[MEDIUM] implement bind-process to limit service presence by process

The "bind-process" keyword lets the admin select which instances may
run on which process (in multi-process mode). It makes it easier to
more evenly distribute the load across multiple processes by avoiding
having too many listen to the same IP:ports.

doc/configuration.txt

@@ -523,6 +523,7 @@ appsession                  -          -         X         X
 backlog                     X          X         X         -
 balance                     X          -         X         X   
 bind                        -          X         X         -   
+bind-process                X          X         X         X   
 block                       -          X         X         X
 capture cookie              -          X         X         -
 capture request header      -          X         X         -
@@ -903,6 +904,57 @@ bind [<address>]:<port> [, ...] transparent
   See also : "source".
 
 
+bind-process [ all | odd | even | <number 1-32> ] ...
+  Limit visibility of an instance to a certain set of processes numbers.
+  May be used in sections :   defaults | frontend | listen | backend
+                                 yes   |    yes   |   yes  |   yes
+  Arguments :
+    all           All process will see this instance. This is the default. It
+                  may be used to override a default value.
+
+    odd           This instance will be enabled on processes 1,3,5,...31. This
+                  option may be combined with other numbers.
+
+    even          This instance will be enabled on processes 2,4,6,...32. This
+                  option may be combined with other numbers. Do not use it
+                  with less than 2 processes otherwise some instances might be
+                  missing from all processes.
+
+    number        The instance will be enabled on this process number, between
+                  1 and 32. You must be careful not to reference a process
+                  number greater than the configured global.nbproc, otherwise
+                  some instances might be missing from all processes.
+
+  This keyword limits binding of certain instances to certain processes. This
+  is useful in order not to have too many processes listening to the same
+  ports. For instance, on a dual-core machine, it might make sense to set
+  'nbproc 2' in the global section, then distributes the listeners among 'odd'
+  and 'even' instances.
+
+  At the moment, it is not possible to reference more than 32 processes using
+  this keyword, but this should be more than enough for most setups. Please
+  note that 'all' really means all processes and is not limited to the first
+  32.
+
+  If some backends are referenced by frontends bound to other processes, the
+  backend automatically inherits the frontend's processes.
+
+  Example :
+        listen app_ip1
+            bind 10.0.0.1:80
+            bind_process odd
+
+        listen app_ip2
+            bind 10.0.0.2:80
+            bind_process even
+
+        listen management
+            bind 10.0.0.3:80
+            bind_process 1 2 3 4
+
+  See also : "nbproc" in global section.
+
+
 block { if | unless } <condition>
   Block a layer 7 request if/unless a condition is matched
   May be used in sections :   defaults | frontend | listen | backend

include/types/proxy.h

@@ -258,6 +258,7 @@ struct proxy {
 	int uuid;				/* universally unique proxy ID, used for SNMP */
 	int next_svid;				/* next server-id, used for SNMP */
 	unsigned int backlog;			/* force the frontend's listen backlog */
+	unsigned int bind_proc;			/* bitmask of processes using this proxy. 0 = all. */
 };
 
 struct switching_rule {

src/cfgparse.c

@@ -668,6 +668,7 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int inv)
 		curproxy->state = defproxy.state;
 		curproxy->options = defproxy.options;
 		curproxy->options2 = defproxy.options2;
+		curproxy->bind_proc = defproxy.bind_proc;
 		curproxy->lbprm.algo = defproxy.lbprm.algo;
 		curproxy->except_net = defproxy.except_net;
 		curproxy->except_mask = defproxy.except_mask;
@@ -930,6 +931,39 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int inv)
 	else if (!strcmp(args[0], "enabled")) {  /* enables this proxy (used to revert a disabled default) */
 		curproxy->state = PR_STNEW;
 	}
+	else if (!strcmp(args[0], "bind-process")) {  /* enable this proxy only on some processes */
+		int cur_arg = 1;
+		unsigned int set = 0;
+
+		while (*args[cur_arg]) {
+			int u;
+			if (strcmp(args[cur_arg], "all") == 0) {
+				set = 0;
+				break;
+			}
+			else if (strcmp(args[cur_arg], "odd") == 0) {
+				set |= 0x55555555;
+			}
+			else if (strcmp(args[cur_arg], "even") == 0) {
+				set |= 0xAAAAAAAA;
+			}
+			else {
+				u = str2uic(args[cur_arg]);
+				if (u < 1 || u > 32) {
+					Alert("parsing [%s:%d]: %s expects 'all', 'odd', 'even', or process numbers from 1 to 32.\n",
+					      file, linenum, args[0]);
+					return -1;
+				}
+				if (u > global.nbproc) {
+					Warning("parsing [%s:%d]: %s references process number higher than global.nbproc.\n",
+						file, linenum, args[0]);
+				}
+				set |= 1 << (u - 1);
+			}
+			cur_arg++;
+		}
+		curproxy->bind_proc = set;
+	}
 	else if (!strcmp(args[0], "acl")) {  /* add an ACL */
 		if (curproxy == &defproxy) {
 			Alert("parsing [%s:%d] : '%s' not allowed in 'defaults' section.\n", file, linenum, args[0]);
@@ -3168,6 +3202,11 @@ int readcfgfile(const char *file)
 			} else {
 				free(curproxy->defbe.name);
 				curproxy->defbe.be = target;
+				/* we force the backend to be present on at least all of
+				 * the frontend's processes.
+				 */
+				target->bind_proc = curproxy->bind_proc ?
+					(target->bind_proc | curproxy->bind_proc) : 0;
 			}
 		}
 
@@ -3193,6 +3232,11 @@ int readcfgfile(const char *file)
 				} else {
 					free((void *)exp->replace);
 					exp->replace = (const char *)target;
+					/* we force the backend to be present on at least all of
+					 * the frontend's processes.
+					 */
+					target->bind_proc = curproxy->bind_proc ?
+						(target->bind_proc | curproxy->bind_proc) : 0;
 				}
 			}
 		}
@@ -3214,6 +3258,11 @@ int readcfgfile(const char *file)
 			} else {
 				free((void *)rule->be.name);
 				rule->be.backend = target;
+				/* we force the backend to be present on at least all of
+				 * the frontend's processes.
+				 */
+				target->bind_proc = curproxy->bind_proc ?
+					(target->bind_proc | curproxy->bind_proc) : 0;
 			}
 		}
 

src/haproxy.c

@@ -1106,6 +1106,7 @@ int main(int argc, char **argv)
 	}
 
 	if (global.mode & MODE_DAEMON) {
+		struct proxy *px;
 		int ret = 0;
 		int proc;
 
@@ -1131,6 +1132,16 @@ int main(int argc, char **argv)
 		free(global.pidfile);
 		global.pidfile = NULL;
 
+		/* we might have to unbind some proxies from some processes */
+		px = proxy;
+		while (px != NULL) {
+			if (px->bind_proc && px->state != PR_STSTOPPED) {
+				if (!(px->bind_proc & (1 << proc)))
+					stop_proxy(px);
+			}
+			px = px->next;
+		}
+
 		if (proc == global.nbproc)
 			exit(0); /* parent must leave */