rpc_control.3n (2010 09)

r
rpc_control(3N) rpc_control(3N)
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. 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 # 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_USER User MT mode
RPC_SVC_MT_AUTO Automatic MT mode
Unless the application sets the Automatic or User MT modes, it will stay in the default (single-threaded)
mode. 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 limita-
tions in the historical interfaces
svc_fdset and svc_getreqset()
(see respective manpages).
Applications written to use the preferred interfaces of
svc_pollfd and svc_getreq_poll()
(see
respective manpages) 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. If the value pointed to by info is -1, then the maximum
recoed size is set to RPC_MAXDATASIZE.
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 (3N).
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. Non-connection RPC transports
ignore RPC_SVC_CONNMAXREC_SET and RPC_SVC_CONNMAXREC_GET.
info is a pointer to an argument of type
int.
MULTITHREAD USAGE
Thread Safe: Yes
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1