1 files changed, 153 insertions, 0 deletions
diff --git a/main/src/main/java/org/onap/policy/pap/main/comm/PdpTracker.java b/main/src/main/java/org/onap/policy/pap/main/comm/PdpTracker.java
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+++ b/main/src/main/java/org/onap/policy/pap/main/comm/PdpTracker.java
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+/*
+ * ============LICENSE_START=======================================================
+ * ONAP PAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.pap.main.comm;
+
+import java.util.HashMap;
+import java.util.Map;
+import lombok.Builder;
+import lombok.NonNull;
+import org.onap.policy.models.base.PfModelException;
+import org.onap.policy.models.pdp.concepts.Pdp;
+import org.onap.policy.models.pdp.concepts.PdpGroup;
+import org.onap.policy.models.pdp.concepts.PdpSubGroup;
+import org.onap.policy.models.provider.PolicyModelsProvider;
+import org.onap.policy.pap.main.PolicyModelsProviderFactoryWrapper;
+import org.onap.policy.pap.main.PolicyPapRuntimeException;
+import org.onap.policy.pap.main.comm.TimerManager.Timer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Tracks PDPs. When a PDP is added to the tracker, a timer is started. If the PDP is not
+ * re-added to the tracker before the timer expires, then
+ * {@link PdpModifyRequestMap#removeFromGroups(String)} is called.
+ */
+public class PdpTracker {
+    private static final Logger logger = LoggerFactory.getLogger(PdpTracker.class);
+
+    /**
+     * PDP expiration timers.
+     */
+    private final TimerManager timers;
+
+    /**
+     * Maps a PDP name to its expiration timer.
+     */
+    private final Map<String, TimerManager.Timer> pdp2timer = new HashMap<>();
+
+    /**
+     * PDP modification lock.
+     */
+    private final Object modifyLock;
+
+    /**
+     * Used to remove a PDP from its group/subgroup.
+     */
+    private final PdpModifyRequestMap requestMap;
+
+
+    /**
+     * Constructs the object. Loads the list of PDPs to be tracked, from the DB.
+     *
+     * @param requestMap map used to remove a PDP from its group/subgroup
+     * @param modifyLock object to be locked while data structures are updated
+     * @param timers timers used to detect missed heart beats
+     * @param daoFactory DAO factory
+     */
+    @Builder
+    public PdpTracker(@NonNull PdpModifyRequestMap requestMap, @NonNull Object modifyLock, @NonNull TimerManager timers,
+                    @NonNull PolicyModelsProviderFactoryWrapper daoFactory) {
+
+        this.requestMap = requestMap;
+        this.modifyLock = modifyLock;
+        this.timers = timers;
+
+        loadPdps(daoFactory);
+    }
+
+    /**
+     * Loads the PDPs from the DB.
+     *
+     * @param daoFactory DAO factory
+     */
+    private void loadPdps(PolicyModelsProviderFactoryWrapper daoFactory) {
+        synchronized (modifyLock) {
+            try (PolicyModelsProvider dao = daoFactory.create()) {
+                for (PdpGroup group : dao.getPdpGroups(null)) {
+                    loadPdpsFromGroup(group);
+                }
+
+            } catch (PfModelException e) {
+                throw new PolicyPapRuntimeException("cannot load PDPs from the DB", e);
+            }
+        }
+    }
+
+    /**
+     * Loads the PDPs appearing within a group.
+     *
+     * @param group group whose PDPs are to be loaded
+     */
+    private void loadPdpsFromGroup(PdpGroup group) {
+        for (PdpSubGroup subgrp : group.getPdpSubgroups()) {
+            for (Pdp pdp : subgrp.getPdpInstances()) {
+                add(pdp.getInstanceId());
+            }
+        }
+    }
+
+    /**
+     * Adds a PDP to the tracker and starts its timer. If a timer is already running, the
+     * old timer is cancelled.
+     *
+     * @param pdpName name of the PDP
+     */
+    public void add(String pdpName) {
+        synchronized (modifyLock) {
+            Timer timer = pdp2timer.remove(pdpName);
+            if (timer != null) {
+                timer.cancel();
+            }
+
+            timer = timers.register(pdpName, this::handleTimeout);
+            pdp2timer.put(pdpName, timer);
+        }
+    }
+
+    /**
+     * Handles a timeout. Removes the PDP from {@link #pdp2timer}.
+     *
+     * @param pdpName name of the PDP whose timer has expired
+     */
+    private void handleTimeout(String pdpName) {
+        synchronized (modifyLock) {
+            // remove timer - no need to cancel it, as TimerManager does that
+            pdp2timer.remove(pdpName);
+
+            try {
+                requestMap.removeFromGroups(pdpName);
+
+            } catch (PfModelException e) {
+                logger.warn("unable to remove PDP {} from its group/subgroup", pdpName, e);
+            }
+        }
+    }
+}