));
+        Preconditions.checkArgument(state != null, "Invalid combination of wasOwner: %s, isOwner: %s, hasOwner: %s",
+                wasOwner, isOwner, hasOwner);
+        return state;
+    }
+
+    private static final class Key {
+        private final boolean wasOwner;
+        private final boolean isOwner;
+        private final boolean hasOwner;
+
+        Key(boolean wasOwner, boolean isOwner, boolean hasOwner) {
+            this.wasOwner = wasOwner;
+            this.isOwner = isOwner;
+            this.hasOwner = hasOwner;
+        }
+
+        @Override
+        public int hashCode() {
+            final int prime = 31;
+            int result = 1;
+            result = prime * result + (hasOwner ? 1231 : 1237);
+            result = prime * result + (isOwner ? 1231 : 1237);
+            result = prime * result + (wasOwner ? 1231 : 1237);
+            return result;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            Key other = (Key) obj;
+            return hasOwner == other.hasOwner && isOwner == other.isOwner && wasOwner == other.wasOwner;
+        }
+    }
+}