perf(gateway): add map capacity preallocation hints

- Add capacity hint to aiServices map in admin/server_ai.go
- Add capacity hint to subscribers map in ir/store.go
- Add capacity hint to activeStreams map in xds/server.go
- Add capacity hint to snapshots map in xds/snapshot_proto_cache.go

Author: mahmut-Abi

internal/admin/server_ai.go

@@ -77,7 +77,7 @@ type AICostTrend struct {
 var (
 	aiTotalTokens   atomic.Uint64
 	aiTotalRequests atomic.Uint64
-	aiServices      = make(map[string]*AIServiceSummary)
+	aiServices      = make(map[string]*AIServiceSummary, 16)
 	aiTokenUsage    []AITokenUsage
 	aiTraces        []AITraceSummary
 	aiModelCosts    = make(map[string]float64)

internal/ir/store.go

@@ -31,7 +31,7 @@ type SnapshotStoreHooks struct {
 func NewSnapshotStore(logger *slog.Logger) *SnapshotStore {
 	return &SnapshotStore{
 		logger:      logger,
-		subscribers: make(map[int]*snapshotSubscriber),
+		subscribers: make(map[int]*snapshotSubscriber, 8),
 	}
 }
 

internal/xds/server.go

@@ -84,7 +84,7 @@ func New(
 		protoCache:    newSnapshotProtoCache(nil),
 		serverOptions: serverOptions,
 		shutdownCh:    make(chan struct{}),
-		activeStreams: make(map[string]*streamRegistration),
+		activeStreams: make(map[string]*streamRegistration, 64),
 	}, nil
 }
 

internal/xds/snapshot_proto_cache.go

@@ -37,7 +37,7 @@ func (c *snapshotProtoCache) get(snapshot *ir.Snapshot, profile projectionProfil
 		c.snapshots = nil
 	}
 	if c.snapshots == nil {
-		c.snapshots = make(map[string]*controlv1.ConfigSnapshot)
+		c.snapshots = make(map[string]*controlv1.ConfigSnapshot, 32)
 	}
 	cached := c.snapshots[profile.projectionKey]
 	if cached == nil {