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   1 /**
   2  * Copyright (c) 2010-2023 Contributors to the openHAB project
   3  *
   4  * See the NOTICE file(s) distributed with this work for additional
   5  * information.
   6  *
   7  * This program and the accompanying materials are made available under the
   8  * terms of the Eclipse Public License 2.0 which is available at
   9  * http://www.eclipse.org/legal/epl-2.0
  10  *
  11  * SPDX-License-Identifier: EPL-2.0
  12  */
  13 package org.openhab.binding.mqtt.discovery;
  14
  15 import java.util.Date;
  16 import java.util.Set;
  17 import java.util.concurrent.ScheduledFuture;
  18 import java.util.concurrent.TimeUnit;
  19 import java.util.concurrent.atomic.AtomicBoolean;
  20
  21 import org.eclipse.jdt.annotation.NonNullByDefault;
  22 import org.eclipse.jdt.annotation.Nullable;
  23 import org.openhab.core.config.discovery.AbstractDiscoveryService;
  24 import org.openhab.core.thing.ThingTypeUID;
  25 import org.slf4j.Logger;
  26 import org.slf4j.LoggerFactory;
  27
  28 /**
  29  * Base MQTT discovery class. Responsible for connecting to the {@link MQTTTopicDiscoveryService}.
  30  *
  31  * Implement MQTT discovery services on top of this. You still need to reference
  32  * the MQTTTopicDiscoveryService like in:
  33  *
  34  * <pre>
  35  * &#64;NonNullByDefault({})
  36  * &#64;Reference
  37  * protected MQTTTopicDiscoveryService mqttTopicDiscovery;
  38  * </pre>
  39  *
  40  * @author David Graeff - Initial contribution
  41  */
  42 @NonNullByDefault
  43 public abstract class AbstractMQTTDiscovery extends AbstractDiscoveryService implements MQTTTopicDiscoveryParticipant {
  44     private final Logger logger = LoggerFactory.getLogger(AbstractMQTTDiscovery.class);
  45
  46     protected final String subscribeTopic;
  47
  48     private int timeout;
  49
  50     private @Nullable ScheduledFuture<?> scheduledStop;
  51
  52     private AtomicBoolean isSubscribed;
  53
  54     public AbstractMQTTDiscovery(@Nullable Set<ThingTypeUID> supportedThingTypes, int timeout,
  55             boolean backgroundDiscoveryEnabledByDefault, String baseTopic) {
  56         super(supportedThingTypes, 0, backgroundDiscoveryEnabledByDefault);
  57         this.subscribeTopic = baseTopic;
  58         this.timeout = timeout;
  59         isSubscribed = new AtomicBoolean(false);
  60     }
  61
  62     /**
  63      * Only subscribe if we were not already subscribed
  64      */
  65     private void subscribe() {
  66         if (!isSubscribed.getAndSet(true)) {
  67             getDiscoveryService().subscribe(this, subscribeTopic);
  68         }
  69     }
  70
  71     /**
  72      * Only unsubscribe if we were already subscribed
  73      */
  74     private void unSubscribe() {
  75         if (isSubscribed.getAndSet(false)) {
  76             getDiscoveryService().unsubscribe(this);
  77         }
  78     }
  79
  80     /**
  81      * Return the topic discovery service.
  82      */
  83     protected abstract MQTTTopicDiscoveryService getDiscoveryService();
  84
  85     private synchronized void stopTimeout() {
  86         if (scheduledStop != null) {
  87             scheduledStop.cancel(false);
  88             scheduledStop = null;
  89         }
  90     }
  91
  92     protected synchronized void resetTimeout() {
  93         stopTimeout();
  94
  95         // schedule an automatic call of stopScan when timeout is reached
  96         if (timeout > 0) {
  97             Runnable runnable = new Runnable() {
  98                 @Override
  99                 public void run() {
 100                     try {
 101                         stopScan();
 102                     } catch (Exception e) {
 103                         logger.debug("Exception occurred during execution: {}", e.getMessage(), e);
 104                     }
 105                 }
 106             };
 107
 108             scheduledStop = scheduler.schedule(runnable, timeout, TimeUnit.SECONDS);
 109         }
 110     }
 111
 112     @Override
 113     protected void startScan() {
 114         if (isBackgroundDiscoveryEnabled()) {
 115             super.stopScan();
 116             return;
 117         }
 118         resetTimeout();
 119         subscribe();
 120     }
 121
 122     @Override
 123     protected synchronized void stopScan() {
 124         if (isBackgroundDiscoveryEnabled()) {
 125             super.stopScan();
 126             return;
 127         }
 128         stopTimeout();
 129         unSubscribe();
 130         super.stopScan();
 131     }
 132
 133     @Override
 134     public synchronized void abortScan() {
 135         stopTimeout();
 136         super.abortScan();
 137     }
 138
 139     @Override
 140     protected void startBackgroundDiscovery() {
 141         // Remove results that are restored after a restart
 142         removeOlderResults(new Date().getTime());
 143         subscribe();
 144     }
 145
 146     @Override
 147     protected void stopBackgroundDiscovery() {
 148         unSubscribe();
 149     }
 150 }