[MEDIUM] slightly optimize the scheduler for non-expirable tasks.

The non-expirable tasks are now sent to a dedicated wait-queue so that
they do not pollute the other ones anymore. This is a temporary dirty
hack which will go away with the new O(log(n)) scheduler.

diff --git a/haproxy.c b/haproxy.c
index 10cb6e5d8bbbd8a2d439ef1fd050d3260e2321f7..5a3f1cb237bc292ad0f18e7bce747e518ed57b7d 100644 (file)
--- a/haproxy.c
+++ b/haproxy.c
@@ -733,9 +733,15 @@ void **pool_session = NULL,
 struct proxy *proxy  = NULL;   /* list of all existing proxies */
 struct fdtab *fdtab = NULL;    /* array of all the file descriptors */
 struct task *rq = NULL;                /* global run queue */
-struct task wait_queue = {     /* global wait queue */
-    prev:LIST_HEAD(wait_queue),
-    next:LIST_HEAD(wait_queue)
+struct task wait_queue[2] = {  /* global wait queue */
+    {
+       prev:LIST_HEAD(wait_queue[0]),  /* expirable tasks */
+       next:LIST_HEAD(wait_queue[0]),
+    },
+    {
+       prev:LIST_HEAD(wait_queue[1]),  /* non-expirable tasks */
+       next:LIST_HEAD(wait_queue[1]),
+    },
 };
 
 static int totalconn = 0;      /* total # of terminated sessions */
@@ -1695,7 +1701,31 @@ struct task *task_queue(struct task *task) {
     struct task *list = task->wq;
     struct task *start_from;
 
-    /* first, test if the task was already in a list */
+    /* This is a very dirty hack to queue non-expirable tasks in another queue
+     * in order to avoid pulluting the tail of the standard queue. This will go
+     * away with the new O(log(n)) scheduler anyway.
+     */
+    if (tv_iseternity(&task->expire)) {
+       /* if the task was queued in the standard wait queue, we must dequeue it */
+       if (task->prev) {
+           if (task->wq == LIST_HEAD(wait_queue[1]))
+               return task;
+           else {
+               task_delete(task);
+               task->prev = NULL;
+           }
+       }
+       list = task->wq = LIST_HEAD(wait_queue[1]);
+    } else {
+       /* if the task was queued in the eternity queue, we must dequeue it */
+       if (task->prev && (task->wq == LIST_HEAD(wait_queue[1]))) {
+           task_delete(task);
+           task->prev = NULL;
+           list = task->wq = LIST_HEAD(wait_queue[0]);
+       }
+    }
+
+    /* next, test if the task was already in a list */
     if (task->prev == NULL) {
        //      start_from = list;
        start_from = list->prev;
@@ -3085,7 +3115,7 @@ int event_accept(int fd) {
            setsockopt(cfd, SOL_SOCKET, SO_KEEPALIVE, (char *) &one, sizeof(one));
 
        t->next = t->prev = t->rqnext = NULL; /* task not in run queue yet */
-       t->wq = LIST_HEAD(wait_queue); /* but already has a wait queue assigned */
+       t->wq = LIST_HEAD(wait_queue[0]); /* but already has a wait queue assigned */
        t->state = TASK_IDLE;
        t->process = process_session;
        t->context = s;
@@ -5973,8 +6003,8 @@ int process_runnable_tasks() {
 
   /* look for expired tasks and add them to the run queue.
    */
-  tnext = ((struct task *)LIST_HEAD(wait_queue))->next;
-  while ((t = tnext) != LIST_HEAD(wait_queue)) { /* we haven't looped ? */
+  tnext = ((struct task *)LIST_HEAD(wait_queue[0]))->next;
+  while ((t = tnext) != LIST_HEAD(wait_queue[0])) { /* we haven't looped ? */
       tnext = t->next;
       if (t->state & TASK_RUNNING)
          continue;
@@ -6735,8 +6765,8 @@ void dump(int sig) {
     struct task *t, *tnext;
     struct session *s;
 
-    tnext = ((struct task *)LIST_HEAD(wait_queue))->next;
-    while ((t = tnext) != LIST_HEAD(wait_queue)) { /* we haven't looped ? */
+    tnext = ((struct task *)LIST_HEAD(wait_queue[0]))->next;
+    while ((t = tnext) != LIST_HEAD(wait_queue[0])) { /* we haven't looped ? */
        tnext = t->next;
        s = t->context;
        qfprintf(stderr,"[dump] wq: task %p, still %ld ms, "
@@ -8532,7 +8562,7 @@ int readcfgfile(char *file) {
                    }
                
                    t->next = t->prev = t->rqnext = NULL; /* task not in run queue yet */
-                   t->wq = LIST_HEAD(wait_queue); /* but already has a wait queue assigned */
+                   t->wq = LIST_HEAD(wait_queue[0]); /* but already has a wait queue assigned */
                    t->state = TASK_IDLE;
                    t->process = process_chk;
                    t->context = newsrv;
@@ -9351,7 +9381,7 @@ static int appsession_task_init(void)
        if ((t = pool_alloc(task)) == NULL)
            return -1;
        t->next = t->prev = t->rqnext = NULL;
-       t->wq = LIST_HEAD(wait_queue);
+       t->wq = LIST_HEAD(wait_queue[0]);
        t->state = TASK_IDLE;
        t->context = NULL;
        tv_delayfrom(&t->expire, &now, TBLCHKINT);