Write files to disk atomically so they are never empty#126
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This fixes a bug where if multiple parallel worker threads in a wds project start around the same time, one will trigger a build of the whole project and another will soon after trigger a build of just one file. Both builds are processed in parallel for speed, but if the timing is just right, both try to write to the same destination file around the same time. If one of the project threads is unlucky enough to read the file at around when it is being written, it can read an empty or half written file. Whoops! `write-file-atomic` solves this problem by using a tmpfile and serializing writes made from within the same process. COMPUTERS [no-changelog-required]
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This fixes a bug where if multiple parallel worker threads in a wds project start around the same time, one will trigger a build of the whole project and another will soon after trigger a build of just one file. Both builds are processed in parallel for speed, but if the timing is just right, both try to write to the same destination file around the same time. If one of the project threads is unlucky enough to read the file at around when it is being written, it can read an empty or half written file. Whoops!
write-file-atomicsolves this problem by using a tmpfile and serializing writes made from within the same process.I ran a stress test in the Gadget repo that boots many worker threads in parallel that almost always failed after one or two iterations before this change, and didn't fail after 10 mins of continuous booting locally!
COMPUTERS
[no-changelog-required]