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Diffstat (limited to 'Documentation/libtracecmd/libtracecmd-instances.txt')
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diff --git a/Documentation/libtracecmd/libtracecmd-instances.txt b/Documentation/libtracecmd/libtracecmd-instances.txt new file mode 100644 index 00000000..df8fdc4e --- /dev/null +++ b/Documentation/libtracecmd/libtracecmd-instances.txt @@ -0,0 +1,129 @@ +libtracecmd(3) +============= + +NAME +---- +tracecmd_buffer_instances, tracecmd_buffer_instance_name, tracecmd_buffer_instance_handle +- Read tracing instances from a trace file. + +SYNOPSIS +-------- +[verse] +-- +*#include <trace-cmd.h>* + +int *tracecmd_buffer_instances*(struct tracecmd_input pass:[*]_handle_); +const char pass:[*]*tracecmd_buffer_instance_name*(struct tracecmd_input pass:[*]_handle_, int _indx_); +struct tracecmd_input pass:[*]*tracecmd_buffer_instance_handle*(struct tracecmd_input pass:[*]_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 +------- +[source,c] +-- +#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 +----- +[verse] +-- +*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 +------ +[verse] +-- +*Steven Rostedt* <rostedt@goodmis.org> +*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com> +-- +REPORTING BUGS +-------------- +Report bugs to <linux-trace-devel@vger.kernel.org> + +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). |