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

["Zhenwei.Pi" <zhenwei.pi@youruncloud.com>]

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 <zhenwei.pi@youruncloud.com>
>> ---
>>   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.
>>
>