HONEYCOMB-61: Detect VPP disconnect using keepalives

Change-Id: Ic664dbf452504d0fff97e8c766d735d9c5d95c72
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>

2 files changed, 167 insertions, 9 deletions

diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/KeepaliveReaderWrapper.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/KeepaliveReaderWrapper.java
new file mode 100644
index 000000000..d59111faa
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/KeepaliveReaderWrapper.java
@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.fd.honeycomb.v3po.translate.util;
+
+import com.google.common.base.Optional;
+import com.google.common.base.Preconditions;
+import io.fd.honeycomb.v3po.translate.MappingContext;
+import io.fd.honeycomb.v3po.translate.ModificationCache;
+import io.fd.honeycomb.v3po.translate.read.ChildReader;
+import io.fd.honeycomb.v3po.translate.read.ReadContext;
+import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
+import java.io.Closeable;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+import javax.annotation.Nonnegative;
+import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Reader wrapper that periodically invokes a read to determine whether reads are still fully functional.
+ * In case a specific error occurs, Keep-alive failure listener gets notified.
+ */
+public final class KeepaliveReaderWrapper<D extends DataObject> implements ChildReader<D>, Runnable, Closeable {
+
+    private static final Logger LOG = LoggerFactory.getLogger(KeepaliveReaderWrapper.class);
+
+    private static final NoopReadContext CTX = new NoopReadContext();
+
+    private final ChildReader<D> delegate;
+    private final Class<? extends Exception> exceptionType;
+    private final KeepaliveFailureListener failureListener;
+    private final ScheduledFuture<?> scheduledFuture;
+
+    /**
+     * Create new Keepalive wrapper
+     *
+     * @param delegate underlying reader performing actual reads
+     * @param executor scheduled executor service to schedule keepalive calls
+     * @param exception type of exception used to differentiate keepalive exception from other exceptions
+     * @param delayInSeconds number of seconds to wait between keepalive calls
+     * @param failureListener listener to be called whenever a keepalive failure is detected
+     */
+    public KeepaliveReaderWrapper(@Nonnull final ChildReader<D> delegate,
+                                  @Nonnull final ScheduledExecutorService executor,
+                                  @Nonnull final Class<? extends Exception> exception,
+                                  @Nonnegative final int delayInSeconds,
+                                  @Nonnull final KeepaliveFailureListener failureListener) {
+        this.delegate = delegate;
+        this.exceptionType = exception;
+        this.failureListener = failureListener;
+        Preconditions.checkArgument(delayInSeconds > 0, "Delay cannot be < 0");
+        LOG.debug("Starting keep-alive execution on top of: {} with delay of: {} seconds", delegate, delayInSeconds);
+        scheduledFuture = executor.scheduleWithFixedDelay(this, delayInSeconds, delayInSeconds, TimeUnit.SECONDS);
+    }
+
+    @Nonnull
+    @Override
+    public Optional<? extends DataObject> read(@Nonnull final InstanceIdentifier<? extends DataObject> id,
+                                               @Nonnull final ReadContext ctx) throws ReadFailedException {
+        return delegate.read(id, ctx);
+    }
+
+    @Override
+    public void read(@Nonnull final InstanceIdentifier<? extends DataObject> id,
+                     @Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final ReadContext ctx)
+        throws ReadFailedException {
+        delegate.read(id, parentBuilder, ctx);
+    }
+
+    @Nonnull
+    @Override
+    public InstanceIdentifier<D> getManagedDataObjectType() {
+        return delegate.getManagedDataObjectType();
+    }
+
+    @Override
+    public void run() {
+        LOG.trace("Invoking keepalive");
+        try {
+            final Optional<? extends DataObject> read = read(delegate.getManagedDataObjectType(), CTX);
+            LOG.debug("Keepalive executed successfully with data: {}", read);
+        } catch (Exception e) {
+            if(exceptionType.isAssignableFrom(e.getClass())) {
+                LOG.warn("Keepalive failed. Notifying listener", e);
+                failureListener.onKeepaliveFailure();
+            }
+            LOG.warn("Keepalive failed unexpectedly", e);
+            throw new IllegalArgumentException("Unexpected failure during keep-alive execution", e);
+        }
+    }
+
+    @Override
+    public void close() {
+        // Do not interrupt, it's not our executor
+        scheduledFuture.cancel(false);
+    }
+
+    /**
+     * Listener that gets called whenever keepalive fails as expected
+     */
+    public interface KeepaliveFailureListener {
+
+        void onKeepaliveFailure();
+    }
+
+    private static final class NoopMappingContext implements MappingContext {
+        @Override
+        public <T extends DataObject> Optional<T> read(@Nonnull final InstanceIdentifier<T> currentId) {
+            return Optional.absent();
+        }
+
+        @Override
+        public void delete(final InstanceIdentifier<?> path) {}
+
+        @Override
+        public <T extends DataObject> void merge(final InstanceIdentifier<T> path, final T data) {}
+
+        @Override
+        public <T extends DataObject> void put(final InstanceIdentifier<T> path, final T data) {}
+
+        @Override
+        public void close() {}
+    }
+
+    private static class NoopReadContext implements ReadContext {
+
+        private final ModificationCache modificationCache = new ModificationCache();
+
+        @Nonnull
+        @Override
+        public ModificationCache getModificationCache() {
+            return modificationCache;
+        }
+
+        @Nonnull
+        @Override
+        public MappingContext getMappingContext() {
+            return new NoopMappingContext();
+        }
+
+        @Override
+        public void close() {
+
+        }
+    }
+}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/DelegatingWriterRegistry.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/DelegatingWriterRegistry.java
index 7eba98a07..8b981af0d 100644
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/DelegatingWriterRegistry.java
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/DelegatingWriterRegistry.java
@@ -50,14 +50,6 @@ public final class DelegatingWriterRegistry implements WriterRegistry {
 
     private static final Logger LOG = LoggerFactory.getLogger(DelegatingWriterRegistry.class);
 
-    private static final Function<InstanceIdentifier<?>, Class<? extends DataObject>> ID_TO_CLASS =
-            new Function<InstanceIdentifier<?>, Class<? extends DataObject>>() {
-                @Override
-                public Class<? extends DataObject> apply(final InstanceIdentifier<?> input) {
-                    return input.getTargetType();
-                }
-            };
-
     private final Map<Class<? extends DataObject>, Writer<? extends DataObject>> rootWriters;
 
     /**
@@ -130,7 +122,8 @@ public final class DelegatingWriterRegistry implements WriterRegistry {
 
     private void checkAllWritersPresent(final @Nonnull Map<InstanceIdentifier<?>, DataObject> nodesBefore) {
         final Set<Class<? extends DataObject>> nodesBeforeClasses =
-            Sets.newHashSet(Collections2.transform(nodesBefore.keySet(), ID_TO_CLASS));
+            Sets.newHashSet(Collections2.transform(nodesBefore.keySet(),
+                (Function<InstanceIdentifier<?>, Class<? extends DataObject>>) InstanceIdentifier::getTargetType));
         checkArgument(rootWriters.keySet().containsAll(nodesBeforeClasses),
                 "Unable to handle all changes. Missing dedicated writers for: %s",
                 Sets.difference(nodesBeforeClasses, rootWriters.keySet()));