feat: dagrunner, initial version

benches/basic/scaling.rs

@@ -0,0 +1,32 @@
+//! DAG scaling benchmarks - how performance scales with task count
+
+use criterion::{BenchmarkId, Criterion};
+use dagx::{task_fn, DagRunner};
+
+pub fn bench_dag_scaling(c: &mut Criterion) {
+    let rt = tokio::runtime::Runtime::new().unwrap();
+    let mut group = c.benchmark_group("scaling");
+
+    // Give extra time for 1000-task benchmark (needs ~5.8s, set to 8s for headroom)
+    group.measurement_time(std::time::Duration::from_secs(8));
+
+    for size in [10, 50, 100, 500, 1000].iter() {
+        group.bench_with_input(BenchmarkId::from_parameter(size), size, |b, &size| {
+            b.iter(|| {
+                rt.block_on(async {
+                    let dag = DagRunner::new();
+                    for i in 0..size {
+                        dag.add_task(task_fn(move |_: ()| async move { i }));
+                    }
+                    dag.run(|fut| {
+                        tokio::spawn(fut);
+                    })
+                    .await
+                    .unwrap();
+                })
+            });
+        });
+    }
+
+    group.finish();
+}