add new realtime event loop abstraction which precise time keeping by using hrtimers on Linux, if they are available

git-svn-id: file:///home/lennart/svn/public/pulseaudio/branches/lennart@1689 fefdeb5f-60dc-0310-8127-8f9354f1896f

2 files changed, 525 insertions, 0 deletions

diff --git a/src/pulsecore/rtpoll.c b/src/pulsecore/rtpoll.c
new file mode 100644
index 00000000..36549b5e
--- /dev/null
+++ b/src/pulsecore/rtpoll.c
@@ -0,0 +1,454 @@
+/* $Id$ */
+
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2004-2006 Lennart Poettering
+  Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <sys/utsname.h>
+#include <sys/types.h>
+#include <stdio.h>
+#include <signal.h>
+#include <string.h>
+#include <errno.h>
+
+#include <pulse/xmalloc.h>
+
+#include <pulsecore/core-error.h>
+#include <pulsecore/rtclock.h>
+#include <pulsecore/macro.h>
+#include <pulsecore/llist.h>
+#include <pulsecore/rtsig.h>
+#include <pulsecore/flist.h>
+
+#include "rtpoll.h"
+
+struct pa_rtpoll {
+
+    struct pollfd *pollfd, *pollfd2;
+    unsigned n_pollfd_alloc, n_pollfd_used;
+
+    pa_usec_t interval;
+
+    int scan_for_dead;
+    int running, installed, rebuild_needed;
+
+#ifdef HAVE_PPOLL
+    int rtsig;
+    sigset_t sigset_unblocked;
+    struct timespec interval_timespec;
+    timer_t timer;
+#ifdef __linux__
+    int dont_use_ppoll;
+#endif    
+#endif
+    
+    PA_LLIST_HEAD(pa_rtpoll_item, items);
+};
+
+struct pa_rtpoll_item {
+    pa_rtpoll *rtpoll;
+    int dead;
+
+    struct pollfd *pollfd;
+    unsigned n_pollfd;
+
+    int (*before_cb)(pa_rtpoll_item *i);
+    void (*after_cb)(pa_rtpoll_item *i);
+    void *userdata;
+    
+    PA_LLIST_FIELDS(pa_rtpoll_item);
+};
+
+PA_STATIC_FLIST_DECLARE(items, 0, pa_xfree);
+
+static void signal_handler_noop(int s) { }
+
+pa_rtpoll *pa_rtpoll_new(void) {
+    pa_rtpoll *p;
+
+    p = pa_xnew(pa_rtpoll, 1);
+
+#ifdef HAVE_PPOLL
+
+#ifdef __linux__
+    /* ppoll is broken on Linux < 2.6.16 */
+    
+    p->dont_use_ppoll = 0;
+
+    {
+        struct utsname u;
+        unsigned major, minor, micro;
+    
+        pa_assert_se(uname(&u) == 0);
+
+        if (sscanf(u.release, "%u.%u.%u", &major, &minor, &micro) != 3 ||
+            (major < 2) ||
+            (major == 2 && minor < 6) ||
+            (major == 2 && minor == 6 && micro < 16))
+
+            p->dont_use_ppoll = 1;
+    }
+
+#endif
+
+    p->rtsig = -1;
+    sigemptyset(&p->sigset_unblocked);
+    memset(&p->interval_timespec, 0, sizeof(p->interval_timespec));
+    p->timer = (timer_t) -1;
+        
+#endif
+
+    p->n_pollfd_alloc = 32;
+    p->pollfd = pa_xnew(struct pollfd, p->n_pollfd_alloc);
+    p->pollfd2 = pa_xnew(struct pollfd, p->n_pollfd_alloc);
+    p->n_pollfd_used = 0;
+
+    p->interval = 0;
+
+    p->running = 0;
+    p->installed = 0;
+    p->scan_for_dead = 0;
+    p->rebuild_needed = 0;
+    
+    PA_LLIST_HEAD_INIT(pa_rtpoll_item, p->items);
+
+    return p;
+}
+
+void pa_rtpoll_install(pa_rtpoll *p) {
+    pa_assert(p);
+    pa_assert(!p->installed);
+    
+    p->installed = 1;
+
+#ifdef HAVE_PPOLL
+    if (p->dont_use_ppoll)
+        return;
+
+    if ((p->rtsig = pa_rtsig_get_for_thread()) < 0) {
+        pa_log_warn("Failed to reserve POSIX realtime signal.");
+        return;
+    }
+
+    pa_log_debug("Acquired POSIX realtime signal SIGRTMIN+%i", p->rtsig - SIGRTMIN);
+
+    {
+        sigset_t ss;
+        struct sigaction sa;
+        
+        pa_assert_se(sigemptyset(&ss) == 0);
+        pa_assert_se(sigaddset(&ss, p->rtsig) == 0);
+        pa_assert_se(pthread_sigmask(SIG_BLOCK, &ss, &p->sigset_unblocked) == 0);
+        pa_assert_se(sigdelset(&p->sigset_unblocked, p->rtsig) == 0);
+
+        memset(&sa, 0, sizeof(sa));
+        sa.sa_handler = signal_handler_noop;
+        pa_assert_se(sigemptyset(&sa.sa_mask) == 0);
+        
+        pa_assert_se(sigaction(p->rtsig, &sa, NULL) == 0);
+        
+        /* We never reset the signal handler. Why should we? */
+    }
+    
+#endif
+}
+
+static void rtpoll_rebuild(pa_rtpoll *p) {
+
+    struct pollfd *e, *t;
+    pa_rtpoll_item *i;
+    int ra = 0;
+    
+    pa_assert(p);
+
+    p->rebuild_needed = 0;
+
+    if (p->n_pollfd_used > p->n_pollfd_alloc) {
+        /* Hmm, we have to allocate some more space */
+        p->n_pollfd_alloc = p->n_pollfd_used * 2;
+        p->pollfd2 = pa_xrealloc(p->pollfd2, p->n_pollfd_alloc * sizeof(struct pollfd));
+        ra = 1;
+    }
+
+    e = p->pollfd2;
+
+    for (i = p->items; i; i = i->next) {
+
+        if (i->n_pollfd > 0)  {
+            size_t l = i->n_pollfd * sizeof(struct pollfd);
+            
+            if (i->pollfd)
+                memcpy(e, i->pollfd, l);
+            else
+                memset(e, 0, l);
+
+            i->pollfd = e;
+        } else
+            i->pollfd = NULL;
+        
+        e += i->n_pollfd;
+    }
+
+    pa_assert((unsigned) (e - p->pollfd2) == p->n_pollfd_used);
+    t = p->pollfd;
+    p->pollfd = p->pollfd2;
+    p->pollfd2 = t;
+    
+    if (ra)
+        p->pollfd2 = pa_xrealloc(p->pollfd2, p->n_pollfd_alloc * sizeof(struct pollfd));
+
+}
+
+static void rtpoll_item_destroy(pa_rtpoll_item *i) {
+    pa_rtpoll *p;
+
+    pa_assert(i);
+
+    p = i->rtpoll;
+
+    PA_LLIST_REMOVE(pa_rtpoll_item, p->items, i);
+
+    p->n_pollfd_used -= i->n_pollfd;
+    
+    if (pa_flist_push(PA_STATIC_FLIST_GET(items), i) < 0)
+        pa_xfree(i);
+
+    p->rebuild_needed = 1;
+}
+
+void pa_rtpoll_free(pa_rtpoll *p) {
+    pa_assert(p);
+
+    pa_assert(!p->items);
+    pa_xfree(p->pollfd);
+    pa_xfree(p->pollfd2);
+
+#ifdef HAVE_PPOLL
+    if (p->timer != (timer_t) -1) 
+        timer_delete(p->timer);
+#endif
+    
+    pa_xfree(p);
+}
+
+int pa_rtpoll_run(pa_rtpoll *p) {
+    pa_rtpoll_item *i;
+    int r = 0;
+    
+    pa_assert(p);
+    pa_assert(!p->running);
+    pa_assert(p->installed);
+    
+    p->running = 1;
+
+    for (i = p->items; i; i = i->next) {
+
+        if (i->dead)
+            continue;
+        
+        if (!i->before_cb)
+            continue;
+
+        if (i->before_cb(i) < 0) {
+
+            /* Hmm, this one doesn't let us enter the poll, so rewind everything */
+
+            for (i = i->prev; i; i = i->prev) {
+
+                if (i->dead)
+                    continue;
+                
+                if (!i->after_cb)
+                    continue;
+
+                i->after_cb(i);
+            }
+            
+            goto finish;
+        }
+    }
+
+    if (p->rebuild_needed)
+        rtpoll_rebuild(p);
+    
+    /* OK, now let's sleep */
+#ifdef HAVE_PPOLL
+
+#ifdef __linux__
+    if (!p->dont_use_ppoll)
+#endif
+        r = ppoll(p->pollfd, p->n_pollfd_used, p->interval > 0  ? &p->interval_timespec : NULL, p->rtsig < 0 ? NULL : &p->sigset_unblocked);
+#ifdef __linux__
+    else
+#endif
+
+#else
+        r = poll(p->pollfd, p->n_pollfd_used, p->interval > 0 ? p->interval / 1000 : -1);
+#endif
+
+    if (r < 0 && (errno == EAGAIN || errno == EINTR))
+        r = 0;
+
+    for (i = p->items; i; i = i->next) {
+
+        if (i->dead)
+            continue;
+
+        if (!i->after_cb)
+            continue;
+
+        i->after_cb(i);
+    }
+
+finish:
+
+    p->running = 0;
+        
+    if (p->scan_for_dead) {
+        pa_rtpoll_item *n;
+
+        p->scan_for_dead = 0;
+        
+        for (i = p->items; i; i = n) {
+            n = i->next;
+
+            if (i->dead)
+                rtpoll_item_destroy(i);
+        }
+    }
+
+    return r;
+}
+
+void pa_rtpoll_set_itimer(pa_rtpoll *p, pa_usec_t usec) {
+    pa_assert(p);
+
+    p->interval = usec;
+
+#ifdef HAVE_PPOLL
+    pa_timespec_store(&p->interval_timespec, usec);
+
+#ifdef __linux__
+    if (!p->dont_use_ppoll) {
+#endif
+        
+        if (p->timer == (timer_t) -1) {
+            struct sigevent se;
+
+            memset(&se, 0, sizeof(se));
+            se.sigev_notify = SIGEV_SIGNAL;
+            se.sigev_signo = p->rtsig;
+
+            if (timer_create(CLOCK_MONOTONIC, &se, &p->timer) < 0)
+                if (timer_create(CLOCK_REALTIME, &se, &p->timer) < 0) {
+                    pa_log_warn("Failed to allocate POSIX timer: %s", pa_cstrerror(errno));
+                    p->timer = (timer_t) -1;
+                }
+        }
+
+        if (p->timer != (timer_t) -1) {
+            struct itimerspec its;
+
+            memset(&its, 0, sizeof(its));
+            pa_timespec_store(&its.it_value, usec);
+            pa_timespec_store(&its.it_interval, usec);
+
+            assert(timer_settime(p->timer, 0, &its, NULL) == 0);
+        }
+
+#ifdef __linux__
+    }
+#endif
+    
+#endif
+}
+
+pa_rtpoll_item *pa_rtpoll_item_new(pa_rtpoll *p, unsigned n_fds) {
+    pa_rtpoll_item *i;
+    
+    pa_assert(p);
+    pa_assert(n_fds > 0);
+
+    if (!(i = pa_flist_pop(PA_STATIC_FLIST_GET(items))))
+        i = pa_xnew(pa_rtpoll_item, 1);
+
+    i->rtpoll = p;
+    i->dead = 0;
+    i->n_pollfd = n_fds;
+    i->pollfd = NULL;
+
+    i->userdata = NULL;
+    i->before_cb = NULL;
+    i->after_cb = NULL;
+    
+    PA_LLIST_PREPEND(pa_rtpoll_item, p->items, i);
+
+    p->rebuild_needed = 1;
+    p->n_pollfd_used += n_fds;
+
+    return i;
+}
+
+void pa_rtpoll_item_free(pa_rtpoll_item *i) {
+    pa_assert(i);
+
+    if (i->rtpoll->running) {
+        i->dead = 1;
+        i->rtpoll->scan_for_dead = 1;
+        return;
+    }
+
+    rtpoll_item_destroy(i);
+}
+
+struct pollfd *pa_rtpoll_item_get_pollfd(pa_rtpoll_item *i, unsigned *n_fds) {
+    pa_assert(i);
+
+    if (i->rtpoll->rebuild_needed)
+        rtpoll_rebuild(i->rtpoll);
+    
+    if (n_fds)
+        *n_fds = i->n_pollfd;
+    
+    return i->pollfd;
+}
+
+void pa_rtpoll_item_set_before_callback(pa_rtpoll_item *i, int (*before_cb)(pa_rtpoll_item *i)) {
+    pa_assert(i);
+
+    i->before_cb = before_cb;
+}
+
+void pa_rtpoll_item_set_after_callback(pa_rtpoll_item *i, void (*after_cb)(pa_rtpoll_item *i)) {
+    pa_assert(i);
+
+    i->after_cb = after_cb;
+}
+
+void pa_rtpoll_item_set_userdata(pa_rtpoll_item *i, void *userdata) {
+    pa_assert(i);
+
+    i->userdata = userdata;
+}
diff --git a/src/pulsecore/rtpoll.h b/src/pulsecore/rtpoll.h
new file mode 100644
index 00000000..5e508e1b
--- /dev/null
+++ b/src/pulsecore/rtpoll.h
@@ -0,0 +1,71 @@
+#ifndef foopulsertpollhfoo
+#define foopulsertpollhfoo
+
+/* $Id$ */
+
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2004-2006 Lennart Poettering
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#include <poll.h>
+#include <sys/types.h>
+
+#include <pulse/sample.h>
+
+/* An implementation of a "real-time" poll loop. Basically, this is
+ * yet another wrapper around poll(). However it has certain
+ * advantages over pa_mainloop and suchlike:
+ *
+ * 1) It uses timer_create() and POSIX real time signals to guarantee
+ * optimal high-resolution timing. Starting with Linux 2.6.21 hrtimers
+ * are available, and since right now only nanosleep() and the POSIX
+ * clock and timer interfaces have been ported to hrtimers (and not
+ * ppoll/pselect!) we have to combine ppoll() with timer_create(). The
+ * fact that POSIX timers and POSIX rt signals are used internally is
+ * completely hidden.
+ *
+ * 2) It allows raw access to the pollfd data to users
+ *
+ * 3) It allows arbitrary functions to be run before entering the
+ * actual poll() and after it.
+ *
+ * Only a single interval timer is supported..*/
+
+typedef struct pa_rtpoll pa_rtpoll;
+typedef struct pa_rtpoll_item pa_rtpoll_item;
+
+pa_rtpoll *pa_rtpoll_new(void);
+void pa_rtpoll_free(pa_rtpoll *p);
+
+void pa_rtpoll_install(pa_rtpoll *p);
+
+int pa_rtpoll_run(pa_rtpoll *f);
+void pa_rtpoll_set_itimer(pa_rtpoll *p, pa_usec_t usec);
+
+pa_rtpoll_item *pa_rtpoll_item_new(pa_rtpoll *p, unsigned n_fds);
+void pa_rtpoll_item_free(pa_rtpoll_item *i);
+
+struct pollfd *pa_rtpoll_item_get_pollfd(pa_rtpoll_item *i, unsigned *n_fds);
+
+void pa_rtpoll_item_set_before_callback(pa_rtpoll_item *i, int (*before_cb)(pa_rtpoll_item *i));
+void pa_rtpoll_item_set_after_callback(pa_rtpoll_item *i, void (*after_cb)(pa_rtpoll_item *i));
+void pa_rtpoll_item_set_userdata(pa_rtpoll_item *i, void *userdata);
+
+#endif