Adding upstream version 3.4.23.upstream/3.4.23upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 251 insertions, 0 deletions

diff --git a/src/master/master_avail.c b/src/master/master_avail.c
new file mode 100644
index 0000000..046503d
--- /dev/null
+++ b/src/master/master_avail.c
@@ -0,0 +1,251 @@
+/*++
+/* 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.
+/*
+/*	When the service runs out of process slots, and the service
+/*	is eligible for stress-mode operation, a warning is logged,
+/*	servers are asked to restart at their convenience, and new
+/*	servers are created with stress mode enabled.
+/*
+/*	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 times, but it must be called after each status
+/*	change of a service (throttled, process limit, etc.) or child
+/*	process (taken, available, dead, etc.).
+/*
+/*	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.
+/*	This function updates the process availability status and
+/*	counter, and implicitly calls master_avail_listen().
+/*
+/*	master_avail_less() should be called when the named process
+/*	has become unavailable for servicing new connection requests.
+/*	This function updates the process availability status and
+/*	counter, and implicitly calls master_avail_listen().
+/* 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, void *context)
+{
+    MASTER_SERV *serv = (MASTER_SERV *) context;
+    time_t  now;
+
+    if (event == 0)				/* XXX Can this happen? */
+	msg_panic("master_avail_event: null event");
+    else {
+
+	/*
+	 * When all servers for a public internet service are busy, we start
+	 * creating server processes with "-o stress=yes" on the command
+	 * line, and keep creating such processes until the process count is
+	 * below the limit for at least 1000 seconds. This provides a minimal
+	 * solution that can be adopted into legacy and stable Postfix
+	 * releases.
+	 * 
+	 * This is not the right place to update serv->stress_param_val in
+	 * response to stress level changes. Doing so would would contaminate
+	 * the "postfix reload" code with stress management implementation
+	 * details, creating a source of future bugs. Instead, we update
+	 * simple counters or flags here, and use their values to determine
+	 * the proper serv->stress_param_val value when exec-ing a server
+	 * process.
+	 */
+	if (serv->stress_param_val != 0
+	    && !MASTER_LIMIT_OK(serv->max_proc, serv->total_proc + 1)) {
+	    now = event_time();
+	    if (serv->stress_expire_time < now)
+		master_restart_service(serv, NO_CONF_RELOAD);
+	    serv->stress_expire_time = now + 1000;
+	}
+	master_spawn(serv);
+    }
+}
+
+/* master_avail_listen - enforce the socket monitoring policy */
+
+void    master_avail_listen(MASTER_SERV *serv)
+{
+    const char *myname = "master_avail_listen";
+    int     listen_flag;
+    time_t  now;
+    int     n;
+
+    /*
+     * Caution: several other master_XXX modules call master_avail_listen(),
+     * master_avail_more() or master_avail_less(). To avoid mutual dependency
+     * problems, the code below invokes no code in other master_XXX modules,
+     * and modifies no data that is maintained by other master_XXX modules.
+     * 
+     * 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: %s avail %d total %d max %d", myname, serv->name,
+		 serv->avail_proc, serv->total_proc, serv->max_proc);
+    if (MASTER_THROTTLED(serv) || serv->avail_proc > 0) {
+	listen_flag = 0;
+    } else if (MASTER_LIMIT_OK(serv->max_proc, serv->total_proc)) {
+	listen_flag = 1;
+    } else {
+	listen_flag = 0;
+	if (serv->stress_param_val != 0) {
+	    now = event_time();
+	    if (serv->busy_warn_time < now - 1000) {
+		serv->busy_warn_time = now;
+		msg_warn("service \"%s\" (%s) has reached its process limit \"%d\": "
+			 "new clients may experience noticeable delays",
+			 serv->ext_name, serv->name, serv->max_proc);
+		msg_warn("to avoid this condition, increase the process count "
+		      "in master.cf or reduce the service time per client");
+		msg_warn("see http://www.postfix.org/STRESS_README.html for "
+		      "examples of stress-adapting configuration settings");
+	    }
+	}
+    }
+    if (listen_flag && !MASTER_LISTENING(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,
+			      (void *) serv);
+	serv->flags |= MASTER_FLAG_LISTEN;
+    } else if (!listen_flag && MASTER_LISTENING(serv)) {
+	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]);
+	serv->flags &= ~MASTER_FLAG_LISTEN;
+    }
+}
+
+/* master_avail_cleanup - cleanup */
+
+void    master_avail_cleanup(MASTER_SERV *serv)
+{
+    int     n;
+
+    master_delete_children(serv);		/* XXX calls
+						 * master_avail_listen */
+
+    /*
+     * This code is redundant because master_delete_children() throttles the
+     * service temporarily before calling master_avail_listen/less(), which
+     * then turn off read events. This temporary throttling is not documented
+     * (it is only an optimization), and therefore we must not depend on it.
+     */
+    if (MASTER_LISTENING(serv)) {
+	for (n = 0; n < serv->listen_fd_count; n++)
+	    event_disable_readwrite(serv->listen_fd[n]);
+	serv->flags &= ~MASTER_FLAG_LISTEN;
+    }
+}
+
+/* master_avail_more - one more available child process */
+
+void    master_avail_more(MASTER_SERV *serv, MASTER_PROC *proc)
+{
+    const char *myname = "master_avail_more";
+
+    /*
+     * Caution: several other master_XXX modules call master_avail_listen(),
+     * master_avail_more() or master_avail_less(). To avoid mutual dependency
+     * problems, the code below invokes no code in other master_XXX modules,
+     * and modifies no data that is maintained by other master_XXX modules.
+     * 
+     * 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;
+    master_avail_listen(serv);
+}
+
+/* master_avail_less - one less available child process */
+
+void    master_avail_less(MASTER_SERV *serv, MASTER_PROC *proc)
+{
+    const char *myname = "master_avail_less";
+
+    /*
+     * Caution: several other master_XXX modules call master_avail_listen(),
+     * master_avail_more() or master_avail_less(). To avoid mutual dependency
+     * problems, the code below invokes no code in other master_XXX modules,
+     * and modifies no data that is maintained by other master_XXX modules.
+     * 
+     * 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);
+}