Adding retry logic for SDC Client in Distribution

* SdcReceptionHandler in distribution tries to initialize & start the
SDC Client when distribution framework comes up. If by any chance the
SDC service is not up then currently the SdcReceptionHandler throws an
exception to the distribution activator and the distribution framework
goes down. And the health check fails.

* This review fixes it by adding a retry mechanism in
SdcReceptionHandler for all lifecycle methods of SdcClient (init, start,
stop). After failure the same operation is retried again with some
delay. The delay is passed as parameter from configuration json file.
The minimum default value for the delay is kept as 30 seconds.

* Adding SdcClientHandler timer task for performing the retries
asynchronously.

Change-Id: Ibb6d936fcf4872c82f87e2cd04a00583b81c92ff
Issue-ID: POLICY-1035
Signed-off-by: ramverma <ram.krishna.verma@ericsson.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcClientHandler.java b/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcClientHandler.java
new file mode 100644
index 00000000..f69fb155
--- /dev/null
+++ b/plugins/reception-plugins/src/main/java/org/onap/policy/distribution/reception/handling/sdc/SdcClientHandler.java
@@ -0,0 +1,76 @@
+/*-
+ * ============LICENSE_START=======================================================
+ *  Copyright (C) 2018 Ericsson. All rights reserved.
+ * ================================================================================
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.distribution.reception.handling.sdc;
+
+import java.util.Timer;
+import java.util.TimerTask;
+
+/**
+ * This class implements TimerTask for calling life cycle methods of SdcClient iteratively after specified interval
+ * until the operation is successful.
+ *
+ * @author Ram Krishna Verma (ram.krishna.verma@ericsson.com)
+ */
+public class SdcClientHandler extends TimerTask {
+
+    private SdcReceptionHandler sdcReceptionHandler;
+    private SdcClientOperationType operationType;
+    private Timer timer;
+
+    public enum SdcClientOperationType {
+        START, STOP
+    }
+
+    /**
+     * Constructs an instance of {@link SdcClientHandler} class.
+     *
+     * @param sdcReceptionHandler the sdcReceptionHandler
+     */
+    public SdcClientHandler(final SdcReceptionHandler sdcReceptionHandler, final SdcClientOperationType operationType,
+            final long retryDelay) {
+        this.sdcReceptionHandler = sdcReceptionHandler;
+        this.operationType = operationType;
+        timer = new Timer(false);
+        timer.scheduleAtFixedRate(this, 0, retryDelay * 1000L);
+    }
+
+    /**
+     * {@inheritDoc}.
+     */
+    @Override
+    public void run() {
+        if (SdcClientOperationType.START.equals(operationType)) {
+            sdcReceptionHandler.initializeSdcClient();
+            sdcReceptionHandler.startSdcClient();
+        } else {
+            sdcReceptionHandler.stopSdcClient();
+        }
+    }
+
+    /**
+     * {@inheritDoc}.
+     */
+    @Override
+    public boolean cancel() {
+        timer.cancel();
+        return true;
+    }
+}