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Fix #88: Timeout handling. (#91)

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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
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tests/integrationtests/DBusConnectionTests.cpp
+43
View File
@@ -37,9 +37,11 @@
// STL
#include <thread>
#include <chrono>
using ::testing::Eq;
using namespace sdbus::test;
using namespace std::chrono_literals;
/*-------------------------------------*/
/* -- TEST CASES -- */
@@ -88,3 +90,44 @@ TEST(Connection, CanEnterAndLeaveEventLoop)
t.join();
}
TEST(Connection, PollDataGetZeroTimeout)
{
sdbus::IConnection::PollData pd{};
pd.timeout_usec = 0;
ASSERT_TRUE(pd.getRelativeTimeout().has_value());
EXPECT_THAT(pd.getRelativeTimeout().value(), Eq(std::chrono::microseconds::zero()));
EXPECT_THAT(pd.getPollTimeout(), Eq(0));
}
TEST(Connection, PollDataGetInfiniteTimeout)
{
sdbus::IConnection::PollData pd{};
pd.timeout_usec = UINT64_MAX;
ASSERT_FALSE(pd.getRelativeTimeout().has_value());
EXPECT_THAT(pd.getPollTimeout(), Eq(-1));
}
TEST(Connection, PollDataGetZeroRelativeTimeoutForPast)
{
sdbus::IConnection::PollData pd{};
auto past = std::chrono::steady_clock::now() - 10s;
pd.timeout_usec = std::chrono::duration_cast<std::chrono::microseconds>(past.time_since_epoch()).count();
ASSERT_TRUE(pd.getRelativeTimeout().has_value());
EXPECT_THAT(pd.getRelativeTimeout().value(), Eq(0us));
EXPECT_THAT(pd.getPollTimeout(), Eq(0));
}
TEST(Connection, PollDataGetRelativeTimeoutInTolerance)
{
sdbus::IConnection::PollData pd{};
constexpr auto TIMEOUT = 1s;
constexpr auto TOLERANCE = 100ms;
auto future = std::chrono::steady_clock::now() + TIMEOUT;
pd.timeout_usec = std::chrono::duration_cast<std::chrono::microseconds>(future.time_since_epoch()).count();
ASSERT_TRUE(pd.getRelativeTimeout().has_value());
EXPECT_GE(pd.getRelativeTimeout().value(), TIMEOUT - TOLERANCE);
EXPECT_LE(pd.getRelativeTimeout().value(), TIMEOUT + TOLERANCE);
EXPECT_GE(pd.getPollTimeout(), 900);
EXPECT_LE(pd.getPollTimeout(), 1100);
}