QtrcWriteTextPPrintF()--Write Text Trace Data Using Pointer-based Print Formatted

 #include <qtrc.h>

 int QtrcWriteTextPPrintF
         (unsigned int    Coded_Level,
          const char     *Component,
          const char     *Subcomponent,
          const char     *Function,
          const char     *Format,
          ...);

The QtrcWriteTextPPrintF() function writes a component trace record as text string data, using a pointer-based print formatted layout, to an active trace collection if certain trace conditions are met. Note: The QtrcWriteTextPPrintF() function is intended to be used only by prototyped call languages, such as RPG. Other languages, such as C and C++, should instead use the QtrcWriteTextPrintF() function.

The QtrcWriteTextPPrintF() uses the Format parameter to process any additional parameters (Argument_List) that are specified following the Format parameter. The QtrcWriteTextPPrintF() function works just like the QtrcWriteTextPrintF() function, except that the additional parameters (Argument_List) are all expected to be pointers (references) to the entries to be formatted. Format specifications, which begin with a percent sign (%), are used to convert each corresponding argument list entry referenced by the pointer, and include the resulting text string in the trace record. If there are more argument list referenced entries than there are format specifications, the extra arguments are evaluated and ignored. The results are undefined if there are not enough argument list referenced entries for all the format specifications.

Each call to the QtrcWriteTextPPrintF() function is considered a trace point. A component trace record is written to the trace collection when all the trace conditions are met for a given trace point. The trace conditions include:

• A trace collection must be active for the current thread.
• The specified Component must be part of the trace collection.
• The active trace level that was used for the specified Component when the trace collection was started must allow the Coded_Level of the trace point.

Each trace point must indicate the desired trace level using the Coded_Level parameter. This trace level is compared against the active trace level that was used for the specified Component when the trace collection was started. Components are defined to the trace collection using the Start Trace (STRTRC) CL command. The Coded_Level must be one of the following values:

Parameters

Coded_Level

(Input)

The trace level of the trace point.

Component

(Input)

A pointer to the null-terminated component name. The component name should be 10 characters in length or less. If more than 10 characters are specified, only the first 10 characters are used.

Subcomponent

(Input)

A pointer to the null-terminated subcomponent name. The subcomponent name should be 10 characters in length or less. If more than 10 characters are specified, only the first 10 characters are used. This parameter can be set to NULL if no subcomponent is to be defined.

Function

(Input)

A pointer to the null-terminated function name. The function name should be 512 characters in length or less. If more than 512 characters are specified, only the first 512 characters are used. This parameter can be set to NULL if no function is to be defined.

Format

(Input)

A pointer to the null-terminated format string. The format string provides the format specification of the text to be written as a trace record. See the printf()--Print Formatted Characters function for a description of valid format strings and how the format specifications are used along with an argument list.

... (Argument_List)

(Input)

An optional list of arguments that contain pointers (references) to entries that are to be formatted and written as part of the text string trace record.

Authorities and Locks

None.

Return Value

0

QtrcWriteTextPPrintF() was successful. However, the component trace record will only be written if the trace conditions are met.

value

QtrcWriteTextPPrintF() was not successful. An error condition was detected which would prevent the component trace record from ever being written.

Error Conditions

If QtrcWriteTextPPrintF() was not successful, the error condition returned usually indicates one of the following errors. Under some conditions, the value returned could indicate an error other than those listed here.

Error Messages

None.

Usage Notes

1. If the QtrcWriteTextPPrintF() function is called multiple times, there may be a noticeable performance impact. The QtrcGetActiveLevel() API can be used, and the results saved into a variable for later, multiple uses. The variable can be used to quickly check if the specified Component is currently active at the appropriate trace level, prior to calling the QtrcWriteTextPPrintF() function. The variable should be periodically updated, to ensure a current view of the component's active trace level. Refer to the QTRC Trace APIs for additional information concerning the use of trace levels.
2. Refer to the QTRC Trace APIs for additional information concerning the Coded_Level, Component, Subcomponent, and Function parameters.
3. The Format parameter and the corresponding Argument_List is used to write a string of characters as trace data, in a style similar to the printf() function. This provides a simple way to write out text trace data with replacement values. For example, the Format could be something like "Function myLocator() returned %d" and the argument list would be a pointer (reference) to the return code variable myRC (namely, &myRC), if the function was called with myRC=myLocator(). The Format string is assumed to be in the CCSID of the job.
4. A single prototype of this function can be declared, such that all the parameters following the Format parameter are pointers. This Argument_List would contain pointer parameters that correspond to the Format, and any additional pointer parameters should be specified as NULL.
5. The major difference between the QtrcWriteTextPPrintF() API and the printf() function is that a pointer (reference) to the data type must be provided in the Argument_List for the various format types. The format types s, p, and S are already specified as a pointer, in the exact same manner as the printf() function.
6. The Format parameter supports most of the format specifications, as defined by the printf() function, as of the release that this QtrcWriteTextPPrintF() function was introduced. Any format specification added to the printf() function in a subsequent release is not supported, unless specifically indicated by this documentation. The following format specifications are not supported, and the results are undefined if they are used:
   • The %n$ form, where n is a positive integer constant which represents an argument number.
   • The %D(n,p) packed decimal format type.
   • The %n pointer to integer format type.
   • The %lc wide character format type. Use %C instead.
   • The %ls wide character format type. Use %S instead.
   • The asterisk (*), used as a width specification.
   • The asterisk (*), used as a precision specification.
7. The Format parameter should only contain characters in the invariant character set. This is also true for any strings that may be used in the Argument_List.
8. The total amount of text data that can be written as trace data is limited to 2048 characters. In order to trace more than 2048 characters of text data, the QtrcWriteHexDumpF function could be used to write the text data as hexadecimal trace data with a formatting option that includes the appropriate text representation. An alternative would be to split up the text data into multiple sections and call the QtrcWriteTextPPrintF() function for each section.

Related Information

• QtrcGetActiveLevel()--Get Active Trace Level
• QtrcWriteHexDump()--Write Hexadecimal Dump Trace Data
• QtrcWriteHexDumpF()--Write Hexadecimal Dump Formatted Trace Data
• QtrcWriteStack()--Write Call Stack Trace Data
• QtrcWriteText()--Write Text Trace Data
• QtrcWriteTextPrintF()--Write Text Trace Data Using Print Formatted
• QtrcWriteTextVPrintF()--Write Text Trace Data Using Variable Argument List Print Formatted
• printf()--Print Formatted Characters
• Start Trace (STRTRC) CL command
• For additional information about the QTRC Trace environment, see QTRC Trace APIs.

Example

The following example uses an INFO-level trace point to write formatted text trace data for a component named MYCOMP. The component trace record will be written to the active trace collection if the program is called with at least one parameter and the STRTRC CL command was used before calling the example, specifying either TRCTYPE((MYCOMP *INFO)) or TRCTYPE((MYCOMP *VERBOSE)).

Note: By using the code examples, you agree to the terms of the Code license and disclaimer information.

#include <qtrc.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
  const char *myComp = "MYCOMP";
  const int ParmNum = 1;
  int rc;

  if (argc > 1) {
    rc = QtrcWriteTextPPrintF(QTRC_LEVEL_INFO,
             myComp,
             "SUBCOMP",
             argv[0],
             "Parameter %d is %s", &ParmNum, argv[ParmNum] );
    if (rc != 0) {
      printf("QtrcWriteTextPPrintF() failed with error %d\n", rc);
      return -1;
    }
  }

  printf("Use the ENDTRC CL command with PRTTRC(*YES) in order to\n");
  printf("see the component trace records that were written to the\n");
  printf("trace collection.\n");

  return 0;
}

Use the ENDTRC CL command with PRTTRC(*YES) in order to
see the component trace records that were written to the
trace collection.

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