This set of functions can be used to manage trace instances. A
trace instance is a sub buffer used by the Linux tracing system.
Given a unique name, the events enabled in an instance do not
affect the main tracing system, nor other instances, as events
enabled in the main tracing system or other instances do not
affect the given instance.
The tracefs_instance_create() function allocates and initializes
a new tracefs_instance structure and returns it. If the instance
with name does not yet exist in the system, it will be created.
The name could be NULL, then the new tracefs_instance structure
is initialized for the top instance. Note that the top instance
cannot be created in the system, if it does not exist.
The tracefs_instance_destroy() removes the instance from the
system, but does not free the structure. tracefs_instance_free()
must still be called on instance.
The tracefs_instance_alloc()* function allocates a new
tracefs_instance structure for existing trace instance. If the
instance does not exist in the system, the function fails. The
tracing_dir parameter points to the system trace directory. It
can be NULL, then default system trace directory is used. This
parameter is useful to allocate instances to trace directories,
copied from another machine. The name is the name of the
instance, or NULL for the top instance in the given tracing_dir.
The tracefs_instance_free() function frees the tracefs_instance
structure, without removing the trace instance from the system.
The tracefs_instance_is_new() function checks if the given
instance is newly created by tracefs_instance_create(), or it has
been in the system before that.
The tracefs_instances() function returns a list of instances that
exist in the system that match the regular expression regex. If
regex is NULL, then it will match all instances that exist. The
returned list must be freed with tracefs_list_free(3). Note, if
no instances are found an empty list is returned and that too
needs to be free with tracefs_list_free(3).
The tracefs_instance_reset() function resets the given instance
to its default state.
ЗНАЧЕНИЕ ВОЗВРАЩАЕМОГО ЗНАЧЕНИЯ
The tracefs_instance_create() and tracefs_instance_alloc()
functions return a pointer to a newly allocated tracefs_instance
structure. It must be freed with tracefs_instance_free().
The tracefs_instance_destroy() function returns 0 if it succeeds
to remove the instance, otherwise it returns -1 if the instance
does not exist or it fails to remove it.
The tracefs_instance_is_new() function returns true if the
tracefs_instance_create() that allocated instance also created
the trace instance in the system, or false if the trace instance
already existed in the system when instance was allocated by
tracefs_instance_create() or tracefs_instance_alloc().
The tracefs_instances() returns a list of instance names that
exist on the system. The list must be freed with
tracefs_list_free(3). An empty list is returned if no instance
exists that matches regex, and this needs to be freed with
tracefs_list_free(3) as well. NULL is returned on error.
ПРИМЕР
#include <tracefs.h>
struct tracefs_instance *inst = tracefs_instance_create("foo");
if (!inst) {
/* Error creating a new trace instance */
...
}
...
if (tracefs_instance_is_new(inst))
tracefs_instance_destroy(inst);
tracefs_instance_free(inst);
...
struct tracefs_instance *inst = tracefs_instance_alloc(NULL, "bar");
if (!inst) {
/* Error allocating 'bar' trace instance */
...
}
...
tracefs_instance_reset(inst);
tracefs_instance_free(inst);
ФАЙЛЫ
tracefs.h
Header file to include in order to have access to the library APIs.
-ltracefs
Linker switch to add when building a program that uses the library.
This page is part of the libtracefs (Linux kernel trace file
system library) project. Information about the project can be
found at ⟨https://www.trace-cmd.org/⟩. If you have a bug report
for this manual page, see ⟨https://www.trace-cmd.org/⟩. This
page was obtained from the project's upstream Git repository
⟨https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git⟩ on
2024-06-14. (At that time, the date of the most recent commit
that was found in the repository was 2024-05-17.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
libtracefs 1.7.0 12/22/2023 LIBTRACEFS(3)
