1 files changed, 66 insertions, 0 deletions
diff --git a/vespalib/src/tests/coro/active_work/active_work_test.cpp b/vespalib/src/tests/coro/active_work/active_work_test.cpp
new file mode 100644
index 00000000000..26c0c3dd71a
--- /dev/null
+++ b/vespalib/src/tests/coro/active_work/active_work_test.cpp
@@ -0,0 +1,66 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include <vespa/vespalib/coro/lazy.h>
+#include <vespa/vespalib/coro/schedule.h>
+#include <vespa/vespalib/coro/completion.h>
+#include <vespa/vespalib/coro/active_work.h>
+#include <vespa/vespalib/util/time.h>
+#include <vespa/vespalib/util/threadstackexecutor.h>
+#include <vespa/vespalib/gtest/gtest.h>
+
+using namespace vespalib;
+using namespace vespalib::coro;
+
+Lazy<int> make_expensive_task(Executor &executor, int value) {
+    co_await schedule(executor);
+    auto cpu_cost = 20ms;
+    std::this_thread::sleep_for(cpu_cost);
+    co_return value;
+}
+
+Lazy<int> make_cheap_task(Executor &, int value) {
+    co_return value;
+}
+
+Lazy<int> concurrent_sum(Executor &executor, std::vector<int> values,
+                         std::function<Lazy<int>(Executor &,int)> make_task)
+{
+    std::vector<Lazy<int>> work;
+    for (int v: values) {
+        work.push_back(make_task(executor, v));
+    }
+    ActiveWork active;
+    for (auto &task: work) {
+        active.start(task);
+    }
+    co_await active.join();
+    int res = 0;
+    for (auto &task: work) {
+        res += co_await task; // await_ready == true
+    }
+    co_return res;
+}
+
+TEST(ActiveWorkTest, run_expensive_subtasks_concurrently) {
+    vespalib::ThreadStackExecutor executor(8);
+    auto t0 = steady_clock::now();
+    auto result = sync_wait(concurrent_sum(executor, {1, 2, 3, 4, 5, 6, 7, 8,
+                                                      9,10,11,12,13,14,15,16},
+            make_expensive_task));
+    auto td = steady_clock::now() - t0;
+    EXPECT_EQ(result, 136);
+    fprintf(stderr, "time spent: %zu ms\n", count_ms(td));
+}
+
+TEST(ActiveWorkTest, run_cheap_subtasks_concurrently) {
+    vespalib::ThreadStackExecutor executor(1);
+    auto t0 = steady_clock::now();
+    auto result = sync_wait(concurrent_sum(executor, {1, 2, 3, 4, 5, 6, 7, 8,
+                                                      9,10,11,12,13,14,15,16},
+            make_cheap_task));
+    auto td = steady_clock::now() - t0;
+    EXPECT_EQ(result, 136);
+    fprintf(stderr, "time spent: %zu ms\n", count_ms(td));
+}
+
+GTEST_MAIN_RUN_ALL_TESTS()