Document a significant caveat to SideEffect funcs #1399
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| // // Bad example: this will work until a replay occurs, | ||
| // // but then the workflow will fail to replay with a non-deterministic error. | ||
| // var out string | ||
| // err := workflow.SideEffect(func(ctx workflow.Context) interface{} { |
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Is there a ticket/initiative to fix this?
We cannot change the API since it is used everywhere, but we could introduce workflow.Context check will fail in the case of history-related operations inside these calls.
Something like:
workflow.Context{
insideSidefffect: true
}
and inside forbidden things bail out if this flag is set.
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yea, a context-flag of some kind is I think our only real option, but I haven't dug into that code enough to know how much of an effort it will be. I know we have similar behavior for other things though (in queries maybe?).
I have an internal ticket for it (did so before writing this out), nothing public yet though.
) An unfortunate edge-case-use was discovered recently, and SideEffect does not have adequate protections to prevent breaking workflows at the moment. For now, just document it. A true fix will require failing calls to blocking or history-recording funcs while the callback runs, as they cannot be used safely. Future versions of this API should remove the context arg, to stop implying it can be used.
An unfortunate edge-case-use was discovered recently, and SideEffect does not have adequate protections to prevent breaking workflows at the moment.
For now, just document it.
A true fix will require failing calls to blocking or history-recording funcs while the callback runs, as they cannot be used safely.
Future versions of this API should remove the context arg, to stop implying it can be used.