RPC_CONTROL(3NSL) Networking Services Library Functions RPC_CONTROL(3NSL)


NAME


rpc_control - library routine for manipulating global RPC attributes for
client and server applications

SYNOPSIS


bool_t rpc_control(int op, void *info);


DESCRIPTION


This RPC library routine allows applications to set and modify global RPC
attributes that apply to clients as well as servers. At present, it
supports only server side operations. This function allows applications
to set and modify global attributes that apply to client as well as
server functions. op indicates the type of operation, and info is a
pointer to the operation specific information. The supported values of op
and their argument types, and what they do are:

RPC_SVC_MTMODE_SET int * set multithread mode
RPC_SVC_MTMODE_GET int * get multithread mode
RPC_SVC_THRMAX_SET int * set maximum number of threads
RPC_SVC_THRMAX_GET int * get maximum number of threads
RPC_SVC_THRTOTAL_GET int * get number of active threads
RPC_SVC_THRCREATES_GET int * get number of threads created
RPC_SVC_THRERRORS_GET int * get number of thread create errors
RPC_SVC_USE_POLLFD int * set number of file descriptors to unlimited
RPC_SVC_CONNMAXREC_SET int * set non-blocking max rec size
RPC_SVC_CONNMAXREC_GET int * get non-blocking max rec size


There are three multithread (MT) modes. These are:

RPC_SVC_MT_NONE Single threaded mode (default)
RPC_SVC_MT_AUTO Automatic MT mode
RPC_SVC_MT_USER User MT mode


Unless the application sets the Automatic or User MT modes, it will stay
in the default (single threaded) mode. See the Network Interfaces
Programmer's Guide for the meanings of these modes and programming
examples. Once a mode is set, it cannot be changed.


By default, the maximum number of threads that the server will create at
any time is 16. This allows the service developer to put a bound on
thread resources consumed by a server. If a server needs to process more
than 16 client requests concurrently, the maximum number of threads must
be set to the desired number. This parameter may be set at any time by
the server.


Set and get operations will succeed even in modes where the operations
don't apply. For example, you can set the maximum number of threads in
any mode, even though it makes sense only for the Automatic MT mode. All
of the get operations except RPC_SVC_MTMODE_GET apply only to the
Automatic MT mode, so values returned in other modes may be undefined.


By default, RPC servers are limited to a maximum of 1024 file descriptors
or connections due to limitations in the historical interfaces
svc_fdset(3NSL) and svc_getreqset(3NSL). Applications written to use the
preferred interfaces of svc_pollfd(3NSL) and svc_getreq_poll(3NSL) can
use an unlimited number of file descriptors. Setting info to point to a
non-zero integer and op to RPC_SVC_USE_POLLFD removes the limitation.


Connection oriented RPC transports read RPC requests in blocking mode by
default. Thus, they may be adversely affected by network delays and
broken clients. RPC_SVC_CONNMAXREC_SET enables non-blocking mode and
establishes the maximum record size (in bytes) for RPC requests; RPC
responses are not affected. Buffer space is allocated as needed up to the
specified maximum, starting at the maximum or RPC_MAXDATASIZE, whichever
is smaller.


The value established by RPC_SVC_CONNMAXREC_SET is used when a connection
is created, and it remains in effect for that connection until it is
closed. To change the value for existing connections on a per-connection
basis, see svc_control(3NSL).


RPC_SVC_CONNMAXREC_GET retrieves the current maximum record size. A zero
value means that no maximum is in effect, and that the connections are in
blocking mode.


info is a pointer to an argument of type int. Non-connection RPC
transports ignore RPC_SVC_CONNMAXREC_SET and RPC_SVC_CONNMAXREC_GET.

RETURN VALUES


This routine returns TRUE if the operation was successful and returns
FALSE otherwise.

ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|MT-Level | MT-Safe |
+---------------+-----------------+

SEE ALSO


rpcbind(1M), rpc(3NSL), rpc_svc_calls(3NSL), attributes(5)


Network Interfaces Programmer's Guide


February 18, 2015 RPC_CONTROL(3NSL)