perf(engine): optimize vm object to initialize all the fields in advance #1098
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pmdartus
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@caridy @diervo It appears that this change directly results in performance improvement in LGC:
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Benchmark resultsBase commit: lwc-engine-benchmark
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pmdartus
commented
Mar 7, 2019
| @@ -84,10 +83,12 @@ export interface UninitializedVM { | |||
| data: VNodeData; | |||
| children: VNodes; | |||
| velements: VCustomElement[]; | |||
| cmpTemplate?: Template; | |||
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The bulk of the change is here. Initializing the cmpTemplate and component. The rest of the PR is just type-cast cleaning.
diervo
reviewed
Mar 7, 2019
| @@ -158,7 +158,7 @@ export function BaseLightningElement(this: ComponentInterface) { | |||
| const vm = vmBeingConstructed; | |||
| const { elm, cmpRoot, uid } = vm; | |||
| const component = this; | |||
| (vm as VM).component = component; | |||
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What was this transpiling to in typescript?
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Same thing: vm.component = component
Except that we don't need to type-casting here since we UnitializedVM has nullable component property which wasn't the case before.
caridy
approved these changes
Mar 8, 2019
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Details
When the
VMis initially created in thecreateVMmethods all the properties attached to it are set exceptcmpTemplate(set inevaluateTemplate) andcomponent(set inBaseLightningElementconstructor). By adding all the properties at the creation of the objects, javascript VMs will be able to share the same hidden class for theVMobject through the life cycle of the object.Misc. changes:
UninitalizedVMtype to reflect the addition of the 2 fieldsDoes this PR introduce a breaking change?