NAME
    SCI_Query - Queries runtime information of the SCI execution environment

C Syntax
    #include <sci.h>
    int SCI_Query(sci_query_t query, void *ret_val)

INPUT PARAMETERS
    query
        Specifies the type of query you want to request (IN).
    ret_val
        Specifies the reference parameter for SCI to store as the result of the 
        query. The value of this parameter cannot be NULL (OUT).

DESCRIPTION
    This subroutine is used to query runtime settings and statistics from SCI.
    SCI defines a set of query types as an enumeration in sci.h.

    For example, you can query the backend id using the query value of BACKEND_ID: 
    SCI_Query(BACKEND_ID, &ret_val);

    In SCI, sci_query_t defines the following valid query types:

    JOB_KEY
        Query the job key of the current job
    NUM_BACKENDS
        Query the number of back ends in the job
    BACKEND_ID
        Query the back end id of current back end in the job
    POLLING_FD
        Query the external polling file descriptor in polling mode of the current job
    NUM_FILTERS
        Query the number of loaded filters in the current job
    FILTER_IDLIST
        Query the loaded filter id list of the current job
    AGENT_ID
        Query the agent id of current agent in the job
    NUM_SUCCESSORS
        Query the number of successors of current entity in the job
    SUCCESSOR_IDLIST
        Query the successor id list of current entity in the job
    HEALTH_STATUS
        Query the running status of current entity in the job, can be 0 (normal) or
        1 (exited)

    For more information, please refer to SCI's online documents.

EXAMPLE
        {
                int my_id;
                SCI_Query(BACKEND_ID, &my_id);
                int be_num;
                SCI_Query(NUM_BACKENDS, &be_num);
        }

ERRORS
    All SCI routines return an error value.

    SCI_ERR_UNINTIALIZED
        Uninitialized SCI execution environment
    SCI_ERR_UNKNOWN_INFO
        Can't set NULL to ret_val
    SCI_ERR_INVALID_CALLER
        Invalid query type for current entity. e.g., BACKEND_NUM can only be used
        for back end
    SCI_ERR_MODE
        For POLLING_FD only, can only be used in polling mode

SEE ALSO
    SCI_Group_query(3)