|author||Dave Presotto <email@example.com>||Sun Dec 24 11:01:51 2017 -0800|
|committer||David Presotto <firstname.lastname@example.org>||Tue Jan 02 21:43:56 2018 +0000|
cmd/upspinfs: replace timed refeshes in upspinfs with Watch based refresh The previous version had a very short valid time for anything it gave the kernel to limit the periods of inconsistency between the kernel and the directory servers. It also refreshed any cached DirEntries fairly often to limit its own inconsistency. This created performance issues where we could only trade performance against duration of inconsistency. This version uses Watch to maintain consistency. There is still a window of inconsistency as the Watch events percolate across the network but a much smaller one. Also since we know when things change, we can force the kernel to invalidate cached information and thereby feel safe in increasing the kernel cache validity time. If Watch is not supported by a DirServer, it falls back to refresh entries once a minute. That gives us the benefit of caching but with a larger window of inconsistency. A somewhat related change in dircache removes an unnecessary check that was proportional to the size of a directory. This too was affecting performance, though only in very large directories. The new watch.go is very similar to proxied.go in dircache. I should eventually merge them but not until I have had more experience with this version. The one thing I learned is that one must drain the Watch channel after closing done or future RPCs on the same connection can hang. Fixes #549 Change-Id: I8df66be9d606f7d43dfd4abd4bc3d9f389267f57 Reviewed-on: https://upspin-review.googlesource.com/17880 Reviewed-by: Rob Pike <email@example.com>
Upspin is an experimental project to build a framework for naming and sharing files and other data securely, uniformly, and globally: a global name system of sorts.
It is not a file system, but a set of protocols and reference implementations that can be used to join things like file systems and other storage services to the name space.
Performance is not a primary goal. Uniformity and security are.
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