more coroutines

1 files changed, 74 insertions, 0 deletions

diff --git a/vespalib/src/tests/coro/lazy/lazy_test.cpp b/vespalib/src/tests/coro/lazy/lazy_test.cpp
index a715e473aaf..4ba1c950ad0 100644
--- a/vespalib/src/tests/coro/lazy/lazy_test.cpp
+++ b/vespalib/src/tests/coro/lazy/lazy_test.cpp
@@ -2,11 +2,35 @@
 
 #include <vespa/vespalib/coro/lazy.h>
 #include <vespa/vespalib/coro/sync_wait.h>
+#include <vespa/vespalib/util/require.h>
 #include <vespa/vespalib/gtest/gtest.h>
 
+#include <thread>
+
 using vespalib::coro::Lazy;
 using vespalib::coro::sync_wait;
 
+std::vector<std::thread> threads;
+struct JoinThreads {
+    ~JoinThreads() {
+        for (auto &thread: threads) {
+            thread.join();
+        }
+        threads.clear();
+    }
+};
+
+auto run_in_other_thread() {
+    struct awaiter {
+        bool await_ready() const noexcept { return false; }
+        void await_suspend(std::coroutine_handle<> handle) const {
+            threads.push_back(std::thread(handle));
+        }
+        void await_resume() const noexcept {}
+    };
+    return awaiter();
+}
+
 Lazy<int> make_lazy(int value) {
     co_return value;
 }
@@ -21,6 +45,33 @@ Lazy<int> async_sum(Lazy<int> a, Lazy<int> b) {
     co_return (co_await a + co_await b);
 }
 
+Lazy<std::unique_ptr<int>> move_only_int() {
+    co_return std::make_unique<int>(123);
+}
+
+Lazy<int> extract_rvalue() {
+    auto res = co_await move_only_int();
+    co_return *res;
+}
+
+Lazy<int> will_throw() {
+    REQUIRE_FAILED("failed on purpose");
+    co_return 123;
+}
+
+template<typename T>
+Lazy<T> forward_value(Lazy<T> value) {
+    co_return co_await std::move(value);
+}
+
+template <typename T>
+Lazy<T> switch_thread(Lazy<T> value) {
+    std::cerr << "switching from thread " << std::this_thread::get_id() << std::endl;
+    co_await run_in_other_thread();
+    std::cerr << "........... to thread " << std::this_thread::get_id() << std::endl;
+    co_return co_await value;
+}
+
 TEST(LazyTest, simple_lazy_value) {
     auto lazy = make_lazy(42);
     auto result = sync_wait(lazy);
@@ -41,4 +92,27 @@ TEST(LazyTest, async_sum_of_external_async_values) {
     EXPECT_EQ(result, 300);
 }
 
+TEST(LazyTest, extract_rvalue_from_lazy_in_coroutine) {
+    auto lazy = extract_rvalue();
+    auto result = sync_wait(lazy);
+    EXPECT_EQ(result, 123);
+}
+
+TEST(LazyTest, extract_rvalue_from_lazy_in_sync_wait) {
+    auto result = sync_wait(move_only_int());
+    EXPECT_EQ(*result, 123);
+}
+
+TEST(LazyTest, calculate_result_in_another_thread) {
+    JoinThreads thread_guard;
+    auto result = sync_wait(switch_thread(make_lazy(7)));
+    EXPECT_EQ(result, 7);
+}
+
+TEST(LazyTest, exceptions_are_propagated) {
+    JoinThreads thread_guard;
+    auto lazy = switch_thread(forward_value(will_throw()));
+    EXPECT_THROW(sync_wait(lazy), vespalib::RequireFailedException);
+}
+
 GTEST_MAIN_RUN_ALL_TESTS()