On 25 Apr 2020, at 17:12, Robert Oxspring <[email protected]> wrote:
>> I tend to think it does not need any hash but just a lastUpdated >> track (the most recent file invalidating previous cache, it is enough and >> faster than any hash computation) > > I’m not totally sure of this. Filtering, for example, is particularly > dependant on properties and configuration which aren’t directly linked with a > source file change. Exactly - this is the key limitation. I think we’re doomed to having to recreate the file each time, because we have no way of knowing whether the file has changed until you generate it. But - there is nothing stopping us, when we detect the file is the same, from not updating the original file. This will have the effect of not triggering unnecessary downstream changes. Concrete example: A filter generates a file that is input to a code generator. Because the file changes every time, the code generator runs every time, not good. But if we detected the file as the same, and didn’t write the filtered file, the code generator wouldn’t run, and we would safely avoid an unnecessary rebuild. Regards, Graham —
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