From: Lennart Poettering <lennart@poettering.net>
Date: Sun, 2 Oct 2005 02:16:02 +0000 (+0000)
Subject: * Split up avahi_simple_poll_iterate() into avahi_simple_poll_prepare(),avahi_simple_... 
X-Git-Url: https://git.meshlink.io/?a=commitdiff_plain;h=d3e893754d3158b72d488e515535dfcac980e1c3;p=catta

* Split up avahi_simple_poll_iterate() into avahi_simple_poll_prepare(),avahi_simple_poll_run() and avahi_simple_poll_dispatch()
* Export wakeup function()
* add a userdata argument to poll() function
* add avahi_simple_poll_loop()
* minimize number of system calls
* threading compat improvements
* request pollfd rebuild in avahi_simple_poll_new()


git-svn-id: file:///home/lennart/svn/public/avahi/trunk@671 941a03a8-eaeb-0310-b9a0-b1bbd8fe43fe
---

diff --git a/avahi-common/simple-watch.c b/avahi-common/simple-watch.c
index 6872389..b8a1b82 100644
--- a/avahi-common/simple-watch.c
+++ b/avahi-common/simple-watch.c
@@ -29,6 +29,7 @@
 #include <errno.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <stdio.h>
 
 #include <avahi-common/llist.h>
 #include <avahi-common/malloc.h>
@@ -64,6 +65,7 @@ struct AvahiTimeout {
 struct AvahiSimplePoll {
     AvahiPoll api;
     AvahiPollFunc poll_func;
+    void *poll_func_userdata;
 
     struct pollfd* pollfds;
     int n_pollfds, max_pollfds, rebuild_pollfds;
@@ -77,18 +79,39 @@ struct AvahiSimplePoll {
     AVAHI_LLIST_HEAD(AvahiTimeout, timeouts);
 
     int wakeup_pipe[2];
+    int wakeup_issued;
+
+    int prepared_timeout;
+
+    enum {
+        STATE_INIT,
+        STATE_PREPARING,
+        STATE_PREPARED,
+        STATE_RUNNING,
+        STATE_RAN,
+        STATE_DISPATCHING,
+        STATE_DISPATCHED,
+        STATE_QUIT,
+        STATE_FAILURE
+    } state;
 };
 
-static void wakeup(AvahiSimplePoll *s) {
-    char c = 'x';
+void avahi_simple_poll_wakeup(AvahiSimplePoll *s) {
+    char c = 'W';
     assert(s);
 
     write(s->wakeup_pipe[1], &c, sizeof(c));
+    s->wakeup_issued = 1;
 }
 
 static void clear_wakeup(AvahiSimplePoll *s) {
     char c[10]; /* Read ten at a time */
 
+    if (!s->wakeup_issued)
+        return;
+
+    s->wakeup_issued = 0;
+    
     for(;;)
         if (read(s->wakeup_pipe[0], &c, sizeof(c)) != sizeof(c))
             break;
@@ -121,6 +144,9 @@ static AvahiWatch* watch_new(const AvahiPoll *api, int fd, AvahiWatchEvent event
 
     if (!(w = avahi_new(AvahiWatch, 1)))
         return NULL;
+
+    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
+    avahi_simple_poll_wakeup(s);
     
     w->simple_poll = s;
     w->dead = 0;
@@ -131,22 +157,12 @@ static AvahiWatch* watch_new(const AvahiPoll *api, int fd, AvahiWatchEvent event
     w->callback = callback;
     w->userdata = userdata;
 
-    if (s->n_pollfds < s->max_pollfds) {
-        /* If there's space for this pollfd, go on and allocate it */
-        w->idx = s->n_pollfds++;
-        s->pollfds[w->idx] = w->pollfd;
-        
-    } else {
-        /* Unfortunately there's no place for this pollfd, so request a rebuild of the array */
-        w->idx = -1;
-        s->rebuild_pollfds = 1;
-    }
+    w->idx = -1;
+    s->rebuild_pollfds = 1;
 
     AVAHI_LLIST_PREPEND(AvahiWatch, watches, s->watches, w);
     s->n_watches++;
 
-    wakeup(w->simple_poll);
-
     return w;
 }
 
@@ -154,6 +170,9 @@ static void watch_update(AvahiWatch *w, AvahiWatchEvent events) {
     assert(w);
     assert(!w->dead);
 
+    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
+    avahi_simple_poll_wakeup(w->simple_poll);
+
     w->pollfd.events = events;
 
     if (w->idx != -1) {
@@ -161,8 +180,6 @@ static void watch_update(AvahiWatch *w, AvahiWatchEvent events) {
         w->simple_poll->pollfds[w->idx] = w->pollfd;
     } else
         w->simple_poll->rebuild_pollfds = 1;
-
-    wakeup(w->simple_poll);
 }
 
 static AvahiWatchEvent watch_get_events(AvahiWatch *w) {
@@ -181,16 +198,7 @@ static void remove_pollfd(AvahiWatch *w) {
     if (w->idx == -1)
         return;
     
-    if (w->idx == w->simple_poll->n_pollfds-1) {
-
-        /* This pollfd is at the end of the array, so we can easily cut it */
-
-        assert(w->simple_poll->n_pollfds > 0);
-        w->simple_poll->n_pollfds -= 1;
-    } else
-
-        /* Unfortunately this pollfd is in the middle of the array, so request a rebuild of it */
-        w->simple_poll->rebuild_pollfds = 1;
+    w->simple_poll->rebuild_pollfds = 1;
 }
 
 static void watch_free(AvahiWatch *w) {
@@ -198,13 +206,14 @@ static void watch_free(AvahiWatch *w) {
 
     assert(!w->dead);
 
+    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
+    avahi_simple_poll_wakeup(w->simple_poll);
+    
     remove_pollfd(w);
     
     w->dead = 1;
     w->simple_poll->n_watches --;
     w->simple_poll->watch_req_cleanup = 1;
-
-    wakeup(w->simple_poll);
 }
 
 static void destroy_watch(AvahiWatch *w) {
@@ -245,6 +254,9 @@ static AvahiTimeout* timeout_new(const AvahiPoll *api, const struct timeval *tv,
 
     if (!(t = avahi_new(AvahiTimeout, 1)))
         return NULL;
+
+    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
+    avahi_simple_poll_wakeup(s);
     
     t->simple_poll = s;
     t->dead = 0;
@@ -256,29 +268,29 @@ static AvahiTimeout* timeout_new(const AvahiPoll *api, const struct timeval *tv,
     t->userdata = userdata;
 
     AVAHI_LLIST_PREPEND(AvahiTimeout, timeouts, s->timeouts, t);
-
-    wakeup(t->simple_poll);
     return t;
 }
 
 static void timeout_update(AvahiTimeout *t, const struct timeval *tv) {
     assert(t);
     assert(!t->dead);
+
+    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
+    avahi_simple_poll_wakeup(t->simple_poll);
     
     if ((t->enabled = !!tv))
         t->expiry = *tv;
-
-    wakeup(t->simple_poll);
 }
 
 static void timeout_free(AvahiTimeout *t) {
     assert(t);
     assert(!t->dead);
 
+    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
+    avahi_simple_poll_wakeup(t->simple_poll);
+
     t->dead = 1;
     t->simple_poll->timeout_req_cleanup = 1;
-
-    wakeup(t->simple_poll);
 }
 
 
@@ -331,7 +343,7 @@ AvahiSimplePoll *avahi_simple_poll_new(void) {
     
     s->pollfds = NULL;
     s->max_pollfds = s->n_pollfds = 0;
-    s->rebuild_pollfds = 0;
+    s->rebuild_pollfds = 1;
     s->quit = 0;
     s->n_watches = 0;
     s->events_valid = 0;
@@ -339,7 +351,13 @@ AvahiSimplePoll *avahi_simple_poll_new(void) {
     s->watch_req_cleanup = 0;
     s->timeout_req_cleanup = 0;
 
-    avahi_simple_poll_set_func(s, NULL);
+    s->prepared_timeout = 0;
+
+    s->state = STATE_INIT;
+
+    s->wakeup_issued = 0;
+    
+    avahi_simple_poll_set_func(s, NULL, NULL);
 
     AVAHI_LLIST_HEAD_INIT(AvahiWatch, s->watches);
     AVAHI_LLIST_HEAD_INIT(AvahiTimeout, s->timeouts);
@@ -386,8 +404,10 @@ static int rebuild(AvahiSimplePoll *s) {
     s->pollfds[0].fd = s->wakeup_pipe[0];
     s->pollfds[0].events = POLLIN;
     s->pollfds[0].revents = 0;
+
+    idx = 1;
     
-    for (idx = 1, w = s->watches; w; w = w->watches_next) {
+    for (w = s->watches; w; w = w->watches_next) {
 
         if(w->dead)
             continue;
@@ -419,21 +439,22 @@ static AvahiTimeout* find_next_timeout(AvahiSimplePoll *s) {
     return n;
 }
 
-static int start_timeout_callback(AvahiTimeout *t) {
+static void timeout_callback(AvahiTimeout *t) {
     assert(t);
     assert(!t->dead);
     assert(t->enabled);
 
     t->enabled = 0;
     t->callback(t, t->userdata);
-    return 0;
 }
 
-int avahi_simple_poll_iterate(AvahiSimplePoll *s, int timeout) {
-    int r;
+int avahi_simple_poll_prepare(AvahiSimplePoll *s, int timeout) {
     AvahiTimeout *next_timeout;
+    
     assert(s);
-
+    assert(s->state == STATE_INIT || s->state == STATE_DISPATCHED || s->state == STATE_FAILURE);
+    s->state = STATE_PREPARING;
+    
     /* Clear pending wakeup requests */
     clear_wakeup(s);
 
@@ -445,13 +466,17 @@ int avahi_simple_poll_iterate(AvahiSimplePoll *s, int timeout) {
         cleanup_timeouts(s, 0);
 
     /* Check whether a quit was requested */
-    if (s->quit)
+    if (s->quit) {
+        s->state = STATE_QUIT;
         return 1;
+    }
 
     /* Do we need to rebuild our array of pollfds? */
     if (s->rebuild_pollfds)
-        if (rebuild(s) < 0)
+        if (rebuild(s) < 0) {
+            s->state = STATE_FAILURE;
             return -1;
+        }
 
     /* Calculate the wakeup time */
     if ((next_timeout = find_next_timeout(s))) {
@@ -463,12 +488,9 @@ int avahi_simple_poll_iterate(AvahiSimplePoll *s, int timeout) {
             next_timeout->expiry.tv_usec == 0) {
 
             /* Just a shortcut so that we don't need to call gettimeofday() */
-            
-            /* The events poll() returned in the last call are now no longer valid */
-            s->events_valid = 0;
-            return start_timeout_callback(next_timeout);
+            timeout = 0;
+            goto finish;
         }
-
             
         gettimeofday(&now, NULL);
         usec = avahi_timeval_diff(&next_timeout->expiry, &now);
@@ -476,9 +498,8 @@ int avahi_simple_poll_iterate(AvahiSimplePoll *s, int timeout) {
         if (usec <= 0) {
             /* Timeout elapsed */
 
-            /* The events poll() returned in the last call are now no longer valid */
-            s->events_valid = 0;
-            return start_timeout_callback(next_timeout);
+            timeout = 0;
+            goto finish;
         }
 
         /* Calculate sleep time. We add 1ms because otherwise we'd
@@ -489,44 +510,96 @@ int avahi_simple_poll_iterate(AvahiSimplePoll *s, int timeout) {
             timeout = t;
     }
 
-    if ((r = s->poll_func(s->pollfds, s->n_pollfds, timeout)) < 0)
-        return -1;
+finish:
+    s->prepared_timeout = timeout;
+    s->state = STATE_PREPARED;
+    return 0;
+}
+
+int avahi_simple_poll_run(AvahiSimplePoll *s) {
+    assert(s);
+    assert(s->state == STATE_PREPARED);
+    
+    s->state = STATE_RUNNING;
+
+    if (s->prepared_timeout != 0) {
+    
+        if (s->poll_func(s->pollfds, s->n_pollfds, s->prepared_timeout, s->poll_func_userdata) < 0) {
+            s->state = STATE_FAILURE;
+            return -1;
+        }
+        
+        /* The poll events are now valid again */
+        s->events_valid = 1;
+    } else
+        s->events_valid = 0;
+        
+    /* Update state */
+    s->state = STATE_RAN;
+    return 0;
+}
+
+int avahi_simple_poll_dispatch(AvahiSimplePoll *s) {
+    AvahiTimeout *next_timeout;
+    AvahiWatch *w;
 
-    /* The pollf events are now valid again */
-    s->events_valid = 1;
+    assert(s);
+    assert(s->state == STATE_RAN);
+    s->state = STATE_DISPATCHING;
 
+    /* We execute only on callback in every iteration */
+    
     /* Check whether the wakeup time has been reached now */
     if ((next_timeout = find_next_timeout(s))) {
-        struct timeval now;
         
-        gettimeofday(&now, NULL);
+        if (next_timeout->expiry.tv_sec == 0 && next_timeout->expiry.tv_usec == 0) {
+
+            /* Just a shortcut so that we don't need to call gettimeofday() */
+            timeout_callback(next_timeout);
+            goto finish;
+        }
+        
+        if (avahi_age(&next_timeout->expiry) >= 0) {
 
-        if (avahi_timeval_compare(&next_timeout->expiry, &now) <= 0)
-            /* Time elapsed */
-            return start_timeout_callback(next_timeout);
+            /* Timeout elapsed */
+            timeout_callback(next_timeout);
+            goto finish;
+        }
     }
-    
-    if (r > 0) {
-        AvahiWatch *w;
 
-        /* Look for some kind of I/O event */
+    /* Look for some kind of I/O event */
+    for (w = s->watches; w; w = w->watches_next) {
+        
+        if (w->dead)
+            continue;
+        
+        assert(w->idx >= 0);
+        assert(w->idx < s->n_pollfds);
+        
+        if (s->pollfds[w->idx].revents != 0) {
+            w->callback(w, w->pollfd.fd, s->pollfds[w->idx].revents, w->userdata);
+            goto finish;
+        }
+    }
 
-        for (w = s->watches; w; w = w->watches_next) {
+finish:
 
-            if (w->dead)
-                continue;
+    s->state = STATE_DISPATCHED;
+    return 0;
+}
 
-            assert(w->idx >= 0);
-            assert(w->idx < s->n_pollfds);
+int avahi_simple_poll_iterate(AvahiSimplePoll *s, int timeout) {
+    int r;
 
-            if (s->pollfds[w->idx].revents > 0) {
-                /* We execute only on callback in every iteration */
-                w->callback(w, w->pollfd.fd, s->pollfds[w->idx].revents, w->userdata);
-                return 0;
-            }
-        }
-    }
+    if ((r = avahi_simple_poll_prepare(s, timeout)) != 0)
+        return r;
+
+    if ((r = avahi_simple_poll_run(s)) != 0)
+        return r;
 
+    if ((r = avahi_simple_poll_dispatch(s)) != 0)
+        return r;
+    
     return 0;
 }
 
@@ -534,7 +607,9 @@ void avahi_simple_poll_quit(AvahiSimplePoll *s) {
     assert(s);
 
     s->quit = 1;
-    wakeup(s);
+
+    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
+    avahi_simple_poll_wakeup(s);
 }
 
 const AvahiPoll* avahi_simple_poll_get(AvahiSimplePoll *s) {
@@ -543,9 +618,26 @@ const AvahiPoll* avahi_simple_poll_get(AvahiSimplePoll *s) {
     return &s->api;
 }
 
-void avahi_simple_poll_set_func(AvahiSimplePoll *s, AvahiPollFunc func) {
+static int system_poll(struct pollfd *ufds, unsigned int nfds, int timeout, void *userdata) {
+    return poll(ufds, nfds, timeout);
+}
+
+void avahi_simple_poll_set_func(AvahiSimplePoll *s, AvahiPollFunc func, void *userdata) {
     assert(s);
 
-    s->poll_func = func ? func : (AvahiPollFunc) poll;
-    wakeup(s);
+    s->poll_func = func ? func : system_poll;
+    s->poll_func_userdata = func ? userdata : NULL;
+
+    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
+    avahi_simple_poll_wakeup(s);
+}
+
+int avahi_simple_poll_loop(AvahiSimplePoll *s) {
+    int r;
+
+    assert(s);
+    
+    for (;;)
+        if ((r = avahi_simple_poll_iterate(s, -1)) != 0)
+            return r;
 }
diff --git a/avahi-common/simple-watch.h b/avahi-common/simple-watch.h
index c8234f2..0833570 100644
--- a/avahi-common/simple-watch.h
+++ b/avahi-common/simple-watch.h
@@ -65,10 +65,25 @@ int avahi_simple_poll_iterate(AvahiSimplePoll *s, int sleep_time);
 void avahi_simple_poll_quit(AvahiSimplePoll *s);
 
 /** Prototype for a poll() type function */
-typedef int (*AvahiPollFunc)(struct pollfd *ufds, unsigned int nfds, int timeout);
+typedef int (*AvahiPollFunc)(struct pollfd *ufds, unsigned int nfds, int timeout, void *userdata);
 
 /** Replace the internally used poll() function. By default the system's poll() will be used */
-void avahi_simple_poll_set_func(AvahiSimplePoll *s, AvahiPollFunc func);
+void avahi_simple_poll_set_func(AvahiSimplePoll *s, AvahiPollFunc func, void *userdata);
+
+/** The first stage of avahi_simple_poll_iterate(), use this function only if you know what you do */
+int avahi_simple_poll_prepare(AvahiSimplePoll *s, int timeout);
+
+/** The second stage of avahi_simple_poll_iterate(), use this function only if you know what you do */
+int avahi_simple_poll_run(AvahiSimplePoll *s);
+
+/** The third and final stage of avahi_simple_poll_iterate(), use this function only if you know what you do */
+int avahi_simple_poll_dispatch(AvahiSimplePoll *s);
+
+/** Call avahi_simple_poll_iterate() in a loop and return if it returns non-zero */
+int avahi_simple_poll_loop(AvahiSimplePoll *s);
+
+/** Wakeup the main loop. (for threaded environments) */
+void avahi_simple_poll_wakeup(AvahiSimplePoll *s);
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
 AVAHI_C_DECL_END
diff --git a/avahi-common/watch-test.c b/avahi-common/watch-test.c
index ffb2149..921a8f7 100644
--- a/avahi-common/watch-test.c
+++ b/avahi-common/watch-test.c
@@ -78,9 +78,10 @@ int main(int argc, char *argv[]) {
     api->timeout_new(api, &tv, wakeup, NULL);
 
     /* Our main loop */
-    for (;;)
-        if (avahi_simple_poll_iterate(simple_poll, -1) != 0)
-            break;
+    avahi_simple_poll_loop(simple_poll);
+
+
+    avahi_simple_poll_free(simple_poll);
     
     return 0;
 }