Re: [Qemu-devel] [PATCH] coroutine-gthread.c: Avoid threading APIs deprecated in GLib 2.31

[Blue Swirl]

On Thu, Apr 12, 2012 at 11:13, Peter Maydell <address@hidden> wrote:
> Ping^3 ?

Thanks, applied.

When pinging for not very recent patches, including for example the
Patchwork ID would help locate the actual patch. Resending the patch
would work too, or adding a link to message archives. I didn't find
the patch so easily since it was already deleted by garbage collector
so I had to search the archives.

>
> On 3 April 2012 12:54, Peter Maydell <address@hidden> wrote:
>> Ping^2 ?
>>
>> On 14 March 2012 14:50, Peter Maydell <address@hidden> wrote:
>>> Ping?
>>>
>>> On 3 March 2012 14:52, Peter Maydell <address@hidden> wrote:
>>>> The GLib threading APIs were revamped in GLib 2.31 and a number
>>>> of the old interfaces were deprecated, which means they provoke
>>>> compilation warnings (errors if -Werror) now. Add support for the
>>>> new interfaces while retaining the old ones so we can still compile
>>>> on older versions of GLib too.
>>>>
>>>> Signed-off-by: Peter Maydell <address@hidden>
>>>> ---
>>>> In particular, this fixes compilation failure on ARM hosts running
>>>> Ubuntu Precise. Seems kinda ugly to me, suggestions for improvement
>>>> welcomed.
>>>>
>>>>  coroutine-gthread.c |   96 
>>>> ++++++++++++++++++++++++++++++++++++++++++++++-----
>>>>  1 files changed, 87 insertions(+), 9 deletions(-)
>>>>
>>>> diff --git a/coroutine-gthread.c b/coroutine-gthread.c
>>>> index 662801b..30c24c9 100644
>>>> --- a/coroutine-gthread.c
>>>> +++ b/coroutine-gthread.c
>>>> @@ -26,13 +26,93 @@ typedef struct {
>>>>     Coroutine base;
>>>>     GThread *thread;
>>>>     bool runnable;
>>>> +    bool free_on_thread_exit;
>>>>     CoroutineAction action;
>>>>  } CoroutineGThread;
>>>>
>>>> -static GCond *coroutine_cond;
>>>>  static GStaticMutex coroutine_lock = G_STATIC_MUTEX_INIT;
>>>> +
>>>> +/* GLib 2.31 and beyond deprecated various parts of the thread API,
>>>> + * but the new interfaces are not available in older GLib versions
>>>> + * so we have to cope with both.
>>>> + */
>>>> +#if GLIB_CHECK_VERSION(2, 31, 0)
>>>> +/* Default zero-initialisation is sufficient for 2.31+ GCond */
>>>> +static GCond the_coroutine_cond;
>>>> +static GCond *coroutine_cond = &the_coroutine_cond;
>>>> +static inline void init_coroutine_cond(void)
>>>> +{
>>>> +}
>>>> +
>>>> +/* Awkwardly, the GPrivate API doesn't provide a way to update the
>>>> + * GDestroyNotify handler for the coroutine key dynamically. So instead
>>>> + * we track whether or not the CoroutineGThread should be freed on
>>>> + * thread exit / coroutine key update using the free_on_thread_exit
>>>> + * field.
>>>> + */
>>>> +static void coroutine_destroy_notify(gpointer data)
>>>> +{
>>>> +    CoroutineGThread *co = data;
>>>> +    if (co && co->free_on_thread_exit) {
>>>> +        g_free(co);
>>>> +    }
>>>> +}
>>>> +
>>>> +static GPrivate coroutine_key = G_PRIVATE_INIT(coroutine_destroy_notify);
>>>> +
>>>> +static inline CoroutineGThread *get_coroutine_key(void)
>>>> +{
>>>> +    return g_private_get(&coroutine_key);
>>>> +}
>>>> +
>>>> +static inline void set_coroutine_key(CoroutineGThread *co,
>>>> +                                     bool free_on_thread_exit)
>>>> +{
>>>> +    /* Unlike g_static_private_set() this does not call the GDestroyNotify
>>>> +     * if the previous value of the key was NULL. Fortunately we only need
>>>> +     * the GDestroyNotify in the non-NULL key case.
>>>> +     */
>>>> +    co->free_on_thread_exit = free_on_thread_exit;
>>>> +    g_private_replace(&coroutine_key, co);
>>>> +}
>>>> +
>>>> +static inline GThread *create_thread(GThreadFunc func, gpointer data)
>>>> +{
>>>> +    return g_thread_new("coroutine", func, data);
>>>> +}
>>>> +
>>>> +#else
>>>> +
>>>> +/* Handle older GLib versions */
>>>> +static GCond *coroutine_cond;
>>>> +static inline void init_coroutine_cond(void)
>>>> +{
>>>> +    coroutine_cond = g_cond_new();
>>>> +}
>>>> +
>>>>  static GStaticPrivate coroutine_key = G_STATIC_PRIVATE_INIT;
>>>>
>>>> +static inline CoroutineGThread *get_coroutine_key(void)
>>>> +{
>>>> +    return g_static_private_get(&coroutine_key);
>>>> +}
>>>> +
>>>> +static inline void set_coroutine_key(CoroutineGThread *co,
>>>> +                                     bool free_on_thread_exit)
>>>> +{
>>>> +    g_static_private_set(&coroutine_key, co,
>>>> +                         free_on_thread_exit ? (GDestroyNotify)g_free : 
>>>> NULL);
>>>> +}
>>>> +
>>>> +static inline GThread *create_thread(GThreadFunc func, gpointer data)
>>>> +{
>>>> +    return g_thread_create_full(func, data, 0, TRUE, TRUE,
>>>> +                                G_THREAD_PRIORITY_NORMAL, NULL);
>>>> +}
>>>> +
>>>> +#endif
>>>> +
>>>> +
>>>>  static void __attribute__((constructor)) coroutine_init(void)
>>>>  {
>>>>     if (!g_thread_supported()) {
>>>> @@ -44,7 +124,7 @@ static void __attribute__((constructor)) 
>>>> coroutine_init(void)
>>>>  #endif
>>>>     }
>>>>
>>>> -    coroutine_cond = g_cond_new();
>>>> +    init_coroutine_cond();
>>>>  }
>>>>
>>>>  static void coroutine_wait_runnable_locked(CoroutineGThread *co)
>>>> @@ -65,7 +145,7 @@ static gpointer coroutine_thread(gpointer opaque)
>>>>  {
>>>>     CoroutineGThread *co = opaque;
>>>>
>>>> -    g_static_private_set(&coroutine_key, co, NULL);
>>>> +    set_coroutine_key(co, false);
>>>>     coroutine_wait_runnable(co);
>>>>     co->base.entry(co->base.entry_arg);
>>>>     qemu_coroutine_switch(&co->base, co->base.caller, COROUTINE_TERMINATE);
>>>> @@ -77,8 +157,7 @@ Coroutine *qemu_coroutine_new(void)
>>>>     CoroutineGThread *co;
>>>>
>>>>     co = g_malloc0(sizeof(*co));
>>>> -    co->thread = g_thread_create_full(coroutine_thread, co, 0, TRUE, TRUE,
>>>> -                                      G_THREAD_PRIORITY_NORMAL, NULL);
>>>> +    co->thread = create_thread(coroutine_thread, co);
>>>>     if (!co->thread) {
>>>>         g_free(co);
>>>>         return NULL;
>>>> @@ -117,12 +196,11 @@ CoroutineAction qemu_coroutine_switch(Coroutine 
>>>> *from_,
>>>>
>>>>  Coroutine *qemu_coroutine_self(void)
>>>>  {
>>>> -    CoroutineGThread *co = g_static_private_get(&coroutine_key);
>>>> -
>>>> +    CoroutineGThread *co = get_coroutine_key();
>>>>     if (!co) {
>>>>         co = g_malloc0(sizeof(*co));
>>>>         co->runnable = true;
>>>> -        g_static_private_set(&coroutine_key, co, (GDestroyNotify)g_free);
>>>> +        set_coroutine_key(co, true);
>>>>     }
>>>>
>>>>     return &co->base;
>>>> @@ -130,7 +208,7 @@ Coroutine *qemu_coroutine_self(void)
>>>>
>>>>  bool qemu_in_coroutine(void)
>>>>  {
>>>> -    CoroutineGThread *co = g_static_private_get(&coroutine_key);
>>>> +    CoroutineGThread *co = get_coroutine_key();
>>>>
>>>>     return co && co->base.caller;
>>>>  }
>>>> --
>>>> 1.7.5.4
>