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_without_ using fork(). The problem with YPPROC_ALL is that it transmits an entire map through a TCP pipe as the result of a single RPC call. First of all, this requires certain hackery in the XDR filter. Second, if the map being sent is large, the server can end up spending lots of time in the XDR filter sending to just the one client, while requests for other clients will go unanswered. My original solution for this was to fork() the request into a child process which terminates after the map has been transmitted (or the transfer is interrupted due to an error). This leaves the parent free to handle other requests. But this solution is kind of lame: fork() is relatively expensive, and we have to keep a cap on the number of child processes to keep from swamping the system. What we do now is grab control of the service transport handle and XDR handle from the RPC library and send the records one at a time ourselves instead of letting the RPC library do it. We send a record, then go back to the svc_run() loop and select() on the socket. If select() says we can still write data, we send the next record. Then we call svc_getreqset() and handle other RPCs and loop around again. This way, we can handle other RPCs between records. We manage multiple YPPROC_ALL requests using a circular queue. When a request is done, we dequeue it and destroy the handle. We also tag each request with a ttl which is decremented whevever we run the queue and a handle isn't serviced. This lets us nuke requests that have sat idle for too long (if we didn't do this, we might run out of socket descriptors.) Now all I have to do is come up with an async resolver, and ypserv won't need to fork() at all. :) Note: these changes should not go into 2.2 unless they get a very throrough shakedown before the final cutoff date.
92 lines
3.4 KiB
C
92 lines
3.4 KiB
C
/*
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* Copyright (c) 1995
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* Bill Paul <wpaul@ctr.columbia.edu>. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Bill Paul.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: yp_extern.h,v 1.5 1996/10/24 18:58:24 wpaul Exp $
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*/
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/cdefs.h>
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#include <sys/types.h>
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#include <limits.h>
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#include <db.h>
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#include <rpc/rpc.h>
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#ifndef _PATH_YP
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#define _PATH_YP "/var/yp/"
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#endif
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#ifndef _PATH_LIBEXEC
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#define _PATH_LIBEXEC "/usr/libexec/"
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#endif
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#ifndef MAX_CHILDREN
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#define MAX_CHILDREN 20
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#endif
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#define YP_SECURE 0x1
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#define YP_INTERDOMAIN 0x2
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/*
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* External functions and variables.
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*/
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extern int debug;
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extern int ypdb_debug;
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extern int do_dns;
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extern int children;
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extern char *progname;
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extern char *yp_dir;
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extern int yp_errno;
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extern void yp_error __P((const char *, ...));
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extern int yp_get_record __P(( const char *, const char *, const DBT *, DBT *, int));
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extern int yp_first_record __P((const DB *, DBT *, DBT *, int));
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extern int yp_next_record __P((const DB *, DBT *, DBT *, int, int));
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extern char *yp_dnsname __P(( char * ));
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extern char *yp_dnsaddr __P(( const char * ));
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#ifdef DB_CACHE
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extern int yp_access __P((const char *, const char *, const struct svc_req * ));
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#else
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extern int yp_access __P((const char *, const struct svc_req * ));
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#endif
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extern int yp_validdomain __P((const char * ));
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extern DB *yp_open_db __P(( const char *, const char *));
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extern DB *yp_open_db_cache __P(( const char *, const char *, const char *, int ));
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extern void yp_flush_all __P(( void ));
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extern void yp_init_dbs __P(( void ));
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extern int yp_testflag __P(( char *, char *, int ));
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extern void load_securenets __P(( void ));
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extern void yp_svc_run __P(( void ));
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extern void yp_init_async __P(( void ));
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extern bool_t yp_add_async __P(( XDR *, SVCXPRT *, DB * ));
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