s3-prefork: Add common utilities for daemons

Daemons using the prefork infrastructure may want to use these utils to
configure and manage a pool of children.

Signed-off-by: Andreas Schneider <asn@samba.org>
Signed-off-by: Simo Sorce <idra@samba.org>

2 files changed, 166 insertions, 0 deletions

diff --git a/source3/lib/server_prefork_util.c b/source3/lib/server_prefork_util.c
new file mode 100644
index 0000000000..6b1e249335
--- /dev/null
+++ b/source3/lib/server_prefork_util.c
@@ -0,0 +1,117 @@
+/*
+   Unix SMB/Netbios implementation.
+   Prefork Helpers
+   Copyright (C) Simo Sorce <idra@samba.org> 2011
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "lib/server_prefork.h"
+#include "lib/server_prefork_util.h"
+
+void pfh_daemon_config(const char *daemon_name,
+			struct pf_daemon_config *cfg,
+			struct pf_daemon_config *default_cfg)
+{
+	int min, max, rate, allow, life;
+
+	min = lp_parm_int(GLOBAL_SECTION_SNUM,
+				daemon_name,
+				"prefork_min_children",
+				default_cfg->min_children);
+	max = lp_parm_int(GLOBAL_SECTION_SNUM,
+				daemon_name,
+				"prefork_max_children",
+				default_cfg->max_children);
+	rate = lp_parm_int(GLOBAL_SECTION_SNUM,
+				daemon_name,
+				"prefork_spawn_rate",
+				default_cfg->spawn_rate);
+	allow = lp_parm_int(GLOBAL_SECTION_SNUM,
+				daemon_name,
+				"prefork_max_allowed_clients",
+				default_cfg->max_allowed_clients);
+	life = lp_parm_int(GLOBAL_SECTION_SNUM,
+				daemon_name,
+				"prefork_child_min_life",
+				default_cfg->child_min_life);
+
+	if (max > cfg->max_children && cfg->max_children != 0) {
+		cfg->prefork_status |= PFH_NEW_MAX;
+	}
+
+	cfg->min_children = min;
+	cfg->max_children = max;
+	cfg->spawn_rate = rate;
+	cfg->max_allowed_clients = allow;
+	cfg->child_min_life = life;
+}
+
+void pfh_manage_pool(struct tevent_context *ev_ctx,
+		     struct messaging_context *msg_ctx,
+		     struct pf_daemon_config *cfg,
+		     struct prefork_pool *pool)
+{
+	time_t now = time(NULL);
+	int active, total;
+	int ret, n;
+
+	if ((cfg->prefork_status & PFH_NEW_MAX) &&
+	    !(cfg->prefork_status & PFH_ENOSPC)) {
+		ret = prefork_expand_pool(pool, cfg->max_children);
+		if (ret == ENOSPC) {
+			cfg->prefork_status |= PFH_ENOSPC;
+		}
+		cfg->prefork_status &= ~PFH_NEW_MAX;
+	}
+
+	active = prefork_count_active_children(pool, &total);
+
+	if ((total < cfg->max_children) &&
+	    ((total < cfg->min_children) ||
+	     (total - active < cfg->spawn_rate))) {
+		n = prefork_add_children(ev_ctx, msg_ctx,
+					 pool, cfg->spawn_rate);
+		if (n < cfg->spawn_rate) {
+			DEBUG(10, ("Tried to start %d children but only,"
+				   "%d were actually started.!\n",
+				   cfg->spawn_rate, n));
+		}
+	}
+
+	if (total - active > cfg->min_children) {
+		if ((total - cfg->min_children) >= cfg->spawn_rate) {
+			prefork_retire_children(pool, cfg->spawn_rate,
+						now - cfg->child_min_life);
+		}
+	}
+
+	n = prefork_count_allowed_connections(pool);
+	if (n <= cfg->spawn_rate) {
+		do {
+			prefork_increase_allowed_clients(pool,
+						cfg->max_allowed_clients);
+			n = prefork_count_allowed_connections(pool);
+		} while (n <= cfg->spawn_rate);
+	} else if (n > cfg->max_children + cfg->spawn_rate) {
+		do {
+			prefork_decrease_allowed_clients(pool);
+			n = prefork_count_allowed_connections(pool);
+		} while (n > cfg->max_children + cfg->spawn_rate);
+	}
+
+	DEBUG(10, ("Stats: children: %d, allowed connections: %d\n",
+		  total, prefork_count_allowed_connections(pool)));
+}
diff --git a/source3/lib/server_prefork_util.h b/source3/lib/server_prefork_util.h
new file mode 100644
index 0000000000..5715f06f4a
--- /dev/null
+++ b/source3/lib/server_prefork_util.h
@@ -0,0 +1,49 @@
+/*
+   Unix SMB/CIFS implementation.
+   Prefork Helpers.
+
+   Copyright (C) Simo Sorce <idra@samba.org> 2011
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _SERVER_PREFORK_UTIL_H_
+#define _SERVER_PREFORK_UTIL_H_
+
+struct tevent_context;
+struct messaging_context;
+
+#define PFH_INIT	0x00
+#define PFH_NEW_MAX	0x01
+#define PFH_ENOSPC	0x02
+
+struct pf_daemon_config {
+	int prefork_status;
+	int min_children;
+	int max_children;
+	int spawn_rate;
+	int max_allowed_clients;
+	int child_min_life;
+};
+
+void pfh_daemon_config(const char *daemon_name,
+			struct pf_daemon_config *cfg,
+			struct pf_daemon_config *default_cfg);
+
+void pfh_manage_pool(struct tevent_context *ev_ctx,
+		     struct messaging_context *msg_ctx,
+		     struct pf_daemon_config *cfg,
+		     struct prefork_pool *pool);
+
+#endif /* _SERVER_PREFORK_UTIL_H_ */