Re: [PATCH 2/2] scripts/tracetool: Add plainlog backend

[Stefan Hajnoczi]

On Wed, Jun 17, 2020 at 03:36:29PM +0200, BALATON Zoltan wrote:
> Add a backend that is the same as the log backend but omits the
> process id and timestamp so logs are easier to read and diff-able.
> 
> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> ---
>  scripts/tracetool/backend/plainlog.py | 48 +++++++++++++++++++++++++++
>  1 file changed, 48 insertions(+)
>  create mode 100644 scripts/tracetool/backend/plainlog.py
> 
> diff --git a/scripts/tracetool/backend/plainlog.py 
> b/scripts/tracetool/backend/plainlog.py
> new file mode 100644
> index 0000000000..40bbfa6d76
> --- /dev/null
> +++ b/scripts/tracetool/backend/plainlog.py
> @@ -0,0 +1,48 @@
> +# -*- coding: utf-8 -*-
> +
> +"""
> +Stderr built-in backend, plain log without proc ID and time.
> +"""
> +
> +__author__     = "Llu????s Vilanova <vilanova@ac.upc.edu>"
> +__copyright__  = "Copyright 2012-2017, Llu????s Vilanova 
> <vilanova@ac.upc.edu>"

There is a Unicode issue here, Lluís' name is not printed correctly.

> +__license__    = "GPL version 2 or (at your option) any later version"
> +
> +__maintainer__ = "Stefan Hajnoczi"
> +__email__      = "stefanha@linux.vnet.ibm.com"
> +
> +
> +from tracetool import out
> +
> +
> +PUBLIC = True
> +
> +
> +def generate_h_begin(events, group):
> +    out('#include "qemu/log-for-trace.h"',
> +        '')
> +
> +
> +def generate_h(event, group):
> +    argnames = ", ".join(event.args.names())
> +    if len(event.args) > 0:
> +        argnames = ", " + argnames
> +
> +    if "vcpu" in event.properties:
> +        # already checked on the generic format code
> +        cond = "true"
> +    else:
> +        cond = "trace_event_get_state(%s)" % ("TRACE_" + event.name.upper())
> +
> +    out('    if (%(cond)s && qemu_loglevel_mask(LOG_TRACE)) {',
> +        '        qemu_log("%(name)s " %(fmt)s "\\n" %(argnames)s);',
> +        '    }',
> +        cond=cond,
> +        name=event.name,
> +        fmt=event.fmt.rstrip("\n"),
> +        argnames=argnames)

It is not necessary to introduce a new backend. There could be an option
that controls whether or not the timestamp/tid is printed. For example,
-trace timestamp=off or maybe the timestmap/tid can be integrated into
qemu_log() itself so that it's used more consistently and a -d timestamp
option enables it.

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