[Qemu-devel] Re: [Tracing] [RFC PATCH 1/2] : Introduce 'query-trace' & 'query-trace-events' interfaces

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

On Thu, Oct 14, 2010 at 11:26:04AM +0530, Prerna Saxena wrote:
> [PATCH 1/2] Introduce QMP interfaces : query-trace & query-trace-events
> 
> 
> Signed-off-by: Prerna Saxena <prerna@linux.vnet.ibm.com>
> ---
>  monitor.c     |   46 ++++++++++++++++++++++++++++++++++++++++++----
>  simpletrace.c |   54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  simpletrace.h |    2 ++
>  3 files changed, 98 insertions(+), 4 deletions(-)
> 
> diff --git a/monitor.c b/monitor.c
> index fbb678d..7a150ae 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -941,15 +941,33 @@ static void do_info_cpu_stats(Monitor *mon)
>  #endif
> 
>  #if defined(CONFIG_SIMPLE_TRACE)
> -static void do_info_trace(Monitor *mon)
> +static void do_info_trace_print(Monitor *mon)
>  {
>      st_print_trace((FILE *)mon, &monitor_fprintf);
>  }
> 
> -static void do_info_trace_events(Monitor *mon)
> +static void do_info_trace(Monitor *mon, QObject **ret_data)
> +{
> +    QList *trace_event_list = NULL;
> +
> +    st_print_trace_to_qlist(&trace_event_list);
> +
> +    *ret_data = QOBJECT(trace_event_list);
> +}
> +
> +static void do_info_trace_events_print(Monitor *mon, const QObject *data)
>  {
>      st_print_trace_events((FILE *)mon, &monitor_fprintf);
>  }
> +
> +static void do_info_trace_events(Monitor *mon, QObject **ret_data)
> +{
> +    QList *trace_event_list = NULL;
> +
> +    st_print_trace_events_to_qlist(&trace_event_list);
> +
> +    *ret_data = QOBJECT(trace_event_list);
> +}
>  #endif
> 
>  /**
> @@ -2606,14 +2624,16 @@ static const mon_cmd_t info_cmds[] = {
>          .args_type  = "",
>          .params     = "",
>          .help       = "show current contents of trace buffer",
> -        .mhandler.info = do_info_trace,
> +        .user_print = do_info_trace_print,
> +        .mhandler.info_new = do_info_trace,
>      },
>      {
>          .name       = "trace-events",
>          .args_type  = "",
>          .params     = "",
>          .help       = "show available trace-events & their state",
> -        .mhandler.info = do_info_trace_events,
> +        .user_print = do_info_trace_events_print,
> +        .mhandler.info_new = do_info_trace_events,
>      },
>  #endif
>      {
> @@ -2748,6 +2768,24 @@ static const mon_cmd_t qmp_query_cmds[] = {
>          .mhandler.info_async = do_info_balloon,
>          .flags      = MONITOR_CMD_ASYNC,
>      },
> +#if defined(CONFIG_SIMPLE_TRACE)
> +    {
> +        .name       = "trace",
> +        .args_type  = "",
> +        .params     = "",
> +        .help       = "show current contents of trace buffer",
> +        .user_print = do_info_trace_print,
> +        .mhandler.info_new = do_info_trace,
> +    },
> +    {
> +        .name       = "trace-events",
> +        .args_type  = "",
> +        .params     = "",
> +        .help       = "show available trace-events & their state",
> +        .user_print = do_info_trace_events_print,
> +        .mhandler.info_new = do_info_trace_events,
> +    },
> +#endif
>      { /* NULL */ },
>  };
> 
> diff --git a/simpletrace.c b/simpletrace.c
> index f849e42..d1f66b4 100644
> --- a/simpletrace.c
> +++ b/simpletrace.c
> @@ -220,6 +220,39 @@ void st_print_trace(FILE *stream, int (*stream_printf)(FILE *stream, const char
>      }
>  }
> 
> +void st_print_trace_to_qlist(QList **tlist)
> +{
> +    QObject *data;
> +    unsigned int i;
> +
> +    if (!tlist || *tlist )
> +        return;

This silences bugs.  If you want to check these please use asserts.

> +
> +    /* NOTE : This assumes trace_list hasnt already been allocated with a QList.
> +     *        The initialization happens here.
> +     */

This should be in a doc comment for this function to make it clear that
tlist will be allocated a new list.

> +    *tlist = qlist_new();
> +
> +    for (i = 0; i < trace_idx; i++) {
> +          data = qobject_from_jsonf("{"
> +                                    " 'Event': %" PRId64 ","
> +                                    " 'arg1': %" PRId64 ","
> +                                    " 'arg2': %" PRId64 ","
> +                                    " 'arg3': %" PRId64 ","
> +                                    " 'arg4': %" PRId64 ","
> +                                    " 'arg5': %" PRId64 ","
> +                                    " 'arg6': %" PRId64
> +                                    "}",
> +                                    trace_buf[i].event, trace_buf[i].x1,
> +                                    trace_buf[i].x2, trace_buf[i].x3,
> +                                    trace_buf[i].x4, trace_buf[i].x5,
> +                                    trace_buf[i].x6);
> +          qlist_append_obj(*tlist, data);
> +    }
> +
> +    return;

Not needed for a void function and not used in QEMU coding style.

> +}
> +
>  void st_print_trace_events(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
>  {
>      unsigned int i;
> @@ -230,6 +263,27 @@ void st_print_trace_events(FILE *stream, int (*stream_printf)(FILE *stream, cons
>      }
>  }
> 
> +void st_print_trace_events_to_qlist(QList **tlist)

The same comments apply to this function.

> +{
> +    QObject *data;
> +    unsigned int i;
> +
> +    if (!tlist || *tlist )
> +        return;
> +
> +    /* NOTE : This assumes trace_list hasnt already been allocated with a QList.
> +     *        The initialization happens here.
> +     */
> +    *tlist = qlist_new();
> +
> +    for (i = 0; i < NR_TRACE_EVENTS; i++) {
> +          data = qobject_from_jsonf("{ 'name': %s, 'eventID': %d, 'state': %d }", trace_list[i].tp_name, i, trace_list[i].state);
> +          qlist_append_obj(*tlist, data);
> +    }
> +
> +    return;
> +}
> +
>  static TraceEvent* find_trace_event_by_name(const char *tname)
>  {
>      unsigned int i;
> diff --git a/simpletrace.h b/simpletrace.h
> index cf35897..9c1f535 100644
> --- a/simpletrace.h
> +++ b/simpletrace.h
> @@ -14,6 +14,8 @@
>  #include <stdint.h>
>  #include <stdbool.h>
>  #include <stdio.h>
> +#include "qdict.h"
> +#include "qjson.h"

Where are the prototypes for st_print_trace_to_qlist() and st_print_trace_events_to_qlist()?

Stefan