m4_comment([$Id: env_class.so,v 10.45 2005/11/30 19:09:47 bostic Exp $])

define(M4PAGELOCAL, [DbEnv, dbenv_create, DB_RPCCLIENT, DB_CXX_NO_EXCEPTIONS])
include(m4/m4.seealso)

ifelse(M4API, C_API, [dnl
m4_pf_header(m4_ref(dbenv_create), [dnl
int
db_env_create(DB_ENV **dbenvp, u_int32_t flags);
])])
ifelse(M4API, CXX_API, [dnl
m4_pf_header(m4_ref(DbEnv), [dnl
class DbEnv {
public:
	DbEnv(u_int32 flags);
	~DbEnv();
m4_blank
	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);
	...
};])])

define(m4_rpcclient, [dnl
m4_tag(m4_idef(DB_RPCCLIENT),
[Create a client environment to connect to a server.])
m4_p([dnl
The m4_ref(DB_RPCCLIENT) flag indicates to the system that this environment
is remote on a server.  The use of this flag causes the environment
methods to use functions that call a server instead of local functions.
Prior to making any environment or database method calls, the application
must call the m4_ref(dbenv_set_rpc_server) function to establish the
connection to the server.])])

m4_p([dnl
The m4_ref(DbEnv) object is the handle for a m4_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 m4_ref(DbEnv) handle are used to configure the
environment as well as to operate on subsystems and databases in the
environment.])

m4_p([dnl
m4_ref(DbEnv) handles are free-threaded if the m4_ref(DB_THREAD) flag
is specified to the m4_refT(dbenv_open) when the environment is opened.
The m4_ref(DbEnv) handle should not be closed while any other handle
remains open that is using it as a reference (for example, m4_ref(Db)
or m4_ref(DbTxn)).  Once either the m4_ref(dbenv_close) or
m4_refT(dbenv_remove)s are called, the handle may not be accessed again,
regardless of the method's return.])

ifelse(M4API, C_API, [dnl
m4_p([dnl
The m4_ref(dbenv_create) function creates a m4_ref(DbEnv) structure that
is the handle for a m4_db environment.  This function allocates memory
for the structure, returning a pointer to the structure in the memory
to which m4_arg(dbenvp) refers.  To release the allocated memory and
discard the handle, call the m4_ref(dbenv_close) or m4_refT(dbenv_remove)s.])

m4_p([dnl
The m4_ref(DbEnv) handle contains a special field, "app_private", which
is declared as type "void *".  This field is provided for the use of
the application program.  It is initialized to NULL and is not further
used by m4_db in any way.])

m4_return(dbenv_create, std)

m4_sf_zmust(0)

m4_tagbegin
m4_rpcclient
m4_tagend

m4_err(dbenv_create)],[dnl
m4_p([dnl
The constructor creates the m4_ref(DbEnv) object.  The constructor
allocates memory internally; calling the m4_ref(dbenv_close) or
m4_refT(dbenv_remove)s will free that memory.])

m4_p([dnl
The following m4_arg(flags) value may be specified:])

m4_tagbegin

ifelse(M4API, CXX_API, [dnl
m4_tag(m4_idef(DB_CXX_NO_EXCEPTIONS), [dnl
The m4_db C++ API supports two different error behaviors.  By default,
whenever an error occurs, an exception is thrown that encapsulates the
error information.  This generally allows for cleaner logic for
transaction processing because a try block can surround a single
transaction.  However, if m4_ref(DB_CXX_NO_EXCEPTIONS) is specified,
exceptions are not thrown; instead, each individual function returns an
error code.])])

m4_rpcclient

m4_tagend

ifelse(M4API, CXX_API, [dnl
m4_p([dnl
Each m4_ref(DbEnv) object has an associated m4_refc(DbEnv) structure,
which is used by the underlying implementation of m4_db and its
C-language API.  The DbEnv::get_DB_ENV method returns a pointer to this
struct.  Given a const m4_ref(DbEnv) object, DbEnv::get_const_DB_ENV
returns a const pointer to the same struct.])

m4_p([dnl
Given a m4_refc(DbEnv) struct, the DbEnv::get_DbEnv method returns the
corresponding m4_ref(DbEnv) object, if there is one.  If the
m4_refc(DbEnv) object was not associated with a m4_ref(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 m4_refc(DbEnv) struct,
DbEnv::get_const_Db_Env returns the associated const m4_ref(DbEnv)
object, if there is one.])

m4_p([dnl
These methods may be useful for m4_db applications including  both C
and C++ language software.  It should not be necessary to use these
calls in a purely C++ application.])])])

m4_seealso(DbEnv)
m4_page_footer