#include <db_cxx.h> int Db::set_feedback(void (*db_feedback_fcn)(DB *dbp, int opcode, int percent));
Some operations performed by the Berkeley DB library can take non-trivial amounts of time.
The Db::set_feedback() method can be used by applications to
monitor progress within these operations. When an operation is likely to take a long time,
Berkeley DB will call the specified callback function with progress information.
It is up to the callback function to display this information in an appropriate manner.
The Db::set_feedback() method may be called at any time during the
life of the application.
The Db::set_feedback() method returns a non-zero error value on
failure and 0 on success.
Berkeley DB is not re-entrant. Callback functions should not attempt to make library calls (for example, to release locks or close open handles). Re-entering Berkeley DB is not guaranteed to work correctly, and the results are undefined.
The db_feedback_fcn parameter is the application-specified feedback function called to report Berkeley DB operation progress. The callback function must take three parameters:
dbp
The dbp parameter is a reference to the enclosing database.
opcode
The opcode parameter is an operation code. The opcode parameter may take on any of the following values:
percent
The percent parameter is the percent of the operation that has been completed, specified as an integer value between 0 and 100.