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vehicle_time: Deliver VehicleClock callbacks from a worker thread #215

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20 changes: 7 additions & 13 deletions docs/module/manuals/api_description/use_cases.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -313,12 +313,13 @@ diagnostics and PTP data sanity checks:

</div>

.. warning::

Both PTP data callbacks (``TimeSlaveSyncData`` and ``PDelayMeasurementData``) are
**not yet delivered**. Calling ``Subscribe<...>()`` compiles and runs without error,
but the registered callbacks will never be invoked. Delivery will be wired from a
dedicated background thread in a future change.
Delivery is performed by a dedicated worker thread owned by the ``VehicleTime`` backend.
The TimeDaemon publishes into a shared-memory segment without a notification facility, so
the worker polls that segment at a fixed interval (50 ms). The thread is started when the
first callback is registered and runs until the backend is destroyed; while no callback is
registered it sleeps until the next registration. A newly registered callback receives the first
frame polled after its registration; afterwards it is invoked only for frames whose sync or
pDelay content differs from the previously delivered one.

.. code-block:: cpp

Expand Down Expand Up @@ -376,13 +377,6 @@ excluded from the comparison.

</div>

.. warning::

The ``VehicleTimeStatus`` callback is **not yet delivered**. Calling
``Subscribe<VehicleTimeStatus>()`` compiles and runs without error, but the registered
callback will never be invoked. Delivery will be wired from a dedicated background
thread in a future change.

.. code-block:: cpp

#include "score/time/vehicle_time/src/vehicle_clock.h"
Expand Down
2 changes: 1 addition & 1 deletion docs/module/manuals/examples/vehicle_time.rst
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Expand Up @@ -114,7 +114,7 @@ Key features:
- **Dual time sources**: Both vehicle and local time in single call
- **Status monitoring**: Reliability and consistency flags
- **Rate tracking**: Clock deviation measurement
- **Callback support**: Status change notifications (future feature)
- **Callback support**: Status change notifications delivered on the backend's worker thread

Main Program
~~~~~~~~~~~~
Expand Down
6 changes: 3 additions & 3 deletions examples/time/vehicle_time/src/vehicle_time_handler.h
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Expand Up @@ -109,9 +109,9 @@ class VehicleTimeHandler

/// @brief Registers a callback that is invoked when VehicleTimeStatus flags change.
///
/// @note Delivery is not yet implemented in the backend. The callback can
/// be registered now; it will be invoked once background-thread
/// delivery is wired up in a future change.
/// The callback fires once with the current status right after registration and
/// afterwards whenever the status flags change. It is invoked on the backend's
/// worker thread, so the callback implementation must be thread-safe.
void RegisterStatusCallback(score::time::VehicleTime::StatusChangedCallback callback) noexcept
{
clock_.Subscribe<score::time::VehicleTimeStatus>(std::move(callback));
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61 changes: 58 additions & 3 deletions score/time/vehicle_time/src/details/td_impl/BUILD
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Expand Up @@ -14,29 +14,78 @@
load("@score_baselibs//:bazel/unit_tests.bzl", "cc_unit_test_suites_for_host_and_qnx")
load("@score_baselibs//score/language/safecpp:toolchain_features.bzl", "COMPILER_WARNING_FEATURES")

# Production backend: reads live PTP data from the TimeDaemon via SvtReceiver.
# Production backend: reads live PTP data from the TimeDaemon via SvtReceiver and
# delivers subscription callbacks from a dedicated worker thread.
# Link this target (or the forwarding alias //score/time/vehicle_time/src/details:td_impl)
# into the production binary to provide CreateBackend<VehicleTime>().
cc_library(
name = "td_impl",
srcs = [
"svt_callback_dispatcher.cpp",
"vehicle_clock_backend_impl.cpp",
"//score/time/vehicle_time/src/details:logging_contexts", # internal header
],
hdrs = ["vehicle_clock_backend_impl.h"],
hdrs = [
"svt_callback_dispatcher.h",
"svt_callback_wrapper.h",
"vehicle_clock_backend_impl.h",
],
features = COMPILER_WARNING_FEATURES,
visibility = ["//score/time/vehicle_time:__subpackages__"],
deps = [
"//score/time/high_res_steady_time/src:high_res_steady_clock",
"//score/time/vehicle_time/src:vehicle_clock",
"//score/time_daemon/src/ipc:svt_receiver",
"@score_baselibs//score/concurrency:condition_variable",
"@score_baselibs//score/language/futurecpp",
"@score_baselibs//score/mw/log:frontend",
],
)

cc_test(
name = "svt_callback_wrapper_test",
srcs = [
"svt_callback_wrapper.h",
"svt_callback_wrapper_test.cpp",
],
features = COMPILER_WARNING_FEATURES,
tags = ["unit"],
deps = [
"@googletest//:gtest",
"@googletest//:gtest_main",
"@score_baselibs//score/language/futurecpp",
],
)

cc_test(
name = "svt_callback_dispatcher_test",
srcs = [
"svt_callback_dispatcher.cpp",
"svt_callback_dispatcher.h",
"svt_callback_dispatcher_test.cpp",
"svt_callback_wrapper.h",
"svt_test_helpers.h",
],
features = COMPILER_WARNING_FEATURES,
tags = ["unit"],
deps = [
"//score/time/vehicle_time/src:vehicle_clock",
"//score/time_daemon/src/ipc:svt_receiver_mock",
"@googletest//:gtest",
"@googletest//:gtest_main",
"@score_baselibs//score/concurrency:condition_variable",
"@score_baselibs//score/language/futurecpp",
"@score_baselibs//score/language/safecpp/coverage_termination_handler",
],
)

cc_test(
name = "vehicle_clock_backend_impl_test",
srcs = [
"svt_callback_dispatcher.cpp",
"svt_callback_dispatcher.h",
"svt_callback_wrapper.h",
"svt_test_helpers.h",
"vehicle_clock_backend_impl.cpp",
"vehicle_clock_backend_impl.h",
"vehicle_clock_backend_impl_test.cpp",
Expand All @@ -53,6 +102,8 @@ cc_test(
"//score/time_daemon/src/ipc:svt_receiver_mock",
"@googletest//:gtest",
"@googletest//:gtest_main",
"@score_baselibs//score/concurrency:condition_variable",
"@score_baselibs//score/language/futurecpp",
"@score_baselibs//score/language/safecpp/coverage_termination_handler",
"@score_baselibs//score/mw/log:console_only_backend",
"@score_baselibs//score/mw/log:frontend",
Expand All @@ -61,6 +112,10 @@ cc_test(

cc_unit_test_suites_for_host_and_qnx(
name = "unit_test_suite",
cc_unit_tests = [":vehicle_clock_backend_impl_test"],
cc_unit_tests = [
":svt_callback_dispatcher_test",
":svt_callback_wrapper_test",
":vehicle_clock_backend_impl_test",
],
visibility = ["//score/time/vehicle_time:__subpackages__"],
)
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