c-treeDB API API for C

User-managed record buffers

While c-treeDB 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 c-treeDB 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 c-treeDB 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");