1 files changed, 162 insertions, 0 deletions
diff --git a/config-lib/src/main/java/com/yahoo/config/ChangesRequiringRestart.java b/config-lib/src/main/java/com/yahoo/config/ChangesRequiringRestart.java
new file mode 100644
index 00000000000..6c17a21c649
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/ChangesRequiringRestart.java
@@ -0,0 +1,162 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+import static java.util.stream.Collectors.joining;
+
+/**
+ * @author <a href="mailto:magnarn@yahoo-inc.com">Magnar Nedland</a>
+ *
+ * This class aggregates information about config changes that causes a restart to be required.
+ */
+public class ChangesRequiringRestart {
+    static class ReportLine {
+        private String name;
+        private final Node from;
+        private final Node to;
+        private final String comment;
+
+        public ReportLine(String name, Node from, Node to, String comment) {
+            this.name = name;
+            this.from = from;
+            this.to = to;
+            this.comment = comment;
+        }
+
+        public void addNamePrefix(String prefix) {
+            if (!name.isEmpty()) {
+                name = prefix + "." + name;
+            } else {
+                name = prefix;
+            }
+        }
+
+        private String getCommentAndName(String indent, String namePrefix) {
+            return indent + (comment.isEmpty()? "" : "# " + comment.replace("\n", "\n" + indent + "# ") + "\n" + indent)
+                    + namePrefix + name;
+        }
+
+        private static String formatValue(String indent, Node n) {
+            String str = n.toString();
+            if (str.contains("\n")) {  // Struct
+                str = "\n" + indent + "  { " + str.replace("\n", "\n" + indent + "    ") + " }";
+            }
+            return str;
+        }
+
+        @Override
+        public String toString() {
+            return toString("", "");
+        }
+
+        public String toString(String indent, String namePrefix) {
+            if (from == null) {
+                return getCommentAndName(indent, namePrefix) + " was added with value " + formatValue(indent, to);
+            } else if (to == null) {
+                return getCommentAndName(indent, namePrefix) + " with value " + formatValue(indent, from) + " was removed";
+            }
+            return getCommentAndName(indent, namePrefix) + " has changed from " + formatValue(indent, from) + " to " + formatValue(indent, to);
+        }
+    }
+
+    private ArrayList<ReportLine> report = new ArrayList<>();
+    private String componentName;
+
+    public ChangesRequiringRestart(String componentName) {
+        this.componentName = componentName;
+    }
+
+    public String getName() {
+        return componentName;
+    }
+
+    public ChangesRequiringRestart compare(Node from, Node to, String name, String comment) {
+        if (!from.equals(to)) {
+            report.add(new ReportLine(name, from, to, comment));
+        }
+        return this;
+    }
+
+    public void mergeChanges(String prefix, ChangesRequiringRestart childReport) {
+        for (ReportLine line : childReport.getReportLines()) {
+            line.addNamePrefix(prefix);
+            report.add(line);
+        }
+    }
+
+    /**
+     * Interface used to pass lambda functions from generated code to compareArray/-Map functions.
+     */
+    public interface CompareFunc {
+        // Generates a report based on a config change.
+        ChangesRequiringRestart getChangesRequiringRestart(Node from, Node to);
+    }
+
+    public ChangesRequiringRestart compareArray(List<? extends Node> from,
+                                                List<? extends Node> to,
+                                                String name,
+                                                String comment,
+                                                CompareFunc func) {
+        if (!from.equals(to)) {
+            int commonElements = Math.min(from.size(), to.size());
+            for (int i = 0; i < commonElements; ++i) {
+                ChangesRequiringRestart childReport = func.getChangesRequiringRestart(from.get(i), to.get(i));
+                String prefix = childReport.componentName + "[" + Integer.toString(i) + "]";
+                mergeChanges(prefix, childReport);
+            }
+            for (int i = commonElements; i < from.size(); ++i) {
+                report.add(new ReportLine(name + "[" + Integer.toString(i) + "]", from.get(i), null, comment));
+            }
+            for (int i = commonElements; i < to.size(); ++i) {
+                report.add(new ReportLine(name + "[" + Integer.toString(i) + "]", null, to.get(i), comment));
+            }
+        }
+        return this;
+    }
+
+    public ChangesRequiringRestart compareMap(Map<String, ? extends Node> from,
+                                              Map<String, ? extends Node> to,
+                                              String name,
+                                              String comment,
+                                              CompareFunc func) {
+        if (!from.equals(to)) {
+            for (String key : from.keySet()) {
+                if (to.containsKey(key)) {
+                    ChangesRequiringRestart childReport = func.getChangesRequiringRestart(from.get(key), to.get(key));
+                    String prefix = childReport.componentName + "{" + key + "}";
+                    mergeChanges(prefix, childReport);
+                } else {
+                    report.add(new ReportLine(name + "{" + key + "}", from.get(key), null, comment));
+                }
+            }
+            for (String key : to.keySet()) {
+                if (!from.containsKey(key)) {
+                    report.add(new ReportLine(name + "{" + key + "}", null, to.get(key), comment));
+                }
+            }
+        }
+        return this;
+    }
+
+    List<ReportLine> getReportLines() {
+        return report;
+    }
+
+    @Override
+    public String toString() {
+        return toString("");
+    }
+
+    public String toString(String indent) {
+        return report.stream()
+                .map(line -> line.toString(indent, componentName + "."))
+                .collect(joining("\n"));
+    }
+
+    public boolean needsRestart() {
+        return !report.isEmpty();
+    }
+}