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Merged
raymondjacobson merged 2 commits into from
Feb 25, 2026
Merged

Improve mirror selection #674

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6d64f34
Improve mirror node selection
raymondjacobson Feb 25, 2026
06236e3
Fix order
raymondjacobson Feb 25, 2026
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3 changes: 1 addition & 2 deletions api/dbv1/media_link.go
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Original file line number Diff line number Diff line change
Expand Up @@ -25,8 +25,7 @@ type Id3Tags struct {
}

func mediaLink(cid string, trackId int32, userId int32, id3Tags *Id3Tags) (*MediaLink, error) {
first, rest := rendezvous.GlobalHasher.ReplicaSet3(cid)
rest = append(config.Cfg.StoreAllNodes, rest...)
first, rest := rendezvous.GlobalHasher.Select(cid)

timestamp := time.Now().Unix() * 1000
data := map[string]interface{}{
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7 changes: 2 additions & 5 deletions api/dbv1/users.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@ import (
"fmt"
"strings"

"api.audius.co/config"
"api.audius.co/rendezvous"
"api.audius.co/trashid"
"github.com/jackc/pgx/v5/pgtype"
Expand Down Expand Up @@ -64,8 +63,7 @@ func (q *Queries) UsersKeyed(ctx context.Context, arg GetUsersParams) (map[int32

if cid != "" {
// rendezvous for cid
first, rest := rendezvous.GlobalHasher.ReplicaSet3(cid)
rest = append(rest, config.Cfg.StoreAllNodes...)
first, rest := rendezvous.GlobalHasher.Select(cid)
coverPhoto = &RectangleImage{
X640: fmt.Sprintf("%s/content/%s/640x.jpg", first, cid),
X2000: fmt.Sprintf("%s/content/%s/2000x.jpg", first, cid),
Expand Down Expand Up @@ -126,8 +124,7 @@ func squareImageStruct(maybeCids ...pgtype.Text) *SquareImage {
}

// rendezvous for cid
first, rest := rendezvous.GlobalHasher.ReplicaSet3(cid)
rest = append(rest, config.Cfg.StoreAllNodes...)
first, rest := rendezvous.GlobalHasher.Select(cid)

return &SquareImage{
X150x150: fmt.Sprintf("%s/content/%s/150x150.jpg", first, cid),
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2 changes: 1 addition & 1 deletion api/v1_rendezvous.go
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Expand Up @@ -20,7 +20,7 @@ func (app *ApiServer) v1Rendezvous(c *fiber.Ctx) error {
for i, node := range nodes {
endpoints[i] = node.Endpoint
}
first, rest := rendezvous.GlobalHasher.ReplicaSet3(cid)
first, rest := rendezvous.GlobalHasher.Select(cid)

return c.JSON(fiber.Map{
"first": first,
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12 changes: 9 additions & 3 deletions rendezvous/rendezvous.go
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Expand Up @@ -94,16 +94,22 @@ func (rh *RendezvousHasher) Rank(key string) []string {
return result
}

// Get a replica set of 3 nodes with random order
func (rh *RendezvousHasher) ReplicaSet3(key string) (string, []string) {
// Select returns a primary node and mirror nodes for the given key.
func (rh *RendezvousHasher) Select(key string) (string, []string) {
ranked := rh.Rank(key)
n := min(len(ranked), 3)
if n == 0 {
return "", []string{}
}

candidates := append([]string(nil), ranked[:n]...)
rand.Shuffle(n, func(i, j int) {
for _, h := range config.Cfg.StoreAllNodes {
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@dylanjeffers dylanjeffers Feb 25, 2026

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nice

if !slices.Contains(candidates, h) {
candidates = append(candidates, h)
}
}

rand.Shuffle(len(candidates), func(i, j int) {
candidates[i], candidates[j] = candidates[j], candidates[i]
})

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4 changes: 2 additions & 2 deletions rendezvous/rendezvous_test.go
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Expand Up @@ -6,7 +6,7 @@ import (
"github.com/stretchr/testify/assert"
)

func TestReplicaSet3(t *testing.T) {
func TestSelect(t *testing.T) {
hosts := []string{
"https://host1.com",
"https://host2.com",
Expand All @@ -16,7 +16,7 @@ func TestReplicaSet3(t *testing.T) {
}

hasher := NewRendezvousHasher(hosts)
first, rest := hasher.ReplicaSet3("test-key")
first, rest := hasher.Select("test-key")
ranked := hasher.Rank("test-key")

assert.Equal(t, 2, len(rest))
Expand Down