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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.oceanic.internal;
  14
  15 import java.util.concurrent.ConcurrentHashMap;
  16 import java.util.concurrent.locks.ReentrantLock;
  17
  18 import org.slf4j.Logger;
  19 import org.slf4j.LoggerFactory;
  20
  21 /**
  22  * The {@link Throttler} is helper class that regulates the frequency at which messages/packets are sent to
  23  * the serial port.
  24  *
  25  * @author Karel Goderis - Initial Contribution
  26  */
  27 public class Throttler {
  28
  29     private static Logger logger = LoggerFactory.getLogger(Throttler.class);
  30
  31     public static final long INTERVAL = 1000;
  32
  33     private static ConcurrentHashMap<String, ReentrantLock> locks = new ConcurrentHashMap<>();
  34     private static ConcurrentHashMap<String, Long> timestamps = new ConcurrentHashMap<>();
  35
  36     public static void lock(String key) {
  37         if (!locks.containsKey(key)) {
  38             locks.put(key, new ReentrantLock());
  39         }
  40
  41         locks.get(key).lock();
  42
  43         if (timestamps.get(key) != null) {
  44             long lastStamp = timestamps.get(key);
  45             long timeToWait = Math.max(INTERVAL - (System.currentTimeMillis() - lastStamp), 0);
  46             if (timeToWait > 0) {
  47                 try {
  48                     Thread.sleep(timeToWait);
  49                 } catch (InterruptedException e) {
  50                     logger.error("An exception occurred while putting the thread to sleep : '{}'", e.getMessage());
  51                 }
  52             }
  53         }
  54     }
  55
  56     public static void unlock(String key) {
  57         if (locks.containsKey(key)) {
  58             timestamps.put(key, System.currentTimeMillis());
  59             locks.get(key).unlock();
  60         }
  61     }
  62
  63     public static void lock() {
  64         for (ReentrantLock aLock : locks.values()) {
  65             aLock.lock();
  66         }
  67
  68         long lastStamp = 0;
  69
  70         for (Long aStamp : timestamps.values()) {
  71             if (aStamp > lastStamp) {
  72                 lastStamp = aStamp;
  73             }
  74         }
  75
  76         long timeToWait = Math.max(INTERVAL - (System.currentTimeMillis() - lastStamp), 0);
  77         if (timeToWait > 0) {
  78             try {
  79                 Thread.sleep(timeToWait);
  80             } catch (InterruptedException e) {
  81                 logger.error("An exception occurred while putting the thread to sleep : '{}'", e.getMessage());
  82             }
  83         }
  84     }
  85
  86     public static void unlock() {
  87         for (String key : locks.keySet()) {
  88             if (locks.get(key).isHeldByCurrentThread()) {
  89                 timestamps.put(key, System.currentTimeMillis());
  90                 locks.get(key).unlock();
  91             }
  92         }
  93     }
  94 }