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c-treeDB API for C++ - Developers Guide

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CTDB_ON_RECORD_AFTER_READ

A CTDB_ON_RECORD_AFTER_READ callback is invoked just after a record is read by one of the FairCom DB record reading functions. This callback is useful to adjust a record buffer just after data is read.

The handle passed as parameter for this callback is a record handle and you can safely typecast the handle parameter to a pCTDBRECORD structure pointer.

The following CTDBRECORD structure members keep information regarding the record buffer kept by the record handle:

CTDBRECORD Structure Member

Explanation

pUTEXT recbuf

record buffer

VRLEN recbuf_size

size in bytes of memory allocated for record buffer

VRLEN recbuf_len

actual length of data in record buffer

c-treeDB C API Example


CTDBRET ctdbDECL OnRecordAfterRead(CTHANDLE Handle)

{

CTDBRET Retval = CTDBRET_OK;

pCTDBRECORD pRecord = (pCTDBRECORD)Handle;

if (!pRecord)

Retval = CTDBRET_NOTRECORD;

else

{

/* swap the record buffer with the localTag */

pUTEXT recptr = pRecord->recbuf;

int i;

pRecord->recbuf = pRecord->localTag;

pRecord->localTag = (pVOID)recptr;


/* make any CT_DATE field compatible with c-treeDB */

for (i = 0; (i < pRecord->fields_count && Retval == CTDBRET_OK); i++)

{

if (pRecord->fields[i].ftype == CT_DATE)

{

time_t* t;

struct tm* ptr;

CTDATE date;

/* get the non standard date into t */

t = (time_t*)&recptr[pRecord->fields[i].offset];


/* convert a C time_t date into CT_DATE */

if ((ptr = gmtime(t)) != NULL)

{

if ((Retval = ctdbDatePack(&date, (ptr->tm_year + 1900), (ptr->tm_mon + 1), ptr->tm_mday)) == CTDBRET_OK

{

/* put converted CTDB date back into record buffer */

memcpy(&pRecord->recptr[pRecord->fields[i].offset], &date, sizeof(CTDATE));

}

}

else

Retval = CTDBRET_INVDATE;

}

}

}

return Retval;

}

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