task.h
void vTaskGetInfo( TaskHandle_t xTask,
TaskStatus_t *pxTaskStatus,
BaseType_t xGetFreeStackSpace,
eTaskState eState );
configUSE_TRACE_FACILITY must be defined as 1 in FreeRTOSConfig.h for
vTaskGetInfo() to be available.
Whereas uxTaskGetSystemState() populates a TaskStatus_t
structure for each task in the system, vTaskGetInfo() populates a TaskStatus_t
structures for just a single task. The TaskStatus_t structure contains, among
other things, members for the task handle, task name, task priority, task state,
and total amount of run time consumed by the task.
NOTE: This function is intended for debugging use only as its use results in
the scheduler remaining suspended for an extended period.
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Parameters:
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xTask
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The handle of the task being queried. Setting xTask to NULL
will return information on the calling task.
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pxTaskStatus
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The TaskStatus_t structure pointed to by pxTaskStatus will be
filled with information about the task referenced by the
handle passed in the xTask parameter.
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xGetFreeStackSpace
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The TaskStatus_t structure contains a member to report
the stack high water mark of the task being queried. The
stack high water mark is the minimum amount of stack space
that has ever existed, so the closer the number is to zero the
closer the task has come to overflowing its stack.Calculating the stack
high water mark takes a relatively long time, and can make the system
temporarily unresponsive - so the xGetFreeStackSpace parameter is provided to
allow the high water mark checking to be skipped. The high watermark value
will only be written to the TaskStatus_t structure if xGetFreeStackSpace is
not set to pdFALSE.
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eState
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The TaskStatus_t structure contains a member to report the
state of the task being queried. Obtaining the task state is not as fast as
a simple assignment - so the eState parameter is provided to allow the state
information to be omitted from the TaskStatus_t structure. To obtain state
information then set eState to eInvalid - otherwise the value passed in
eState will be reported as the task state in the TaskStatus_t structure.
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Example usage:
void vAFunction( void )
{
TaskHandle_t xHandle;
TaskStatus_t xTaskDetails;
/* Obtain the handle of a task from its name. */
xHandle = xTaskGetHandle( "Task_Name" );
/* Check the handle is not NULL. */
configASSERT( xHandle );
/* Use the handle to obtain further information about the task. */
vTaskGetInfo( /* The handle of the task being queried. */
xHandle,
/* The TaskStatus_t structure to complete with information
on xTask. */
&xTaskDetails,
/* Include the stack high water mark value in the
TaskStatus_t structure. */
pdTRUE,
/* Include the task state in the TaskStatus_t structure. */
eInvalid );
}
typedef struct xTASK_STATUS
{
/* The handle of the task to which the rest of the information in the
structure relates. */
TaskHandle_t xHandle;
/* A pointer to the task's name. This value will be invalid if the task was
deleted since the structure was populated! */
const signed char *pcTaskName;
/* A number unique to the task. */
UBaseType_t xTaskNumber;
/* The state in which the task existed when the structure was populated. */
eTaskState eCurrentState;
/* The priority at which the task was running (may be inherited) when the
structure was populated. */
UBaseType_t uxCurrentPriority;
/* The priority to which the task will return if the task's current priority
has been inherited to avoid unbounded priority inversion when obtaining a
mutex. Only valid if configUSE_MUTEXES is defined as 1 in
FreeRTOSConfig.h. */
UBaseType_t uxBasePriority;
/* The total run time allocated to the task so far, as defined by the run
time stats clock. Only valid when configGENERATE_RUN_TIME_STATS is
defined as 1 in FreeRTOSConfig.h. */
unsigned long ulRunTimeCounter;
/* Points to the lowest address of the task's stack area. */
StackType_t *pxStackBase;
/* The minimum amount of stack space that has remained for the task since
the task was created. The closer this value is to zero the closer the task
has come to overflowing its stack. */
configSTACK_DEPTH_TYPE usStackHighWaterMark;
} TaskStatus_t;
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