#include <db_cxx.h>
class DbMultipleKeyDataBuilder
{
public:
DbMultipleKeyDataBuilder(Dbt &dbt);
bool append(void *kbuf, size_t klen, void *dbuf, size_t dlen);
bool reserve(void *&kdest, size_t klen, void *&ddest, size_t dlen);
};
This class builds a bulk buffer for use when the DB_MULTIPLE_KEY flag is specified to either the Db::put() or Db::del() methods with the btree or hash access methods. The buffer in the Dbt passed to the constructor is filled by calls to DbMultipleKeyDataBuilder.append() or DbMultipleKeyDataBuilder.reserve().
The constructor takes a
The Dbt Handle
that must be configured to contain a buffer managed by the application,
with the ulen field set to the size of the buffer.
All instances of the bulk retrieval classes may be used only once, and to build the bulk buffer in the forward direction only.
Parameters are:
dbt
The dbt parameter is a
The Dbt Handle
that must already be configured to contain a buffer managed by the application, with the ulen field set to the size of the buffer, which must be a multiple of 4.
The DbMultipleKeyDataBuilder.append()
method copies a key/data pair to the end of the buffer.
The DbMultipleKeyDataBuilder.append()
method returns false if the key/data
pair does not fit in the buffer and true
otherwise.
Parameters are:
kbuf
A pointer to the key to be copied into the bulk buffer.
klen
The number of bytes of the key to be copied.
dbuf
A pointer to the data item to be copied into the bulk buffer.
dlen
The number of bytes of the data item to be copied.
The DbMultipleKeyDataBuilder.reserve()
method reserves space for the next key/data pair in the bulk
buffer. Unlike the append(), no data is
actually copied into the bulk buffer by
reserve(): copying the data is the
responsibility of the application.
The DbMultipleKeyDataBuilder.reserve()
method returns false if the data does
not fit in the buffer and true otherwise.
Parameters are:
kdest
Set to a pointer to the position in the bulk buffer reserved for the key, if enough space is available.
klen
The number of bytes to reserve for the key.
ddest
Set to a pointer to the position in the bulk buffer reserved for the data item, if enough space is available.
dlen
The number of bytes to reserve for the data item.