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Extending HCL OneDB™Beyond standard relational database objects, HCL OneDB™ can be extended to handle specialized data types, access methods, routines, and other objects. HCL OneDB™ includes many built-in extensions that are fully integrated in the database server. HCL OneDB™ also provides DataBlade® modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for HCL OneDB™.
Creating extensionsYou can create user-defined data types, routines, access methods, and other database objects to suit your needs. You can use application programming interfaces to write user-defined routines and applications that access data in HCL OneDB™ databases.
DataBlade® API Function ReferenceThe HCL OneDB™ DataBlade® API Function Reference describes the DataBlade® API functions and the subset of functions that the DataBlade® API supports.
Function descriptionsThis section gives comprehensive reference information about the functions that are valid within DataBlade® API modules. It lists the function descriptions in alphabetical order, with syntax, usage information, and return values for the functions.
The mi_call_on_vp() functionThe mi_call_on_vp() function enables you to switch execution to a specified virtual processor (VP) to execute a specified C function.

The mi_call_on_vp() function

The mi_call_on_vp() function enables you to switch execution to a specified virtual processor (VP) to execute a specified C function.

Syntax

mi_integer mi_call_on_vp(VP_id, retval, C_func, nargs, argument_list)
   mi_integer VP_id;
   mi_integer *retval;
   mi_integer (*C_func)();
   mi_integer nargs;
   argument_list;

VP_id: The integer VP-class identifier of the VP on which to execute the specified C function. The VP that executes this C function must be a CPU VP or in a user-defined VP class. You cannot execute the C function in some other system VP class.
retval: A pointer to the integer return value of the specified C function.
C_func: A pointer to the executable C function to execute on the specified VP.
nargs: The number of arguments (up to a maximum of 10) to pass to the specified C function.
argument_list: A comma-separated list of value from 0 - 10 arguments to pass to the specified C function.


Valid in client LIBMI application?	Valid in user-defined routine?
No	Yes

Important: This advanced function can adversely affect your UDR if you use the function incorrectly. Use it only when no regular DataBlade® API function can perform the task you need done.

Usage

The mi_call_on_vp() function calls the C function that C_func references on the VP that VP_id identifies. To the specified C function, mi_call_on_vp() passes the number of arguments that nargs specifies. In the mi_call_on_vp() function call, pass the actual argument values as a comma-separated list following the nargs value. When the C function completes execution, mi_call_on_vp() puts its return value in the address that retval references.

The mi_call_on_vp() function takes the following steps:

Switches the current thread to the VP of the specified VP identifier
Executes the C function that the C_func pointer indicates
Returns control to the originating VP

After a successful return, the C_func function has been executed on the specified VP.

The mi_call_on_vp() function does not switch VPs in the following cases:

If the originating VP and specified VP (VP_id) are identical
The mi_call_on_vp() function performs no switching but does not return an error.
If the specified VP (VP_id) is not a CPU VP or user-defined VP
The mi_call_on_vp() function performs no switching and returns an error (MI_ERROR). The message log provides more information about why the switch failed.

For more information about how to switch VPs, see the HCL OneDB™ DataBlade API Programmer's Guide.

Return values

MI_DONE: The C_func function was successfully called and its return value is referenced by retval.
MI_TOOMANY: The nargs argument is greater than 10.
MI_ERROR: The function was unable to switch VPs. The online log provides more information about why the switch failed.