#include <db_cxx.h>

class DbEnv { 
        DbEnv(u_int32 flags); 

        DB_ENV *DbEnv::get_DB_ENV(); 
        const DB_ENV *DbEnv::get_const_DB_ENV() const; 
        static DbEnv *DbEnv::get_DbEnv(DB_ENV *dbenv); 
        static const DbEnv *DbEnv::get_const_DbEnv(const DB_ENV *dbenv); 

The DbEnv object is the handle for a Berkeley DB environment — a collection including support for some or all of caching, locking, logging and transaction subsystems, as well as databases and log files. Methods of the DbEnv handle are used to configure the environment as well as to operate on subsystems and databases in the environment.

DbEnv handles are free-threaded if the DB_THREAD flag is specified to the DbEnv::open() method when the environment is opened. The DbEnv handle should not be closed while any other handle remains open that is using it as a reference (for example, Db or DbTxn). Once either the DbEnv::close() or DbEnv::remove() methods are called, the handle may not be accessed again, regardless of the method's return.

The constructor creates the DbEnv object. The constructor allocates memory internally; calling the DbEnv::close() or DbEnv::remove() methods will free that memory.

Before the handle may be used, you must open it using the DbEnv::open() method.

The flags parameter must be set to 0.

Each DbEnv object has an associated DB_ENV structure, which is used by the underlying implementation of Berkeley DB and its C-language API. The DbEnv::get_DB_ENV() method returns a pointer to this struct. Given a const DbEnv object, DbEnv::get_const_DB_ENV() returns a const pointer to the same struct.

Given a DB_ENV struct, the DbEnv::get_DbEnv() method returns the corresponding DbEnv object, if there is one. If the DB_ENV struct was not associated with a DbEnv (that is, it was not returned from a call to DbEnv::get_DB_ENV()), then the result of DbEnv::get_DbEnv() is undefined. Given a const DB_ENV struct, DbEnv::get_const_Db_Env() returns the associated const DbEnv object, if there is one.

These methods may be useful for Berkeley DB applications including both C and C++ language software. It should not be necessary to use these calls in a purely C++ application.



See Also

Database Environments and Related Methods