Extract NodeVersionSerializer

2 files changed, 68 insertions, 17 deletions

diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/NodeVersionSerializer.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/NodeVersionSerializer.java
new file mode 100644
index 00000000000..088808f5942
--- /dev/null
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/NodeVersionSerializer.java
@@ -0,0 +1,61 @@
+// Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.hosted.controller.persistence;
+
+import com.yahoo.component.Version;
+import com.yahoo.config.provision.HostName;
+import com.yahoo.slime.ArrayTraverser;
+import com.yahoo.slime.Cursor;
+import com.yahoo.slime.Inspector;
+import com.yahoo.vespa.hosted.controller.versions.NodeVersion;
+
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * Serializer for {@link com.yahoo.vespa.hosted.controller.versions.NodeVersion}.
+ *
+ * @author mpolden
+ */
+public class NodeVersionSerializer {
+
+    // WARNING: Since there are multiple servers in a ZooKeeper cluster and they upgrade one by one
+    //          (and rewrite all nodes on startup), changes to the serialized format must be made
+    //          such that what is serialized on version N+1 can be read by version N:
+    //          - ADDING FIELDS: Always ok
+    //          - REMOVING FIELDS: Stop reading the field first. Stop writing it on a later version.
+    //          - CHANGING THE FORMAT OF A FIELD: Don't do it bro.
+
+    private static final String hostnameField = "hostname";
+    private static final String currentVersionField = "currentVersion";
+    private static final String wantedVersionField = "wantedVersion";
+    private static final String changedAtField = "changedAt";
+
+    public void nodeVersionsToSlime(Collection<NodeVersion> nodeVersions, Cursor array, boolean writeCurrentVersion) {
+        for (var nodeVersion : nodeVersions) {
+            var nodeVersionObject = array.addObject();
+            nodeVersionObject.setString(hostnameField, nodeVersion.hostname().value());
+            if (writeCurrentVersion) {
+                nodeVersionObject.setString(currentVersionField, nodeVersion.currentVersion().toFullString());
+            }
+            nodeVersionObject.setString(wantedVersionField, nodeVersion.wantedVersion().toFullString());
+            nodeVersionObject.setLong(changedAtField, nodeVersion.changedAt().toEpochMilli());
+        }
+    }
+
+    public List<NodeVersion> nodeVersionsFromSlime(Inspector object, Optional<Version> version) {
+        var nodeVersions = new ArrayList<NodeVersion>();
+        object.traverse((ArrayTraverser) (i, entry) -> {
+            var hostname = HostName.from(entry.field(hostnameField).asString());
+            var currentVersion = version.orElseGet(() -> Version.fromString(entry.field(currentVersionField).asString()));
+            var wantedVersion = Version.fromString(entry.field(wantedVersionField).asString());
+            var changedAt = Instant.ofEpochMilli(entry.field(changedAtField).asLong());
+            nodeVersions.add(new NodeVersion(hostname, currentVersion, wantedVersion, changedAt));
+        });
+        return Collections.unmodifiableList(nodeVersions);
+    }
+
+}
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializer.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializer.java
index 5061f32da68..62fca7a419b 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializer.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializer.java
@@ -21,6 +21,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 
 /**
@@ -53,17 +54,14 @@ public class VersionStatusSerializer {
     // NodeVersions fields
     private static final String nodeVersionsField = "nodeVersions";
 
-    // NodeVersion fields
-    private static final String hostnameField = "hostname";
-    private static final String wantedVersionField = "wantedVersion";
-    private static final String changedAtField = "changedAt";
-
     // DeploymentStatistics fields
     private static final String versionField = "version";
     private static final String failingField = "failing";
     private static final String productionField = "production";
     private static final String deployingField = "deploying";
 
+    private final NodeVersionSerializer nodeVersionSerializer = new NodeVersionSerializer();
+
     public Slime toSlime(VersionStatus status) {
         Slime slime = new Slime();
         Cursor root = slime.setObject();
@@ -93,12 +91,7 @@ public class VersionStatusSerializer {
     }
 
     private void nodeVersionsToSlime(NodeVersions nodeVersions, Cursor array) {
-        for (NodeVersion nodeVersion : nodeVersions.asMap().values()) {
-            var nodeVersionObject = array.addObject();
-            nodeVersionObject.setString(hostnameField, nodeVersion.hostname().value());
-            nodeVersionObject.setString(wantedVersionField, nodeVersion.wantedVersion().toFullString());
-            nodeVersionObject.setLong(changedAtField, nodeVersion.changedAt().toEpochMilli());
-        }
+        nodeVersionSerializer.nodeVersionsToSlime(nodeVersions.asMap().values(), array, false);
     }
 
     // TODO(mpolden): Remove after October 2019
@@ -140,12 +133,9 @@ public class VersionStatusSerializer {
         var nodeVersions = ImmutableMap.<HostName, NodeVersion>builder();
         var nodeVersionsRoot = root.field(nodeVersionsField);
         if (nodeVersionsRoot.valid()) {
-            nodeVersionsRoot.traverse((ArrayTraverser) (i, entry) -> {
-                var hostname = HostName.from(entry.field(hostnameField).asString());
-                var wantedVersion = Version.fromString(entry.field(wantedVersionField).asString());
-                var changedAt = Instant.ofEpochMilli(entry.field(changedAtField).asLong());
-                nodeVersions.put(hostname, new NodeVersion(hostname, version, wantedVersion, changedAt));
-            });
+            for (var nodeVersion : nodeVersionSerializer.nodeVersionsFromSlime(nodeVersionsRoot, Optional.of(version))) {
+                nodeVersions.put(nodeVersion.hostname(), nodeVersion);
+            }
         } else {
             // TODO(mpolden): Remove after October 2019
             var configServerHostnames = configServersFromSlime(root.field(configServersField));