Ensure writing to the digester completes before the digest calculation. #25
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Sometimes, stargzifying an image fails with DIGEST_INVALID. There is a race condition on `digester`. The method `layer.Compressed()` calculates the digest(with `Sum()` method) immediately after the `PipeWriter` is unblocked. But even if the `PipeWriter` is unblocked, it isn't guaranteed that the `TeeReader` completes writing the data to the `digester`. This commit solves this issue by ensuring wrinting to the `digester` completes before the digest calculation using `MultiWriter` instead of `TeeReader`. Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
bradfitz
approved these changes
Oct 14, 2019
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Sometimes, stargzifying an image fails with DIGEST_INVALID.
There is a race condition on the
digester.The method
layer.Compressed()calculates the digest(withSum()method)immediately after the
PipeWriteris unblocked. But even if thePipeWriterisunblocked, it isn't guaranteed that the
TeeReadercompletes writing the datato the
digester.This commit solves this issue by ensuring wrinting to the
digestercompletesbefore the digest calculation using
MultiWriterinstead ofTeeReader.