rpc_svc_calls(3N)

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_pollset, svc_run, svc_sendreply — library routines for RPC servers

SYNOPSIS

#include <rpc/rpc.h>

int svc_dg_enablecache(SVCXPRT *xprt, const unsigned long cache_size);

int svc_done(SVCXPRT *xprt);

void svc_exit(void);

fd_set svc_fdset;

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

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

void svc_getreq_common(const int fd);

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

void svc_getreqset(fd_set *rdfds);

struct netbuf *svc_getrpccaller(const SVCXPRT *xprt);

void svc_run(void);

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

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.

Multithread Considerations

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 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

See rpc(3N) for the definition of the SVCXPRT data structure.

int svc_dg_enablecache()

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()

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(3N) functions, or using xprt_register().

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(2)! Instead, pass the address of a copy.

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

bool_t svc_freeargs()

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 User MT modes.

bool_t svc_getargs()

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 User MT modes.

void svc_getreq_common()

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

This function macro is unsafe in MT applications.

void svc_getreq_poll()

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 poll(2) has determined that an RPC request has arrived on some RPC file descriptors; pollretval is the return value from poll(2) and pfdp is the array of pollfd structures on which the poll(2) was done. It is assumed to be an array large enough to contain the maximal number of descriptors allowed.

This function macro is unsafe in MT applications.

void svc_getreqset()

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(2) 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()

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 is usually waiting for the poll(2) library call to return.

Applications executing in the User MT modes should invoke this function exactly once. 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()

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 User MT modes.

MULTITHREAD USAGE

Thread Safe:: See the NOTES section of this page.
Cancel Safe:: See the NOTES section of this page.
Fork Safe:: No
Async-cancel Safe:: No
Async-signal Safe:: No

In a multithreaded environment, these functions are not safe to be called by a child process after fork() and before exec(). These functions should not be called by a multithreaded application that support asynchronous cancellation or asynchronous signals.

NOTES

svc_dg_enablecache() and svc_getrpccaller() are Thread Safe and Cancel Safe in multithreaded applications. svc_freeargs(), svc_getargs(), and svc_sendreply() are Thread safe and Cancel Safe in multithreaded applications utilizing the 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.

rpc_svc_calls(3N)

Technical documentation

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NAME

SYNOPSIS

DESCRIPTION

Multithread Considerations

Routines

MULTITHREAD USAGE

NOTES

SEE ALSO