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prober: add Priority field; honour it in latency-sorted order

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Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Iba0ff781c4ce863379378b4ca6039dc96a6a6964
This commit is contained in:
raf 2026-03-06 17:38:58 +03:00
commit 8da709dc98
Signed by: NotAShelf
GPG key ID: 29D95B64378DB4BF
1 changed files with 20 additions and 11 deletions
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31
internal/prober/prober.go
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@ -1,10 +1,13 @@
package prober
import (
"math"
"net/http"
"sort"
"sync"
"time"
"notashelf.dev/ncro/internal/config"
)
// Upstream health status.
@ -30,6 +33,7 @@ func (s Status) String() string {
// In-memory metrics for one upstream.
type UpstreamHealth struct {
URL string
Priority int
EMALatency float64
LastProbe time.Time
ConsecutiveFails uint32
@ -56,13 +60,13 @@ func New(alpha float64) *Prober {
}
}
// Seeds the prober with upstream URLs (no measurements yet).
func (p *Prober) InitUpstreams(urls []string) {
// Seeds the prober with upstream configs (records priority, no measurements yet).
func (p *Prober) InitUpstreams(upstreams []config.UpstreamConfig) {
p.mu.Lock()
defer p.mu.Unlock()
for _, u := range urls {
if _, ok := p.table[u]; !ok {
p.table[u] = &UpstreamHealth{URL: u, Status: StatusActive}
for _, u := range upstreams {
if _, ok := p.table[u.URL]; !ok {
p.table[u.URL] = &UpstreamHealth{URL: u.URL, Priority: u.Priority, Status: StatusActive}
}
}
}
@ -109,7 +113,8 @@ func (p *Prober) GetHealth(url string) *UpstreamHealth {
return &cp
}
// Returns all known upstreams sorted by EMA latency (ascending). DOWN upstreams last.
// Returns all known upstreams sorted by EMA latency ascending.
// DOWN upstreams are sorted last. Within 10% EMA difference, lower Priority wins.
func (p *Prober) SortedByLatency() []*UpstreamHealth {
p.mu.RLock()
defer p.mu.RUnlock()
@ -119,13 +124,17 @@ func (p *Prober) SortedByLatency() []*UpstreamHealth {
result = append(result, &cp)
}
sort.Slice(result, func(i, j int) bool {
if result[i].Status == StatusDown && result[j].Status != StatusDown {
return false
a, b := result[i], result[j]
aDown := a.Status == StatusDown
bDown := b.Status == StatusDown
if aDown != bDown {
return bDown // non-down first
}
if result[j].Status == StatusDown && result[i].Status != StatusDown {
return true
// Within 10% latency difference: prefer lower priority number.
if b.EMALatency > 0 && math.Abs(a.EMALatency-b.EMALatency)/b.EMALatency < 0.10 {
return a.Priority < b.Priority
}
return result[i].EMALatency < result[j].EMALatency
return a.EMALatency < b.EMALatency
})
return result
}