Revert "Revert "Balder/remove config race""

16 files changed, 171 insertions, 163 deletions

diff --git a/config/src/main/java/com/yahoo/config/subscription/ConfigHandle.java b/config/src/main/java/com/yahoo/config/subscription/ConfigHandle.java
index 6b8059ad5af..bb29e329121 100644
--- a/config/src/main/java/com/yahoo/config/subscription/ConfigHandle.java
+++ b/config/src/main/java/com/yahoo/config/subscription/ConfigHandle.java
@@ -52,7 +52,7 @@ public class ConfigHandle<T extends ConfigInstance> {
      */
     public T getConfig() {
         // TODO throw if subscriber not frozen?
-        return sub.getConfig();
+        return sub.getConfigState().getConfig();
     }
 
     @Override
diff --git a/config/src/main/java/com/yahoo/config/subscription/ConfigSubscriber.java b/config/src/main/java/com/yahoo/config/subscription/ConfigSubscriber.java
index 1c9f659b45f..bf8b9372d58 100644
--- a/config/src/main/java/com/yahoo/config/subscription/ConfigSubscriber.java
+++ b/config/src/main/java/com/yahoo/config/subscription/ConfigSubscriber.java
@@ -230,7 +230,7 @@ public class ConfigSubscriber {
         boolean anyConfigChanged = false;
         boolean allGenerationsChanged = true;
         boolean allGenerationsTheSame = true;
-        Long currentGenChecker = null;
+        Long currentGen = null;
         for (ConfigHandle<? extends ConfigInstance> h : subscriptionHandles) {
             h.setChanged(false); // Reset this flag, if it was set, the user should have acted on it the last time this method returned true.
         }
@@ -244,10 +244,11 @@ public class ConfigSubscriber {
                     return false;
                 }
                 throwIfExceptionSet(subscription);
-                if (currentGenChecker == null) currentGenChecker = subscription.getGeneration();
-                if (!currentGenChecker.equals(subscription.getGeneration())) allGenerationsTheSame = false;
-                allGenerationsChanged = allGenerationsChanged && subscription.isGenerationChanged();
-                if (subscription.isConfigChanged()) anyConfigChanged = true;
+                ConfigSubscription.ConfigState<? extends ConfigInstance> config = subscription.getConfigState();
+                if (currentGen == null) currentGen = config.getGeneration();
+                if (!currentGen.equals(config.getGeneration())) allGenerationsTheSame = false;
+                allGenerationsChanged = allGenerationsChanged && config.isGenerationChanged();
+                if (config.isConfigChanged()) anyConfigChanged = true;
                 timeLeftMillis = timeLeftMillis - (System.currentTimeMillis() - started);
             }
             reconfigDue = (anyConfigChanged || !requireChange) && allGenerationsChanged && allGenerationsTheSame;
@@ -258,8 +259,8 @@ public class ConfigSubscriber {
         if (reconfigDue) {
             // This indicates the clients will possibly reconfigure their services, so "reset" changed-logic in subscriptions.
             // Also if appropriate update the changed flag on the handler, which clients use.
-            markSubsChangedSeen();
-            generation = subscriptionHandles.get(0).subscription().getGeneration();
+            markSubsChangedSeen(currentGen);
+            generation = currentGen;
         }
         return reconfigDue;
     }
@@ -285,11 +286,10 @@ public class ConfigSubscriber {
         }
     }
 
-    private void markSubsChangedSeen() {
+    private void markSubsChangedSeen(Long requiredGen) {
         for (ConfigHandle<? extends ConfigInstance> h : subscriptionHandles) {
             ConfigSubscription<? extends ConfigInstance> sub = h.subscription();
-            h.setChanged(sub.isConfigChanged());
-            sub.resetChangedFlags();
+            h.setChanged(sub.isConfigChangedAndReset(requiredGen));
         }
     }
 
diff --git a/config/src/main/java/com/yahoo/config/subscription/impl/ConfigSetSubscription.java b/config/src/main/java/com/yahoo/config/subscription/impl/ConfigSetSubscription.java
index b39ae9e93cc..acd5b823af3 100644
--- a/config/src/main/java/com/yahoo/config/subscription/impl/ConfigSetSubscription.java
+++ b/config/src/main/java/com/yahoo/config/subscription/impl/ConfigSetSubscription.java
@@ -35,22 +35,19 @@ public class ConfigSetSubscription<T extends ConfigInstance> extends ConfigSubsc
     public boolean nextConfig(long timeout) {
         long end = System.currentTimeMillis() + timeout;
         do {
-            ConfigInstance myInstance = getNewInstance();
+            T myInstance = getNewInstance();
+            ConfigState<T> configState = getConfigState();
             // User forced reload
             if (checkReloaded()) {
-                updateInstance(myInstance);
+                setConfigIfChanged(myInstance);
                 return true;
             }
-            if (!myInstance.equals(config)) {
-                generation++;
-                updateInstance(myInstance);
+            if (!myInstance.equals(configState.getConfig())) {
+                setConfigIfChangedIncGen(myInstance);
                 return true;
             }
             sleep();
         } while (System.currentTimeMillis() < end);
-        // These shouldn't be checked anywhere since we return false now, but setting them still
-        setGenerationChanged(false);
-        setConfigChanged(false);
         return false;
     }
 
@@ -62,25 +59,17 @@ public class ConfigSetSubscription<T extends ConfigInstance> extends ConfigSubsc
         }
     }
 
-    @SuppressWarnings("unchecked")
-    private void updateInstance(ConfigInstance myInstance) {
-        if (!myInstance.equals(config)) {
-            setConfigChanged(true);
-        }
-        setConfig((T) myInstance);
-        setGenerationChanged(true);
-    }
-
     @Override
     public boolean subscribe(long timeout) {
         return true;
     }
 
-    public ConfigInstance getNewInstance() {
+    @SuppressWarnings("unchecked")
+    private T getNewInstance() {
         try {
             ConfigInstance.Builder builder = set.get(subKey);
             Constructor<?> constructor = builder.getClass().getDeclaringClass().getConstructor(builder.getClass());
-            return (ConfigInstance) constructor.newInstance(builder);
+            return (T) constructor.newInstance(builder);
         } catch (Exception e) {
             e.printStackTrace();
             throw new RuntimeException(e);
diff --git a/config/src/main/java/com/yahoo/config/subscription/impl/ConfigSubscription.java b/config/src/main/java/com/yahoo/config/subscription/impl/ConfigSubscription.java
index 398392ba8d3..02c455bf1c3 100644
--- a/config/src/main/java/com/yahoo/config/subscription/impl/ConfigSubscription.java
+++ b/config/src/main/java/com/yahoo/config/subscription/impl/ConfigSubscription.java
@@ -2,6 +2,8 @@
 package com.yahoo.config.subscription.impl;
 
 import java.io.File;
+import java.util.concurrent.Callable;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Logger;
 
 import com.yahoo.config.ConfigInstance;
@@ -25,22 +27,43 @@ import com.yahoo.vespa.config.protocol.DefContent;
  */
 public abstract class ConfigSubscription<T extends ConfigInstance> {
     protected static Logger log = Logger.getLogger(ConfigSubscription.class.getName());
-    protected ConfigSubscriber subscriber;
-    protected boolean configChanged = false;
-    protected boolean generationChanged = false;
-    protected volatile T config = null;
-    protected Long generation = null;
-    protected ConfigKey<T> key;
-    protected Class<T> configClass;
+    protected final ConfigSubscriber subscriber;
+    private final AtomicReference<ConfigState<T>> config = new AtomicReference<>();
+    protected final ConfigKey<T> key;
+    protected final Class<T> configClass;
     private volatile RuntimeException exception = null;
     private State state = State.OPEN;
+
+    public static class ConfigState<T extends ConfigInstance> {
+        private final boolean configChanged;
+        private final boolean generationChanged;
+        private final T config;
+        private final Long generation;
+        private ConfigState(boolean generationChanged, Long generation, boolean configChanged, T config) {
+            this.configChanged = configChanged;
+            this.config = config;
+            this.generationChanged = generationChanged;
+            this.generation = generation;
+        }
+        private ConfigState(Long generation, T config) {
+            this(false, generation,false, config);
+        }
+        private ConfigState() {
+            this(false, 0L, false, null);
+        }
+        private ConfigState<T> createUnchanged() { return new ConfigState<T>(generation, config); }
+        public boolean isConfigChanged() { return configChanged; }
+        public boolean isGenerationChanged() { return generationChanged; }
+        public Long getGeneration() { return generation; }
+        public T getConfig() { return config; }
+    }
     /**
      * If non-null: The user has set this generation explicitly. nextConfig should take this into account.
      * Access to these variables _must_ be synchronized, as nextConfig and reload() is likely to be run from
      * independent threads.
      */
-    private boolean doReload = false;
-    private long reloadedGeneration = -1;
+
+    private final AtomicReference<Long> reloadedGeneration = new AtomicReference<>();
 
     enum State {
         OPEN, CLOSED
@@ -56,6 +79,7 @@ public abstract class ConfigSubscription<T extends ConfigInstance> {
         this.key = key;
         this.configClass = key.getConfigClass();
         this.subscriber = subscriber;
+        this.config.set(new ConfigState<T>());
     }
 
 
@@ -66,7 +90,8 @@ public abstract class ConfigSubscription<T extends ConfigInstance> {
      * @param subscriber the subscriber for this subscription
      * @return a subclass of a ConfigsSubscription
      */
-    public static <T extends ConfigInstance> ConfigSubscription<T> get(ConfigKey<T> key, ConfigSubscriber subscriber, ConfigSource source, TimingValues timingValues) {
+    public static <T extends ConfigInstance> ConfigSubscription<T> get(ConfigKey<T> key, ConfigSubscriber subscriber,
+                                                                       ConfigSource source, TimingValues timingValues) {
         String configId = key.getConfigId();
         if (source instanceof RawSource || configId.startsWith("raw:")) return getRawSub(key, subscriber, source);
         if (source instanceof FileSource || configId.startsWith("file:")) return getFileSub(key, subscriber, source);
@@ -129,50 +154,54 @@ public abstract class ConfigSubscription<T extends ConfigInstance> {
         return false;
     }
 
-    void setConfigChanged(boolean changed) {
-        this.configChanged = changed;
-    }
-
-    void setGenerationChanged(boolean genChanged) {
-        this.generationChanged = genChanged;
-    }
 
     /**
      * Called from {@link ConfigSubscriber} when the changed status of this config is propagated to the clients
      */
-    public void resetChangedFlags() {
-        setConfigChanged(false);
-        setGenerationChanged(false);
+    public boolean isConfigChangedAndReset(Long requiredGen) {
+        ConfigState<T> prev = config.get();
+        while ( prev.getGeneration().equals(requiredGen) && !config.compareAndSet(prev, prev.createUnchanged())) {
+            prev = config.get();
+        }
+        // A false positive is a lot better than a false negative
+        return !prev.getGeneration().equals(requiredGen) || prev.isConfigChanged();
     }
 
-    public boolean isConfigChanged() {
-        return configChanged;
+    void setConfig(Long generation, T config) {
+        this.config.set(new ConfigState<>(true, generation, true, config));
     }
 
-    public boolean isGenerationChanged() {
-        return generationChanged;
+    // Only used by {@link FileConfigSubscription}
+    protected void setConfigIncGen(T config) {
+        ConfigState<T> prev = this.config.get();
+        setConfig(prev.getGeneration() + 1, config);
     }
 
-    void setConfig(T config) {
-        this.config = config;
+    // Only used by {@link FileConfigSubscription} and {@link ConfigSetSubscription}
+    protected void setConfigIfChangedIncGen(T config) {
+        ConfigState<T> prev = this.config.get();
+        this.config.set(new ConfigState<>(true, prev.getGeneration() + 1,
+                                          !config.equals(prev.getConfig()), config));
+    }
+    protected void setConfigIfChanged(T config) {
+        ConfigState<T> prev = this.config.get();
+        this.config.set(new ConfigState<>(true, prev.getGeneration(),
+                !config.equals(prev.getConfig()), config));
     }
 
-    /**
-     * The config object of this subscription
-     *
-     * @return the ConfigInstance (the config) of this subscription
-     */
-    public T getConfig() {
-        return config;
+    void setGeneration(Long generation) {
+        ConfigState<T> c = config.get();
+        this.config.set(new ConfigState<>(true, generation, c.isConfigChanged(), c.getConfig()));
     }
 
     /**
-     * The generation of this subscription
+     * The config state object of this subscription
      *
-     * @return the generation of this subscription
+     * @return the ConfigInstance (the config) of this subscription
      */
-    public Long getGeneration() {
-        return generation;
+
+    public ConfigState<T> getConfigState() {
+        return config.get();
     }
 
     /**
@@ -183,16 +212,13 @@ public abstract class ConfigSubscription<T extends ConfigInstance> {
         return configClass;
     }
 
-    void setGeneration(Long generation) {
-        this.generation = generation;
-    }
-
     @Override
     public String toString() {
         StringBuilder s = new StringBuilder(key.toString());
-        s.append(", Current generation: ").append(generation)
-                .append(", Generation changed: ").append(generationChanged)
-                .append(", Config changed: ").append(configChanged);
+        ConfigState<T> c = config.get();
+        s.append(", Current generation: ").append(c.getGeneration())
+                .append(", Generation changed: ").append(c.isGenerationChanged())
+                .append(", Config changed: ").append(c.isConfigChanged());
         if (exception != null)
             s.append(", Exception: ").append(exception);
         return s.toString();
@@ -212,7 +238,7 @@ public abstract class ConfigSubscription<T extends ConfigInstance> {
      * that can be set by {@link ConfigSubscriber#reload(long)}.
      *
      * @param timeout in milliseconds
-     * @return false if timed out, true if the state of {@link #configChanged}, {@link #generationChanged} or {@link #exception} changed. If true, the {@link #config} field will be set also.
+     * @return false if timed out, true if generation or config or {@link #exception} changed. If true, the {@link #config} field will be set also.
      *         has changed
      */
     public abstract boolean nextConfig(long timeout);
@@ -277,23 +303,20 @@ public abstract class ConfigSubscription<T extends ConfigInstance> {
      * Force this into the given generation, used in testing
      * @param generation a config generation
      */
-    public synchronized void reload(long generation) {
-        this.doReload = true;
-        this.reloadedGeneration = generation;
+    public void reload(long generation) {
+        reloadedGeneration.set(generation);
     }
 
     /**
      * True if someone has set the {@link #reloadedGeneration} number by calling {@link #reload(long)}
      * and hence wants to force a given generation programmatically. If that is the case,
-     * sets the {@link #generation} and {@link #generationChanged} fields accordingly.
+     * sets the generation and flags it as changed accordingly.
      * @return true if {@link #reload(long)} has been called, false otherwise
      */
-    protected synchronized boolean checkReloaded() {
-        if (doReload) {
-            // User has called reload
-            generation = reloadedGeneration;
-            setGenerationChanged(true);
-            doReload = false;
+    protected boolean checkReloaded() {
+        Long reloaded = reloadedGeneration.getAndSet(null);
+        if (reloaded != null) {
+            setGeneration(reloaded);
             return true;
         }
         return false;
diff --git a/config/src/main/java/com/yahoo/config/subscription/impl/FileConfigSubscription.java b/config/src/main/java/com/yahoo/config/subscription/impl/FileConfigSubscription.java
index 60c702895f8..8c3f87d0702 100644
--- a/config/src/main/java/com/yahoo/config/subscription/impl/FileConfigSubscription.java
+++ b/config/src/main/java/com/yahoo/config/subscription/impl/FileConfigSubscription.java
@@ -40,15 +40,14 @@ public class FileConfigSubscription<T extends ConfigInstance> extends ConfigSubs
         if (checkReloaded()) {
             log.log(LogLevel.DEBUG, "User forced config reload at " + System.currentTimeMillis());
             // User forced reload
-            updateConfig();
-            log.log(LogLevel.DEBUG, "Config updated at " + System.currentTimeMillis() + ", changed: " + isConfigChanged());
-            log.log(LogLevel.DEBUG, "Config: " + config.toString());
+            setConfigIfChanged(updateConfig());
+            ConfigState<T> configState = getConfigState();
+            log.log(LogLevel.DEBUG, "Config updated at " + System.currentTimeMillis() + ", changed: " + configState.isConfigChanged());
+            log.log(LogLevel.DEBUG, "Config: " + configState.getConfig().toString());
             return true;
         }
         if (file.lastModified()!=ts) {
-            updateConfig();
-            generation++;
-            setGenerationChanged(true);
+            setConfigIncGen(updateConfig());
             return true;
         }
         try {
@@ -56,22 +55,18 @@ public class FileConfigSubscription<T extends ConfigInstance> extends ConfigSubs
         } catch (InterruptedException e) {
             throw new ConfigInterruptedException(e);
         }
-        // These shouldn't be checked anywhere since we return false now, but setting them still
-        setGenerationChanged(false);
-        setConfigChanged(false);
+
         return false;
     }
 
-    private void updateConfig() {
+    private T updateConfig() {
         ts=file.lastModified();
-        ConfigInstance prev = config;
         try {
             ConfigPayload payload = new CfgConfigPayloadBuilder().deserialize(Arrays.asList(IOUtils.readFile(file).split("\n")));
-            config = payload.toInstance(configClass, key.getConfigId());
+            return payload.toInstance(configClass, key.getConfigId());
         } catch (IOException e) {
             throw new ConfigurationRuntimeException(e);
         }
-        setConfigChanged(!config.equals(prev));
     }
 
     @Override
diff --git a/config/src/main/java/com/yahoo/config/subscription/impl/GenericConfigSubscriber.java b/config/src/main/java/com/yahoo/config/subscription/impl/GenericConfigSubscriber.java
index 7ef94e98cc8..a33c1556dd3 100644
--- a/config/src/main/java/com/yahoo/config/subscription/impl/GenericConfigSubscriber.java
+++ b/config/src/main/java/com/yahoo/config/subscription/impl/GenericConfigSubscriber.java
@@ -10,6 +10,7 @@ import com.yahoo.config.subscription.ConfigSource;
 import com.yahoo.config.subscription.ConfigSourceSet;
 import com.yahoo.config.subscription.ConfigSubscriber;
 import com.yahoo.vespa.config.ConfigKey;
+import com.yahoo.vespa.config.RawConfig;
 import com.yahoo.vespa.config.TimingValues;
 
 /**
@@ -43,7 +44,7 @@ public class GenericConfigSubscriber extends ConfigSubscriber {
      * @param timingValues {@link TimingValues}
      * @return generic handle
      */
-    public GenericConfigHandle subscribe(ConfigKey<?> key, List<String> defContent, ConfigSource source, TimingValues timingValues) {
+    public GenericConfigHandle subscribe(ConfigKey<RawConfig> key, List<String> defContent, ConfigSource source, TimingValues timingValues) {
         checkStateBeforeSubscribe();
         GenericJRTConfigSubscription sub = new GenericJRTConfigSubscription(key, defContent, this, source, timingValues);
         GenericConfigHandle handle = new GenericConfigHandle(sub);
diff --git a/config/src/main/java/com/yahoo/config/subscription/impl/GenericJRTConfigSubscription.java b/config/src/main/java/com/yahoo/config/subscription/impl/GenericJRTConfigSubscription.java
index ab53ce6dc50..068b24cdf1a 100644
--- a/config/src/main/java/com/yahoo/config/subscription/impl/GenericJRTConfigSubscription.java
+++ b/config/src/main/java/com/yahoo/config/subscription/impl/GenericJRTConfigSubscription.java
@@ -3,7 +3,6 @@ package com.yahoo.config.subscription.impl;
 
 import java.util.List;
 
-import com.yahoo.config.ConfigInstance;
 import com.yahoo.config.subscription.ConfigSource;
 import com.yahoo.config.subscription.ConfigSubscriber;
 import com.yahoo.log.LogLevel;
@@ -19,27 +18,22 @@ import com.yahoo.vespa.config.protocol.JRTClientConfigRequest;
  * @author vegardh
  *
  */
-@SuppressWarnings("rawtypes")
-public class GenericJRTConfigSubscription extends JRTConfigSubscription {
+public class GenericJRTConfigSubscription extends JRTConfigSubscription<RawConfig> {
 
-    private RawConfig config;
     private final List<String> defContent;
 
-    @SuppressWarnings("unchecked")
-    public GenericJRTConfigSubscription(ConfigKey<?> key,
-                                        List<String> defContent,
-            ConfigSubscriber subscriber,
-            ConfigSource source,
-            TimingValues timingValues) {
+    public GenericJRTConfigSubscription(ConfigKey<RawConfig> key, List<String> defContent, ConfigSubscriber subscriber,
+                                        ConfigSource source, TimingValues timingValues)
+    {
         super(key, subscriber, source, timingValues);
         this.defContent = defContent;
     }
 
     @Override
     protected void setNewConfig(JRTClientConfigRequest jrtReq) {
-        this.config = RawConfig.createFromResponseParameters(jrtReq);
+        setConfig(jrtReq.getNewGeneration(), RawConfig.createFromResponseParameters(jrtReq) );
         if (log.isLoggable(LogLevel.DEBUG)) {
-            log.log(LogLevel.DEBUG, "in setNewConfig, config=" + this.config);
+            log.log(LogLevel.DEBUG, "in setNewConfig, config=" + this.getConfigState().getConfig());
         }
     }
 
@@ -48,13 +42,15 @@ public class GenericJRTConfigSubscription extends JRTConfigSubscription {
     @Override
     void setGeneration(Long generation) {
         super.setGeneration(generation);
-        if (this.config != null) {
-            this.config.setGeneration(generation);
+        ConfigState<RawConfig> configState = getConfigState();
+
+        if (configState.getConfig() != null) {
+            configState.getConfig().setGeneration(generation);
         }
     }
 
     public RawConfig getRawConfig() {
-        return config;
+        return getConfigState().getConfig();
     }
 
     /**
@@ -66,9 +62,4 @@ public class GenericJRTConfigSubscription extends JRTConfigSubscription {
     public DefContent getDefContent() {
         return (DefContent.fromList(defContent));
     }
-
-    @Override
-    public ConfigInstance getConfig() {
-        return null;
-    }
 }
diff --git a/config/src/main/java/com/yahoo/config/subscription/impl/JRTConfigRequester.java b/config/src/main/java/com/yahoo/config/subscription/impl/JRTConfigRequester.java
index 7d830484edd..88af414e28d 100644
--- a/config/src/main/java/com/yahoo/config/subscription/impl/JRTConfigRequester.java
+++ b/config/src/main/java/com/yahoo/config/subscription/impl/JRTConfigRequester.java
@@ -163,7 +163,7 @@ public class JRTConfigRequester implements RequestWaiter {
     }
 
     private void handleFailedRequest(JRTClientConfigRequest jrtReq, JRTConfigSubscription<ConfigInstance> sub, Connection connection) {
-        final boolean configured = (sub.getConfig() != null);
+        final boolean configured = (sub.getConfigState().getConfig() != null);
         if (configured) {
             // The subscription object has an "old" config, which is all we have to offer back now
             log.log(LogLevel.INFO, "Failure of config subscription, clients will keep existing config until resolved: " + sub);
@@ -226,7 +226,7 @@ public class JRTConfigRequester implements RequestWaiter {
         if (sub.getState() != ConfigSubscription.State.OPEN) return;
         fatalFailures++;
         // The logging depends on whether we are configured or not.
-        Level logLevel = sub.getConfig() == null ? LogLevel.DEBUG : LogLevel.INFO;
+        Level logLevel = sub.getConfigState().getConfig() == null ? LogLevel.DEBUG : LogLevel.INFO;
         String logMessage = "Request for config " + jrtReq.getShortDescription() + "' failed with error code " +
                 jrtReq.errorCode() + " (" + jrtReq.errorMessage() + "), scheduling new connect " +
                 " in " + delay + " ms";
diff --git a/config/src/main/java/com/yahoo/config/subscription/impl/JRTConfigSubscription.java b/config/src/main/java/com/yahoo/config/subscription/impl/JRTConfigSubscription.java
index 6adeaa80cd1..9ae3e226d89 100644
--- a/config/src/main/java/com/yahoo/config/subscription/impl/JRTConfigSubscription.java
+++ b/config/src/main/java/com/yahoo/config/subscription/impl/JRTConfigSubscription.java
@@ -49,7 +49,8 @@ public class JRTConfigSubscription<T extends ConfigInstance> extends ConfigSubsc
     public boolean nextConfig(long timeoutMillis) {
         // These flags may have been left true from a previous call, since ConfigSubscriber's nextConfig
         // not necessarily returned true and reset the flags then
-        boolean gotNew = isGenerationChanged() || isConfigChanged() || hasException();
+        ConfigState<T> configState = getConfigState();
+        boolean gotNew = configState.isGenerationChanged() || configState.isConfigChanged() || hasException();
         // Return that now, if there's nothing in queue, so that ConfigSubscriber can move on to other subscriptions to check
         if (getReqQueue().peek()==null && gotNew) {
             return true;
@@ -60,7 +61,8 @@ public class JRTConfigSubscription<T extends ConfigInstance> extends ConfigSubsc
         // there is a race here. However: the caller will handle it no matter what it gets from the queue here,
         // the important part is that local state on the subscription objects is preserved.
         if (!pollQueue(timeoutMillis)) return gotNew;
-        gotNew = isGenerationChanged() || isConfigChanged() || hasException();
+        configState = getConfigState();
+        gotNew = configState.isGenerationChanged() || configState.isConfigChanged() || hasException();
         return gotNew;
     }
 
@@ -83,20 +85,17 @@ public class JRTConfigSubscription<T extends ConfigInstance> extends ConfigSubsc
             return false;
         }
         if (jrtReq.hasUpdatedGeneration()) {
-            //printStatus(jrtReq, "Updated generation or config");
-            setGeneration(jrtReq.getNewGeneration());
-            setGenerationChanged(true);
             if (jrtReq.hasUpdatedConfig()) {
-                // payload changed
                 setNewConfig(jrtReq);
-                setConfigChanged(true);
+            } else {
+                setGeneration(jrtReq.getNewGeneration());
             }
         }
         return true;
     }
 
     protected void setNewConfig(JRTClientConfigRequest jrtReq) {
-        setConfig(toConfigInstance(jrtReq));
+        setConfig(jrtReq.getNewGeneration(), toConfigInstance(jrtReq) );
     }
 
     /**
diff --git a/config/src/main/java/com/yahoo/config/subscription/impl/JarConfigSubscription.java b/config/src/main/java/com/yahoo/config/subscription/impl/JarConfigSubscription.java
index 2b656b0f498..4870d69bb23 100644
--- a/config/src/main/java/com/yahoo/config/subscription/impl/JarConfigSubscription.java
+++ b/config/src/main/java/com/yahoo/config/subscription/impl/JarConfigSubscription.java
@@ -53,6 +53,7 @@ public class JarConfigSubscription<T extends ConfigInstance> extends ConfigSubsc
             }
             zipEntry = getEntry(jarFile, path);
             if (zipEntry==null) throw new IllegalArgumentException("Config '" + key.getName() + "' not found in '" + jarName + "!/" + path + "'.");
+            T config = null;
             try {
                 ConfigPayload payload = new CfgConfigPayloadBuilder().deserialize(Arrays.asList(IOUtils.readAll(new InputStreamReader(jarFile.getInputStream(zipEntry), "UTF-8")).split("\n")));
                 config = payload.toInstance(configClass, key.getConfigId());
@@ -61,9 +62,7 @@ public class JarConfigSubscription<T extends ConfigInstance> extends ConfigSubsc
             } catch (IOException e) {
                 throw new ConfigurationRuntimeException(e);
             }
-            setGeneration(0L);
-            setGenerationChanged(true);
-            setConfigChanged(true);
+            setConfig(0L, config);
             try {
                 jarFile.close();
             } catch (IOException e) {
@@ -77,9 +76,6 @@ public class JarConfigSubscription<T extends ConfigInstance> extends ConfigSubsc
         } catch (InterruptedException e) {
             throw new ConfigInterruptedException(e);
         }
-        // These shouldn't be checked anywhere since we return false now, but setting them still
-        setGenerationChanged(false);
-        setConfigChanged(false);
         return false;
     }
     /**
diff --git a/config/src/main/java/com/yahoo/config/subscription/impl/RawConfigSubscription.java b/config/src/main/java/com/yahoo/config/subscription/impl/RawConfigSubscription.java
index ce82b62cfd2..0d3f04361aa 100644
--- a/config/src/main/java/com/yahoo/config/subscription/impl/RawConfigSubscription.java
+++ b/config/src/main/java/com/yahoo/config/subscription/impl/RawConfigSubscription.java
@@ -35,12 +35,8 @@ public class RawConfigSubscription<T extends ConfigInstance> extends ConfigSubsc
         }
         if (payload==null) {
             payload = inputPayload;
-            setGeneration(0L);
-            setGenerationChanged(true);
-            setConfigChanged(true);
-
             ConfigPayload configPayload = new CfgConfigPayloadBuilder().deserialize(Arrays.asList(payload.split("\n")));
-            config = configPayload.toInstance(configClass, key.getConfigId());
+            setConfig(0L, configPayload.toInstance(configClass, key.getConfigId()));
             return true;
         }
         try {
@@ -48,9 +44,6 @@ public class RawConfigSubscription<T extends ConfigInstance> extends ConfigSubsc
         } catch (InterruptedException e) {
             throw new ConfigInterruptedException(e);
         }
-        // These shouldn't be checked anywhere since we return false now, but setting them still
-        setGenerationChanged(false);
-        setConfigChanged(false);
         return false;
     }
 
diff --git a/config/src/main/java/com/yahoo/vespa/config/RawConfig.java b/config/src/main/java/com/yahoo/vespa/config/RawConfig.java
index 898e8edfb08..75c5161103e 100755
--- a/config/src/main/java/com/yahoo/vespa/config/RawConfig.java
+++ b/config/src/main/java/com/yahoo/vespa/config/RawConfig.java
@@ -1,6 +1,7 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.config;
 
+import com.yahoo.config.ConfigInstance;
 import com.yahoo.text.Utf8String;
 import com.yahoo.vespa.config.protocol.CompressionInfo;
 import com.yahoo.vespa.config.protocol.JRTClientConfigRequest;
@@ -20,7 +21,7 @@ import java.util.Optional;
  *
  * @author hmusum
  */
-public class RawConfig {
+public class RawConfig extends ConfigInstance {
 
     private final ConfigKey<?> key;
     private final String defMd5;
diff --git a/config/src/main/java/com/yahoo/vespa/config/protocol/JRTClientConfigRequestV3.java b/config/src/main/java/com/yahoo/vespa/config/protocol/JRTClientConfigRequestV3.java
index 4ba6a74ce6f..3d7c0dc1e80 100644
--- a/config/src/main/java/com/yahoo/vespa/config/protocol/JRTClientConfigRequestV3.java
+++ b/config/src/main/java/com/yahoo/vespa/config/protocol/JRTClientConfigRequestV3.java
@@ -2,6 +2,7 @@
 package com.yahoo.vespa.config.protocol;
 
 import com.yahoo.config.ConfigInstance;
+import com.yahoo.config.subscription.impl.ConfigSubscription;
 import com.yahoo.config.subscription.impl.JRTConfigSubscription;
 import com.yahoo.jrt.Request;
 import com.yahoo.text.Utf8Array;
@@ -73,12 +74,13 @@ public class JRTClientConfigRequestV3 extends SlimeClientConfigRequest {
     public static <T extends ConfigInstance> JRTClientConfigRequest createFromSub(JRTConfigSubscription<T> sub, Trace trace, CompressionType compressionType, Optional<VespaVersion> vespaVersion) {
         String hostname = ConfigUtils.getCanonicalHostName();
         ConfigKey<T> key = sub.getKey();
-        T i = sub.getConfig();
+        ConfigSubscription.ConfigState<T> configState = sub.getConfigState();
+        T i = configState.getConfig();
         return createWithParams(key,
                 sub.getDefContent(),
                 hostname,
                 i != null ? i.getConfigMd5() : "",
-                sub.getGeneration() != null ? sub.getGeneration() : 0L,
+                configState.getGeneration() != null ? configState.getGeneration() : 0L,
                 sub.timingValues().getSubscribeTimeout(),
                 trace,
                 compressionType,
diff --git a/config/src/test/java/com/yahoo/config/subscription/impl/FileConfigSubscriptionTest.java b/config/src/test/java/com/yahoo/config/subscription/impl/FileConfigSubscriptionTest.java
index 3862cfc9069..8fdd9d5e3b3 100644
--- a/config/src/test/java/com/yahoo/config/subscription/impl/FileConfigSubscriptionTest.java
+++ b/config/src/test/java/com/yahoo/config/subscription/impl/FileConfigSubscriptionTest.java
@@ -18,6 +18,8 @@ import java.nio.file.Files;
 
 import static org.hamcrest.CoreMatchers.is;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotSame;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 
@@ -48,11 +50,11 @@ public class FileConfigSubscriptionTest {
                 subscriber,
                 TEST_TYPES_FILE);
         assertTrue(sub.nextConfig(1000));
-        assertThat(sub.config.intval(), is(23));
+        assertThat(sub.getConfigState().getConfig().intval(), is(23));
         Thread.sleep(1000);
         writeConfig("intval", "33");
         assertTrue(sub.nextConfig(1000));
-        assertThat(sub.config.intval(), is(33));
+        assertThat(sub.getConfigState().getConfig().intval(), is(33));
     }
 
     @Test
@@ -64,18 +66,37 @@ public class FileConfigSubscriptionTest {
                 subscriber,
                 TEST_TYPES_FILE);
         assertTrue(sub.nextConfig(1000));
-        assertThat(sub.config.intval(), is(23));
+        assertThat(sub.getConfigState().getConfig().intval(), is(23));
         writeConfig("intval", "33");
         sub.reload(1);
         assertTrue(sub.nextConfig(1000));
-        assertThat(sub.config.intval(), is(33));
-        assertTrue(sub.isConfigChanged());
-        assertTrue(sub.isGenerationChanged());
+        ConfigSubscription.ConfigState<SimpletypesConfig> configState = sub.getConfigState();
+        assertThat(configState.getConfig().intval(), is(33));
+        assertTrue(configState.isConfigChanged());
+        assertTrue(configState.isGenerationChanged());
+
+        assertTrue(sub.isConfigChangedAndReset(7L));
+        assertSame(configState, sub.getConfigState());
+        assertTrue(configState.isConfigChanged());
+        assertTrue(configState.isGenerationChanged());
+        assertTrue(sub.isConfigChangedAndReset(1L));
+        assertNotSame(configState, sub.getConfigState());
+        configState = sub.getConfigState();
+        assertFalse(configState.isConfigChanged());
+        assertFalse(configState.isGenerationChanged());
+
         sub.reload(2);
         assertTrue(sub.nextConfig(1000));
-        assertThat(sub.config.intval(), is(33));
-        assertFalse(sub.isConfigChanged());
-        assertTrue(sub.isGenerationChanged());
+        configState = sub.getConfigState();
+        assertThat(configState.getConfig().intval(), is(33));
+        assertFalse(configState.isConfigChanged());
+        assertTrue(configState.isGenerationChanged());
+
+        assertFalse(sub.isConfigChangedAndReset(2L));
+        assertNotSame(configState, sub.getConfigState());
+        configState = sub.getConfigState();
+        assertFalse(configState.isConfigChanged());
+        assertFalse(configState.isGenerationChanged());
     }
 
     @Test
@@ -86,7 +107,7 @@ public class FileConfigSubscriptionTest {
         ConfigSubscriber subscriber = new ConfigSubscriber();
         ConfigSubscription<TestReferenceConfig> sub = ConfigSubscription.get(key, subscriber, new DirSource(new File(cfgDir)), new TimingValues());
         assertTrue(sub.nextConfig(1000));
-        assertThat(sub.config.configId(), is(cfgId));
+        assertThat(sub.getConfigState().getConfig().configId(), is(cfgId));
     }
 
     @Test(expected = IllegalArgumentException.class)
diff --git a/config/src/test/java/com/yahoo/config/subscription/impl/JRTConfigRequesterTest.java b/config/src/test/java/com/yahoo/config/subscription/impl/JRTConfigRequesterTest.java
index 402c3b9b23f..1ad66cbaf58 100644
--- a/config/src/test/java/com/yahoo/config/subscription/impl/JRTConfigRequesterTest.java
+++ b/config/src/test/java/com/yahoo/config/subscription/impl/JRTConfigRequesterTest.java
@@ -181,8 +181,7 @@ public class JRTConfigRequesterTest {
         ConfigSubscriber subscriber = new ConfigSubscriber();
         final TimingValues timingValues = getTestTimingValues();
         JRTConfigSubscription<SimpletypesConfig> sub = createSubscription(subscriber, timingValues);
-        sub.setConfig(config());
-        sub.setGeneration(1L);
+        sub.setConfig(1L, config());
 
         final MockConnection connection = new MockConnection(new ErrorResponseHandler());
         JRTConfigRequester requester = new JRTConfigRequester(connection, timingValues);
@@ -210,8 +209,7 @@ public class JRTConfigRequesterTest {
         ConfigSubscriber subscriber = new ConfigSubscriber();
         final TimingValues timingValues = getTestTimingValues();
         JRTConfigSubscription<SimpletypesConfig> sub = createSubscription(subscriber, timingValues);
-        sub.setConfig(config());
-        sub.setGeneration(1L);
+        sub.setConfig(1L, config());
 
         final MockConnection connection = new MockConnection(new ErrorResponseHandler(com.yahoo.jrt.ErrorCode.TIMEOUT));
         JRTConfigRequester requester = new JRTConfigRequester(connection, timingValues);
@@ -226,8 +224,7 @@ public class JRTConfigRequesterTest {
         ConfigSubscriber subscriber = new ConfigSubscriber();
         final TimingValues timingValues = getTestTimingValues();
         JRTConfigSubscription<SimpletypesConfig> sub = createSubscription(subscriber, timingValues);
-        sub.setConfig(config());
-        sub.setGeneration(1L);
+        sub.setConfig(1L, config());
 
         final MockConnection connection = new MockConnection(new ErrorResponseHandler(ErrorCode.UNKNOWN_DEFINITION));
         JRTConfigRequester requester = new JRTConfigRequester(connection, timingValues);
diff --git a/config/src/test/java/com/yahoo/vespa/config/protocol/JRTConfigRequestBase.java b/config/src/test/java/com/yahoo/vespa/config/protocol/JRTConfigRequestBase.java
index 7fa205fef15..1f5274b832b 100644
--- a/config/src/test/java/com/yahoo/vespa/config/protocol/JRTConfigRequestBase.java
+++ b/config/src/test/java/com/yahoo/vespa/config/protocol/JRTConfigRequestBase.java
@@ -249,7 +249,7 @@ public abstract class JRTConfigRequestBase {
         assertTrue(sub.nextConfig(120_0000));
         sub.close();
         JRTClientConfigRequest nextReq = createReq(sub, Trace.createNew());
-        SimpletypesConfig config = sub.getConfig();
+        SimpletypesConfig config = sub.getConfigState().getConfig();
         assertThat(nextReq.getRequestConfigMd5(), is(config.getConfigMd5()));
         assertThat(nextReq.getRequestGeneration(), is(currentGeneration));
         System.setProperty("VESPA_CONFIG_PROTOCOL_VERSION", "");