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A CTDB_ON_RECORD_BEFORE_WRITE callback is invoked just before a record is written with one of the FairCom DB record writing or updating functions. This callback is useful to prepare a record buffer just before data is written to disk.
The handle passed as a parameter with 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 OnRecordBeforeWrite(CTHANDLE Handle)
{
CTDBRET Retval = CTDBRET_OK;
pCTDBRECORD pRecord = (pCTDBRECORD)Handle;
if (!pRecord)
Retval = CTDBRET_NOTRECORD;
else
{
/* change any CT_DATE dates to C time_t dates */
pUTEXT recptr = pRecord->recbuf;
int i;
for (i = 0; (i < pRecord->fields_count && Retval == CTDBRET_OK); i++)
{
if (pRecord->fields[i].ftype == CT_DATE)
{
struct tm m;
CTDATE* dateptr;
/* get the CTDB date */
dateptr = (CTDATE*)&recptr[pRecord->fields[i].offset];
/* convert a CT_DATE date to a C time_t date */
if ((Retval = ctdbDateUnpack(*dateptr, &m.tm_year, &m.tm_mon, &m.tm_mday)) == CTDBRET_OK)
{
time_t* tptr = (time_t*)&recptr[pRecord->fields[i].offset];
m.tm_year -= 1900;
m.tm_mon--;
m.tm_sec = 0;
m.tm_min = 0;
m.tm_hour = 0;
m.tm_isdst = 0;
*t = mktime(&m);
}
}
}
}
return Retval;
}
