s3-spoolssd: Use parametric option for prefork parameters

example:
spoolssd:prefork = 10:100:5

will configure spoolssd to start with a minimum of 10 preforked children,
a max set to 100 children and spawns/retires 5 children at a time when
ramping up/scaling down.

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

diff --git a/source3/printing/spoolssd.c b/source3/printing/spoolssd.c
index b4444de52f05d90367ab35d92b34970e4a4ccff6..ab0ab236876fb011090409fcb6c3afc644c97930 100644 (file)
--- a/source3/printing/spoolssd.c
+++ b/source3/printing/spoolssd.c
@@ -40,6 +40,40 @@
 #define SPOOLSS_SPAWN_RATE 5
 #define SPOOLSS_MIN_LIFE 60 /* 1 minute minimum life time */
 
+static int spoolss_min_children;
+static int spoolss_max_children;
+static int spoolss_spawn_rate;
+
+static void spoolss_prefork_config(void)
+{
+       const char *prefork_str;
+       int min, max, rate;
+       bool use_defaults = false;
+       int ret;
+
+       prefork_str = lp_parm_const_string(GLOBAL_SECTION_SNUM,
+                                          "spoolssd", "prefork", "none");
+       if (strcmp(prefork_str, "none") == 0) {
+               use_defaults = true;
+       } else {
+               ret = sscanf(prefork_str, "%d:%d:%d", &min, &max, &rate);
+               if (ret != 3) {
+                       DEBUG(0, ("invalid format for spoolssd:prefork!\n"));
+                       use_defaults = true;
+               }
+       }
+
+       if (use_defaults) {
+               spoolss_min_children = SPOOLSS_MIN_CHILDREN;
+               spoolss_max_children = SPOOLSS_MAX_CHILDREN;
+               spoolss_spawn_rate = SPOOLSS_SPAWN_RATE;
+       } else {
+               spoolss_min_children = min;
+               spoolss_max_children = max;
+               spoolss_spawn_rate = rate;
+       }
+}
+
 void start_spoolssd(struct tevent_context *ev_ctx,
                    struct messaging_context *msg_ctx);
 
@@ -80,6 +114,7 @@ static void smb_conf_updated(struct messaging_context *msg,
        change_to_root_user();
        reload_printers(ev_ctx, msg);
        spoolss_reopen_logs();
+       spoolss_prefork_config();
 }
 
 static void spoolss_sig_term_handler(struct tevent_context *ev,
@@ -462,10 +497,10 @@ static void spoolssd_sig_chld_handler(struct tevent_context *ev_ctx,
        active = prefork_count_active_children(pfp, &total);
 
        n = 0;
-       if (total < SPOOLSS_MIN_CHILDREN) {
-               n = total - SPOOLSS_MIN_CHILDREN;
+       if (total < spoolss_min_children) {
+               n = total - spoolss_min_children;
        } else if (total - active < (total / 4)) {
-               n = SPOOLSS_MIN_CHILDREN;
+               n = spoolss_min_children;
        }
 
        if (n > 0) {
@@ -551,17 +586,17 @@ static void spoolssd_check_children(struct tevent_context *ev_ctx,
 
        active = prefork_count_active_children(pfp, &total);
 
-       if (total - active < SPOOLSS_SPAWN_RATE) {
-               n = prefork_add_children(ev_ctx, pfp, SPOOLSS_SPAWN_RATE);
-               if (n < SPOOLSS_SPAWN_RATE) {
+       if (total - active < spoolss_spawn_rate) {
+               n = prefork_add_children(ev_ctx, pfp, spoolss_spawn_rate);
+               if (n < spoolss_spawn_rate) {
                        DEBUG(10, ("Tried to start 5 children but only,"
                                   "%d were actually started.!\n", n));
                }
        }
 
-       if (total - active > SPOOLSS_MIN_CHILDREN) {
-               if ((total - SPOOLSS_MIN_CHILDREN) >= SPOOLSS_SPAWN_RATE) {
-                       prefork_retire_children(pfp, SPOOLSS_SPAWN_RATE,
+       if (total - active > spoolss_min_children) {
+               if ((total - spoolss_min_children) >= spoolss_spawn_rate) {
+                       prefork_retire_children(pfp, spoolss_spawn_rate,
                                                time(NULL) - SPOOLSS_MIN_LIFE);
                }
        }
@@ -609,6 +644,7 @@ void start_spoolssd(struct tevent_context *ev_ctx,
        }
 
        spoolss_reopen_logs();
+       spoolss_prefork_config();
 
        /* the listening fd must be created before the children are actually
         * forked out. */
@@ -617,7 +653,7 @@ void start_spoolssd(struct tevent_context *ev_ctx,
                exit(1);
        }
 
-       ret = listen(listen_fd, SPOOLSS_MAX_CHILDREN);
+       ret = listen(listen_fd, spoolss_max_children);
        if (ret == -1) {
                DEBUG(0, ("Failed to listen on spoolss pipe - %s\n",
                          strerror(errno)));
@@ -627,8 +663,8 @@ void start_spoolssd(struct tevent_context *ev_ctx,
 
        /* start children before any more initialization is done */
        ok = prefork_create_pool(ev_ctx, ev_ctx, listen_fd,
-                                SPOOLSS_MIN_CHILDREN,
-                                SPOOLSS_MAX_CHILDREN,
+                                spoolss_min_children,
+                                spoolss_max_children,
                                 &spoolss_children_main, NULL,
                                 &pool);