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

[Peter Maydell]

Ping^3 ?

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