[Sensors] Fix:avoid calling setState() when mounted is false. #2361
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It is an error to call [setState] unless [mounted] is true.
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Hi @Notzuonotdied thank you for the PR, would you like to continue working on it? There are few comments which would be great if you can include them.
Please also follow the standard PR issue template (we have a check list etc).
Finally, please add an entry to the change log and increment the version (+1).
| @@ -73,12 +73,14 @@ class SnakeState extends State<Snake> { | |||
| void initState() { | |||
| super.initState(); | |||
| accelerometerEvents.listen((AccelerometerEvent event) { | |||
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The return value of listen is a StreamSubscription<AccelerometerEvent>. That should move into a _accelerometerEventSubscription field. Please cancel() it in the dispose method.
| @@ -73,12 +73,14 @@ class SnakeState extends State<Snake> { | |||
| void initState() { | |||
| super.initState(); | |||
| accelerometerEvents.listen((AccelerometerEvent event) { | |||
| if (!mounted) return; | |||
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please add { and } to make things a bit cleared in the sample
| setState(() { | ||
| acceleration = event; | ||
| }); | ||
| }); | ||
|
|
||
| Timer.periodic(const Duration(milliseconds: 200), (_) { | ||
| if (!mounted) return; |
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You can actually replace the _ with timer and then cancel the timer as well, when not mounted.
Perhaps keep the timer in a _timer field and cancel in the dispose method as above. Sorry.
cyanglaz
changed the title
|
Closing due to lack of updates. |
It is an error to call [setState] unless [mounted] is true.
Description
The preferred solution is to cancel the timer or stop listening to the animation in the dispose() callback. Another solution is to check the "mounted" property of this object before calling setState() to ensure the object is still in the tree.
This error might indicate a memory leak if setState() is being called because another object is retaining a reference to this State object after it has been removed from the tree. To avoid memory leaks, consider breaking the reference to this object during dispose().
#0 State.setState. (package:flutter/src/widgets/framework.dart:1105:9)
#1 State.setState (package:flutter/src/widgets/framework.dart:1140:6)
#2 SnakeState.initState. (package:.../qy_sensors/snake.dart:77:7) // setState()
#3 _rootRunUnary (dart:async/zone.dart:1132:38)
#4 _CustomZone.runUnary (dart:async/zone.dart:1029:19)
#5 _CustomZone.runUnaryGuarded (dart:async/zone.dart:931:7)
#6 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336:11)
#7 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263:7)
#8 _ForwardingStreamSubscription._add (dart:async/stream_pipe.dart:132:11)
#9 _MapStream._handleData (dart:async/stream_pipe.dart:232:10)
#10 _ForwardingStreamSubscription._handleData (dart:async/stream_pipe.dart:164:13)
#11 _rootRunUnary (dart:async/zone.dart:1132:38)
#12 _CustomZone.runUnary (dart:async/zone.dart:1029:19)
#13 _CustomZone.runUnaryGuarded (dart:async/zone.dart:931:7)
#14 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336:11)
#15 _DelayedData.perform (dart:async/stream_impl.dart:591:14)
#16 _StreamImplEvents.handleNext (dart:async/stream_impl.dart:707:11)
#17 _PendingEvents.schedule. (dart:async/stream_impl.dart:667:7)
#18 _rootRun (dart:async/zone.dart:1120:38)
#19 _CustomZone.run (dart:async/zone.dart:1021:19)
#20 _CustomZone.runGuarded (dart:async/zone.dart:923:7)
#21 _CustomZone.bindCallbackGuarded. (dart:async/zone.dart:963:23)
#22 _rootRun (dart:async/zone.dart:1124:13)
#23 _CustomZone.run (dart:async/zone.dart:1021:19)
#24 _CustomZone.runGuarded (dart:async/zone.dart:923:7)
#25 _CustomZone.bindCallbackGuarded. (dart:async/zone.dart:963:23)
#26 _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
#27 _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)