#include <db_cxx.h>

int
DbEnv::set_feedback(void (*db_feedback_fcn)(DbEnv *dbenv, int opcode, int percent));

Some operations performed by the Berkeley DB library can take non-trivial amounts of time. The DbEnv::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 DbEnv::set_feedback method configures operations performed using the specified DbEnv handle

The DbEnv::set_feedback method may be called at any time during the life of the application.

The DbEnv::set_feedback method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

• 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:
  dbenv
  • The dbenv parameter is a reference to the enclosing database environment.
  opcode
  • The opcode parameter is an operation code. The opcode parameter may take on any of the following values:
    DB_RECOVER
    • The environment is being recovered.
    
    
  percent
  • The percent parameter is the percent of the operation that has been completed, specified as an integer value between 0 and 100.
  
  

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.