Commit f89fe72a authored by Jim Jagielski's avatar Jim Jagielski
Browse files

Merge r1666468, r1666618, r1674697 from trunk: 

mpm_event: Allow for timer events duplicates. 
Meanwhile ap[r]_skiplist_add()...


mpm_event: follow up to r1666468.
We only need one compare function for add semantic with apr_skiplist_insert()
and unique timers (pointers). It also should work with apr_skiplist_remove()
and apr_skiplist_find(), be they used some day.


mpm_event: follow up to r1666468 and r1666618.
We don't need to return 0 in the compare function, but for debugging purpose
which we could implement later if necessary (in a separate function).
For now, keep the function simple as in 2.4.x to ease backport, and add a
comment about why we never return 0 here.

Submitted by: ylavic
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1674921 13f79535-47bb-0310-9956-ffa450edef68
parent eec276d7

CHANGES

+2 −0
Changes for CHANGES: 2 added lines, 0 removed lines.
Original line number Diff line number Diff line
@@ -12,6 +12,8 @@ Changes with Apache 2.4.13 
     calls r:wsupgrade() can cause a child process crash. 

     [Edward Lu <Chaosed0 gmail.com>]



  *) mpm_event: Allow for timer events duplicates. [Jim Jagielski, Yann Ylavic]



  *) mod_proxy, mod_ssl, mod_cache_socache, mod_socache_*: Support machine

     readable server-status produced when using the "?auto" query string.

     [Rainer Jung]

server/mpm/event/event.c

+20 −16
Changes for server/mpm/event/event.c: 20 added lines, 16 removed lines.
Original line number Diff line number Diff line
@@ -1333,21 +1333,25 @@ static APR_RING_HEAD(timer_free_ring_t, timer_event_t) timer_free_ring; 


static apr_skiplist *timer_skiplist;



static int indexing_comp(void *a, void *b)

{

    apr_time_t t1 = (apr_time_t) (((timer_event_t *) a)->when);

    apr_time_t t2 = (apr_time_t) (((timer_event_t *) b)->when);

/* The following compare function is used by apr_skiplist_insert() to keep the

 * elements (timers) sorted and provide O(log n) complexity (this is also true

 * for apr_skiplist_{find,remove}(), but those are not used in MPM event where

 * inserted timers are not searched nor removed, but with apr_skiplist_pop()

 * which does use any compare function).  It is meant to return 0 when a == b,

 * <0 when a < b, and >0 when a > b.  However apr_skiplist_insert() will not

 * add duplicates (i.e. a == b), and apr_skiplist_add() is only available in

 * APR 1.6, yet multiple timers could possibly be created in the same micro-

 * second (duplicates with regard to apr_time_t); therefore we implement the

 * compare function to return +1 instead of 0 when compared timers are equal,

 * thus duplicates are still added after each other (in order of insertion).

 */

static int timer_comp(void *a, void *b)

{

    apr_time_t t1 = (apr_time_t) ((timer_event_t *)a)->when;

    apr_time_t t2 = (apr_time_t) ((timer_event_t *)b)->when;

    AP_DEBUG_ASSERT(t1);

    AP_DEBUG_ASSERT(t2);

    return ((t1 < t2) ? -1 : ((t1 > t2) ? 1 : 0));

}



static int indexing_compk(void *ac, void *b)

{

    apr_time_t *t1 = (apr_time_t *) ac;

    apr_time_t t2 = (apr_time_t) (((timer_event_t *) b)->when);

    AP_DEBUG_ASSERT(t2);

    return ((*t1 < t2) ? -1 : ((*t1 > t2) ? 1 : 0));

    return ((t1 < t2) ? -1 : 1);

}



static apr_thread_mutex_t *g_timer_skiplist_mtx;
@@ -1374,8 +1378,8 @@ static apr_status_t event_register_timed_callback(apr_time_t t, 
    /* XXXXX: optimize */

    te->when = t + apr_time_now();



    /* Okay, insert sorted by when.. */

    apr_skiplist_insert(timer_skiplist, (void *)te);

    /* Okay, add sorted by when.. */

    apr_skiplist_insert(timer_skiplist, te);



    apr_thread_mutex_unlock(g_timer_skiplist_mtx);
@@ -2237,7 +2241,7 @@ static void child_main(int child_num_arg) 
    apr_thread_mutex_create(&g_timer_skiplist_mtx, APR_THREAD_MUTEX_DEFAULT, pchild);

    APR_RING_INIT(&timer_free_ring, timer_event_t, link);

    apr_skiplist_init(&timer_skiplist, pchild);

    apr_skiplist_set_compare(timer_skiplist, indexing_comp, indexing_compk);

    apr_skiplist_set_compare(timer_skiplist, timer_comp, timer_comp);

    ap_run_child_init(pchild, ap_server_conf);



    /* done with init critical section */