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wdclient: read the vid map cache link before the live map (#10505)

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resetVidMap trims the cache chain by storing nil into a node's cache
pointer once it ages past vidMapCacheSize. A lookup that missed in its
own map and only then loaded that pointer could find the link already
severed, reporting "not found" for a volume that stayed resolvable the
whole time.

Load the link first, while it is still guaranteed live. A published
vidMap's cache pointer only ever goes from its ancestor to nil, so
reading it earlier can never yield staler history.
This commit is contained in:
Chris Lu
2026-07-31 00:52:04 -07:00
committed by GitHub
parent 3514925581
commit 7fb36025b3
1 changed files with 10 additions and 2 deletions
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weed/wdclient/vid_map.go
+10 -2
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@@ -129,6 +129,11 @@ func (vc *vidMap) GetVidLocations(vid string) (locations []Location, err error)
func (vc *vidMap) GetLocations(vid uint32) (locations []Location, found bool) {
// glog.V(4).Infof("~ lookup volume id %d: %+v ec:%+v", vid, vc.vid2Locations, vc.ecVid2Locations)
// Read the cache link before the live map: resetVidMap trims the chain, so a
// link loaded after the local miss may already be severed, turning a lookup
// that could have been served by the cache into a spurious miss.
cachedMap := vc.cache.Load()
locations, found = vc.getLocations(vid)
if found {
// If volume is explicitly tracked (found=true), return its locations even if empty.
@@ -143,7 +148,7 @@ func (vc *vidMap) GetLocations(vid uint32) (locations []Location, found bool) {
}
// Volume not found in current map - check cache for unknown volumes
if cachedMap := vc.cache.Load(); cachedMap != nil {
if cachedMap != nil {
return cachedMap.GetLocations(vid)
}
@@ -185,13 +190,16 @@ func (vc *vidMap) hasVolumeServer(addr pb.ServerAddress) bool {
if key == "" {
return false
}
// Same ordering requirement as GetLocations: grab the cache link before the
// local lookup so a concurrent reset cannot sever it underneath us.
cachedMap := vc.cache.Load()
vc.RLock()
count := vc.serverRefCount[key]
vc.RUnlock()
if count > 0 {
return true
}
if cachedMap := vc.cache.Load(); cachedMap != nil {
if cachedMap != nil {
return cachedMap.hasVolumeServer(addr)
}
return false