Initialize mostRecentTimestamp in SMSPlugin constructor

src/org/kde/kdeconnect/Helpers/SMSHelper.java

@@ -127,6 +127,27 @@ public class SMSHelper {
         return Telephony.MmsSms.TYPE_DISCRIMINATOR_COLUMN;
     }
 
+    /**
+     * Get the timestamp of the newest known message. Will return Integer.MIN_VALUE if there are no messages.
+     *
+     * @param context  android.content.Context running the request
+     * @return Timestamp of the oldest known message.
+     */
+    public static @Nullable long getNewestMessageTimestamp(
+            @NonNull Context context
+    ) {
+        long oldestMessageTimestamp = Long.MIN_VALUE;
+        List<SMSHelper.Message> newestMessage = SMSHelper.getMessagesInRange(context, null, Long.MAX_VALUE, 1l, true);
+        // There should only be one, but in case for some reason there are more, take the latest
+        for (SMSHelper.Message message : newestMessage) {
+            if (message != null && message.date > oldestMessageTimestamp) {
+                oldestMessageTimestamp = message.date;
+            }
+        }
+
+        return oldestMessageTimestamp;
+    }
+
     /**
      * Get some or all the messages in a requested thread, starting with the most-recent message
      *

src/org/kde/kdeconnect/Helpers/ThreadHelper.kt

@@ -15,8 +15,4 @@ object ThreadHelper {
 
     @JvmStatic
     fun execute(command: Runnable) = executor.execute(command)
-
-    @JvmStatic
-    fun <T> executeCallable(callable: Callable<T>): Future<T> = executor.submit(callable)
-
 }

src/org/kde/kdeconnect/Plugins/SMSPlugin/SMSPlugin.java

@@ -30,6 +30,7 @@ import android.telephony.PhoneNumberUtils;
 import android.telephony.SmsManager;
 import android.telephony.SmsMessage;
 
+import androidx.annotation.WorkerThread;
 import androidx.annotation.NonNull;
 import androidx.core.content.ContextCompat;
 
@@ -222,6 +223,13 @@ public class SMSPlugin extends Plugin {
     // thread, make sure that access is coherent
     private final Lock mostRecentTimestampLock = new ReentrantLock();
 
+    /**
+     * Keep track of whether we have received any packet which requested messages.
+     *
+     * If not, we will not send updates, since probably the user doesn't care.
+     */
+    private boolean haveMessagesBeenRequested = false;
+
     private class MessageContentObserver extends ContentObserver {
 
         /**
@@ -266,16 +274,18 @@ public class SMSPlugin extends Plugin {
 
     /**
      * Helper method to read the latest message from the sms-mms database and sends it to the desktop
+     *
+     * Should only be called after initializing the mostRecentTimestamp
      */
     private void sendLatestMessage() {
         // Lock so no one uses the mostRecentTimestamp between the moment we read it and the
         // moment we update it. This is because reading the Messages DB can take long.
         mostRecentTimestampLock.lock();
 
-        if (mostRecentTimestamp == 0) {
+        if (!haveMessagesBeenRequested) {
-            // Since the timestamp has not been initialized, we know that nobody else
+            // Since the user has not requested a message, there is most likely nobody listening
-            // has requested a message. That being the case, there is most likely
+            // for message updates, so just drop them rather than spending battery/time sending
-            // nobody listening for message updates, so just drop them
+            // updates that don't matter.
             mostRecentTimestampLock.unlock();
             return;
         }
@@ -375,6 +385,10 @@ public class SMSPlugin extends Plugin {
         // To see debug messages for Klinker library, uncomment the below line
         //Log.setDebug(true);
 
+        mostRecentTimestampLock.lock();
+        mostRecentTimestamp = SMSHelper.getNewestMessageTimestamp(context);
+        mostRecentTimestampLock.unlock();
+
         return true;
     }
 
@@ -394,12 +408,15 @@ public class SMSPlugin extends Plugin {
 
         switch (np.getType()) {
             case PACKET_TYPE_SMS_REQUEST_CONVERSATIONS:
-                Callable<Boolean> callable = () -> this.handleRequestAllConversations(np);
+                Runnable handleRequestAllConversationsRunnable = () -> this.handleRequestAllConversations(np);
-                ThreadHelper.executeCallable(callable);
+                ThreadHelper.execute(handleRequestAllConversationsRunnable);
                 return true;
 
             case PACKET_TYPE_SMS_REQUEST_CONVERSATION:
-                return this.handleRequestSingleConversation(np);
+                Runnable handleRequestSingleConversationRunnable = () -> this.handleRequestSingleConversation(np);
+                ThreadHelper.execute(handleRequestSingleConversationRunnable);
+                return true;
+
             case PACKET_TYPE_SMS_REQUEST:
                 String textMessage = np.getString("messageBody");
                 subID = np.getLong("subID", -1);
@@ -491,25 +508,22 @@ public class SMSPlugin extends Plugin {
      * <p>
      * Send one packet of type PACKET_TYPE_SMS_MESSAGE with the first message in all conversations
      */
+    @WorkerThread
     private boolean handleRequestAllConversations(NetworkPacket packet) {
+        haveMessagesBeenRequested = true;
         Iterable<SMSHelper.Message> conversations = SMSHelper.getConversations(this.context);
 
-        // Prepare the mostRecentTimestamp counter based on these messages, since they are the most
-        // recent in every conversation
-        mostRecentTimestampLock.lock();
         for (SMSHelper.Message message : conversations) {
-            if (message.date > mostRecentTimestamp) {
-                mostRecentTimestamp = message.date;
-            }
             NetworkPacket partialReply = constructBulkMessagePacket(Collections.singleton(message));
             device.sendPacket(partialReply);
         }
-        mostRecentTimestampLock.unlock();
 
         return true;
     }
 
+    @WorkerThread
     private boolean handleRequestSingleConversation(NetworkPacket packet) {
+        haveMessagesBeenRequested = true;
         SMSHelper.ThreadID threadID = new SMSHelper.ThreadID(packet.getLong("threadID"));
 
         long rangeStartTimestamp = packet.getLong("rangeStartTimestamp", -1);
@@ -526,17 +540,6 @@ public class SMSPlugin extends Plugin {
             conversation = SMSHelper.getMessagesInRange(this.context, threadID, rangeStartTimestamp, numberToGet, true);
         }
 
-        // Sometimes when desktop app is kept open while android app is restarted for any reason
-        // mostRecentTimeStamp must be updated in that scenario too if a user request for a
-        // single conversation and not the entire conversation list
-        mostRecentTimestampLock.lock();
-        for (SMSHelper.Message message : conversation) {
-            if (message.date > mostRecentTimestamp) {
-                mostRecentTimestamp = message.date;
-            }
-        }
-        mostRecentTimestampLock.unlock();
-
         NetworkPacket reply = constructBulkMessagePacket(conversation);
 
         device.sendPacket(reply);