/*++ /* NAME /* master_avail 3 /* SUMMARY /* Postfix master - process creation policy /* SYNOPSIS /* #include "master.h" /* /* void master_avail_listen(serv) /* MASTER_SERV *serv; /* /* void master_avail_cleanup(serv) /* MASTER_SERV *serv; /* /* void master_avail_more(serv, proc) /* MASTER_SERV *serv; /* MASTER_PROC *proc; /* /* void master_avail_less(serv, proc) /* MASTER_SERV *serv; /* MASTER_PROC *proc; /* DESCRIPTION /* This module implements the process creation policy. As long as /* the allowed number of processes for the given service is not /* exceeded, a connection request is either handled by an existing /* available process, or this module causes a new process to be /* created to service the request. /* /* master_avail_listen() ensures that someone monitors the service's /* listen socket for connection requests (as long as resources /* to handle connection requests are available). This function may /* be called at random. When the maximum number of servers is running, /* connection requests are left in the system queue. /* /* master_avail_cleanup() should be called when the named service /* is taken out of operation. It terminates child processes by /* sending SIGTERM. /* /* master_avail_more() should be called when the named process /* has become available for servicing new connection requests. /* /* master_avail_less() should be called when the named process /* has become unavailable for servicing new connection requests. /* DIAGNOSTICS /* Panic: internal inconsistencies. /* BUGS /* SEE ALSO /* master_spawn(3), child process birth and death /* LICENSE /* .ad /* .fi /* The Secure Mailer license must be distributed with this software. /* AUTHOR(S) /* Wietse Venema /* IBM T.J. Watson Research /* P.O. Box 704 /* Yorktown Heights, NY 10598, USA /*--*/ /* System libraries. */ #include <sys_defs.h> /* Utility library. */ #include <events.h> #include <msg.h> /* Application-specific. */ #include "master_proto.h" #include "master.h" /* master_avail_event - create child process to handle connection request */ static void master_avail_event(int event, char *context) { MASTER_SERV *serv = (MASTER_SERV *) context; int n; if (event == 0) /* XXX Can this happen? */ return; if (MASTER_THROTTLED(serv)) { /* XXX interface botch */ for (n = 0; n < serv->listen_fd_count; n++) event_disable_readwrite(serv->listen_fd[n]); } else { master_spawn(serv); } } /* master_avail_listen - make sure that someone monitors the listen socket */ void master_avail_listen(MASTER_SERV *serv) { char *myname = "master_avail_listen"; int n; /* * When no-one else is monitoring the service's listen socket, start * monitoring the socket for connection requests. All this under the * restriction that we have sufficient resources to service a connection * request. */ if (msg_verbose) msg_info("%s: avail %d total %d max %d", myname, serv->avail_proc, serv->total_proc, serv->max_proc); if (serv->avail_proc < 1 && MASTER_LIMIT_OK(serv->max_proc, serv->total_proc) && !MASTER_THROTTLED(serv)) { if (msg_verbose) msg_info("%s: enable events %s", myname, serv->name); for (n = 0; n < serv->listen_fd_count; n++) event_enable_read(serv->listen_fd[n], master_avail_event, (char *) serv); } } /* master_avail_cleanup - cleanup */ void master_avail_cleanup(MASTER_SERV *serv) { int n; master_delete_children(serv); /* XXX calls * master_avail_listen */ for (n = 0; n < serv->listen_fd_count; n++) event_disable_readwrite(serv->listen_fd[n]); /* XXX must be last */ } /* master_avail_more - one more available child process */ void master_avail_more(MASTER_SERV *serv, MASTER_PROC *proc) { char *myname = "master_avail_more"; int n; /* * This child process has become available for servicing connection * requests, so we can stop monitoring the service's listen socket. The * child will do it for us. */ if (msg_verbose) msg_info("%s: pid %d (%s)", myname, proc->pid, proc->serv->name); if (proc->avail == MASTER_STAT_AVAIL) msg_panic("%s: process already available", myname); serv->avail_proc++; proc->avail = MASTER_STAT_AVAIL; if (msg_verbose) msg_info("%s: disable events %s", myname, serv->name); for (n = 0; n < serv->listen_fd_count; n++) event_disable_readwrite(serv->listen_fd[n]); } /* master_avail_less - one less available child process */ void master_avail_less(MASTER_SERV *serv, MASTER_PROC *proc) { char *myname = "master_avail_less"; /* * This child is no longer available for servicing connection requests. * When no child processes are available, start monitoring the service's * listen socket for new connection requests. */ if (msg_verbose) msg_info("%s: pid %d (%s)", myname, proc->pid, proc->serv->name); if (proc->avail != MASTER_STAT_AVAIL) msg_panic("%s: process not available", myname); serv->avail_proc--; proc->avail = MASTER_STAT_TAKEN; master_avail_listen(serv); }