Implement progress tracking for clique finding

Introduces a mechanism for tracking progress during clique finding operations. This includes implementing a progress bar state management system, handling visibility checks, and integrating progress reporting into the clique finding logic and result processing.

pkg/obigraph/clique.go

@@ -21,6 +21,10 @@ type CliqueOptions struct {
 	Workers int
 	// Seed seeds the random vertex orders of the restarts.
 	Seed int64
+	// Progress, if set, is called with the size of the best clique each time a
+	// larger one is found. Calls are serialized and made while a lock is held:
+	// it must return quickly and must not call FindClique.
+	Progress func(best int)
 }
 
 // CliqueResult is the outcome of FindClique.
@@ -68,6 +72,9 @@ func FindClique(ctx context.Context, n int, filter NeighborFilter, target int, o
 		mutex.Lock()
 		if len(clique) > len(best) {
 			best = append(best[:0], clique...)
+			if opts.Progress != nil {
+				opts.Progress(len(best))
+			}
 		}
 		mutex.Unlock()
 	}

pkg/obigraph/clique_test.go

@@ -141,3 +141,23 @@ func TestFindCliqueTimeout(t *testing.T) {
 		t.Fatalf("invalid best clique %v", r.Clique)
 	}
 }
+
+func TestFindCliqueProgress(t *testing.T) {
+	adj := randomGraph(rand.New(rand.NewSource(4)), 40, 0.7)
+
+	var seen []int
+	r := FindClique(context.Background(), 40, matrixFilter(adj), 5, CliqueOptions{
+		Progress: func(best int) { seen = append(seen, best) },
+	})
+	if !r.Reached {
+		t.Fatalf("size 5 should be reached: %+v", r)
+	}
+	if len(seen) == 0 || seen[len(seen)-1] != len(r.Clique) {
+		t.Fatalf("progress %v does not end at the clique size %d", seen, len(r.Clique))
+	}
+	for i := 1; i < len(seen); i++ {
+		if seen[i] <= seen[i-1] {
+			t.Fatalf("progress must be strictly increasing: %v", seen)
+		}
+	}
+}