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


From: Anthony Liguori
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 09:34:01 -0600
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.15) Gecko/20101027 Lightning/1.0b1 Thunderbird/3.0.10

On 01/25/2011 08:24 AM, Aurelien Jarno wrote:
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>?

It looked like unnecessary includes crept in so I remove them all. It still built for me but apparently not for you. I'll update accordingly.

Maybe we should put signal.h in qemu-common.h?

Regards,

Anthony Liguori

-#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







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