Previously, the compiler performed an incremental build by analyzing and
resolving all classes in the program (even unchanged ones) and then using
the dependency graph information to determine which .js files were stale and
needed to be re-emitted. This algorithm produced "correct" rebuilds, but the
cost of re-analyzing the entire program turned out to be higher than
anticipated, especially for component-heavy compilations.
To achieve performant rebuilds, it is necessary to reuse previous analysis
results if possible. Doing this safely requires knowing when prior work is
viable and when it is stale and needs to be re-done.
The new algorithm implemented by this commit is such:
1) Each incremental build starts with knowledge of the last known good
dependency graph and analysis results from the last successful build,
plus of course information about the set of files changed.
2) The previous dependency graph's information is used to determine the
set of source files which have "logically" changed. A source file is
considered logically changed if it or any of its dependencies have
physically changed (on disk) since the last successful compilation. Any
logically unchanged dependencies have their dependency information copied
over to the new dependency graph.
3) During the `TraitCompiler`'s loop to consider all source files in the
program, if a source file is logically unchanged then its previous
analyses are "adopted" (and their 'register' steps are run). If the file
is logically changed, then it is re-analyzed as usual.
4) Then, incremental build proceeds as before, with the new dependency graph
being used to determine the set of files which require re-emitting.
This analysis reuse avoids template parsing operations in many circumstances
and significantly reduces the time it takes ngtsc to rebuild a large
application.
Future work will increase performance even more, by tackling a variety of
other opportunities to reuse or avoid work.
PR Close#34288
With the next version of the CLI we don't need to add logging for the description of the schematic as part of the schematic itself.
This is because now, the CLI will print the description defined in the `migrations.json` file.
See: https://github.com/angular/angular-cli/pull/15951
PR Close#33440
Static methods that return a type of ModuleWithProviders currently
do not have to specify a type because the generic falls back to any.
This is problematic because the type of the actual module being
returned is not present in the type information.
Since Ivy uses d.ts files exclusively for downstream packages
(rather than metadata.json files, for example), we no longer have
the type of the actual module being created.
For this reason, a generic type should be added for
ModuleWithProviders that specifies the module type. This will be
required for all users in v10, but will only be necessary for
users of Ivy in v9.
PR Close#33217
Alex Rickabaugh
Alan Agius
Kara Erickson
Adam Plumer