FairCom DB API for C

User-managed record buffers

While FairCom DB API performs all record buffer memory management dynamically, the API is flexible enough to permit the user to perform record buffer memory management. ctdbSetRecordBuffer() allows developers to control how FairCom DB API performs data record memory management.

/* define my own static record structure */

typedef struct

{

NINT id;

TEXT name[32];

CTDATE birthday;

} MyRecordDef;

/* declare my own record buffer variable */

MyRecordDef MyRecord;

/* declare and allocate a record handle */

CTHANDLE hRecord = ctdbAllocRecord(hTable);

/* tell record handle to use my own record variable */

if (ctdbSetRecordBuffer(hRecord, &MyRecord, sizeof(MyRecord), CTRECBUF_STATIC) != CTDBRET_OK)

printf("Set record buffer failed\n");

ctdbSetRecordBuffer() takes as parameters the record handle, a user-supplied record buffer address, the size of the buffer, and the record buffer mode.

The valid record buffer modes are:

Mode	Explanation
CTRECBUF_AUTO	This is the default record buffer management mode. When a record handle is allocated by calling ctdbAllocRecord(), the record buffer management mode is set to CTRECBUF_AUTO. This mode implies that the FairCom DB API will perform the data record buffer management dynamically.
CTRECBUF_STATIC	When this mode is set, the data record buffer is set to pBuffer and the user is responsible to supply a buffer that is large enough to perform all record operations for the table.
CTRECBUF_RAW	OR with CTRECBUF_STATIC to indicate the record manager is not allowed to update the internal control structures of the record buffer for variable-length records.

To reset the record buffer management back to CTRECBUF_AUTO, after it has been changed to CTRECBUF_STATIC, call ctdbSetRecordBuffer() passing the record handle, NULL buffer, with length of zero and CTRECBUF_AUTO mode.

/* reset the record buffer to automatic */

if (ctdbSetRecordBuffer(hRecord, NULL, 0, CTRECBUF_AUTO) != CTDBRET_OK)

printf("Reset record buffer failed\n");