From ac7ac99ced0a470b2d1d59db1cfd1e3ed41392a3 Mon Sep 17 00:00:00 2001
From: Rongsong Shen <rshen@shenrs.eu>
Date: Fri, 17 Apr 2026 06:48:25 +0000
Subject: [PATCH] refactor: make merge semantics explicit in
 OnHostConfigUpdated/OnClusterUpdated

Start from existing entry and apply this-source's fields, rather than
starting from incoming and restoring the other-source's fields. The new
pattern makes it immediately clear which fields each push type WRITES,
without having to reason about which fields are being "restored".

OnHostUpdated keeps the merged := *incoming + if ok guard because the
worker push also populates HostModel/HostType from attrs; config-sourced
values must only win when a prior config push has already set them.

All 37 backend unit tests pass.
---
 src/frontend/apiserver/backend/handler.go | 64 ++++++++---------------
 1 file changed, 22 insertions(+), 42 deletions(-)

diff --git a/src/frontend/apiserver/backend/handler.go b/src/frontend/apiserver/backend/handler.go
index c3964c4..0a76824 100644
--- a/src/frontend/apiserver/backend/handler.go
+++ b/src/frontend/apiserver/backend/handler.go
@@ -38,52 +38,32 @@ func (h *DefaultHandler) OnHostUpdated(incoming *models.HostInfo) {
 	store.Hosts.Put(merged.HostName, merged)
 }
 
-// OnHostConfigUpdated merges config-sourced fields into an existing host entry.
-// Worker-sourced fields (HostStatus, CPUFactor, NumCPUs, MaxMem, MaxSwap,
-// MaxTmp, NumDisk, NumRun, NumSSusp, NumUSusp, NumDone) are preserved from
-// the prior entry if one exists.
-// NumCores, NumThreads, Topology, SchedStop are preserved here but currently
-// have no write path in rawWorkerData — they remain zero until a future worker
-// push source populates them (analogous to the DisptWindow deferral).
+// OnHostConfigUpdated applies config-sourced fields onto the existing host entry.
+// All other fields (worker-sourced) are preserved from the prior entry.
+// NumCores, NumThreads, Topology, SchedStop have no current write path in
+// rawWorkerData and remain zero until a future push source populates them
+// (analogous to the DisptWindow deferral).
 func (h *DefaultHandler) OnHostConfigUpdated(incoming *models.HostInfo) {
-	merged := *incoming
-	if existing, ok := store.Hosts.Get(merged.HostName); ok {
-		merged.HostStatus = existing.HostStatus
-		merged.CPUFactor = existing.CPUFactor
-		merged.NumCPUs = existing.NumCPUs
-		merged.NumCores = existing.NumCores
-		merged.NumThreads = existing.NumThreads
-		merged.MaxMem = existing.MaxMem
-		merged.MaxSwap = existing.MaxSwap
-		merged.MaxTmp = existing.MaxTmp
-		merged.NumDisk = existing.NumDisk
-		merged.NumRun = existing.NumRun
-		merged.NumSSusp = existing.NumSSusp
-		merged.NumUSusp = existing.NumUSusp
-		merged.NumDone = existing.NumDone
-		merged.Topology = existing.Topology
-		merged.SchedStop = existing.SchedStop
-	}
-	store.Hosts.Put(merged.HostName, merged)
+	existing, _ := store.Hosts.Get(incoming.HostName)
+	existing.HostName = incoming.HostName
+	existing.HostModel = incoming.HostModel
+	existing.HostType = incoming.HostType
+	existing.MaxSlot = incoming.MaxSlot
+	existing.DisptWindow = incoming.DisptWindow
+	store.Hosts.Put(existing.HostName, existing)
 }
 
-// OnClusterUpdated merges config-sourced fields into an existing cluster entry.
-// Built-in fields (Version, Status, ControllerName, NumServers, Resources,
-// HostTypes, HostModels, ClusterAdmins) are preserved from the prior entry
-// if one exists.
+// OnClusterUpdated applies config-sourced fields onto the existing cluster entry.
+// All other fields (built-in/worker-sourced: Version, Status, ControllerName,
+// NumServers, Resources, HostTypes, HostModels, ClusterAdmins) are preserved
+// from the prior entry.
 func (h *DefaultHandler) OnClusterUpdated(incoming *models.ClusterInfo) {
-	merged := *incoming
-	if existing, ok := store.Clusters.Get(merged.ClusterName); ok {
-		merged.Version = existing.Version
-		merged.Status = existing.Status
-		merged.ControllerName = existing.ControllerName
-		merged.NumServers = existing.NumServers
-		merged.Resources = existing.Resources
-		merged.HostTypes = existing.HostTypes
-		merged.HostModels = existing.HostModels
-		merged.ClusterAdmins = existing.ClusterAdmins
-	}
-	store.Clusters.Put(merged.ClusterName, merged)
+	existing, _ := store.Clusters.Get(incoming.ClusterName)
+	existing.ClusterName = incoming.ClusterName
+	existing.HeartbeatInterval = incoming.HeartbeatInterval
+	existing.Vcpus = incoming.Vcpus
+	existing.InactiveHeartbeatCount = incoming.InactiveHeartbeatCount
+	store.Clusters.Put(existing.ClusterName, existing)
 }
 
 func (h *DefaultHandler) OnResourceUpdated(res *models.ResourceDefinitionInfo) {