ringhash: ensure addresses are consistenly hashed across updates #6066
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dfawley
reviewed
Mar 2, 2023
| // per-address, these entries hash to the same value across address | ||
| // updates. | ||
| idx := 0 | ||
| for currentHashes < targetHashes { |
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Why are we accumulating targetHashes and currentHashes instead of resetting them? e.g.
for _, scw := range normalizedWeights {
targetHashes := scale * scw.weight
for idx := 0; idx < targetHashes; idx++ {
h := xxhash.Sum...
items = append...
}
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Since scw.weight is not a whole number, targetHashes is not a whole number either. In order to ensure that we end up with the correct number of items in the ring, we need to keep a running sum.
I based this change on C-core and Java's implementation. Looks like envoy also does the same: https://github.com/envoyproxy/envoy/blob/main/source/common/upstream/ring_hash_lb.cc#L159.
dfawley
approved these changes
Mar 3, 2023
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This PR ensures that for every address
$addr, the string used to compute the hash is$addr_1,$addr_2..$addr_n. This aligns with implementations in the other languages.RELEASE NOTES: