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Clock API improvements (#580)
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* Improve rcl clock API documentation.

Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>

* Improve rcl clock API error checking.

Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>

* Address peer review comments.

Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>

* Refine rcl_clock_t API thread-safety documentation.

Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>
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hidmic authored Mar 13, 2020
1 parent 85948c7 commit b463168
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224 changes: 224 additions & 0 deletions rcl/include/rcl/time.h
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Original file line number Diff line number Diff line change
Expand Up @@ -159,6 +159,14 @@ typedef struct rcl_time_point_t
* are not invalid.
* Note that if data is uninitialized it may give a false positive.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | Yes
* Uses Atomics | No
* Lock-Free | Yes
*
* \param[in] clock the handle to the clock which is being queried
* \return true if the source is believed to be valid, otherwise return false.
*/
Expand All @@ -171,6 +179,18 @@ rcl_clock_valid(rcl_clock_t * clock);
/**
* This will allocate all necessary internal structures, and initialize variables.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | Yes [1]
* Thread-Safe | No [2]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] If `clock_type` is `RCL_ROS_TIME`</i>
* <i>[2] Function is reentrant, but concurrent calls on the same `clock` object are not safe.
* Thread-safety is also affected by that of the `allocator` object.</i>
*
* \param[in] clock_type the type identifying the time source to provide
* \param[in] clock the handle to the clock which is being initialized
* \param[in] allocator The allocator to use for allocations
Expand All @@ -193,6 +213,21 @@ rcl_clock_init(
* Passing a clock with type RCL_CLOCK_UNINITIALIZED will result in
* RCL_RET_INVALID_ARGUMENT being returned.
*
* This function is not thread-safe with any other function operating on the same
* clock object.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | No [1]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Function is reentrant, but concurrent calls on the same `clock` object are not safe.
* Thread-safety is also affected by that of the `allocator` object associated with the
* `clock` object.</i>
*
* \param[in] clock the handle to the clock which is being finalized
* \return `RCL_RET_OK` if the time source was successfully finalized, or
* \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
Expand All @@ -209,6 +244,17 @@ rcl_clock_fini(
* This will allocate all necessary internal structures, and initialize variables.
* It is specifically setting up a RCL_ROS_TIME time source.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | Yes
* Thread-Safe | No [1]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[2] Function is reentrant, but concurrent calls on the same `clock` object are not safe.
* Thread-safety is also affected by that of the `allocator` object.</i>
*
* \param[in] clock the handle to the clock which is being initialized
* \param[in] allocator The allocator to use for allocations
* \return `RCL_RET_OK` if the time source was successfully initialized, or
Expand All @@ -228,6 +274,21 @@ rcl_ros_clock_init(
* It is specifically setting up a `RCL_ROS_TIME` time source. It is expected
* to be paired with the init fuction.
*
* This function is not thread-safe with any other function operating on the same
* clock object.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | No [1]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Function is reentrant, but concurrent calls on the same `clock` object are not safe.
* Thread-safety is also affected by that of the `allocator` object associated with the
* `clock` object.</i>
*
* \param[in] clock the handle to the clock which is being initialized
* \return `RCL_RET_OK` if the time source was successfully finalized, or
* \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
Expand All @@ -244,6 +305,17 @@ rcl_ros_clock_fini(
* This will allocate all necessary internal structures, and initialize variables.
* It is specifically setting up a `RCL_STEADY_TIME` time source.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | No [1]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Function is reentrant, but concurrent calls on the same `clock` object are not safe.
* Thread-safety is also affected by that of the `allocator` object.</i>
*
* \param[in] clock the handle to the clock which is being initialized
* \param[in] allocator The allocator to use for allocations
* \return `RCL_RET_OK` if the time source was successfully initialized, or
Expand All @@ -265,6 +337,21 @@ rcl_steady_clock_init(
* It is specifically setting up a steady time source. It is expected to be
* paired with the init fuction.
*
* This function is not thread-safe with any other function operating on the same
* clock object.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | No [1]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Function is reentrant, but concurrent calls on the same `clock` object are not safe.
* Thread-safety is also affected by that of the `allocator` object associated with the
* `clock` object.</i>
*
* \param[in] clock the handle to the clock which is being initialized
* \return `RCL_RET_OK` if the time source was successfully finalized, or
* \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
Expand All @@ -283,6 +370,18 @@ rcl_steady_clock_fini(
* This will allocate all necessary internal structures, and initialize variables.
* It is specifically setting up a system time source.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | No [1]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Function is reentrant, but concurrent calls on the same `clock` object are not safe.
* Thread-safety is also affected by that of the `allocator` object associated with the
* `clock` object.</i>
*
* \param[in] clock the handle to the clock which is being initialized
* \param[in] allocator The allocator to use for allocations
* \return `RCL_RET_OK` if the time source was successfully initialized, or
Expand All @@ -304,6 +403,20 @@ rcl_system_clock_init(
* It is specifically setting up a system time source. It is expected to be paired with
* the init fuction.
*
* This function is not thread-safe with any function operating on the same clock object.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | No [1]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Function is reentrant, but concurrent calls on the same `clock` object are not safe.
* Thread-safety is also affected by that of the `allocator` object associated with the
* `clock` object.</i>
*
* \param[in] clock the handle to the clock which is being initialized.
* \return `RCL_RET_OK` if the time source was successfully finalized, or
* \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
Expand All @@ -324,6 +437,14 @@ rcl_system_clock_fini(
* The value will be computed as duration = finish - start. If start is after
* finish the duration will be negative.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | Yes
* Uses Atomics | No
* Lock-Free | Yes
*
* \param[in] start The time point for the start of the duration.
* \param[in] finish The time point for the end of the duration.
* \param[out] delta The duration between the start and finish.
Expand All @@ -341,6 +462,17 @@ rcl_difference_times(
/**
* This function will populate the data of the time_point_value object with the
* current value from it's associated time abstraction.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | Yes
* Uses Atomics | Yes [1]
* Lock-Free | Yes
*
* <i>[1] If `clock` is of `RCL_ROS_TIME` type.</i>
*
* \param[in] clock The time source from which to set the value.
* \param[out] time_point_value The time_point value to populate.
* \return `RCL_RET_OK` if the last call time was retrieved successfully, or
Expand All @@ -359,6 +491,21 @@ rcl_clock_get_now(rcl_clock_t * clock, rcl_time_point_value_t * time_point_value
* such that the time source will report the set value instead of falling
* back to system time.
*
* This function is not thread-safe with `rcl_clock_add_jump_callback`,
* nor `rcl_clock_remove_jump_callback` functions when used on the same
* clock object.
*
* <hr>
* Attribute | Adherence [1]
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | No [2]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Only applies to the function itself, as jump callbacks may not abide to it.</i>
* <i>[2] Function is reentrant, but concurrent calls on the same `clock` object are not safe.</i>
*
* \param[in] clock The clock to enable.
* \return `RCL_RET_OK` if the time source was enabled successfully, or
* \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
Expand All @@ -375,6 +522,21 @@ rcl_enable_ros_time_override(rcl_clock_t * clock);
* such that the time source will report the system time even if a custom
* value has been set.
*
* This function is not thread-safe with `rcl_clock_add_jump_callback`,
* nor `rcl_clock_remove_jump_callback` functions when used on the same
* clock object.
*
* <hr>
* Attribute | Adherence [1]
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | No [2]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Only applies to the function itself, as jump callbacks may not abide to it.</i>
* <i>[2] Function is reentrant, but concurrent calls on the same `clock` object are not safe.</i>
*
* \param[in] clock The clock to disable.
* \return `RCL_RET_OK` if the time source was disabled successfully, or
* \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
Expand All @@ -392,6 +554,19 @@ rcl_disable_ros_time_override(rcl_clock_t * clock);
* time overide is enabled. If it is enabled, the set value will be returned.
* Otherwise this time source will return the equivalent to system time abstraction.
*
* This function is not thread-safe with `rcl_enable_ros_time_override` nor
* `rcl_disable_ros_time_override` functions when used on the same clock object.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | No [1]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Function is reentrant, but concurrent calls on the same `clock` object are not safe.</i>
*
* \param[in] clock The clock to query.
* \param[out] is_enabled Whether the override is enabled..
* \return `RCL_RET_OK` if the time source was queried successfully, or
Expand All @@ -411,6 +586,21 @@ rcl_is_enabled_ros_time_override(
* If queried and override enabled the time source will return this value,
* otherwise it will return the system time.
*
* This function is not thread-safe with `rcl_clock_add_jump_callback`,
* nor `rcl_clock_remove_jump_callback` functions when used on the same
* clock object.
*
* <hr>
* Attribute | Adherence [1]
* ------------------ | -------------
* Allocates Memory | No
* Thread-Safe | No [2]
* Uses Atomics | Yes
* Lock-Free | Yes
*
* <i>[1] Only applies to the function itself, as jump callbacks may not abide to it.</i>
* <i>[2] Function is reentrant, but concurrent calls on the same `clock` object are not safe.</i>
*
* \param[in] clock The clock to update.
* \param[in] time_value The new current time.
* \return `RCL_RET_OK` if the time source was set successfully, or
Expand All @@ -430,11 +620,28 @@ rcl_set_ros_time_override(
* The user_data pointer is passed to the callback as the last argument.
* A callback and user_data pair must be unique among the callbacks added to a clock.
*
* This function is not thread-safe with `rcl_clock_remove_jump_callback`,
* `rcl_enable_ros_time_override`, `rcl_disable_ros_time_override` nor
* `rcl_set_ros_time_override` functions when used on the same clock object.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | Yes
* Thread-Safe | No [1]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Function is reentrant, but concurrent calls on the same `clock` object are not safe.
* Thread-safety is also affected by that of the `allocator` object associated with the
* `clock` object.</i>
*
* \param[in] clock A clock to add a jump callback to.
* \param[in] threshold Criteria indicating when to call the callback.
* \param[in] callback A callback to call.
* \param[in] user_data A pointer to be passed to the callback.
* \return `RCL_RET_OK` if the callback was added successfully, or
* \return `RCL_RET_BAD_ALLOC` if a memory allocation failed, or
* \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
* \return `RCL_RET_ERROR` an unspecified error occurs.
*/
Expand All @@ -447,11 +654,28 @@ rcl_clock_add_jump_callback(

/// Remove a previously added time jump callback.
/**
* This function is not thread-safe with `rcl_clock_add_jump_callback`
* `rcl_enable_ros_time_override`, `rcl_disable_ros_time_override` nor
* `rcl_set_ros_time_override` functions when used on the same clock object.
*
* <hr>
* Attribute | Adherence
* ------------------ | -------------
* Allocates Memory | Yes
* Thread-Safe | No [1]
* Uses Atomics | No
* Lock-Free | Yes
*
* <i>[1] Function is reentrant, but concurrent calls on the same `clock` object are not safe.
* Thread-safety is also affected by that of the `allocator` object associated with the
* `clock` object.</i>
*
* \param[in] clock The clock to remove a jump callback from.
* \param[in] threshold Criteria indicating when to call callback.
* \param[in] callback The callback to call.
* \param[in] user_data A pointer to be passed to the callback.
* \return `RCL_RET_OK` if the callback was added successfully, or
* \return `RCL_RET_BAD_ALLOC` if a memory allocation failed, or
* \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
* \return `RCL_RET_ERROR` the callback was not found or an unspecified error occurs.
*/
Expand Down
3 changes: 3 additions & 0 deletions rcl/src/rcl/time.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -232,6 +232,9 @@ rcl_ret_t
rcl_difference_times(
rcl_time_point_t * start, rcl_time_point_t * finish, rcl_duration_t * delta)
{
RCL_CHECK_ARGUMENT_FOR_NULL(start, RCL_RET_INVALID_ARGUMENT);
RCL_CHECK_ARGUMENT_FOR_NULL(finish, RCL_RET_INVALID_ARGUMENT);
RCL_CHECK_ARGUMENT_FOR_NULL(delta, RCL_RET_INVALID_ARGUMENT);
if (start->clock_type != finish->clock_type) {
RCL_SET_ERROR_MSG("Cannot difference between time points with clocks types.");
return RCL_RET_ERROR;
Expand Down

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