Build_runner ^2.5.0 — huge speed-up (10x faster in our case)

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For those who haven’t noticed yet — as Kevmoo announced here — build_runner ^2.5.0 includes the first round of performance improvements.

In our case, I see a 10x speed-up when running with existing generated files, and a 2x speed-up for clean builds. I shared a comparison here — we went from 105 seconds down to 12 seconds on an M1 Mac. Huge improvement!

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I didn’t even notice that the output totally changed O.o

1s graphql_codegen on 2 inputs: 2 same                                                                                                                                                                                       
18s dart_mappable_builder on 52 inputs: 3 output, 49 no-op; spent 12s analyzing, 3s sdk, 2s resolving                                                                                                                        
                                                                                                                                                                                                                             
Built with build_runner in 20s; wrote 5 outputs.                                                                                                                                                                             
                                                                                                                                                                                                                             
log output for build_runner                                                                                                                                                                                                  
  Deleting 5 declared outputs which already existed on disk.

Still, 20s is A LOT of time =\ I wish the Dart team could replicate C# macros (called Source Generators). Introducing C# Source Generators - .NET Blog They are fast. Like, really, fast (as Dart can be).

What I noticed in the output above is that graphql_codegen only takes 1s. Don’t know exactly how… that is giving me some ideas… back in the old .net framework days, we had T4 (Text Template Transformation Toolkit). Basically a script like ASP or PHP that used C# to generate C#. It run fast. So, if graphql_codegen is fast because it is only dealing with one .gql file, maybe, something like dart_mappable could be achieved by declaring a class using yaml instead of Dart… I’ll try that someday…

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