Fix behaviour of LazyDictWithCache when import fails #32248
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When apache#15330 added docker.task, it also optimized replacement of the callable with it's result in LazyDictWithCache. LazyDictWithCache is used by Provider's Manager to optimize access to hooks - basically hook is only actually imported, when it is accessed. This helps with speeding up importing of connection information The optimization added result of running callable to _resolved set, but it missed the case when None was returned. Previously, when None was returned, the callable was not replaced and it was called again. After the change - the _resolved set was updated with the key and None was returned. But since the key has not been replaced, next time when the same key was retrieved, the original "callable" was returned, not the None value. So if callable returned None, and the same key was retrieved twice, the second time, instead of None, the dictionary returned Callable. This PR fixes it by setting the value to dictionary even if it was None.
potiuk
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Jun 29, 2023
potiuk
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Took a bit to figure out. Generally the whole thing with lazy caching there is likely now too complex (and less needed) after some other optimizations has been implemented by @uranusjr and @ashb much later. Those changes ptimized the usage on other layers - for example #24486, #29625, #29946. So it might be that some of the complexity at the lower layer of caching might be simply not needed any more (those the same lazy cache dict is used for decorators not only for providers, so maybe we still need it) Maybe one day we can revisit that. For now just fixing it is simplest and least risky. |
ephraimbuddy
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Jul 6, 2023
When #15330 added docker.task, it also optimized replacement of the callable with it's result in LazyDictWithCache. LazyDictWithCache is used by Provider's Manager to optimize access to hooks - basically hook is only actually imported, when it is accessed. This helps with speeding up importing of connection information The optimization added result of running callable to _resolved set, but it missed the case when None was returned. Previously, when None was returned, the callable was not replaced and it was called again. After the change - the _resolved set was updated with the key and None was returned. But since the key has not been replaced, next time when the same key was retrieved, the original "callable" was returned, not the None value. So if callable returned None, and the same key was retrieved twice, the second time, instead of None, the dictionary returned Callable. This PR fixes it by setting the value to dictionary even if it was None. (cherry picked from commit 462df0d)
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When #15330 added docker.task, it also optimized replacement of the callable with it's result in LazyDictWithCache. LazyDictWithCache is used by Provider's Manager to optimize access to hooks - basically hook is only actually imported, when it is accessed. This helps with speeding up importing of connection information
The optimization added result of running callable to _resolved set, but it missed the case when None was returned. Previously, when None was returned, the callable was not replaced and it was called again. After the change - the _resolved set was updated with the key and None was returned. But since the key has not been replaced, next time when the same key was retrieved, the original "callable" was returned, not the None value. So if callable returned None, and the same key was retrieved twice, the second time, instead of None, the dictionary returned Callable.
This PR fixes it by setting the value to dictionary even if it was None.
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