Gilles Chanteperdrix wrote:
> When exiting a process, rtdk buffers are not flushed. Fix that by
> introducing a destructor for the library which flushes the buffers.
>
> When forking, if the main thread has an rt_printf buffer, it is reused by
> the child, which is a good thing, however, it is not emptied, so could cause
> the same message to be printed twice. Fix that by emptying the main thread
> buffer upon fork.
>
> When spawning the rt_print thread, it uses a stack size of
> PTHREAD_STACK_MIN, which may be too small for printf to work reliably on
> some architectures, set the stack size to the
> empirically-known-to-be-working size of... 32Kb.
> ---
> src/rtdk/init.c | 5 +++++
> src/rtdk/internal.h | 1 +
> src/rtdk/rt_print.c | 21 ++++++++++++++++++++-
> 3 files changed, 26 insertions(+), 1 deletions(-)
>
> diff --git a/src/rtdk/init.c b/src/rtdk/init.c
> index 2084c73..b864175 100644
> --- a/src/rtdk/init.c
> +++ b/src/rtdk/init.c
> @@ -22,3 +22,8 @@ static __attribute__ ((constructor)) void __init_rtdk(void)
> {
> __rt_print_init();
> }
> +
> +static __attribute__ ((destructor)) void __exit_rtdk(void)
> +{
> + __rt_print_exit();
> +}
> diff --git a/src/rtdk/internal.h b/src/rtdk/internal.h
> index bd15b2d..345d4fa 100644
> --- a/src/rtdk/internal.h
> +++ b/src/rtdk/internal.h
> @@ -23,6 +23,7 @@
> #include <sys/time.h>
>
> void __rt_print_init(void);
> +void __rt_print_exit(void);
>
> void __real_free(void *ptr);
> void *__real_malloc(size_t size);
> diff --git a/src/rtdk/rt_print.c b/src/rtdk/rt_print.c
> index c6b5c55..dae7d7b 100644
> --- a/src/rtdk/rt_print.c
> +++ b/src/rtdk/rt_print.c
> @@ -455,7 +455,7 @@ static void spawn_printer_thread(void)
> pthread_attr_t thattr;
>
> pthread_attr_init(&thattr);
> - pthread_attr_setstacksize(&thattr, PTHREAD_STACK_MIN);
> + pthread_attr_setstacksize(&thattr, 32768);
Mmh... maybe rather $something +PTHREAD_STACK_MIN?
> pthread_create(&printer_thread, &thattr, printer_loop, NULL);
> }
>
> @@ -464,6 +464,15 @@ static void forked_child_init(void)
> struct print_buffer *my_buffer = pthread_getspecific(buffer_key);
> struct print_buffer **pbuffer = &first_buffer;
>
> + if (my_buffer) {
> + /* Any content of my_buffer should be printed by our parent,
> + not us. */
> + memset(my_buffer->ring, 0, my_buffer->size);
> +
> + my_buffer->read_pos = 0;
> + my_buffer->write_pos = 0;
> + }
> +
Ack.
> /* re-init to avoid finding it locked by some parent thread */
> pthread_mutex_init(&buffer_lock, NULL);
>
> @@ -518,3 +527,13 @@ void __rt_print_init(void)
> spawn_printer_thread();
> pthread_atfork(NULL, NULL, forked_child_init);
> }
> +
> +void __rt_print_exit(void)
> +{
> + if (buffers) {
> + /* Flush the buffers. Do not call print_buffers here
> + * since we do not know if our stack is big enough. */
> + nanosleep(&print_period, NULL);
> + nanosleep(&print_period, NULL);
> + }
> +}
IIRC, that's what cleanup_buffer is supposed to do, triggered by the
pthread key destruction. Can you explain why it failed in your scenario.
Jan
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