Add support for version ACK-dependent tasks in cluster controller

Used to enable synchronous operation for set-node-state calls, which
ensure that side-effects of the call are visible when the response
returns.

If controller leadership is lost before state is published, tasks will
be failed back to the client.

1 files changed, 43 insertions, 0 deletions

diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/VersionDependentTaskCompletion.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/VersionDependentTaskCompletion.java
new file mode 100644
index 00000000000..d7b8f96005a
--- /dev/null
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/VersionDependentTaskCompletion.java
@@ -0,0 +1,43 @@
+// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.clustercontroller.core;
+
+import java.util.Objects;
+
+/**
+ * Wrapper for a remote (i.e. REST API) cluster controller task whose
+ * completion depends on side effects by the task becoming visible in
+ * the cluster before a response can be sent. Each such task is associated
+ * with a particular cluster state version number representing a lower bound
+ * on the published state containing the side effect.
+ */
+class VersionDependentTaskCompletion {
+    private final long minimumVersion;
+    private final RemoteClusterControllerTask task;
+
+    VersionDependentTaskCompletion(long minimumVersion, RemoteClusterControllerTask task) {
+        this.minimumVersion = minimumVersion;
+        this.task = task;
+    }
+
+    long getMinimumVersion() {
+        return minimumVersion;
+    }
+
+    RemoteClusterControllerTask getTask() {
+        return task;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        VersionDependentTaskCompletion that = (VersionDependentTaskCompletion) o;
+        return minimumVersion == that.minimumVersion &&
+                Objects.equals(task, that.task);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(minimumVersion, task);
+    }
+}