[Xamarin.Android.Build.Tasks] avoid FileNotFoundException in LinkAssemblies #2487
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…mblies Context: https://github.com/Microsoft/perfview When reviewing the .NET exception report in PerfView, I noticed a `FileNotFoundException` thrown for every assembly such as: Throw(System.IO.FileNotFoundException) Could not find file 'samples\HelloWorld\bin\Debug\HelloWorld.dll.mdb'. All coming from the `LinkAssemblies` MSBuild task. Reviewing the code, it appears we were affectively causing a `throw new FileNotFoundException` + `catch` for every instance where an mdb file was missing! I reworked the mdb code in `LinkAssemblies` to match what we are doing for pdb files. It is an order of magnitude faster to check `File.Exists` over `throw` + `catch`, especially when the file will most likely not exist. The results seem to be a ~29ms improvement: Before: 445 ms LinkAssemblies 1 calls After: 416 ms LinkAssemblies 1 calls Other changes: - The pdb copying code here had a `Path.Combine (copydst, filename)` where we could use the `assemblyDestination` variable instead. This will give a slight perf benefit as well: not concatenating a string.
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Binlogs: logs.zip The project used here was the Xamarin.Forms integration project, in this repo. |
dellis1972
approved these changes
Dec 5, 2018
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Context: https://github.com/Microsoft/perfview
When reviewing the .NET exception report in PerfView, I noticed a
FileNotFoundExceptionthrown for every assembly such as:All coming from the
LinkAssembliesMSBuild task.Reviewing the code, it appears we were affectively causing a
throw new FileNotFoundException+catchfor every instance where an mdbfile was missing!
I reworked the mdb code in
LinkAssembliesto match what we are doingfor pdb files. It is an order of magnitude faster to check
File.Existsoverthrow+catch, especially when the file willmost likely not exist.
The results seem to be a ~29ms improvement:
Other changes:
Path.Combine (copydst, filename)where we could use the
assemblyDestinationvariable instead. Thiswill give a slight perf benefit as well: not concatenating a string.