handleEventLoopCallback method Null safety
visibleForTesting">@visibleForTesting
Execute the highest-priority task, if it is of a high enough priority.
Returns true if a task was executed and there are other tasks remaining (even if they are not high-enough priority).
Returns false if no task was executed, which can occur if there are no tasks scheduled, if the scheduler is locked, or if the highest-priority task is of too low a priority given the current schedulingStrategy.
Also returns false if there are no tasks remaining.
Implementation
@visibleForTesting
@pragma('vm:notify-debugger-on-exception')
bool handleEventLoopCallback() {
if (_taskQueue.isEmpty || locked) {
return false;
}
final _TaskEntry<dynamic> entry = _taskQueue.first;
if (schedulingStrategy(priority: entry.priority, scheduler: this)) {
try {
_taskQueue.removeFirst();
entry.run();
} catch (exception, exceptionStack) {
StackTrace? callbackStack;
assert(() {
callbackStack = entry.debugStack;
return true;
}());
FlutterError.reportError(FlutterErrorDetails(
exception: exception,
stack: exceptionStack,
library: 'scheduler library',
context: ErrorDescription('during a task callback'),
informationCollector: (callbackStack == null) ? null : () {
return <DiagnosticsNode>[
DiagnosticsStackTrace(
'\nThis exception was thrown in the context of a scheduler callback. '
'When the scheduler callback was _registered_ (as opposed to when the '
'exception was thrown), this was the stack',
callbackStack,
),
];
},
));
}
return _taskQueue.isNotEmpty;
}
return false;
}