Re: [PATCH 3/6] trace-cmd library man pages: Read recorded events from a trace file.

[Steven Rostedt <rostedt@goodmis.org>]

I think the below example should be also used in the tracecmd_open_head()
man page. That's because the current example in tracecmd_open_head() is
rather useless as nothing really can be done without the
tracecmd_init_data() call. By using the below example in the
tracecmd_open_head() page, it will show people a more informative way of
using that call.

Note, these man pages are already applied, any update should be done on top
of the current repo.

-- Steve


On Wed, 23 Dec 2020 06:34:26 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> +EXAMPLE
> +-------
> +[source,c]
> +--
> +#include <trace-cmd.h>
> +...
> +struct tracecmd_input *handle = tracecmd_open_head("trace.dat");
> +	if (!handle) {
> +		/* Failed to open trace.dat file */
> +	}
> +...
> +unsigned long long offset = 0;
> +struct tep_record *rec;
> +int cpu = 0;
> +
> +	if (tracecmd_init_data(handle) < 0) {
> +		/* Failed to initialize hadle for reading the trace data */
> +	}
> +
> +	rec = tracecmd_read_cpu_first(handle, cpu);
> +	while (rec) {
> +		...
> +		if ( /* some interesting record noticed */) {
> +			/* store the offset of the interesting record */
> +			offset = rec->offset;
> +		}
> +		...
> +		tracecmd_free_record(rec);
> +		rec = tracecmd_read_data(handle, cpu);
> +	}
> +	...
> +	if (offset) {
> +		rec = tracecmd_read_at(handle, offset, &cpu);
> +		if (rec) {
> +			/* Got record at offset on cpu */
> +			...
> +			tracecmd_free_record(rec);
> +		}
> +	}
> +
> +...
> +	tracecmd_close(hadle);
> +