Berkeley DB: DbEnv::log_archive
Description: Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++

# DbEnv::log_archive |

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    #include <db_cxx.h>

    int
    DbEnv::log_archive(char *(*listp)[],
        u_int32_t flags, void *(*db_malloc)(size_t));

# Description

The DbEnv::log_archive method creates a NULL-terminated array of log or database file names and copies a pointer to them into the user-specified memory location listp.

By default, DbEnv::log_archive returns the names of all of the log files that are no longer in use (e.g., no longer involved in active transactions), and that may safely be archived for catastrophic recovery and then removed from the system. If there were no file names to return, the memory location referenced by listp will be set to NULL.

Arrays of log file names are created in allocated memory. If db_malloc is non-NULL, it is called to allocate the memory, otherwise, the library function malloc(3) is used. The function db_malloc must match the calling conventions of the malloc(3) library routine. Regardless, the caller is responsible for deallocating the returned memory. To deallocate returned memory, free the returned memory reference, references inside the returned memory do not need to be individually freed.

The flags value must be set to 0 or by bitwise inclusively OR'ing together one or more of the following values.

DB_ARCH_ABS
  All pathnames are returned as absolute pathnames, instead of relative to the database home directory.

DB_ARCH_DATA
  Return the database files that need to be archived in order to recover the database from catastrophic failure. If any of the database files have not been accessed during the lifetime of the current log files, DbEnv::log_archive will not include them in this list. It is also possible that some of the files referenced in the log have since been deleted from the system.

DB_ARCH_LOG
  Return all the log file names regardless of whether or not they are in use.

The DB_ARCH_DATA and DB_ARCH_LOG flags are mutually exclusive.

See the db_archive manual page for more information on database archival procedures.

The DbEnv::log_archive 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.

# Bugs

In a threaded application (i.e., one where the environment was created with the DB_THREAD flag specified), calling DbEnv::log_archive with the DB_ARCH_DATA flag will fail, returning EINVAL. To work around this problem, re-open the log explicitly without specifying DB_THREAD. This restriction is expected to be removed in a future version of Berkeley DB.

# Errors

If a fatal error occurs in Berkeley DB, the DbEnv::log_archive method will fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, at which point all subsequent database calls will fail in the same way.

In addition, the DbEnv::log_archive method may fail and throw an exception or return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

  The log was corrupted.

In addition, the DbEnv::log_archive method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods.

### Class

DbEnv

# See Also

DbEnv::set_lg_bsize, DbEnv::set_lg_max, DbEnv::log_archive, DbEnv::log_compare, DbEnv::log_file, DbEnv::log_flush, DbEnv::log_get, DbEnv::log_put, DbEnv::log_register, DbEnv::log_stat and DbEnv::log_unregister.`

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