Fixed an infinite loop when initially spawned actor responded synchronously to its parent #2943
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| context: TContext, | ||
| _event: SCXML.Event<TEvent> = initEvent as SCXML.Event<TEvent> |
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arguments were reordered to make context required and a required param can't follow an optional one (_event)
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oh, and this was OK to do because resolveTransition is a private method, so it's not a breaking change
| }); | ||
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| // https://github.com/statelyai/xstate/issues/2565 | ||
| it('should only spawn an initial actor once when it synchronously responds with an event', () => { |
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this is the only new test here
…nously to its parent
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| @@ -1151,9 +1156,9 @@ class StateNode< | |||
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| private resolveTransition( | |||
| stateTransition: StateTransition<TContext, TEvent>, | |||
| currentState?: State<TContext, TEvent, any, any>, | |||
| _event: SCXML.Event<TEvent> = initEvent as SCXML.Event<TEvent>, | |||
| context: TContext = this.machine.context | |||
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this is the only line that has truly changed - the other stuff is just reordering etc
The reason behind the infinite loop was that this code was running within a "service scope" and thus it has been executing the spawnMachine. The problem was that this this.machine.context is actually a getter (yet one reason to hate getters for me :P) and it was executed almost always because the default value for the context parameter had to be assigned here. In the vast majority of use cases, we are only interested in currentState.context though - and we were chosing that a couple of lines below:
xstate/packages/core/src/StateNode.ts
Line 1174 in 56842cb
but that was only happening after a default value for
context was already assigned and the contained side-effect logic executed.
So new child actors were constantly created and their initial actions were constantly executed in response to sendParent that was contained in those initial actions - thus creating an infinite loop and a memory leak.
I've fixed this by getting rid of this default value and by just providing the appropriate context explicitly at 2 call sites of this function
fixes #2565