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Frontend Asset Optimization #3

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Frontend Asset Optimization #3

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16 changes: 13 additions & 3 deletions pkg/api/webassets/webassets.go
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ import (
"net/http"
"os"
"path/filepath"
"sync"

"github.com/grafana/grafana/pkg/api/dtos"
"github.com/grafana/grafana/pkg/services/licensing"
Expand All @@ -31,12 +32,21 @@ type EntryPointInfo struct {
} `json:"assets,omitempty"`
}

var entryPointAssetsCache *dtos.EntryPointAssets = nil
var (
entryPointAssetsCacheMu sync.RWMutex // guard entryPointAssetsCache
entryPointAssetsCache *dtos.EntryPointAssets // TODO: get rid of global state
)

func GetWebAssets(ctx context.Context, cfg *setting.Cfg, license licensing.Licensing) (*dtos.EntryPointAssets, error) {
if cfg.Env != setting.Dev && entryPointAssetsCache != nil {
return entryPointAssetsCache, nil
entryPointAssetsCacheMu.RLock()
ret := entryPointAssetsCache
entryPointAssetsCacheMu.RUnlock()

if cfg.Env != setting.Dev && ret != nil {
return ret, nil
}
entryPointAssetsCacheMu.Lock()
defer entryPointAssetsCacheMu.Unlock()
Comment on lines +41 to +49
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@coderabbitai coderabbitai bot Nov 22, 2025

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⚠️ Potential issue | 🟠 Major

Incomplete double-checked locking pattern.

After releasing the read lock (line 43) and before acquiring the write lock (line 48), another goroutine may have already updated the cache. Without a second check after acquiring the write lock, multiple concurrent callers could redundantly perform the expensive asset-reading operation.

Apply this diff to complete the double-checked locking pattern:

 	entryPointAssetsCacheMu.Lock()
 	defer entryPointAssetsCacheMu.Unlock()
+
+	// Double-check: another goroutine may have updated the cache
+	if cfg.Env != setting.Dev && entryPointAssetsCache != nil {
+		return entryPointAssetsCache, nil
+	}

 	var err error
🤖 Prompt for AI Agents 
In pkg/api/webassets/webassets.go around lines 41 to 49, the double-checked
locking is incomplete: after releasing the read lock and before acquiring the
write lock another goroutine may have populated entryPointAssetsCache. Update
the code to re-check entryPointAssetsCache after acquiring the write lock and if
it's now non-nil (and cfg.Env != setting.Dev) return it immediately; only
proceed with the expensive asset-reading and assignment when the cache is still
nil (or env requires reload). Ensure the write-lock is held while assigning
entryPointAssetsCache and that defer entryPointAssetsCacheMu.Unlock() remains in
place.


var err error
var result *dtos.EntryPointAssets
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