BUG-7556: update version tracking

[controller.git] / opendaylight / md-sal / sal-remoterpc-connector / src / main / java / org / opendaylight / controller / remote / rpc / registry / gossip / LocalBucket.java

diff --git a/opendaylight/md-sal/sal-remoterpc-connector/src/main/java/org/opendaylight/controller/remote/rpc/registry/gossip/LocalBucket.java b/opendaylight/md-sal/sal-remoterpc-connector/src/main/java/org/opendaylight/controller/remote/rpc/registry/gossip/LocalBucket.java
new file mode 100644 (file)
index 0000000..b2c5e0c
--- /dev/null
+++ b/opendaylight/md-sal/sal-remoterpc-connector/src/main/java/org/opendaylight/controller/remote/rpc/registry/gossip/LocalBucket.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2017 Cisco 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.controller.remote.rpc.registry.gossip;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * Local bucket implementation. Unlike a full-blown {@link Bucket}, this class is mutable and tracks when it has been
+ * changed and when it has been sent anywhere.
+ *
+ * @author Robert Varga
+ */
+final class LocalBucket<T extends BucketData<T>> {
+    /*
+     * Decomposed 64bit signed version number. Always non-negative, hence the most significant bit is always zero.
+     * - incarnation number (most-significant 31 bits, forming an unsigned int)
+     * - version number (least-significant 32 bits, treated as unsigned int)
+     *
+     * We are keeping a boxed version here, as we stick it into a map anyway.
+     */
+    private Long version;
+    private T data;
+
+    // We bump versions only if we took a snapshot since last data update
+    private boolean bumpVersion;
+
+    LocalBucket(final int incarnation, final T data) {
+        Preconditions.checkArgument(incarnation >= 0);
+        this.version = ((long)incarnation) << Integer.SIZE;
+        this.data = Preconditions.checkNotNull(data);
+    }
+
+    T getData() {
+        return data;
+    }
+
+    Long getVersion() {
+        return version;
+    }
+
+    Bucket<T> snapshot() {
+        bumpVersion = true;
+        return new BucketImpl<>(version, data);
+    }
+
+    boolean setData(final T data) {
+        this.data = Preconditions.checkNotNull(data);
+        if (bumpVersion) {
+            final long next = version.longValue() + 1;
+            if ((next & 0xffff_ffffL) == 0) {
+                return true;
+            }
+
+            version = next;
+            bumpVersion = false;
+        }
+        return false;
+    }
+}