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Re: [Qemu-devel] [PATCH 3/7] Add support for glib based threading and co


From: Aurelien Jarno
Subject: Re: [Qemu-devel] [PATCH 3/7] Add support for glib based threading and convert qemu thread to use it
Date: Tue, 25 Jan 2011 15:24:48 +0100
User-agent: Mutt/1.5.18 (2008-05-17)

On Mon, Jan 24, 2011 at 03:00:41PM -0600, Anthony Liguori wrote:
> GLib is an extremely common library that has a portable thread implementation
> along with tons of other goodies.
> 
> GLib and GObject have a fantastic amount of infrastructure we can leverage in
> QEMU including an object oriented programming infrastructure.
> 
> Short term, it has a very nice thread pool implementation that we could 
> leverage
> in something like virtio-9p.
> 
> Signed-off-by: Anthony Liguori <address@hidden>
> 
> diff --git a/Makefile b/Makefile
> index 6d601ee..bf24d1b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -104,6 +104,8 @@ audio/audio.o audio/fmodaudio.o: QEMU_CFLAGS += 
> $(FMOD_CFLAGS)
>  
>  QEMU_CFLAGS+=$(CURL_CFLAGS)
>  
> +QEMU_CFLAGS+=$(GLIB_CFLAGS)
> +
>  ui/cocoa.o: ui/cocoa.m
>  
>  ui/sdl.o audio/sdlaudio.o ui/sdl_zoom.o baum.o: QEMU_CFLAGS += $(SDL_CFLAGS)
> diff --git a/Makefile.objs b/Makefile.objs
> index c3e52c5..283e62a 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -316,3 +316,5 @@ vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
>  
>  vl.o: QEMU_CFLAGS+=$(SDL_CFLAGS)
>  
> +vl.o: QEMU_CFLAGS+=$(GLIB_CFLAGS)
> +
> diff --git a/Makefile.target b/Makefile.target
> index e15b1c4..2c1c90e 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -204,6 +204,7 @@ QEMU_CFLAGS += $(VNC_TLS_CFLAGS)
>  QEMU_CFLAGS += $(VNC_SASL_CFLAGS)
>  QEMU_CFLAGS += $(VNC_JPEG_CFLAGS)
>  QEMU_CFLAGS += $(VNC_PNG_CFLAGS)
> +QEMU_CFLAGS += $(GLIB_CFLAGS)
>  
>  # xen backend driver support
>  obj-$(CONFIG_XEN) += xen_machine_pv.o xen_domainbuild.o
> diff --git a/configure b/configure
> index d5ac074..820fde9 100755
> --- a/configure
> +++ b/configure
> @@ -1658,6 +1658,17 @@ EOF
>  fi
>  
>  ##########################################
> +# glib support probe
> +if $pkg_config --modversion gthread-2.0 > /dev/null 2>&1 ; then
> +    glib_cflags=`$pkg_config --cflags gthread-2.0 2>/dev/null`
> +    glib_libs=`$pkg_config --libs gthread-2.0 2>/dev/null`
> +    libs_softmmu="$glib_libs $libs_softmmu"
> +else
> +    echo "glib-2.0 required to compile QEMU"
> +    exit 1
> +fi
> +
> +##########################################
>  # kvm probe
>  if test "$kvm" != "no" ; then
>      cat > $TMPC <<EOF
> @@ -2677,6 +2688,7 @@ if test "$bluez" = "yes" ; then
>    echo "CONFIG_BLUEZ=y" >> $config_host_mak
>    echo "BLUEZ_CFLAGS=$bluez_cflags" >> $config_host_mak
>  fi
> +echo "GLIB_CFLAGS=$glib_cflags" >> $config_host_mak
>  if test "$xen" = "yes" ; then
>    echo "CONFIG_XEN=y" >> $config_host_mak
>  fi
> diff --git a/qemu-thread.c b/qemu-thread.c
> index fbc78fe..2c521ab 100644
> --- a/qemu-thread.c
> +++ b/qemu-thread.c
> @@ -10,183 +10,142 @@
>   * See the COPYING file in the top-level directory.
>   *
>   */
> -#include <stdlib.h>
> -#include <stdio.h>
> -#include <errno.h>
> -#include <time.h>
> -#include <signal.h>
> -#include <stdint.h>
> -#include <string.h>

Why removing <signal.h>?

> -#include "qemu-thread.h"
>  
> -static void error_exit(int err, const char *msg)
> -{
> -    fprintf(stderr, "qemu: %s: %s\n", msg, strerror(err));
> -    exit(1);
> -}
> +#include "qemu-common.h"
> +#include "qemu-thread.h"
>  
>  void qemu_mutex_init(QemuMutex *mutex)
>  {
> -    int err;
> -
> -    err = pthread_mutex_init(&mutex->lock, NULL);
> -    if (err)
> -        error_exit(err, __func__);
> +    g_static_mutex_init(&mutex->lock);
>  }
>  
>  void qemu_mutex_destroy(QemuMutex *mutex)
>  {
> -    int err;
> -
> -    err = pthread_mutex_destroy(&mutex->lock);
> -    if (err)
> -        error_exit(err, __func__);
> +    g_static_mutex_free(&mutex->lock);
>  }
>  
>  void qemu_mutex_lock(QemuMutex *mutex)
>  {
> -    int err;
> -
> -    err = pthread_mutex_lock(&mutex->lock);
> -    if (err)
> -        error_exit(err, __func__);
> +    g_static_mutex_lock(&mutex->lock);
>  }
>  
>  int qemu_mutex_trylock(QemuMutex *mutex)
>  {
> -    return pthread_mutex_trylock(&mutex->lock);
> -}
> -
> -static void timespec_add_ms(struct timespec *ts, uint64_t msecs)
> -{
> -    ts->tv_sec = ts->tv_sec + (long)(msecs / 1000);
> -    ts->tv_nsec = (ts->tv_nsec + ((long)msecs % 1000) * 1000000);
> -    if (ts->tv_nsec >= 1000000000) {
> -        ts->tv_nsec -= 1000000000;
> -        ts->tv_sec++;
> -    }
> -}
> -
> -int qemu_mutex_timedlock(QemuMutex *mutex, uint64_t msecs)
> -{
> -    int err;
> -    struct timespec ts;
> -
> -    clock_gettime(CLOCK_REALTIME, &ts);
> -    timespec_add_ms(&ts, msecs);
> -
> -    err = pthread_mutex_timedlock(&mutex->lock, &ts);
> -    if (err && err != ETIMEDOUT)
> -        error_exit(err, __func__);
> -    return err;
> +    return g_static_mutex_trylock(&mutex->lock);
>  }
>  
>  void qemu_mutex_unlock(QemuMutex *mutex)
>  {
> -    int err;
> -
> -    err = pthread_mutex_unlock(&mutex->lock);
> -    if (err)
> -        error_exit(err, __func__);
> +    g_static_mutex_unlock(&mutex->lock);
>  }
>  
>  void qemu_cond_init(QemuCond *cond)
>  {
> -    int err;
> -
> -    err = pthread_cond_init(&cond->cond, NULL);
> -    if (err)
> -        error_exit(err, __func__);
> +    cond->cond = g_cond_new();
>  }
>  
>  void qemu_cond_destroy(QemuCond *cond)
>  {
> -    int err;
> -
> -    err = pthread_cond_destroy(&cond->cond);
> -    if (err)
> -        error_exit(err, __func__);
> +    g_cond_free(cond->cond);
>  }
>  
>  void qemu_cond_signal(QemuCond *cond)
>  {
> -    int err;
> -
> -    err = pthread_cond_signal(&cond->cond);
> -    if (err)
> -        error_exit(err, __func__);
> +    g_cond_signal(cond->cond);
>  }
>  
>  void qemu_cond_broadcast(QemuCond *cond)
>  {
> -    int err;
> -
> -    err = pthread_cond_broadcast(&cond->cond);
> -    if (err)
> -        error_exit(err, __func__);
> +    g_cond_broadcast(cond->cond);
>  }
>  
>  void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex)
>  {
> -    int err;
> -
> -    err = pthread_cond_wait(&cond->cond, &mutex->lock);
> -    if (err)
> -        error_exit(err, __func__);
> +    g_cond_wait(cond->cond, g_static_mutex_get_mutex(&mutex->lock));
>  }
>  
>  int qemu_cond_timedwait(QemuCond *cond, QemuMutex *mutex, uint64_t msecs)
>  {
> -    struct timespec ts;
> -    int err;
> +    GTimeVal abs_time;
> +
> +    assert(cond->cond != NULL);
>  
> -    clock_gettime(CLOCK_REALTIME, &ts);
> -    timespec_add_ms(&ts, msecs);
> +    g_get_current_time(&abs_time);
> +    g_time_val_add(&abs_time, msecs * 1000); /* MSEC to USEC */
>  
> -    err = pthread_cond_timedwait(&cond->cond, &mutex->lock, &ts);
> -    if (err && err != ETIMEDOUT)
> -        error_exit(err, __func__);
> -    return err;
> +    return g_cond_timed_wait(cond->cond,
> +                             g_static_mutex_get_mutex(&mutex->lock), 
> &abs_time);
> +}
> +
> +struct trampoline_data
> +{
> +    QemuThread *thread;
> +    void *(*startfn)(void *);
> +    void *opaque;
> +    QemuMutex lock;
> +};
> +
> +static gpointer thread_trampoline(gpointer data)
> +{
> +    struct trampoline_data *td = data;
> +    gpointer retval;
> +
> +    td->thread->tid = pthread_self();
> +    qemu_mutex_unlock(&td->lock);
> +
> +    retval = td->startfn(td->opaque);
> +    qemu_free(td);
> +
> +    return retval;
>  }
>  
>  void qemu_thread_create(QemuThread *thread,
> -                       void *(*start_routine)(void*),
> -                       void *arg)
> +                        void *(*start_routine)(void*),
> +                        void *arg)
>  {
> -    int err;
> +    struct trampoline_data *td = qemu_malloc(sizeof(*td));
> +    sigset_t set, old;
>  
> -    /* Leave signal handling to the iothread.  */
> -    sigset_t set, oldset;
> +    td->startfn = start_routine;
> +    td->opaque = arg;
> +    td->thread = thread;
> +    qemu_mutex_init(&td->lock);
> +
> +    /* on behalf of the new thread */
> +    qemu_mutex_lock(&td->lock);
>  
>      sigfillset(&set);

If it is still in use here? This simply doesn't build:

qemu-thread.c: In function ‘q_thread_create_nosignal’:
qemu-thread.c:34: error: implicit declaration of function ‘sigfillset’
qemu-thread.c:34: error: nested extern declaration of ‘sigfillset’
qemu-thread.c:35: error: implicit declaration of function ‘pthread_sigmask’
qemu-thread.c:35: error: nested extern declaration of ‘pthread_sigmask’
qemu-thread.c:35: error: ‘SIG_SETMASK’ undeclared (first use in this function)
qemu-thread.c:35: error: (Each undeclared identifier is reported only once
qemu-thread.c:35: error: for each function it appears in.)
qemu-thread.c: In function ‘qemu_sthread_create’:
qemu-thread.c:80: error: ‘SIG_SETMASK’ undeclared (first use in this function)
qemu-thread.c: In function ‘qemu_sthread_signal’:
qemu-thread.c:96: error: implicit declaration of function ‘pthread_kill’
qemu-thread.c:96: error: nested extern declaration of ‘pthread_kill’


> -    pthread_sigmask(SIG_SETMASK, &set, &oldset);
> -    err = pthread_create(&thread->thread, NULL, start_routine, arg);
> -    if (err)
> -        error_exit(err, __func__);
> +    pthread_sigmask(SIG_SETMASK, &set, &old);
> +    thread->thread = g_thread_create(thread_trampoline, td, TRUE, NULL);
> +    pthread_sigmask(SIG_SETMASK, &old, NULL);
> +
> +    /* we're transfering ownership of this lock to the thread so we no
> +     * longer hold it here */
>  
> -    pthread_sigmask(SIG_SETMASK, &oldset, NULL);
> +    qemu_mutex_lock(&td->lock);
> +    /* validate tid */
> +    qemu_mutex_unlock(&td->lock);
> +
> +    qemu_mutex_destroy(&td->lock);
>  }
>  
>  void qemu_thread_signal(QemuThread *thread, int sig)
>  {
> -    int err;
> -
> -    err = pthread_kill(thread->thread, sig);
> -    if (err)
> -        error_exit(err, __func__);
> +    pthread_kill(thread->tid, sig);
>  }
>  
>  void qemu_thread_self(QemuThread *thread)
>  {
> -    thread->thread = pthread_self();
> +    thread->thread = g_thread_self();
> +    thread->tid = pthread_self();
>  }
>  
>  int qemu_thread_equal(QemuThread *thread1, QemuThread *thread2)
>  {
> -   return pthread_equal(thread1->thread, thread2->thread);
> +    return (thread1->thread == thread2->thread);
>  }
>  
>  void qemu_thread_exit(void *retval)
>  {
> -    pthread_exit(retval);
> +    g_thread_exit(retval);
>  }
> diff --git a/qemu-thread.h b/qemu-thread.h
> index 19bb30c..dc22a60 100644
> --- a/qemu-thread.h
> +++ b/qemu-thread.h
> @@ -1,18 +1,19 @@
>  #ifndef __QEMU_THREAD_H
>  #define __QEMU_THREAD_H 1
> -#include "semaphore.h"
> -#include "pthread.h"
> +#include <glib.h>
> +#include <pthread.h>
>  
>  struct QemuMutex {
> -    pthread_mutex_t lock;
> +    GStaticMutex lock;
>  };
>  
>  struct QemuCond {
> -    pthread_cond_t cond;
> +    GCond *cond;
>  };
>  
>  struct QemuThread {
> -    pthread_t thread;
> +    GThread *thread;
> +    pthread_t tid;
>  };
>  
>  typedef struct QemuMutex QemuMutex;
> diff --git a/vl.c b/vl.c
> index 0292184..bbe0931 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -165,6 +165,8 @@ int main(int argc, char **argv)
>  
>  #include "ui/qemu-spice.h"
>  
> +#include <glib.h>
> +
>  //#define DEBUG_NET
>  //#define DEBUG_SLIRP
>  
> @@ -1918,6 +1920,8 @@ int main(int argc, char **argv, char **envp)
>      atexit(qemu_run_exit_notifiers);
>      error_set_progname(argv[0]);
>  
> +    g_thread_init(NULL);
> +
>      init_clocks();
>  
>      qemu_cache_utils_init(envp);
> -- 
> 1.7.0.4
> 
> 
> 

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net



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