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GenerateRandomID has a check to verify if the generated ID was numeric. This check was added because a container's short-ID is used as default hostname for containers, which isn't allowed to be consisting of only numbers (see [moby#3869] and https://bugzilla.redhat.com/show_bug.cgi?id=1059122. Producing an random ID with only numbers is a rare corner-case, but the check would always be executed and wasn't optimized. This patch applies some optimizations: - The code was using `strconv.ParseUInt`, which has additional checks for signs ("+" or "-"); `hex.EncodeToString` would never produce these, so we can use `strconv.ParseInt` instead (which doesn't have these checks). - The code was using `TruncateID(id)` to get the short-ID. The `TruncateID` function is designed to also handle digests, and for that checks for the given ID to contain colons (`:`), which it would split to remove the algorithm (`sha256:`) before truncating to the short-ID length. That check wasn't needed either, because those would not be produced by `hex.EncodeToString`, so instead, we can just truncate the ID. - Finally, all we _really_ need to check for is if the ID consists of only numeric characters (`0-9`) so, let's do just that; if any non-numeric value is found, the ID is valid, and we can terminate the loop. I did some basic benchmark to compare all of the above in isolation; - BenchmarkParseInt: `strconv.ParseInt(TruncateID(id), 10, 64)` - BenchmarkParseUInt: `strconv.ParseUint(TruncateID(id), 10, 64)` - BenchmarkParseUIntNoTrunc: `strconv.ParseUint(id[:shortLen], 10, 64)` - BenchmarkAllNum: `allNum(id[:shortLen])` Results of the above: BenchmarkParseInt-10 1713937 691.0 ns/op 480 B/op 18 allocs/op BenchmarkParseIntNoTrunc-10 3385483 356.1 ns/op 480 B/op 18 allocs/op BenchmarkParseUInt-10 2112538 567.7 ns/op 384 B/op 12 allocs/op BenchmarkParseUIntNoTrunc-10 4325847 266.7 ns/op 384 B/op 12 allocs/op BenchmarkAllNum-10 77277264 15.29 ns/op 0 B/op 0 allocs/op Difference for `GenerateRandomID` as a whole is less dramatic, as in most cases `ParseInt` would bail out early, but still saves some allocations, and performance is ~14% better: BenchmarkGenerateRandomID-10 2807764 424.5 ns/op 240 B/op 6 allocs/op BenchmarkGenerateRandomIDNew-10 3288866 366.6 ns/op 160 B/op 3 allocs/op [moby#3869]: https://github.com/moby/moby/issues/3869 Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
pkg/ is a collection of utility packages used by the Moby project without being specific to its internals.
Utility packages are kept separate from the moby core codebase to keep it as small and concise as possible. If some utilities grow larger and their APIs stabilize, they may be moved to their own repository under the Moby organization, to facilitate re-use by other projects. However that is not the priority.
The directory pkg is named after the same directory in the camlistore project. Since Brad is a core
Go maintainer, we thought it made sense to copy his methods for organizing Go code :) Thanks Brad!
Because utility packages are small and neatly separated from the rest of the codebase, they are a good place to start for aspiring maintainers and contributors. Get in touch if you want to help maintain them!