Move mutex into portBitmap so it is self-contained thread-safe

The external portAllocatorMu in BoundEndpointPoller protected the
portAllocator pointer from being swapped while other goroutines called
methods on it. Instead, add a Replace method to portBitmap that
atomically swaps the internal bitmap state under its own mutex,
removing the need for callers to manage locking.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/controller/bindings/boundendpoint_poller.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"fmt"
 	"reflect"
-	"sync"
 	"time"
 
 	"github.com/go-logr/logr"
@@ -65,11 +64,8 @@ type BoundEndpointPoller struct {
 	// If draining, polling is skipped to prevent creating new resources.
 	DrainState DrainState
 
-	// portAllocatorMu protects concurrent access to portAllocator.
-	// The polling goroutine reassigns it while reconcile action goroutines call methods on it.
-	portAllocatorMu sync.Mutex
-
-	// portAllocator manages the unique port allocations
+	// portAllocator manages the unique port allocations.
+	// portBitmap is internally thread-safe.
 	portAllocator *portBitmap
 
 	// Channel to stop the API polling goroutine
@@ -249,9 +245,7 @@ func (r *BoundEndpointPoller) reconcileBoundEndpointsFromAPI(ctx context.Context
 	}
 
 	// reassign port allocations
-	r.portAllocatorMu.Lock()
-	r.portAllocator = currentPortAllocations
-	r.portAllocatorMu.Unlock()
+	r.portAllocator.Replace(currentPortAllocations)
 
 	toCreate, toUpdate, toDelete := r.filterBoundEndpointActions(ctx, existingBoundEndpoints, desiredBoundEndpoints)
 
@@ -384,9 +378,7 @@ func (r *BoundEndpointPoller) createBinding(ctx context.Context, desired binding
 	name := hashURL(desired.Spec.GetEndpointURL())
 
 	// allocate a port
-	r.portAllocatorMu.Lock()
 	port, err := r.portAllocator.SetAny()
-	r.portAllocatorMu.Unlock()
 	if err != nil {
 		r.Log.Error(err, "Failed to allocate port for BoundEndpoint", "name", name, "url", desired.Spec.GetEndpointURL())
 		return err
@@ -548,11 +540,9 @@ func (r *BoundEndpointPoller) deleteBinding(ctx context.Context, boundEndpoint b
 	log.Info("Deleted BoundEndpoint", "name", boundEndpoint.Name, "url", boundEndpoint.Spec.GetEndpointURL())
 
 	// unset the port allocation
-	r.portAllocatorMu.Lock()
 	if err := r.portAllocator.Unset(boundEndpoint.Spec.Port); err != nil {
 		log.Error(err, "Failed to unset port allocation", "port", boundEndpoint.Spec.Port, "name", boundEndpoint.Name)
 	}
-	r.portAllocatorMu.Unlock()
 
 	return nil
 }

internal/controller/bindings/port_allocator.go

@@ -76,3 +76,11 @@ func (pb *portBitmap) NumFree() uint64 {
 	defer pb.mu.Unlock()
 	return pb.ports.Unselected()
 }
+
+// Replace atomically swaps the internal bitmap state with that of another portBitmap.
+// The other portBitmap should not be used concurrently during this call.
+func (pb *portBitmap) Replace(other *portBitmap) {
+	pb.mu.Lock()
+	defer pb.mu.Unlock()
+	pb.ports = other.ports
+}