NAME¶

tracecmd_buffer_instances, tracecmd_buffer_instance_name, tracecmd_buffer_instance_handle - Read tracing instances from a trace file.

SYNOPSIS¶

#include <trace-cmd.h>
int tracecmd_buffer_instances(struct tracecmd_input *handle);
const char *tracecmd_buffer_instance_name(struct tracecmd_input *handle, int indx);
struct tracecmd_input *tracecmd_buffer_instance_handle(struct tracecmd_input *handle, int indx);

DESCRIPTION¶

This set of APIs can be used to get information and read tracing data from tracing instances stored in a trace file.

The tracecmd_buffer_instances() function gets the number of tracing instances recorded in a trace file. The top instance is not counted. The handle is a tracecmd_input handler returned by tracecmd_open_head().

The tracecmd_buffer_instance_name() function gets the name of the tracing instance with given index indx, recorded in a trace file. The indx is a number in the interval [0 .. count-1], where count is the number returned by tracecmd_buffer_instances(). The handle is a tracecmd_input handler returned by tracecmd_open_head().

The tracecmd_buffer_instance_handle() allocates and initializes a tracecmd_input handle, associated with trace instance with index indx from a trace file. The handle is a tracecmd_input handler returned by tracecmd_open_head(). The indx is a number in the interval [0 .. count-1], where count is the number returned by tracecmd_buffer_instances().

RETURN VALUE¶

The tracecmd_buffer_instances() function returns the number of tracing instances recorded in a trace file.

The tracecmd_buffer_instance_name() function returns a string, the name of a tracing instance, or NULL in case of an error The string must not be freed.

The tracecmd_buffer_instance_handle() function returns a pointer to newly allocated tracecmd_input handler or NULL in case if an error. The returned handler must be closed by tracecmd_close()(3)

EXAMPLE¶

#include <trace-cmd.h>
...
struct tracecmd_input *handle = tracecmd_open_head("trace.dat");


        if (!handle) {


                /* Failed to open trace.dat file */


        }
...
int num = tracecmd_buffer_instances(handle);


        while(num) {


                struct tracecmd_input *h;


                char *name;


                name = tracecmd_buffer_instance_name(handle, num);


                if (!name) {


                        /* Failed to get name of instance num */


                }


                h = tracecmd_buffer_instance_handle(handle, num);


                if (!h) {


                        /* Failed to initialize handler for instance num */


                }


                ...


                tracecmd_close(h);


                num--;


        }
...


        tracecmd_close(handle);

FILES¶

trace-cmd.h


        Header file to include in order to have access to the library APIs.
-ltracecmd


        Linker switch to add when building a program that uses the library.

SEE ALSO¶

libtracefs(3), libtraceevent(3), trace-cmd(1) trace-cmd.dat(5)

AUTHOR¶

Steven Rostedt <rostedt@goodmis.org[1]>
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>

REPORTING BUGS¶

Report bugs to <linux-trace-devel@vger.kernel.org[3]>

LICENSE¶

libtracecmd is Free Software licensed under the GNU LGPL 2.1

RESOURCES¶

https://git.kernel.org/pub/scm/utils/trace-cmd/trace-cmd.git/

COPYING¶

Copyright (C) 2020 VMware, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL).

NOTES¶

1.

rostedt@goodmis.org

2.

tz.stoyanov@gmail.com

3.

linux-trace-devel@vger.kernel.org