From 695d581cde4c66b4405537fb3a0cdf6d25128a3b Mon Sep 17 00:00:00 2001
From: Håvard Pettersen <havardpe@yahooinc.com>
Date: Fri, 4 Nov 2022 15:53:27 +0000
Subject: wait for the completion of a Lazy<T> in non-coroutine code

---
 vespalib/src/tests/coro/lazy/lazy_test.cpp | 63 +++++++++++++++++++++++++-----
 1 file changed, 54 insertions(+), 9 deletions(-)

(limited to 'vespalib/src/tests/coro/lazy')

diff --git a/vespalib/src/tests/coro/lazy/lazy_test.cpp b/vespalib/src/tests/coro/lazy/lazy_test.cpp
index ead5e8e6427..ec27bf195ec 100644
--- a/vespalib/src/tests/coro/lazy/lazy_test.cpp
+++ b/vespalib/src/tests/coro/lazy/lazy_test.cpp
@@ -1,10 +1,11 @@
 // 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/sync_wait.h>
+#include <vespa/vespalib/coro/completion.h>
 #include <vespa/vespalib/coro/schedule.h>
 #include <vespa/vespalib/util/size_literals.h>
 #include <vespa/vespalib/util/require.h>
+#include <vespa/vespalib/util/gate.h>
 #include <vespa/vespalib/util/threadstackexecutor.h>
 #include <vespa/vespalib/gtest/gtest.h>
 #include <mutex>
@@ -12,7 +13,9 @@
 #include <thread>
 
 using vespalib::Executor;
+using vespalib::Gate;
 using vespalib::coro::Lazy;
+using vespalib::coro::Received;
 using vespalib::coro::ScheduleFailedException;
 using vespalib::coro::schedule;
 using vespalib::coro::sync_wait;
@@ -56,7 +59,7 @@ Lazy<std::pair<bool,T>> try_schedule_on(Executor &executor, Lazy<T> value) {
     std::cerr << "switching from thread " << std::this_thread::get_id() << std::endl;
     bool accepted = co_await try_schedule(executor);
     std::cerr << "........... to thread " << std::this_thread::get_id() << std::endl;
-    co_return std::make_pair(accepted, co_await value);
+    co_return std::make_pair(accepted, co_await std::move(value));
 }
 
 template <typename T>
@@ -64,18 +67,18 @@ Lazy<T> schedule_on(Executor &executor, Lazy<T> value) {
     std::cerr << "switching from thread " << std::this_thread::get_id() << std::endl;
     co_await schedule(executor);
     std::cerr << "........... to thread " << std::this_thread::get_id() << std::endl;
-    co_return co_await value;
+    co_return co_await std::move(value);
 }
 
 TEST(LazyTest, simple_lazy_value) {
     auto lazy = make_lazy(42);
-    auto result = sync_wait(lazy);
+    auto result = sync_wait(std::move(lazy));
     EXPECT_EQ(result, 42);
 }
 
 TEST(LazyTest, async_sum_of_async_values) {
     auto lazy = async_add_values(10, 20);
-    auto result = sync_wait(lazy);
+    auto result = sync_wait(std::move(lazy));
     EXPECT_EQ(result, 30);
 }
 
@@ -83,13 +86,13 @@ TEST(LazyTest, async_sum_of_external_async_values) {
     auto a = make_lazy(100);
     auto b = make_lazy(200);
     auto lazy = async_sum(std::move(a), std::move(b));
-    auto result = sync_wait(lazy);
+    auto result = sync_wait(std::move(lazy));
     EXPECT_EQ(result, 300);
 }
 
 TEST(LazyTest, extract_rvalue_from_lazy_in_coroutine) {
     auto lazy = extract_rvalue();
-    auto result = sync_wait(lazy);
+    auto result = sync_wait(std::move(lazy));
     EXPECT_EQ(result, 123);
 }
 
@@ -110,7 +113,7 @@ TEST(LazyTest, calculate_result_in_another_thread) {
 TEST(LazyTest, exceptions_are_propagated) {
     vespalib::ThreadStackExecutor executor(1, 128_Ki);
     auto lazy = try_schedule_on(executor, forward_value(will_throw()));
-    EXPECT_THROW(sync_wait(lazy), vespalib::RequireFailedException);
+    EXPECT_THROW(sync_wait(std::move(lazy)), vespalib::RequireFailedException);
 }
 
 TEST(LazyTest, not_able_to_switch_thread_if_executor_is_shut_down) {
@@ -120,7 +123,49 @@ TEST(LazyTest, not_able_to_switch_thread_if_executor_is_shut_down) {
     EXPECT_EQ(result.first, false);
     EXPECT_EQ(result.second, 7);
     auto lazy = schedule_on(executor, make_lazy(8));
-    EXPECT_THROW(sync_wait(lazy), ScheduleFailedException);
+    EXPECT_THROW(sync_wait(std::move(lazy)), ScheduleFailedException);
+}
+
+TEST(LazyTest, async_wait_with_lambda) {
+    Gate gate;
+    Received<int> result;
+    vespalib::ThreadStackExecutor executor(1, 128_Ki);
+    auto lazy = schedule_on(executor, make_lazy(7));
+    async_wait(std::move(lazy), [&](auto res)
+                                {
+                                    result = res;
+                                    gate.countDown();
+                                });
+    gate.await();
+    EXPECT_EQ(result.get_value(), 7);
+}
+
+TEST(LazyTest, async_wait_with_error) {
+    Gate gate;
+    Received<int> result;
+    vespalib::ThreadStackExecutor executor(1, 128_Ki);
+    auto lazy = schedule_on(executor, will_throw());
+    async_wait(std::move(lazy), [&](auto res)
+                                {
+                                    result = res;
+                                    gate.countDown();
+                                });
+    gate.await();
+    EXPECT_THROW(result.get_value(), vespalib::RequireFailedException);
+}
+
+TEST(LazyTest, async_wait_with_move_only_result) {
+    Gate gate;
+    Received<std::unique_ptr<int>> result;
+    vespalib::ThreadStackExecutor executor(1, 128_Ki);
+    auto lazy = schedule_on(executor, move_only_int());
+    async_wait(std::move(lazy), [&](auto res)
+                                {
+                                    result = std::move(res);
+                                    gate.countDown();
+                                });
+    gate.await();
+    EXPECT_EQ(*(result.get_value()), 123);
 }
 
 GTEST_MAIN_RUN_ALL_TESTS()
-- 
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