Zepp OS: Do not change GATT Callback unless explicitely set

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/AbstractDeviceSupport.java

@@ -141,6 +141,11 @@ public abstract class AbstractDeviceSupport implements DeviceSupport {
         return autoReconnect;
     }
 
+    @Override
+    public boolean getImplicitCallbackModify() {
+        return true;
+    }
+
     @Override
     public GBDevice getDevice() {
         return gbDevice;

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/DeviceSupport.java

@@ -114,6 +114,16 @@ public interface DeviceSupport extends EventHandler {
      */
     boolean getAutoReconnect();
 
+    /**
+     * Returns whether the gatt callback should be implicitly set to the one on the transaction,
+     * even if it was not set directly on the transaction. If true, the gatt callback will always
+     * be set to the one in the transaction, even if null and not explicitly set to null.
+     * See https://codeberg.org/Freeyourgadget/Gadgetbridge/pulls/2912 for more information.
+     * This should be false by default, but we are making it configurable to avoid breaking
+     * older devices that rely on this behavior.
+     */
+    boolean getImplicitCallbackModify();
+
     /**
      * Returns the associated device this instance communicates with.
      */

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/ServiceDeviceSupport.java

@@ -102,6 +102,11 @@ public class ServiceDeviceSupport implements DeviceSupport {
         return delegate.getAutoReconnect();
     }
 
+    @Override
+    public boolean getImplicitCallbackModify() {
+        return delegate.getImplicitCallbackModify();
+    }
+
     @Override
     public void dispose() {
         delegate.dispose();

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/AbstractBTLEDeviceSupport.java

@@ -22,7 +22,6 @@ import android.bluetooth.BluetoothGatt;
 import android.bluetooth.BluetoothGattCharacteristic;
 import android.bluetooth.BluetoothGattDescriptor;
 import android.bluetooth.BluetoothGattService;
-import android.content.Intent;
 import android.location.Location;
 
 import org.slf4j.Logger;
@@ -78,6 +77,7 @@ public abstract class AbstractBTLEDeviceSupport extends AbstractDeviceSupport im
         if (mQueue == null) {
             mQueue = new BtLEQueue(getBluetoothAdapter(), getDevice(), this, this, getContext(), mSupportedServerServices);
             mQueue.setAutoReconnect(getAutoReconnect());
+            mQueue.setImplicitGattCallbackModify(getImplicitCallbackModify());
         }
         return mQueue.connect();
     }

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/BtLEQueue.java

@@ -79,6 +79,7 @@ public final class BtLEQueue {
     private final InternalGattCallback internalGattCallback;
     private final InternalGattServerCallback internalGattServerCallback;
     private boolean mAutoReconnect;
+    private boolean mImplicitGattCallbackModify = true;
 
     private Thread dispatchThread = new Thread("Gadgetbridge GATT Dispatcher") {
 
@@ -137,7 +138,10 @@ public final class BtLEQueue {
 
                     if(qTransaction instanceof Transaction) {
                         Transaction transaction = (Transaction)qTransaction;
+                        LOG.trace("Changing gatt callback for {}? {}", transaction.getTaskName(), transaction.isModifyGattCallback());
+                        if (mImplicitGattCallbackModify || transaction.isModifyGattCallback()) {
                             internalGattCallback.setTransactionGattCallback(transaction.getGattCallback());
+                        }
                         mAbortTransaction = false;
                         // Run all actions of the transaction until one doesn't succeed
                         for (BtLEAction action : transaction.getActions()) {
@@ -202,6 +206,10 @@ public final class BtLEQueue {
         mAutoReconnect = enable;
     }
 
+    public void setImplicitGattCallbackModify(final boolean enable) {
+        mImplicitGattCallbackModify = enable;
+    }
+
     protected boolean isConnected() {
         return mGbDevice.isConnected();
     }

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/Transaction.java

@@ -31,10 +31,13 @@ import androidx.annotation.Nullable;
  */
 public class Transaction extends AbstractTransaction {
     private final List<BtLEAction> mActions = new ArrayList<>(4);
+
     private
     @Nullable
     GattCallback gattCallback;
 
+    private boolean modifyGattCallback;
+
     public Transaction(String taskName) {
         super(taskName);
     }
@@ -53,6 +56,7 @@ public class Transaction extends AbstractTransaction {
 
     public void setGattCallback(@Nullable GattCallback callback) {
         gattCallback = callback;
+        modifyGattCallback = true;
     }
 
     /**
@@ -64,6 +68,14 @@ public class Transaction extends AbstractTransaction {
         return gattCallback;
     }
 
+    /**
+     * Returns whether the gatt callback should be modified for this transaction (either set, or
+     * unset if {@code getGattCallback} is null.
+     */
+    public boolean isModifyGattCallback() {
+        return modifyGattCallback;
+    }
+
     @Override
     public int getActionCount() {
         return mActions.size();

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/huami/Huami2021Support.java

@@ -161,6 +161,15 @@ public abstract class Huami2021Support extends HuamiSupport {
         return (byte) 0x80;
     }
 
+    /**
+     * Do not reset the gatt callback implicitly, as that would interrupt operations.
+     * See https://codeberg.org/Freeyourgadget/Gadgetbridge/pulls/2912 for more information.
+     */
+    @Override
+    public boolean getImplicitCallbackModify() {
+        return false;
+    }
+
     @Override
     public void onSendConfiguration(final String config) {
         final ConfigSetter configSetter = new ConfigSetter();