Revert "Merge pull request #15549 from vespa-engine/revert-15543-bratseth/apply-on-restart-take-7"

This reverts commit 0f2e5b7dba8f7009d227722b9491cc800d4f371b, reversing
changes made to 1d5e07a044bff2aef764cfee0de10802c376e4b7.

5 files changed, 120 insertions, 4 deletions

diff --git a/config-lib/abi-spec.json b/config-lib/abi-spec.json
index fa352d8f6bd..a9c57c2d1a2 100644
--- a/config-lib/abi-spec.json
+++ b/config-lib/abi-spec.json
@@ -73,7 +73,11 @@
       "public abstract boolean dispatchGetConfig(com.yahoo.config.ConfigInstance$Producer)",
       "public abstract java.lang.String getDefName()",
       "public abstract java.lang.String getDefNamespace()",
-      "public abstract java.lang.String getDefMd5()"
+      "public abstract java.lang.String getDefMd5()",
+      "public boolean getApplyOnRestart()",
+      "public void setApplyOnRestart(boolean)",
+      "public com.yahoo.config.ConfigInstance buildInstance(com.yahoo.config.codegen.InnerCNode)",
+      "public static void applyDef(com.yahoo.config.ConfigBuilder, com.yahoo.config.codegen.InnerCNode)"
     ],
     "fields": []
   },
diff --git a/config-lib/pom.xml b/config-lib/pom.xml
index 1002d43bc37..90c61725466 100644
--- a/config-lib/pom.xml
+++ b/config-lib/pom.xml
@@ -26,6 +26,12 @@
       <artifactId>annotations</artifactId>
       <version>${project.version}</version>
     </dependency>
+    <dependency>
+      <groupId>com.yahoo.vespa</groupId>
+      <artifactId>configgen</artifactId>
+      <version>${project.version}</version>
+      <scope>provided</scope>
+    </dependency>
   </dependencies>
   <build>
     <plugins>
diff --git a/config-lib/src/main/java/com/yahoo/config/ConfigBuilder.java b/config-lib/src/main/java/com/yahoo/config/ConfigBuilder.java
index e35e6916849..30bef223045 100644
--- a/config-lib/src/main/java/com/yahoo/config/ConfigBuilder.java
+++ b/config-lib/src/main/java/com/yahoo/config/ConfigBuilder.java
@@ -5,7 +5,6 @@ package com.yahoo.config;
  * Root interface for all config builders.
  *
  * @author gjoranv
- * @since 5.1.6
  */
 public interface ConfigBuilder {
 }
diff --git a/config-lib/src/main/java/com/yahoo/config/ConfigInstance.java b/config-lib/src/main/java/com/yahoo/config/ConfigInstance.java
index 04405839a9b..b47bd17a5ba 100644
--- a/config-lib/src/main/java/com/yahoo/config/ConfigInstance.java
+++ b/config-lib/src/main/java/com/yahoo/config/ConfigInstance.java
@@ -1,9 +1,16 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.config;
 
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.logging.Level;
+
+import com.yahoo.config.codegen.CNode;
+import com.yahoo.config.codegen.InnerCNode;
+import com.yahoo.config.codegen.LeafCNode;
 
 /**
  * Represents an instance of an application config with a specific configId.
@@ -13,10 +20,13 @@ import java.util.Map;
  */
 public abstract class ConfigInstance extends InnerNode {
 
+    private static final java.util.logging.Logger log = java.util.logging.Logger.getLogger(ConfigInstance.class.getName());
+
     public interface Builder extends ConfigBuilder {
 
         /**
          * Dispatches a getConfig() call if this instance's producer is of the right type
+         *
          * @param producer a config producer
          * @return true if this instance's producer was the correct type, and hence a getConfig call was dispatched
          */
@@ -26,6 +36,103 @@ public abstract class ConfigInstance extends InnerNode {
         String getDefNamespace();
         String getDefMd5();
 
+        /** Returns true if this instance should be applied on restart, false if it should be applied immediately */
+        default boolean getApplyOnRestart() { return false; }
+
+        default void setApplyOnRestart(boolean applyOnRestart) { throw new java.lang.UnsupportedOperationException(); }
+
+        default ConfigInstance buildInstance(InnerCNode targetDef) {
+            try {
+                if (targetDef != null) applyDef(this, targetDef);
+                Class<? extends ConfigInstance> clazz = getConfigClass(getClass());
+                return clazz.getConstructor(getClass()).newInstance(this);
+            } catch (Exception e) {
+                throw new ConfigurationRuntimeException(e);
+            }
+        }
+
+        /**
+         * If some fields on the builder are null now, set them from the def. Do recursively.
+         * <p>
+         * If the targetDef has some schema incompatibilities, they are not handled here
+         * (except logging in some cases), but in ConfigInstance.serialize().
+         *
+         * @param  builder a {@link com.yahoo.config.ConfigBuilder}
+         * @param  targetDef a config definition
+         * @throws Exception if applying values form config definitions fails
+         */
+        static void applyDef(ConfigBuilder builder, InnerCNode targetDef) throws Exception {
+            for (Map.Entry<String, CNode> e: targetDef.children().entrySet()) {
+                CNode node = e.getValue();
+                if (node instanceof LeafCNode) {
+                    setLeafValueIfUnset(targetDef, builder, (LeafCNode)node);
+                } else if (node instanceof InnerCNode) {
+                    // Is there a private field on the builder that matches this inner node in the def?
+                    if (hasField(builder.getClass(), node.getName())) {
+                        Field innerField = builder.getClass().getDeclaredField(node.getName());
+                        innerField.setAccessible(true);
+                        Object innerFieldVal = innerField.get(builder);
+                        if (innerFieldVal instanceof List) {
+                            // inner array? Check that list elems are ConfigBuilder
+                            List<?> innerList = (List<?>) innerFieldVal;
+                            for (Object b : innerList) {
+                                if (b instanceof ConfigBuilder) {
+                                    applyDef((ConfigBuilder) b, (InnerCNode) node);
+                                }
+                            }
+                        } else if (innerFieldVal instanceof ConfigBuilder) {
+                            // Struct perhaps
+                            applyDef((ConfigBuilder) innerFieldVal, (InnerCNode) node);
+                        } else {
+                            // Likely a config value mismatch. That is handled in ConfigInstance.serialize() (error message, omit from response.)
+                        }
+                    }
+                }
+            }
+        }
+
+        private static boolean hasField(Class<?> aClass, String name) {
+            for (Field field : aClass.getDeclaredFields()) {
+                if (name.equals(field.getName())) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        private static void setLeafValueIfUnset(InnerCNode targetDef, Object builder, LeafCNode node) throws Exception {
+            if (hasField(builder.getClass(), node.getName())) {
+                Field field = builder.getClass().getDeclaredField(node.getName());
+                field.setAccessible(true);
+                Object val = field.get(builder);
+                if (val==null) {
+                    // Not set on builder, if the leaf node has a default value, try the private setter that takes String
+                    try {
+                        if (node.getDefaultValue()!=null) {
+                            Method setter = builder.getClass().getDeclaredMethod(node.getName(), String.class);
+                            setter.setAccessible(true);
+                            setter.invoke(builder, node.getDefaultValue().getValue());
+                        }
+                    } catch (Exception e) {
+                        log.log(Level.SEVERE,
+                                "For config '" + targetDef.getFullName() + "': " +
+                                "Unable to apply the default value for field '" + node.getName() +
+                                "' to config Builder (where it wasn't set)",
+                                e);
+                    }
+                }
+            }
+        }
+
+        @SuppressWarnings("unchecked")
+        private static Class<? extends ConfigInstance> getConfigClass(Class<? extends ConfigInstance.Builder> builderClass) {
+            Class<?> configClass = builderClass.getEnclosingClass();
+            if (configClass == null || ! ConfigInstance.class.isAssignableFrom(configClass)) {
+                throw new ConfigurationRuntimeException("Builder class " + builderClass + " has enclosing class " + configClass + ", which is not a ConfigInstance");
+            }
+            return (Class<? extends ConfigInstance>) configClass;
+        }
+
     }
 
     public interface Producer {}
diff --git a/config-lib/src/main/java/com/yahoo/config/Node.java b/config-lib/src/main/java/com/yahoo/config/Node.java
index 8d16b9727c1..ed11bdc9891 100644
--- a/config-lib/src/main/java/com/yahoo/config/Node.java
+++ b/config-lib/src/main/java/com/yahoo/config/Node.java
@@ -5,7 +5,6 @@ package com.yahoo.config;
  * The Node class is superclass for all nodes in a {@link
  * ConfigInstance}.  Important subclasses of this node are {@link
  * InnerNode} and {@link LeafNode}.
- *
  */
 public abstract class Node {
 
@@ -13,7 +12,7 @@ public abstract class Node {
      * Postinitialize this node. Any node needing to process its values depending on the config
      * id should override this method.
      *
-     * @param configId  the configId of the ConfigInstance that owns (or is) this node
+     * @param configId the configId of the ConfigInstance that owns (or is) this node
      */
     public void postInitialize(String configId) { return; }
 
@@ -26,4 +25,5 @@ public abstract class Node {
     protected Object clone() throws CloneNotSupportedException {
         return super.clone();
     }
+
 }