MINOR: queue: replace the linked list with a tree

We'll need trees to manage the queues by priorities. This change replaces
the list with a tree based on a single key. It's effectively a list but
allows us to get rid of the list management right now.

include/proto/queue.h

@@ -52,7 +52,7 @@ void pendconn_unlink(struct pendconn *p);
  */
 static inline void pendconn_cond_unlink(struct pendconn *p)
 {
-	if (p && !LIST_ISEMPTY(&p->list))
+	if (p && p->node.node.leaf_p)
 		pendconn_unlink(p);
 }
 

include/types/proxy.h

@@ -322,7 +322,7 @@ struct proxy {
 		int serverfin;                  /* timeout to apply to server half-closed connections */
 	} timeout;
 	char *id, *desc;			/* proxy id (name) and description */
-	struct list pendconns;			/* pending connections with no server assigned yet */
+	struct eb_root pendconns;		/* pending connections with no server assigned yet */
 	int nbpend;				/* number of pending connections with no server assigned yet */
 	int totpend;				/* total number of pending connections on this instance (for stats) */
 	unsigned int queue_idx;			/* number of pending connections which have been de-queued */

include/types/queue.h

@@ -37,7 +37,7 @@ struct pendconn {
 	struct proxy  *px;
 	struct server *srv;        /* the server we are waiting for, may be NULL if don't care */
 	struct server *target;     /* the server that was assigned, = srv except if srv==NULL */
-	struct list    list;       /* next pendconn */
+	struct eb32_node node;
 };
 
 #endif /* _TYPES_QUEUE_H */

include/types/server.h

@@ -215,7 +215,7 @@ struct server {
 	struct freq_ctr sess_per_sec;		/* sessions per second on this server */
 	struct be_counters counters;		/* statistics counters */
 
-	struct list pendconns;			/* pending connections */
+	struct eb_root pendconns;		/* pending connections */
 	struct list actconns;			/* active connections */
 	struct list *priv_conns;		/* private idle connections attached to stream interfaces */
 	struct list *idle_conns;		/* sharable idle connections attached or not to a stream interface */

src/hlua.c

@@ -8007,7 +8007,7 @@ void hlua_init(void)
 	socket_tcp.proxy = &socket_proxy;
 	socket_tcp.obj_type = OBJ_TYPE_SERVER;
 	LIST_INIT(&socket_tcp.actconns);
-	LIST_INIT(&socket_tcp.pendconns);
+	socket_tcp.pendconns = EB_ROOT;
 	socket_tcp.priv_conns = NULL;
 	socket_tcp.idle_conns = NULL;
 	socket_tcp.safe_conns = NULL;
@@ -8053,7 +8053,7 @@ void hlua_init(void)
 	socket_ssl.proxy = &socket_proxy;
 	socket_ssl.obj_type = OBJ_TYPE_SERVER;
 	LIST_INIT(&socket_ssl.actconns);
-	LIST_INIT(&socket_ssl.pendconns);
+	socket_ssl.pendconns = EB_ROOT;
 	socket_tcp.priv_conns = NULL;
 	socket_tcp.idle_conns = NULL;
 	socket_tcp.safe_conns = NULL;

src/proxy.c

@@ -726,7 +726,7 @@ void init_new_proxy(struct proxy *p)
 {
 	memset(p, 0, sizeof(struct proxy));
 	p->obj_type = OBJ_TYPE_PROXY;
-	LIST_INIT(&p->pendconns);
+	p->pendconns = EB_ROOT;
 	LIST_INIT(&p->acl);
 	LIST_INIT(&p->http_req_rules);
 	LIST_INIT(&p->http_res_rules);

src/queue.c

@@ -21,7 +21,7 @@
  * A stream does not necessarily have such a pendconn. Thus the pendconn is
  * designated by the stream->pend_pos pointer. This results in some properties :
  *   - pendconn->strm->pend_pos is never NULL for any valid pendconn
- *   - if LIST_ISEMPTY(pendconn->list) is true, the element is unlinked,
+ *   - if p->node.node.leaf_p is NULL, the element is unlinked,
  *     otherwise it necessarily belongs to one of the other lists ; this may
  *     not be atomically checked under threads though ;
  *   - pendconn->px is never NULL if pendconn->list is not empty
@@ -73,6 +73,7 @@
 #include <common/memory.h>
 #include <common/time.h>
 #include <common/hathreads.h>
+#include <eb32tree.h>
 
 #include <proto/queue.h>
 #include <proto/server.h>
@@ -137,8 +138,7 @@ static void __pendconn_unlink(struct pendconn *p)
 		p->px->nbpend--;
 	}
 	HA_ATOMIC_SUB(&p->px->totpend, 1);
-	LIST_DEL(&p->list);
-	LIST_INIT(&p->list);
+	eb32_delete(&p->node);
 }
 
 /* Locks the queue the pendconn element belongs to. This relies on both p->px
@@ -204,20 +204,24 @@ static int pendconn_process_next_strm(struct server *srv, struct proxy *px)
 	struct pendconn *p = NULL;
 	struct pendconn *pp = NULL;
 	struct server   *rsrv;
+	struct eb32_node *node;
 
 	rsrv = srv->track;
 	if (!rsrv)
 		rsrv = srv;
 
 	p = NULL;
-	if (srv->nbpend)
-		p = LIST_ELEM(srv->pendconns.n, struct pendconn *, list);
+	if (srv->nbpend) {
+		node = eb32_first(&srv->pendconns);
+		p = eb32_entry(node, struct pendconn, node);
+	}
 
 	if (srv_currently_usable(rsrv) && px->nbpend &&
 	    (!(srv->flags & SRV_F_BACKUP) ||
 	     (!px->srv_act &&
 	      (srv == px->lbprm.fbck || (px->options & PR_O_USE_ALL_BK))))) {
-		pp = LIST_ELEM(px->pendconns.n, struct pendconn *, list);
+		node = eb32_first(&px->pendconns);
+		pp = eb32_entry(node, struct pendconn, node);
 
 		/* If the server pendconn is older than the proxy one,
 		 * we process the server one.
@@ -303,6 +307,7 @@ struct pendconn *pendconn_add(struct stream *strm)
 	px            = strm->be;
 	p->target     = NULL;
 	p->srv        = srv;
+	p->node.key   = 0;
 	p->px         = px;
 	p->strm       = strm;
 	p->strm_flags = strm->flags;
@@ -314,14 +319,14 @@ struct pendconn *pendconn_add(struct stream *strm)
 		if (srv->nbpend > srv->counters.nbpend_max)
 			srv->counters.nbpend_max = srv->nbpend;
 		p->queue_idx = srv->queue_idx - 1; // for increment
-		LIST_ADDQ(&srv->pendconns, &p->list);
+		eb32_insert(&srv->pendconns, &p->node);
 	}
 	else {
 		px->nbpend++;
 		if (px->nbpend > px->be_counters.nbpend_max)
 			px->be_counters.nbpend_max = px->nbpend;
 		p->queue_idx = px->queue_idx - 1; // for increment
-		LIST_ADDQ(&px->pendconns, &p->list);
+		eb32_insert(&px->pendconns, &p->node);
 	}
 	strm->pend_pos = p;
 
@@ -336,7 +341,8 @@ struct pendconn *pendconn_add(struct stream *strm)
  */
 int pendconn_redistribute(struct server *s)
 {
-	struct pendconn *p, *pback;
+	struct pendconn *p;
+	struct eb32_node *node;
 	int xferred = 0;
 
 	/* The REDISP option was specified. We will ignore cookie and force to
@@ -345,7 +351,8 @@ int pendconn_redistribute(struct server *s)
 		return 0;
 
 	HA_SPIN_LOCK(SERVER_LOCK, &s->lock);
-	list_for_each_entry_safe(p, pback, &s->pendconns, list) {
+	for (node = eb32_first(&s->pendconns); node; node = eb32_next(node)) {
+		p = eb32_entry(&node, struct pendconn, node);
 		if (p->strm_flags & SF_FORCE_PRST)
 			continue;
 
@@ -366,7 +373,8 @@ int pendconn_redistribute(struct server *s)
  */
 int pendconn_grab_from_px(struct server *s)
 {
-	struct pendconn *p, *pback;
+	struct pendconn *p;
+	struct eb32_node *node;
 	int maxconn, xferred = 0;
 
 	if (!srv_currently_usable(s))
@@ -383,7 +391,8 @@ int pendconn_grab_from_px(struct server *s)
 
 	HA_SPIN_LOCK(PROXY_LOCK, &s->proxy->lock);
 	maxconn = srv_dynamic_maxconn(s);
-	list_for_each_entry_safe(p, pback, &s->proxy->pendconns, list) {
+	while ((node = eb32_first(&s->proxy->pendconns))) {
+		p = eb32_entry(&node, struct pendconn, node);
 		if (s->maxconn && s->served + xferred >= maxconn)
 			break;
 
@@ -428,7 +437,7 @@ int pendconn_dequeue(struct stream *strm)
 	 * unlinked, these functions were completely done.
 	 */
 	pendconn_queue_lock(p);
-	is_unlinked = LIST_ISEMPTY(&p->list);
+	is_unlinked = !p->node.node.leaf_p;
 	pendconn_queue_unlock(p);
 
 	if (!is_unlinked)

src/server.c

@@ -1627,7 +1627,7 @@ static struct server *new_server(struct proxy *proxy)
 	srv->obj_type = OBJ_TYPE_SERVER;
 	srv->proxy = proxy;
 	LIST_INIT(&srv->actconns);
-	LIST_INIT(&srv->pendconns);
+	srv->pendconns = EB_ROOT;
 
 	if ((srv->priv_conns = calloc(global.nbthread, sizeof(*srv->priv_conns))) == NULL)
 		goto free_srv;