[Tarantool-patches] [PATCH v2] net.box: do not yield in future.wait_result(0)

[Vladimir Davydov]

It didn't yield before commit 954194a1ca5c ("net.box: rewrite request
implementation in C"). It shouldn't yield now.

Follow-up #6241
---
https://github.com/tarantool/tarantool/tree/vdavydov/netbox-dont-yield-in-future-wait-result-if-timeout-is-0

Changes in v2:
 - Improved test.

 src/box/lua/net_box.c                         |  2 +
 test/box/net.box_fiber-async_gh-3107.result   | 48 +++++++++++++++++++
 test/box/net.box_fiber-async_gh-3107.test.lua | 20 ++++++++
 3 files changed, 70 insertions(+)

diff --git a/src/box/lua/net_box.c b/src/box/lua/net_box.c
index 229dec590cf9..43a7d78a1122 100644
--- a/src/box/lua/net_box.c
+++ b/src/box/lua/net_box.c
@@ -235,6 +235,8 @@ netbox_request_complete(struct netbox_request *request)
 static inline bool
 netbox_request_wait(struct netbox_request *request, double *timeout)
 {
+	if (*timeout == 0)
+		return false;
 	double ts = ev_monotonic_now(loop());
 	int rc = fiber_cond_wait_timeout(&request->cond, *timeout);
 	*timeout -= ev_monotonic_now(loop()) - ts;
diff --git a/test/box/net.box_fiber-async_gh-3107.result b/test/box/net.box_fiber-async_gh-3107.result
index aaaca351a579..ec2fd4f6441a 100644
--- a/test/box/net.box_fiber-async_gh-3107.result
+++ b/test/box/net.box_fiber-async_gh-3107.result
@@ -104,6 +104,54 @@ err:find('Usage') ~= nil
 ---
 - true
 ...
+--
+-- Check that there's no unexpected yields.
+--
+function assert_no_csw(func, ...)               \
+    local csw1 = fiber.info()[fiber.id()].csw   \
+    local ret = {func(...)}                     \
+    local csw2 = fiber.info()[fiber.id()].csw   \
+    assert(csw2 - csw1 == 0)                    \
+    return unpack(ret)                          \
+end
+---
+...
+future = c:call('long_function', {1, 2, 3}, {is_async = true})
+---
+...
+assert_no_csw(future.is_ready, future)
+---
+- false
+...
+assert_no_csw(future.result, future)
+---
+- null
+- Response is not ready
+...
+assert_no_csw(future.wait_result, future, 0)
+---
+- null
+- Timeout exceeded
+...
+finalize_long()
+---
+...
+future:wait_result()
+---
+- [1, 2, 3]
+...
+assert_no_csw(future.is_ready, future)
+---
+- true
+...
+assert_no_csw(future.result, future)
+---
+- [1, 2, 3]
+...
+assert_no_csw(future.wait_result, future)
+---
+- [1, 2, 3]
+...
 box.schema.func.drop('long_function')
 ---
 ...
diff --git a/test/box/net.box_fiber-async_gh-3107.test.lua b/test/box/net.box_fiber-async_gh-3107.test.lua
index d23f368cbce4..71ba50b62ccb 100644
--- a/test/box/net.box_fiber-async_gh-3107.test.lua
+++ b/test/box/net.box_fiber-async_gh-3107.test.lua
@@ -36,6 +36,26 @@ err:find('Usage') ~= nil
 _, err = pcall(future.wait_result, future, '100')
 err:find('Usage') ~= nil
 
+--
+-- Check that there's no unexpected yields.
+--
+function assert_no_csw(func, ...)               \
+    local csw1 = fiber.info()[fiber.id()].csw   \
+    local ret = {func(...)}                     \
+    local csw2 = fiber.info()[fiber.id()].csw   \
+    assert(csw2 - csw1 == 0)                    \
+    return unpack(ret)                          \
+end
+future = c:call('long_function', {1, 2, 3}, {is_async = true})
+assert_no_csw(future.is_ready, future)
+assert_no_csw(future.result, future)
+assert_no_csw(future.wait_result, future, 0)
+finalize_long()
+future:wait_result()
+assert_no_csw(future.is_ready, future)
+assert_no_csw(future.result, future)
+assert_no_csw(future.wait_result, future)
+
 box.schema.func.drop('long_function')
 
 c:close()
-- 
2.25.1