# Berkeley DB: DB->set_feedback
Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++

DB->set_feedback |

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    #include <db.h>

    int
    DB->set_feedback(DB *,
        void (*db_feedback_fcn)(DB *dbp, int opcode, int percent));

Description: DB->set_feedback

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.

Parameters
db_feedback_fcn

- 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:
  db
  - The db 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:
    DB_UPGRADE
    - The underlying database is being upgraded.
    DB_VERIFY
    - The underlying database is being verified.
  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.

Class DB
See Also Databases and Related Methods`

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