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Re: [Qemu-devel] [PATCH] coroutine-gthread.c: Avoid threading APIs depre


From: Peter Maydell
Subject: Re: [Qemu-devel] [PATCH] coroutine-gthread.c: Avoid threading APIs deprecated in GLib 2.31
Date: Tue, 3 Apr 2012 12:54:39 +0100

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



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