Fix #88: Timeout handling. (#91)

fix timeout handling

* Despite what is documented in sd_bus_get_timeout(3), the timeout
  returned is actually an absolute time point of Linux's CLOCK_MONOTONIC
  clock. Hence, we first have to subtract the current time from the
  timeout in order to get a relative time that can be passed to poll.

* For async call timeouts to reliably work, we need a way to notify the
  event loop of a connection that is currently blocked waiting in poll.
  I.e. assume the event loop thread entered poll with a timeout set to
  T1. Afterwards, the main thread starts an async call C with a timeout
  T2 < T1. In order for C to be canceled after its timeout T1 has
  elapsed, we have to be able to notify the event loop so that it can
  update its poll data.

Co-authored-by: Urs Ritzmann <ursritzmann@protonmail.ch>
Co-authored-by: Lukasz Marcul <lukasz.marcul@onemeter.com>
This commit is contained in:
Benjamin Kaufmann
2021-12-20 10:00:29 +01:00
committed by GitHub
co-authored by Urs Ritzmann Lukasz Marcul
parent 0b8f2d9752
commit bb0f3f0242
13 changed files with 249 additions and 30 deletions
@@ -42,6 +42,7 @@
using ::testing::Eq;
using ::testing::DoubleEq;
using ::testing::Gt;
using ::testing::Le;
using ::testing::AnyOf;
using ::testing::ElementsAre;
using ::testing::SizeIs;
@@ -56,6 +57,7 @@ using SdbusTestObject = TestFixture;
TEST_F(SdbusTestObject, ThrowsTimeoutErrorWhenClientSideAsyncMethodTimesOut)
{
std::chrono::time_point<std::chrono::steady_clock> start;
try
{
std::promise<uint32_t> promise;
@@ -68,7 +70,8 @@ TEST_F(SdbusTestObject, ThrowsTimeoutErrorWhenClientSideAsyncMethodTimesOut)
promise.set_exception(std::make_exception_ptr(*err));
});
m_proxy->doOperationClientSideAsyncWith500msTimeout(1000); // The operation will take 1s, but the timeout is 500ms, so we should time out
start = std::chrono::steady_clock::now();
m_proxy->doOperationClientSideAsyncWithTimeout(1us, 1000); // The operation will take 1s, but the timeout is 500ms, so we should time out
future.get();
FAIL() << "Expected sdbus::Error exception";
@@ -77,6 +80,8 @@ TEST_F(SdbusTestObject, ThrowsTimeoutErrorWhenClientSideAsyncMethodTimesOut)
{
ASSERT_THAT(e.getName(), AnyOf("org.freedesktop.DBus.Error.Timeout", "org.freedesktop.DBus.Error.NoReply"));
ASSERT_THAT(e.getMessage(), AnyOf("Connection timed out", "Method call timed out"));
auto measuredTimeout = std::chrono::steady_clock::now() - start;
ASSERT_THAT(measuredTimeout, Le(50ms));
}
catch(...)
{