From 29ad12512ba5e109e78a3c8384ae10747e1eabec Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton@traccar.org>
Date: Thu, 30 Jun 2022 09:12:01 -0700
Subject: Device lookup throttling

---
 .../org/traccar/database/DeviceLookupService.java  | 83 ++++++++++++++++++++--
 1 file changed, 77 insertions(+), 6 deletions(-)

(limited to 'src/main/java/org/traccar/database/DeviceLookupService.java')

diff --git a/src/main/java/org/traccar/database/DeviceLookupService.java b/src/main/java/org/traccar/database/DeviceLookupService.java
index f0a4e7bf0..9cf0899ee 100644
--- a/src/main/java/org/traccar/database/DeviceLookupService.java
+++ b/src/main/java/org/traccar/database/DeviceLookupService.java
@@ -15,40 +15,111 @@
  */
 package org.traccar.database;
 
+import io.netty.util.Timeout;
+import io.netty.util.Timer;
+import io.netty.util.TimerTask;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.traccar.model.Device;
 import org.traccar.storage.Storage;
+import org.traccar.storage.StorageException;
 import org.traccar.storage.query.Columns;
 import org.traccar.storage.query.Condition;
 import org.traccar.storage.query.Request;
 
 import javax.inject.Inject;
 import javax.inject.Singleton;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.TimeUnit;
 
 @Singleton
 public class DeviceLookupService {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(DeviceLookupService.class);
 
+    private static final long INFO_TIMEOUT_MS = TimeUnit.MINUTES.toMillis(60);
+    private static final long THROTTLE_MIN_MS = TimeUnit.MINUTES.toMillis(1);
+    private static final long THROTTLE_MAX_MS = TimeUnit.MINUTES.toMillis(30);
+
     private final Storage storage;
+    private final Timer timer;
+
+    private static class IdentifierInfo {
+        private long lastQuery;
+        private long delay;
+        private Timeout timeout;
+    }
+
+    private final class IdentifierTask implements TimerTask {
+        private final String uniqueId;
+
+        private IdentifierTask(String uniqueId) {
+            this.uniqueId = uniqueId;
+        }
+
+        @Override
+        public void run(Timeout timeout) {
+            LOGGER.debug("Device lookup expired {}", uniqueId);
+            synchronized (DeviceLookupService.this) {
+                identifierMap.remove(uniqueId);
+            }
+        }
+    }
+
+    private final Map<String, IdentifierInfo> identifierMap = new ConcurrentHashMap<>();
 
     @Inject
-    public DeviceLookupService(Storage storage) {
+    public DeviceLookupService(Storage storage, Timer timer) {
         this.storage = storage;
+        this.timer = timer;
+    }
+
+    private synchronized boolean isThrottled(String uniqueId) {
+        IdentifierInfo info = identifierMap.get(uniqueId);
+        return info != null && System.currentTimeMillis() < info.lastQuery + info.delay;
+    }
+
+    private synchronized void lookupSucceeded(String uniqueId) {
+        IdentifierInfo info = identifierMap.remove(uniqueId);
+        if (info != null) {
+            info.timeout.cancel();
+        }
+    }
+
+    private synchronized void lookupFailed(String uniqueId) {
+        IdentifierInfo info = identifierMap.get(uniqueId);
+        if (info != null) {
+            info.timeout.cancel();
+            info.delay = Math.min(info.delay * 2, THROTTLE_MAX_MS);
+        } else {
+            info = new IdentifierInfo();
+            identifierMap.put(uniqueId, info);
+            info.delay = THROTTLE_MIN_MS;
+        }
+        info.lastQuery = System.currentTimeMillis();
+        info.timeout = timer.newTimeout(new IdentifierTask(uniqueId), INFO_TIMEOUT_MS, TimeUnit.MILLISECONDS);
+        LOGGER.debug("Device lookup {} throttled for {} ms", uniqueId, info.delay);
     }
 
     public Device lookup(String[] uniqueIds) {
         Device device = null;
         try {
             for (String uniqueId : uniqueIds) {
-                device = storage.getObject(Device.class, new Request(
-                        new Columns.All(), new Condition.Equals("uniqueId", "uniqueId", uniqueId)));
-                if (device != null) {
-                    break;
+                if (!isThrottled(uniqueId)) {
+                    device = storage.getObject(Device.class, new Request(
+                            new Columns.All(), new Condition.Equals("uniqueId", "uniqueId", uniqueId)));
+                    if (device != null) {
+                        lookupSucceeded(uniqueId);
+                        break;
+                    } else {
+                        lookupFailed(uniqueId);
+                    }
+                } else {
+                    LOGGER.debug("Device lookup throttled {}", uniqueId);
                 }
             }
-        } catch (Exception e) {
+        } catch (StorageException e) {
             LOGGER.warn("Find device error", e);
         }
         return device;
-- 
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