Support a per-location nice value. Note that since we now have two different settings
in the per-dir configuration, we need to introduce a merge function.

Index: httpd-2.2.11/server/mpm/experimental/itk/itk.c
===================================================================
--- httpd-2.2.11.orig/server/mpm/experimental/itk/itk.c	2009-04-14 23:29:16.000000000 +0200
+++ httpd-2.2.11/server/mpm/experimental/itk/itk.c	2009-04-14 23:31:05.000000000 +0200
@@ -156,11 +156,14 @@
 
 static volatile int die_now = 0;
 
+#define UNSET_NICE_VALUE 100
+
 typedef struct
 {
     uid_t uid;
     gid_t gid;
     char *username;
+    int nice_value;
 } itk_per_dir_conf;
 
 typedef struct
@@ -511,6 +514,7 @@
         CAP_SETUID,
         CAP_SETGID,
 	CAP_DAC_READ_SEARCH,
+        CAP_SYS_NICE,
     };
 #endif    
 
@@ -1444,6 +1448,12 @@
     strncpy(ap_scoreboard_image->servers[my_child_num][0].vhost, r->server->server_hostname, 31);
     ap_scoreboard_image->servers[my_child_num][0].vhost[31] = 0;
 
+    if (dconf->nice_value != UNSET_NICE_VALUE &&
+        setpriority(PRIO_PROCESS, 0, dconf->nice_value)) {
+        _DBG("setpriority(): %s", strerror(errno));
+        err = 1;
+    }
+
     wanted_uid = dconf->uid;
     wanted_gid = dconf->gid;
     wanted_username = dconf->username;
@@ -1454,7 +1464,7 @@
         wanted_username = unixd_config.user_name;
     }
 
-    if (wanted_uid != -1 && wanted_gid != -1 && (getuid() != wanted_uid || getgid() != wanted_gid)) {
+    if (!err && wanted_uid != -1 && wanted_gid != -1 && (getuid() != wanted_uid || getgid() != wanted_gid)) {
         if (setgid(wanted_gid)) {
             _DBG("setgid(%d): %s", wanted_gid, strerror(errno));
             err = 1;
@@ -1474,7 +1484,7 @@
      */
     if (err) {
         ap_log_error(APLOG_MARK, APLOG_WARNING, 0, NULL, \
-            "Couldn't set uid/gid, closing connection.");
+            "Couldn't set uid/gid/priority, closing connection.");
         ap_lingering_close(r->connection);
         exit(0);
     }
@@ -1630,6 +1640,27 @@
     return NULL;
 }
 
+static const char *set_nice_value (cmd_parms *cmd, void *ptr, const char *arg)
+{
+    itk_per_dir_conf *dconf = (itk_per_dir_conf *) ptr;
+    int nice_value = atoi(arg);
+
+    if (nice_value < -20) {
+        ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
+                     "WARNING: NiceValue of %d is below -20, increasing NiceValue to -20.",
+                     nice_value);
+        nice_value = -20;
+    }
+    else if (nice_value > 19) {
+        ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
+                     "WARNING: NiceValue of %d is above 19, lowering NiceValue to 19.",
+                     nice_value);
+        nice_value = 19;
+    }
+    dconf->nice_value = nice_value;
+    return NULL;
+}
+
 static const command_rec itk_cmds[] = {
 UNIX_DAEMON_COMMANDS,
 LISTEN_COMMANDS,
@@ -1647,6 +1678,8 @@
               "Tie a virtual host to a specific child process."),
 AP_INIT_TAKE1("MaxClientsVHost", set_max_clients_vhost, NULL, RSRC_CONF,
               "Maximum number of children alive at the same time for this virtual host."),
+AP_INIT_TAKE1("NiceValue", set_nice_value, NULL, RSRC_CONF|ACCESS_CONF,
+              "Set nice value for the given vhost, from -20 (highest priority) to 19 (lowest priority)."),
 AP_GRACEFUL_SHUTDOWN_TIMEOUT_COMMAND,
 { NULL }
 };
@@ -1657,6 +1690,32 @@
     itk_per_dir_conf *c = (itk_per_dir_conf *)
         apr_pcalloc(p, sizeof(itk_per_dir_conf));
     c->uid = c->gid = -1;
+    c->nice_value = UNSET_NICE_VALUE;
+    return c;
+}
+
+/* == merge the parent per-dir config structure into ours == */
+static void *itk_merge_dir_config(apr_pool_t *p, void *parent_ptr, void *child_ptr)
+{
+    itk_per_dir_conf *c = (itk_per_dir_conf *)
+        apr_pcalloc(p, sizeof(itk_per_dir_conf));
+    itk_per_dir_conf *parent = (itk_per_dir_conf *) parent_ptr;
+    itk_per_dir_conf *child = (itk_per_dir_conf *) child_ptr;
+
+    if (child->username != NULL) {
+      c->username = apr_pstrdup(p, child->username);
+      c->uid = child->uid;
+      c->gid = child->gid;
+    } else if (parent->username != NULL) {
+      c->username = apr_pstrdup(p, parent->username);
+      c->uid = parent->uid;
+      c->gid = parent->gid;
+    }
+    if (child->nice_value != UNSET_NICE_VALUE) {
+      c->nice_value = child->nice_value;
+    } else {
+      c->nice_value = parent->nice_value;
+    }
     return c;
 }
 
@@ -1673,7 +1732,7 @@
     MPM20_MODULE_STUFF,
     ap_mpm_rewrite_args,        /* hook to run before apache parses args */
     itk_create_dir_config,      /* create per-directory config structure */
-    NULL,                       /* merge per-directory config structures */
+    itk_merge_dir_config,       /* merge per-directory config structures */
     itk_create_server_config,   /* create per-server config structure */
     NULL,                       /* merge per-server config structures */
     itk_cmds,                   /* command apr_table_t */