HONEYCOMB-381 - Shutdown handler

Change-Id: I5cf4317e5838470d1e792090c67d97db76ed14f2
Signed-off-by: Jan Srnicek <jsrnicek@cisco.com>

3 files changed, 111 insertions, 0 deletions

diff --git a/infra/cfg-init/src/main/java/io/fd/honeycomb/data/init/ShutdownHandler.java b/infra/cfg-init/src/main/java/io/fd/honeycomb/data/init/ShutdownHandler.java
new file mode 100644
index 000000000..fc350da6e
--- /dev/null
+++ b/infra/cfg-init/src/main/java/io/fd/honeycomb/data/init/ShutdownHandler.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2017 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.data.init;
+
+import javax.annotation.Nonnull;
+
+/**
+ * Handles closing of closeable components
+ */
+public interface ShutdownHandler {
+
+    /**
+     * Register component to be properly closed on shutdown
+     *
+     * @param name      component name
+     * @param component closeable component
+     */
+    void register(@Nonnull final String name, @Nonnull final AutoCloseable component);
+}
diff --git a/infra/impl/src/main/java/io/fd/honeycomb/impl/ShutdownHandlerImpl.java b/infra/impl/src/main/java/io/fd/honeycomb/impl/ShutdownHandlerImpl.java
new file mode 100644
index 000000000..c7cdb21bb
--- /dev/null
+++ b/infra/impl/src/main/java/io/fd/honeycomb/impl/ShutdownHandlerImpl.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2017 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.impl;
+
+import static java.lang.String.format;
+
+import io.fd.honeycomb.data.init.ShutdownHandler;
+import java.util.Deque;
+import java.util.LinkedList;
+import javax.annotation.Nonnull;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class ShutdownHandlerImpl implements ShutdownHandler {
+
+    private static final Logger LOG = LoggerFactory.getLogger(ShutdownHandlerImpl.class);
+
+    private final Deque<CloseableComponent> components;
+
+    public ShutdownHandlerImpl() {
+        components = new LinkedList<>();
+        Runtime.getRuntime().addShutdownHook(new Thread(() -> {
+            // close components in reverse order that they were registered
+            components.descendingIterator().forEachRemaining(closeable -> {
+                LOG.info("Closing component {}", closeable.getName());
+                try {
+                    closeable.getComponent().close();
+                } catch (Exception e) {
+                    throw new IllegalStateException(format("Unable to close component %s", closeable.getName()), e);
+                }
+            });
+        }));
+    }
+
+    @Override
+    public synchronized void register(@Nonnull final String name, @Nonnull final AutoCloseable component) {
+        LOG.debug("Registering component {} for proper shutdown", name);
+        components.add(new CloseableComponent(name, component));
+        LOG.trace("Component {} properly register", name);
+    }
+
+    private static final class CloseableComponent {
+        private final String name;
+        private final AutoCloseable component;
+
+        private CloseableComponent(final String name, final AutoCloseable component) {
+            this.name = name;
+            this.component = component;
+        }
+
+        private String getName() {
+            return name;
+        }
+
+        private AutoCloseable getComponent() {
+            return component;
+        }
+    }
+}
diff --git a/infra/minimal-distribution-core/src/main/java/io/fd/honeycomb/infra/distro/data/ConfigAndOperationalPipelineModule.java b/infra/minimal-distribution-core/src/main/java/io/fd/honeycomb/infra/distro/data/ConfigAndOperationalPipelineModule.java
index 00e3a61a8..29cccccdf 100644
--- a/infra/minimal-distribution-core/src/main/java/io/fd/honeycomb/infra/distro/data/ConfigAndOperationalPipelineModule.java
+++ b/infra/minimal-distribution-core/src/main/java/io/fd/honeycomb/infra/distro/data/ConfigAndOperationalPipelineModule.java
@@ -22,6 +22,8 @@ import com.google.inject.name.Names;
 import io.fd.honeycomb.data.ModifiableDataManager;
 import io.fd.honeycomb.data.ReadableDataManager;
 import io.fd.honeycomb.data.init.DataTreeInitializer;
+import io.fd.honeycomb.data.init.ShutdownHandler;
+import io.fd.honeycomb.impl.ShutdownHandlerImpl;
 import io.fd.honeycomb.infra.distro.data.config.WriterRegistryProvider;
 import io.fd.honeycomb.infra.distro.data.oper.ReadableDTDelegProvider;
 import io.fd.honeycomb.infra.distro.data.oper.ReaderRegistryProvider;
@@ -42,6 +44,9 @@ public class ConfigAndOperationalPipelineModule extends PrivateModule {
     public static final String HONEYCOMB_CONFIG = "honeycomb-config";
 
     protected void configure() {
+        bind(ShutdownHandler.class).to(ShutdownHandlerImpl.class).in(Singleton.class);
+        expose(ShutdownHandler.class);
+
         // Expose registries for plugin reader/writer factories
         bind(WriterRegistry.class).toProvider(WriterRegistryProvider.class).in(Singleton.class);
         expose(WriterRegistry.class);