chore!: Remove fallback chunk #16592

Artur- · 2023-04-16T06:58:52Z

The fallback chunk contained all JavaScript and CSS for classes which cannot be reached from an entry point (route or exported web component). By removing it we improve performance as we do not need to scan all classes, only the reachable ones. We also fix issues with the license checker as it did not really know how to behave with commercial components that may or may not be used.

The drawback of removing the fallback chunk is that if you are using a component which is not reachable, as determined by the scanner, then your JS/CSS for the component will be missing. The typical case for this is having a factory that can create components using reflection. The scanner is not able to find the referenced classes as they only appear as a string in the source code. For this case, you need to add @Uses(SomeComponent.class) to the factory, for each component it can create using reflection.

To be able to detect unreachable components in development mode, you should set the devmode.optimizeBundle property to true.

Fixes #15929

github-actions · 2023-04-16T07:22:08Z

Test Results

  980 files -   2   980 suites - 2 1h 14m 3s ⏱️ - 4m 31s
6 166 tests - 10 6 128 ✔️ - 10 38 💤 ±0 0 ❌ ±0
6 417 runs - 12 6 372 ✔️ - 12 45 💤 ±0 0 ❌ ±0

Results for commit 5a8a609. ± Comparison against base commit 3dae5ba.

This pull request removes 10 tests.

com.vaadin.flow.server.DeploymentConfigurationFactoryTest ‑ createInitParameters_fallbackChunkIsCreatedViaAppConfig_fallbackChunkObjectIsInInitParams
com.vaadin.flow.server.DeploymentConfigurationFactoryTest ‑ createInitParameters_servletConfigDefinesTokenFile_fallbackChunkObjectIsInInitParams
com.vaadin.flow.server.frontend.NodeUpdateImportsTest ‑ emptyByteCodeScannerData_themeIsDiscovered_fallbackIsGenerated
com.vaadin.flow.server.frontend.NodeUpdateImportsTest ‑ extraComponentsInCP_componentsAreNotDiscoveredByMainScannerWrittenByFallback_fallbackIsGenerated
com.vaadin.flow.server.frontend.NodeUpdateImportsTest ‑ noFallBackScanner_fallbackIsNotGenerated
com.vaadin.flow.server.frontend.NodeUpdateImportsTest ‑ noFallBackScanner_fallbackIsNotImportedEvenIfTheFileExists
com.vaadin.flow.server.frontend.NodeUpdateImportsTest ‑ tokenFileIsStable
com.vaadin.flow.spring.service.SpringServletTest ‑ fallbackChunk_givenInInitParameter_passedOnToDeploymentConfiguration
com.vaadin.flow.testnpmonlyfeatures.bytecodescanning.FallbackByteCodeScanningIT(prodfallback) ‑ buttonIsInitializedInProductionMode[ANY_Chrome_]
com.vaadin.viteapp.TemplateIT ‑ testElementReferencedByReflection[ANY_Chrome_]

♻️ This comment has been updated with latest results.

The fallback chunk contained all JavaScript and CSS for classes which cannot be reached from an entry point (route or exported web component). By removing it we improve performance as we do not need to scan all classes, only the reachable ones. We also fix issues with the license checker as it did not really know how to behave with commercial components that may or may not be used. The drawback of removing the fallback chunk is that if you are using a component which is not reachable, as determined by the scanner, then your JS/CSS for the component will be missing. The typical case for this is having a factory that can create components using reflection. The scanner is not able to find the referenced classes as they only appear as a string in the source code. For this case, you need to add `@Uses(SomeComponent.class)` to the factory, for each component it can create using reflection. To be able to detect unreachable components in development mode, you should set the `devmode.optimizeBundle` property to `true`. Fixes #15929