[lttng-dev] (no subject)

[Zvi Vered]

Hi Phil,

Can you please estimate when version 2 will be released ?

Can you please provide sample code that uses Babeltrace to read metadata,
channel ?

Thank you for the tip. You saved us many hours of work.

Best regards,
Zvika

On Thu, Jun 13, 2019, 07:06 Philippe Proulx <eeppeliteloop at gmail.com> wrote:

> On Wed, Jun 12, 2019 at 11:22 PM Zvi Vered <veredz72 at gmail.com> wrote:
> >
> > Hello,
> >
> > I'm trying to read the file "metadata".
> > I read the struct:
> >
> > struct metadata_packet_header {
> > uint32_t magic; /* 0x75D11D57 */
> > uint8_t  uuid[16]; /* Unique Universal Identifier */
> > uint32_t checksum; /* 0 if unused */
> > uint32_t content_size; /* in bits */
> > uint32_t packet_size; /* in bits */
> > uint8_t  compression_scheme; /* 0 if unused */
> > uint8_t  encryption_scheme; /* 0 if unused */
> > uint8_t  checksum_scheme; /* 0 if unused */
> > uint8_t  major; /* CTF spec major version number */
> > uint8_t  minor; /* CTF spec minor version number */
> > HEADER_END;
> > };
> >
> > the magic is indeed 0x75D11D57.
> > What is next struct I should read ?
> > I would expect "packet context". Am I right ?
> > what struct is it ?
> >
> > I want to write a simple babeltrace for windows.
>
> Not to discourage you, but I think you're only beginning a very long
> journey. Reading a CTF trace entails:
>
> 1. Depacketize the metadata stream to get the metadata text.
>
> 2. Parse the metadata text to get the appropriate trace, stream, clock,
>    and event classes. That's a custom, and somewhat complex,
>    domain-specific language called TSDL.
>
> 3. Use the classes found in 2. to decode each data stream. This involves
>    decoding integer fields with custom sizes (for example, a 27-bit
>    unsigned integer field), dynamically finding the lengths of
>    sequences and the selectors of variants, updating the stream's clock,
>    and much more.
>
> 4. Merge the events of the trace's data streams decoded in 3.  to get a
>    monotonic sequence of events.
>
> Add to this various fixes for known tracer bugs and support for features
> such as trace file rotation and tracing session rotation.
>
> Please don't attempt this.
>
> We are currently polishing the Babeltrace 2 project which does all that,
> and much more, for the Linux, macOS, and Windows platforms. Our goal is
> to offer a flexible, plugin-based framework to read, manipulate, and
> write traces in different formats.
>
> Phil
>
> > If I succeed, and you will find it relevant, I can upload this project.
> >
> > Thank you in advance,
> > Zvika
> > _______________________________________________
> > lttng-dev mailing list
> > lttng-dev at lists.lttng.org
> > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.lttng.org/pipermail/lttng-dev/attachments/20190613/daaa3c1e/attachment.html>