8c6ccdd1ab
* fix: use dsIndexProvider cache on migrations * chore: use same comment as before * feat: org-aware TTL cache for schemaversion migration and warmup for single tenant * chore: use LRU cache * chore: change DefaultCacheTTL to 1 minute * chore: address copilot reviews * chore: use expirable cache * chore: remove unused import
105 lines
3.6 KiB
Go
105 lines
3.6 KiB
Go
package schemaversion
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import (
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"context"
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"sync"
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"time"
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"github.com/grafana/authlib/types"
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"github.com/grafana/grafana/pkg/infra/log"
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"github.com/hashicorp/golang-lru/v2/expirable"
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k8srequest "k8s.io/apiserver/pkg/endpoints/request"
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"github.com/grafana/grafana/pkg/services/apiserver/endpoints/request"
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)
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const defaultCacheSize = 1000
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// CacheProvider is a generic cache interface for schema version providers.
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type CacheProvider[T any] interface {
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// Get returns the cached value if it's still valid, otherwise calls fetch and caches the result.
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Get(ctx context.Context) T
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}
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// PreloadableCache is an interface for providers that support preloading the cache.
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type PreloadableCache interface {
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// Preload loads data into the cache for the given namespaces.
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Preload(ctx context.Context, nsInfos []types.NamespaceInfo)
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}
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// cachedProvider is a thread-safe TTL cache that wraps any fetch function.
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type cachedProvider[T any] struct {
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fetch func(context.Context) T
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cache *expirable.LRU[string, T] // LRU cache: namespace to cache entry
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inFlight sync.Map // map[string]*sync.Mutex - per-namespace fetch locks
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logger log.Logger
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}
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// newCachedProvider creates a new cachedProvider.
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// The fetch function should be able to handle context with different namespaces.
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// A non-positive size turns LRU mechanism off (cache of unlimited size).
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// A non-positive cacheTTL disables TTL expiration.
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func newCachedProvider[T any](fetch func(context.Context) T, size int, cacheTTL time.Duration, logger log.Logger) *cachedProvider[T] {
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cacheProvider := &cachedProvider[T]{
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fetch: fetch,
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logger: logger,
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}
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cacheProvider.cache = expirable.NewLRU(size, func(key string, value T) {
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cacheProvider.inFlight.Delete(key)
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}, cacheTTL)
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return cacheProvider
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}
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// Get returns the cached value if it's still valid, otherwise calls fetch and caches the result.
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func (p *cachedProvider[T]) Get(ctx context.Context) T {
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// Get namespace info from ctx
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nsInfo, err := request.NamespaceInfoFrom(ctx, true)
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if err != nil {
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// No namespace, fall back to direct fetch call without caching
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p.logger.Warn("Unable to get namespace info from context, skipping cache", "error", err)
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return p.fetch(ctx)
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}
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namespace := nsInfo.Value
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// Fast path: check if cache is still valid
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if entry, ok := p.cache.Get(namespace); ok {
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return entry
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}
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// Get or create a per-namespace lock for this fetch operation
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// This ensures only one fetch happens per namespace at a time
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lockInterface, _ := p.inFlight.LoadOrStore(namespace, &sync.Mutex{})
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nsMutex := lockInterface.(*sync.Mutex)
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// Lock this specific namespace - other namespaces can still proceed
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nsMutex.Lock()
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defer nsMutex.Unlock()
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// Double-check: another goroutine might have already fetched while we waited
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if entry, ok := p.cache.Get(namespace); ok {
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return entry
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}
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// Fetch outside the main lock - only this namespace is blocked
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p.logger.Debug("cache miss or expired, fetching new value", "namespace", namespace)
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value := p.fetch(ctx)
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// Update the cache for this namespace
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p.cache.Add(namespace, value)
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return value
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}
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// Preload loads data into the cache for the given namespaces.
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func (p *cachedProvider[T]) Preload(ctx context.Context, nsInfos []types.NamespaceInfo) {
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// Build the cache using a context with the namespace
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p.logger.Info("preloading cache", "nsInfos", len(nsInfos))
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startedAt := time.Now()
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defer func() {
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p.logger.Info("finished preloading cache", "nsInfos", len(nsInfos), "elapsed", time.Since(startedAt))
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}()
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for _, nsInfo := range nsInfos {
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p.cache.Add(nsInfo.Value, p.fetch(k8srequest.WithNamespace(ctx, nsInfo.Value)))
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}
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}
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