maxAll

src/tests/index.tsx

@@ -15,6 +15,7 @@ try {
   await import("./iterable-lifecycle");
   await import("./blend");
   await import("./line");
+  await import("./max-all");
 } catch (error) {
   if (error instanceof AggregateError) {
     console.error(error.errors);

src/tests/max-all.ts

@@ -0,0 +1,39 @@
+
+import {union} from "@virtualstate/union";
+
+{
+
+    async function * maxAll<T>(fns: Iterable<() => Promise<T>>, max: number) {
+        let inProgress: Promise<T>[] = [];
+        for (const next of fns) {
+            while (inProgress.length >= max) {
+                console.log("Waiting for", inProgress);
+                await Promise.race(inProgress);
+            }
+            const promise = next();
+            inProgress.push(promise);
+            promise.finally(() => {
+                inProgress = inProgress.filter(p => p !== promise);
+            });
+            console.log({ inProgress });
+            yield {
+                async *[Symbol.asyncIterator]() {
+                    yield promise;
+                }
+            };
+        }
+     }
+
+     async function sleep<T>(wait = 10, arg: T) {
+        return new Promise<T>(resolve => setTimeout(resolve, wait, arg));
+     }
+
+    for await (const partial of union(maxAll([
+        () => sleep(10, 1),
+        () => sleep(10, 2),
+        () => sleep(10, 3),
+        () => sleep(10, 4)
+    ], 2))) {
+        console.log({ partial });
+    }
+}