2 * ============LICENSE_START=======================================================
3 * feature-active-standby-management
4 * ================================================================================
5 * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
6 * ================================================================================
7 * Licensed under the Apache License, Version 2.0 (the "License");
8 * you may not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
11 * http://www.apache.org/licenses/LICENSE-2.0
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 * ============LICENSE_END=========================================================
21 package org.onap.policy.drools.activestandby;
24 * Per MultiSite_v1-10.ppt:
26 * Extends the StateChangeNotifier class and overwrites the abstract handleStateChange() method to get state changes
27 * and do the following:
29 * When the Standby Status changes (from providingservice) to hotstandby or coldstandby,
30 * the Active/Standby selection algorithm must stand down if the PDP-D is currently the lead/active node
31 * and allow another PDP-D to take over. It must also call lock on all engines in the engine management.
33 * When the Standby Status changes from (hotstandby) to coldstandby, the Active/Standby algorithm must NOT assume
34 * the active/lead role.
36 * When the Standby Status changes (from coldstandby or providingservice) to hotstandby,
37 * the Active/Standby algorithm may assume the active/lead role if the active/lead fails.
39 * When the Standby Status changes to providingservice (from hotstandby or coldstandby) call unlock on all
40 * engines in the engine management layer.
42 import java.util.Date;
43 import java.util.Timer;
44 import java.util.TimerTask;
46 import org.onap.policy.common.im.StateChangeNotifier;
47 import org.onap.policy.common.im.StateManagement;
48 import org.slf4j.Logger;
49 import org.slf4j.LoggerFactory;
50 import org.onap.policy.drools.system.PolicyEngine;
55 * Originally, there was a "StandbyStateChangeNotifier" that belonged to policy-core, and this class's handleStateChange() method
56 * used to take care of invoking conn.standDownPdp(). But testing revealed that when a state change to hot standby occurred
57 * from a demote() operation, first the PMStandbyStateChangeNotifier.handleStateChange() method would be invoked and then the
58 * StandbyStateChangeNotifier.handleStateChange() method would be invoked, and this ordering was creating the following problem:
60 * When PMStandbyStateChangeNotifier.handleStateChange() was invoked it would take a long time to finish, because it would result
61 * in SingleThreadedUebTopicSource.stop() being invoked, which can potentially do a 5 second sleep for each controller being stopped.
62 * Meanwhile, as these controller stoppages and their associated sleeps were occurring, the election handler would discover the
63 * demoted PDP in hotstandby (but still designated!) and promote it, resulting in the standbyStatus going from hotstandby
64 * to providingservice. So then, by the time that PMStandbyStateChangeNotifier.handleStateChange() finished its work and
65 * StandbyStateChangeNotifier.handleStateChange() started executing, the standbyStatus was no longer hotstandby (as effected by
66 * the demote), but providingservice (as reset by the election handling logic) and conn.standDownPdp() would not get called!
68 * To fix this bug, we consolidated StandbyStateChangeNotifier and PMStandbyStateChangeNotifier, with the standDownPdp() always
69 * being invoked prior to the TopicEndpoint.manager.lock(). In this way, when the election handling logic is invoked
70 * during the controller stoppages, the PDP is in hotstandby and the standdown occurs.
73 public class PMStandbyStateChangeNotifier extends StateChangeNotifier {
74 // get an instance of logger
75 private static final Logger logger = LoggerFactory.getLogger(PMStandbyStateChangeNotifier.class);
76 private Timer delayActivateTimer;
77 private int pdpUpdateInterval;
78 private boolean isWaitingForActivation;
79 private long startTimeWaitingForActivationMs;
80 private long waitInterval;
81 private boolean isNowActivating;
82 private String previousStandbyStatus;
83 public static String NONE = "none";
84 public static String UNSUPPORTED = "unsupported";
85 public static String HOTSTANDBY_OR_COLDSTANDBY = "hotstandby_or_coldstandby";
87 public PMStandbyStateChangeNotifier(){
88 pdpUpdateInterval = Integer.parseInt(ActiveStandbyProperties.getProperty(ActiveStandbyProperties.PDP_UPDATE_INTERVAL));
89 isWaitingForActivation = false;
90 startTimeWaitingForActivationMs = new Date().getTime();
91 //delay the activate so the DesignatedWaiter can run twice - give it an extra 2 seconds
92 waitInterval = 2*pdpUpdateInterval + 2000;
93 isNowActivating=false;
94 previousStandbyStatus = PMStandbyStateChangeNotifier.NONE;
98 public void handleStateChange() {
100 * A note on synchronization: This method is not synchronized because the caller, stateManagememt,
101 * has synchronize all of its methods. Only one stateManagement operation can occur at a time. Thus,
102 * only one handleStateChange() call will ever be made at a time.
104 if(logger.isInfoEnabled()){
105 if(logger.isDebugEnabled()){
106 logger.debug("handleStateChange: Entering, message={}, standbyStatus={}",
107 super.getMessage(), super.getStateManagement().getStandbyStatus());
110 String standbyStatus = super.getStateManagement().getStandbyStatus();
111 String pdpId = ActiveStandbyProperties
112 .getProperty(ActiveStandbyProperties.NODE_NAME);
114 if(logger.isDebugEnabled()){
115 logger.debug("handleStateChange: previousStandbyStatus = {}"
116 + "; standbyStatus = {}", previousStandbyStatus, standbyStatus);
119 if (standbyStatus == null || standbyStatus.equals(StateManagement.NULL_VALUE)) {
120 if(logger.isDebugEnabled()){
121 logger.debug("handleStateChange: standbyStatus is null; standing down PDP={}", pdpId);
123 if(previousStandbyStatus.equals(StateManagement.NULL_VALUE)){
124 //We were just here and did this successfully
125 if(logger.isDebugEnabled()){
126 logger.debug("handleStateChange: Is returning because standbyStatus is null and was previously 'null'; PDP={}", pdpId);
130 isWaitingForActivation = false;
133 if(logger.isDebugEnabled()){
134 logger.debug("handleStateChange: null: cancelling delayActivationTimer.");
136 delayActivateTimer.cancel();
138 if(logger.isInfoEnabled()){
139 logger.info("handleStateChange: null no delayActivationTimer existed.", e);
141 //If you end of here, there was no active timer
143 //Only want to lock the endpoints, not the controllers.
144 PolicyEngine.manager.deactivate();
145 //The operation was fully successful, but you cannot assign it a real null value
146 //because later we might try to execute previousStandbyStatus.equals() and get
147 //a null pointer exception.
148 previousStandbyStatus = StateManagement.NULL_VALUE;
150 logger.warn("handleStateChange: standbyStatus == null caught exception: ", e);
152 } else if (standbyStatus.equals(StateManagement.HOT_STANDBY) || standbyStatus.equals(StateManagement.COLD_STANDBY)) {
153 if(logger.isDebugEnabled()){
154 logger.debug("handleStateChange: standbyStatus={}; standing down PDP={}", standbyStatus, pdpId);
156 if(previousStandbyStatus.equals(PMStandbyStateChangeNotifier.HOTSTANDBY_OR_COLDSTANDBY)){
157 //We were just here and did this successfully
158 if(logger.isDebugEnabled()){
159 logger.debug("handleStateChange: Is returning because standbyStatus is {}"
160 + " and was previously {}; PDP= {}", standbyStatus, previousStandbyStatus, pdpId);
164 isWaitingForActivation = false;
167 if(logger.isDebugEnabled()){
168 logger.debug("handleStateChange: HOT_STNDBY || COLD_STANDBY: cancelling delayActivationTimer.");
170 delayActivateTimer.cancel();
172 if(logger.isDebugEnabled()){
173 logger.debug("handleStateChange: HOT_STANDBY || COLD_STANDBY no delayActivationTimer existed.", e);
175 //If you end of here, there was no active timer
177 //Only want to lock the endpoints, not the controllers.
178 PolicyEngine.manager.deactivate();
179 //The operation was fully successful
180 previousStandbyStatus = PMStandbyStateChangeNotifier.HOTSTANDBY_OR_COLDSTANDBY;
182 logger.warn("handleStateChange: standbyStatus = {} caught exception: {}", standbyStatus, e.getMessage(), e);
185 } else if (standbyStatus.equals(StateManagement.PROVIDING_SERVICE)) {
186 if(logger.isDebugEnabled()){
187 logger.debug("handleStateChange: standbyStatus= {} "
188 + "scheduling activation of PDP={}",standbyStatus, pdpId);
190 if(previousStandbyStatus.equals(StateManagement.PROVIDING_SERVICE)){
191 //We were just here and did this successfully
192 if(logger.isDebugEnabled()){
193 logger.debug("handleStateChange: Is returning because standbyStatus is {}"
194 + "and was previously {}; PDP={}", standbyStatus, previousStandbyStatus, pdpId);
199 //UnLock all the endpoints
200 if(logger.isDebugEnabled()){
201 logger.debug("handleStateChange: standbyStatus={}; controllers must be unlocked.",standbyStatus );
204 * Only endpoints should be unlocked. Controllers have not been locked.
205 * Because, sometimes, it is possible for more than one PDP-D to become active (race conditions)
206 * we need to delay the activation of the topic endpoint interfaces to give the election algorithm
207 * time to resolve the conflict.
209 if(logger.isDebugEnabled()){
210 logger.debug("handleStateChange: PROVIDING_SERVICE isWaitingForActivation= {}", isWaitingForActivation);
213 //Delay activation for 2*pdpUpdateInterval+2000 ms in case of an election handler conflict.
214 //You could have multiple election handlers thinking they can take over.
216 // First let's check that the timer has not died
217 if(isWaitingForActivation){
218 if(logger.isDebugEnabled()){
219 logger.debug("handleStateChange: PROVIDING_SERVICE isWaitingForActivation = {}", isWaitingForActivation);
221 long now = new Date().getTime();
222 long waitTimeMs = now - startTimeWaitingForActivationMs;
223 if(waitTimeMs > 3*waitInterval){
224 if(logger.isDebugEnabled()){
225 logger.debug("handleStateChange: PROVIDING_SERVICE looks like the activation wait timer may be hung,"
226 + " waitTimeMs = {} and allowable waitInterval = {}"
227 + " Checking whether it is currently in activation. isNowActivating = {}",
228 waitTimeMs, waitInterval, isNowActivating);
230 //Now check that it is not currently executing an activation
231 if(!isNowActivating){
232 if(logger.isDebugEnabled()){
233 logger.debug("handleStateChange: PROVIDING_SERVICE looks like the activation wait timer died");
235 // This will assure the timer is cancelled and rescheduled.
236 isWaitingForActivation = false;
242 if(!isWaitingForActivation){
244 //Just in case there is an old timer hanging around
245 if(logger.isDebugEnabled()){
246 logger.debug("handleStateChange: PROVIDING_SERVICE cancelling delayActivationTimer.");
248 delayActivateTimer.cancel();
250 if(logger.isDebugEnabled()){
251 logger.debug("handleStateChange: PROVIDING_SERVICE no delayActivationTimer existed.");
253 //If you end of here, there was no active timer
255 delayActivateTimer = new Timer();
256 //delay the activate so the DesignatedWaiter can run twice
257 delayActivateTimer.schedule(new DelayActivateClass(), waitInterval);
258 isWaitingForActivation = true;
259 startTimeWaitingForActivationMs = new Date().getTime();
260 if(logger.isDebugEnabled()){
261 logger.debug("handleStateChange: PROVIDING_SERVICE scheduling delayActivationTimer in {} ms", waitInterval);
264 if(logger.isDebugEnabled()){
265 logger.debug("handleStateChange: PROVIDING_SERVICE delayActivationTimer is waiting for activation.");
270 logger.warn("handleStateChange: PROVIDING_SERVICE standbyStatus == providingservice caught exception: ", e);
274 logger.error("handleStateChange: Unsupported standbyStatus={}; standing down PDP={}", standbyStatus, pdpId);
275 if(previousStandbyStatus.equals(PMStandbyStateChangeNotifier.UNSUPPORTED)){
276 //We were just here and did this successfully
277 if(logger.isDebugEnabled()){
278 logger.debug("handleStateChange: Is returning because standbyStatus is "
279 + "UNSUPPORTED and was previously {}; PDP={}", previousStandbyStatus, pdpId);
283 //Only want to lock the endpoints, not the controllers.
284 isWaitingForActivation = false;
287 if(logger.isDebugEnabled()){
288 logger.debug("handleStateChange: unsupported standbystatus: cancelling delayActivationTimer.");
290 delayActivateTimer.cancel();
292 if(logger.isDebugEnabled()){
293 logger.debug("handleStateChange: unsupported standbystatus: no delayActivationTimer existed.", e);
295 //If you end of here, there was no active timer
297 PolicyEngine.manager.deactivate();
298 //We know the standbystatus is unsupported
299 previousStandbyStatus = PMStandbyStateChangeNotifier.UNSUPPORTED;
301 logger.warn("handleStateChange: Unsupported standbyStatus = {} "
302 + "caught exception: {} ",standbyStatus, e.getMessage(), e);
305 if(logger.isDebugEnabled()){
306 logger.debug("handleStateChange: Exiting");
310 private class DelayActivateClass extends TimerTask{
312 private Object delayActivateLock = new Object();
317 isNowActivating = true;
319 if(logger.isDebugEnabled()){
320 logger.debug("DelayActivateClass.run: entry");
322 synchronized(delayActivateLock){
323 PolicyEngine.manager.activate();
324 // The state change fully succeeded
325 previousStandbyStatus = StateManagement.PROVIDING_SERVICE;
326 // We want to set this to false here because the activate call can take a while
327 isWaitingForActivation = false;
328 isNowActivating = false;
330 if(logger.isDebugEnabled()){
331 logger.debug("DelayActivateClass.run.exit");
334 isWaitingForActivation = false;
335 isNowActivating = false;
336 logger.warn("DelayActivateClass.run: caught an unexpected exception "
337 + "calling PolicyEngine.manager.activate: ", e);
342 public String getPreviousStandbyStatus(){
343 return previousStandbyStatus;