BUG-5280: introduce DistributedDataStoreClientActor

[controller.git] / opendaylight / md-sal / sal-distributed-datastore / src / main / java / org / opendaylight / controller / cluster / databroker / actors / dds / ClientLocalHistory.java

diff --git a/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/actors/dds/ClientLocalHistory.java b/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/actors/dds/ClientLocalHistory.java
new file mode 100644 (file)
index 0000000..b22f2bd
--- /dev/null
+++ b/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/actors/dds/ClientLocalHistory.java
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2016 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.cluster.databroker.actors.dds;
+
+import akka.actor.ActorRef;
+import com.google.common.annotations.Beta;
+import com.google.common.base.Preconditions;
+import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
+import javax.annotation.concurrent.NotThreadSafe;
+import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
+
+/**
+ * Client-side view of a local history. This class tracks all state related to a particular history and routes
+ * frontend requests towards the backend.
+ *
+ * This interface is used by the world outside of the actor system and in the actor system it is manifested via
+ * its client actor. That requires some state transfer with {@link DistributedDataStoreClientBehavior}. In order to
+ * reduce request latency, all messages are carbon-copied (and enqueued first) to the client actor.
+ *
+ * @author Robert Varga
+ */
+@Beta
+@NotThreadSafe
+public final class ClientLocalHistory implements AutoCloseable {
+    private static final AtomicIntegerFieldUpdater<ClientLocalHistory> CLOSED_UPDATER =
+            AtomicIntegerFieldUpdater.newUpdater(ClientLocalHistory.class, "state");
+    private static final int IDLE_STATE = 0;
+    private static final int CLOSED_STATE = 1;
+
+    private final LocalHistoryIdentifier historyId;
+    private final ActorRef backendActor;
+    private final ActorRef clientActor;
+
+    private volatile int state = IDLE_STATE;
+
+    ClientLocalHistory(final DistributedDataStoreClientBehavior client, final long historyId,
+            final ActorRef backendActor) {
+        this.clientActor = client.self();
+        this.backendActor = Preconditions.checkNotNull(backendActor);
+        this.historyId = new LocalHistoryIdentifier(client.getIdentifier(), historyId);
+    }
+
+    private void checkNotClosed() {
+        Preconditions.checkState(state != CLOSED_STATE, "Local history %s has been closed", historyId);
+    }
+
+    @Override
+    public void close() {
+        if (CLOSED_UPDATER.compareAndSet(this, IDLE_STATE, CLOSED_STATE)) {
+            // FIXME: signal close to both client actor and backend actor
+        } else if (state != CLOSED_STATE) {
+            throw new IllegalStateException("Cannot close history with an open transaction");
+        }
+    }
+
+    // FIXME: add client requests related to a particular local history
+}