Re: [Qemu-devel] [PATCH] qemu-progress: redirct qemu progress message to another file stream

[Zhenwei.Pi]

On 04/18/2018 09:06 PM, Max Reitz wrote:

> On 2018-04-16 09:46, zhenwei pi wrote:
> > currently qemu progress message only print into stdout, and other thread may
> > print some log into stdout at the same time.
> > add a new api qemu_progress_set_output to redirect progress message to
> > another file stream.
> >
> > Signed-off-by: zhenwei pi <address@hidden>
> > ---
> >   include/qemu-common.h |  1 +
> >   util/qemu-progress.c  | 22 +++++++++++++++++++---
> >   2 files changed, 20 insertions(+), 3 deletions(-)
> Well, but after this patch, qemu will still only print progress to
> stdout because qemu_progress_set_output() isn't used anywhere...
this patch only provides the basic redirection function. if this patch
is approved, another patch (Ex, qemu convert progress in qemu-img.c)
will be send.

> > diff --git a/include/qemu-common.h b/include/qemu-common.h
> > index 8a4f63c..511e7e0 100644
> > --- a/include/qemu-common.h
> > +++ b/include/qemu-common.h
> > @@ -128,6 +128,7 @@ ssize_t qemu_co_send_recv(int sockfd, void *buf, size_t 
> > bytes, bool do_send);
> >   void qemu_progress_init(int enabled, float min_skip);
> >   void qemu_progress_end(void);
> >   void qemu_progress_print(float delta, int max);
> > +int qemu_progress_set_output(FILE *output);
> >   const char *qemu_get_vm_name(void);
> >   
> >   #define QEMU_FILE_TYPE_BIOS   0
> > diff --git a/util/qemu-progress.c b/util/qemu-progress.c
> > index 3c2223c..dd7aa52 100644
> > --- a/util/qemu-progress.c
> > +++ b/util/qemu-progress.c
> > @@ -31,6 +31,7 @@ struct progress_state {
> >       float min_skip;
> >       void (*print)(void);
> >       void (*end)(void);
> > +    FILE *output;
> >   };
> >   
> >   static struct progress_state state;
> > @@ -43,17 +44,18 @@ static volatile sig_atomic_t print_pending;
> >    */
> >   static void progress_simple_print(void)
> >   {
> > -    printf("    (%3.2f/100%%)\r", state.current);
> > -    fflush(stdout);
> > +    fprintf(state.output, "    (%3.2f/100%%)\r", state.current);
> > +    fflush(state.output);
> Also, I'm not sure we should use \r when printing to anything but stdout.
>
> Max

qemu redirects progress message into a file, other process reads the file
and uses '\r' to split the string, and we can get the progress exactly.

> >   }
> >   
> >   static void progress_simple_end(void)
> >   {
> > -    printf("\n");
> > +    fprintf(state.output, "\n");
> >   }
> >   
> >   static void progress_simple_init(void)
> >   {
> > +    state.output = stdout;
> >       state.print = progress_simple_print;
> >       state.end = progress_simple_end;
> >   }
> > @@ -129,6 +131,20 @@ void qemu_progress_end(void)
> >   }
> >   
> >   /*
> > + * Redirect progress into another file stream.
> > + * @output is the new file stream.
> > + */
> > +int qemu_progress_set_output(FILE *output)
> > +{
> > +    if (!output) {
> > +        return -EINVAL;
> > +    }
> > +
> > +    state.output = output;
> > +    return 0;
> > +}
> > +
> > +/*
> >    * Report progress.
> >    * @delta is how much progress we made.
> >    * If @max is zero, @delta is an absolut value of the total job done.