ChorusOS man pages section 3RPC: RPC Services

svc_run(3RPC)

NAME | DESCRIPTION | ATTRIBUTES | SEE ALSO | NOTES

NAME

rpc_svc_calls, svc_dg_enablecache, svc_done, svc_exit, svc_fdset, svc_freeargs, svc_getargs, svc_getreq_common, svc_getreq_poll, svc_getreqset, svc_getrpccaller, svc_max_pollfd, svc_pollfd, svc_run, svc_sendreply- library routines for RPC servers

DESCRIPTION

These routines are part of the RPC library which allows C language programs to make procedure calls on other machines across the network.

These routines are associated with the server side of the RPC mechanism. Some of them are called by the server side dispatch function, while others (such as svc_run() ) are called when the server is initiated.

In the current implementation, the service transport handle SVCXPRT contains a single data area for decoding arguments and encoding results. Therefore, this structure cannot be freely shared between threads that call functions that do this. However, when a server is operating in the Automatic or User MT modes, a copy of this structure is passed to the service dispatch procedure in order to enable concurrent request processing. Under these circumstances, some routines which would otherwise be unsafe become safe. These are marked as such. Also marked are routines that are unsafe for MT applications, and are not to be used by such applications.

Routines

#include <rpc/rpc.h>

int svc_dg_enablecache(SVCXPRT * xprt , const uint_t cache_size );

This function allocates a duplicate request cache for the service endpoint xprt , large enough to hold cache_size entries. Once enabled, there is no way to disable caching. This routine returns 1 if space necessary for a cache of the given size was successfully allocated, and 0 otherwise.

This function is safe in MT applications.

int svc_done(SVCXPRT * xprt );

This function frees resources allocated to service a client request directed to the service endpoint xprt . This call pertains only to servers executing in the User MT mode. In the User MT mode, service procedures must invoke this call before returning, either after a client request has been serviced, or after an error or abnormal condition that prevents a reply from being sent. After svc_done () is invoked, the service endpoint xprt should not be referenced by the service procedure. Server multithreading modes and parameters can be set using the rpc_control () call.

This function is safe in MT applications. It will have no effect if invoked in modes other than the User MT mode.

void svc_exit(void);

This function, when called by any of the RPC server procedure, or otherwise, destroys all services registered by the server and causes svc_run() to return.

If RPC server activity is to be resumed, services must be reregistered with the RPC library either through one of the rpc_svc_create(3RPC) functions, or using xprt_register(3RPC) .

svc_exit () has global scope and ends all RPC server activity.

fd_set svc_fdset;

A global variable reflecting the RPC server's read file descriptor bit mask. This is only of interest if service implementors do not call svc_run() , but rather do their own asynchronous event processing. This variable is read-only, and it may change after calls to svc_getreqset() or any creation routines. Do not pass its address to select(2POSIX) . Instead, pass the address of a copy.

MT applications executing in either the Automatic MT mode or the User MT mode should never read this variable. They should use auxiliary threads to do asynchronous event processing.

svc_fdset is limited to 1024 file descriptors and is considered obsolete. Use of svc_pollfd is recommended instead.

pollfd_t *svc_pollfd;

A global variable pointing to an array of pollfd_t structures reflecting the RPC server's read file descriptor array. This is only of interest if service implementors do not call svc_run() but rather do their own asynchronous event processing. This variable is read-only, and it may change after calls to svc_getreg_poll() or any creation routines.

By default, svc_pollfd is limited to 1024 entries. Use rpc_control(3RPC) to remove this limitation.

MT applications executing in either the Automatic MT mode or the User MT mode should never read this variable. They should use auxiliary threads to do asynchronous event processing.

int svc_max_pollfd;

A global variable containing the maximum length of the svc_pollfd array. This variable is read-only, and it may change after calls to svc_getreg_poll() or any creation routines.

bool_t svc_freeargs(const SVCXPRT * xprt , const xdrproc_t inproc , caddr_t in );

A function macro that frees any data allocated by the RPC/XDR system when it decoded the arguments to a service procedure using svc_getargs() . This routine returns TRUE if the results were successfully freed, and FALSE otherwise.

This function macro is safe in MT applications utilizing the Automatic or User MT modes.

bool_t svc_getargs(const SVCXPRT * xprt , const xdrproc_t inproc , caddr_t in );

A function macro that decodes the arguments of an RPC request associated with the RPC service transport handle xprt . The parameter in is the address where the arguments will be placed; inproc is the XDR routine used to decode the arguments. This routine returns TRUE if decoding succeeds, and FALSE otherwise.

This function macro is safe in MT applications utilizing the Automatic or User MT modes.

void svc_getreq_common(const int fd );

This routine is called to handle a request on the given file descriptor.

void svc_getreq_poll(struct pollfd * pfdp , const int pollretval );

This routine is only of interest if a service implementor does not call svc_run() , but instead implements custom asynchronous event processing.

This function macro is unsafe in MT applications.

void svc_getreqset(fd_set * rdfds );

This routine is only of interest if a service implementor does not call svc_run() , but instead implements custom asynchronous event processing. It is called when select(2POSIX) has determined that an RPC request has arrived on some RPC file descriptors; rdfds is the resultant read file descriptor bit mask. The routine returns when all file descriptors associated with the value of rdfds have been serviced.

This function macro is unsafe in MT applications.

struct netbuf *svc_getrpccaller(const SVCXPRT * xprt );

The approved way of getting the network address of the caller of a procedure associated with the RPC service transport handle xprt .

This function macro is safe in MT applications.

void svc_run(void);

This routine never returns. In single threaded mode, it waits for RPC requests to arrive, and calls the appropriate service procedure using svc_getreq_poll() when one arrives. This procedure usually waits for the poll(2) library call to return.

Applications executing in the Automatic or User MT modes should invoke this function exactly once. It the Automatic MT mode, it will create threads to service client requests. In the User MT mode, it will provide a framework for service developers to create and manage their own threads for servicing client requests.

bool_t svc_sendreply(const SVCXPRT * xprt , const xdrproc_t outproc , const caddr_t out );

Called by an RPC service's dispatch routine to send the results of a remote procedure call. The parameter xprt is the request's associated transport handle; outproc is the XDR routine which is used to encode the results; and out is the address of the results. This routine returns TRUE if it succeeds, FALSE otherwise.

This function macro is safe in MT applications utilizing the Automatic or User MT modes.

ATTRIBUTES

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

ATTRIBUTE TYPE	ATTRIBUTE VALUE
MT-Level	See `NOTES` below.

NOTES

svc_dg_enablecache() and svc_getrpccaller() are safe in multithreaded applications. svc_freeargs() , svc_getargs() , and svc_sendreply() are safe in MT applications utilizing the Automatic or User MT modes. svc_getreq_common() , svc_getreqset() , and svc_getreq_poll() are unsafe in multithreaded applications and should be called only from the main thread.

ChorusOS 5.0 Last Revised December 2001

NAME | DESCRIPTION | ATTRIBUTES | SEE ALSO | NOTES