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author | vitalyisaev <vitalyisaev@ydb.tech> | 2023-11-30 13:26:22 +0300 |
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committer | vitalyisaev <vitalyisaev@ydb.tech> | 2023-11-30 15:44:45 +0300 |
commit | 0a98fece5a9b54f16afeb3a94b3eb3105e9c3962 (patch) | |
tree | 291d72dbd7e9865399f668c84d11ed86fb190bbf /vendor/github.com/dgryski/go-rendezvous/rdv.go | |
parent | cb2c8d75065e5b3c47094067cb4aa407d4813298 (diff) | |
download | ydb-0a98fece5a9b54f16afeb3a94b3eb3105e9c3962.tar.gz |
YQ Connector:Use docker-compose in integrational tests
Diffstat (limited to 'vendor/github.com/dgryski/go-rendezvous/rdv.go')
-rw-r--r-- | vendor/github.com/dgryski/go-rendezvous/rdv.go | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/vendor/github.com/dgryski/go-rendezvous/rdv.go b/vendor/github.com/dgryski/go-rendezvous/rdv.go new file mode 100644 index 0000000000..7a6f8203c6 --- /dev/null +++ b/vendor/github.com/dgryski/go-rendezvous/rdv.go @@ -0,0 +1,79 @@ +package rendezvous + +type Rendezvous struct { + nodes map[string]int + nstr []string + nhash []uint64 + hash Hasher +} + +type Hasher func(s string) uint64 + +func New(nodes []string, hash Hasher) *Rendezvous { + r := &Rendezvous{ + nodes: make(map[string]int, len(nodes)), + nstr: make([]string, len(nodes)), + nhash: make([]uint64, len(nodes)), + hash: hash, + } + + for i, n := range nodes { + r.nodes[n] = i + r.nstr[i] = n + r.nhash[i] = hash(n) + } + + return r +} + +func (r *Rendezvous) Lookup(k string) string { + // short-circuit if we're empty + if len(r.nodes) == 0 { + return "" + } + + khash := r.hash(k) + + var midx int + var mhash = xorshiftMult64(khash ^ r.nhash[0]) + + for i, nhash := range r.nhash[1:] { + if h := xorshiftMult64(khash ^ nhash); h > mhash { + midx = i + 1 + mhash = h + } + } + + return r.nstr[midx] +} + +func (r *Rendezvous) Add(node string) { + r.nodes[node] = len(r.nstr) + r.nstr = append(r.nstr, node) + r.nhash = append(r.nhash, r.hash(node)) +} + +func (r *Rendezvous) Remove(node string) { + // find index of node to remove + nidx := r.nodes[node] + + // remove from the slices + l := len(r.nstr) + r.nstr[nidx] = r.nstr[l] + r.nstr = r.nstr[:l] + + r.nhash[nidx] = r.nhash[l] + r.nhash = r.nhash[:l] + + // update the map + delete(r.nodes, node) + moved := r.nstr[nidx] + r.nodes[moved] = nidx +} + +func xorshiftMult64(x uint64) uint64 { + x ^= x >> 12 // a + x ^= x << 25 // b + x ^= x >> 27 // c + return x * 2685821657736338717 +} |