Fix false positives when using watch flag. #191
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There were two cases which were causing false positives: 1. Temporary files created by editors which use atomic saves. I fixed this by ignoring changes to temporary files. 2. Mac OS indexing the file and making it look like a change. I fixed this by keeping a hash of each file and comparing the hashes to see if anything actually changed.
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Hey. Thanks for wanting to contribute, much appreciated! The check for temporary files was a good one, but the Finder issue could be more easily resolved by checking |
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Gotcha. Thanks! |
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The watch flag is an awesome feature! However, I noticed one small issue when I watched what was going on closely. There were some false positives triggering a rebuild when it wasn't necessary.
Here's a demo in which I save the file once but two rebuilds are triggered. One immediately, then another about a second later:
I have used fsnotify before to watch for changes, so I had a hunch for where to look. I found two cases which were causing false positives:
I can understand if you have some hesitation about keeping a large number of hashes of files, but in practice, I haven't noticed any impact on performance. I used xxhash which is pretty fast. That being said, it's possible the code could be optimized a bit more. For example, here I'm using ioutil to read the entire source file so I can calculate the hash. If you are already reading the source file somewhere, it might make sense to calculate the hash at that point instead of reading the whole file twice. However, I couldn't find a more appropriate place to put it at first glance.