Berkeley DB: DbLog::archive
Полезная информация

DbLog::archive


#include <db_cxx.h>

int DbLog::archive(char **list[], u_int32_t flags, void *(*db_malloc)(size_t));

Description

The DbLog::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 list.

By default, DbLog::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, list 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 the returned memory, free each returned memory pointer; pointers inside the memory do not need to be individually freed.

The flags argument is specified by logically 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, DbLog::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 DbLog::archive method is the underlying method used by the db_archive utility. See the db_archive utility source code for an example of using DbLog::archive in a POSIX 1003.1 environment.

The DbLog::archive method either returns errno or throws an exception that encapsulates an errno on failure, and 0 on success.

Bugs

In a threaded application (i.e., one where the environment was created with the DB_THREAD flag specified), calling DbLog::archive 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 DbLog::archive method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, at which point all subsequent database calls will also fail in the same way. Methods marked as returning errno will, by default, throw an exception that encapsulates the error information. The default error behavior can be changed, see DbException.

The DbLog::archive method may fail and throw an exception for any of the errors specified for the following Berkeley DB and C library functions: close(3), fcntl(3), fflush(3), fprintf(3), free(3), getcwd(3), getenv(3), getpid(3), getuid(3), isdigit(3), DbLog::compare, DbLog::get, malloc(3), memcpy(3), memset(3), open(3), qsort(3), realloc(3), sigfillset(3), sigprocmask(3), snprintf(3), stat(3), strchr(3), strcmp(3), strerror(3), strlen(3), unlink(3), vfprintf(3), and vsnprintf(3).

In addition, the DbLog::archive method may fail and throw an exception or return errno for the following conditions:

EINVAL
An invalid flag value or parameter was specified.

The log was corrupted.

Class

DbLog

See Also

DbLog::archive, DbLog::close, DbLog::compare, DbLog::file, DbLog::flush, DbLog::get, DbLog::open, DbLog::put, DbLog::db_register, DbLog::stat, DbLog::unlink and DbLog::db_unregister.