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| -rw-r--r-- | tools/lib/traceevent/Documentation/libtraceevent-filter.txt | 209 |
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diff --git a/tools/lib/traceevent/Documentation/libtraceevent-filter.txt b/tools/lib/traceevent/Documentation/libtraceevent-filter.txt new file mode 100644 index 000000000000..4a9962d8cb59 --- /dev/null +++ b/tools/lib/traceevent/Documentation/libtraceevent-filter.txt @@ -0,0 +1,209 @@ +libtraceevent(3) +================ + +NAME +---- +tep_filter_alloc, tep_filter_free, tep_filter_reset, tep_filter_make_string, +tep_filter_copy, tep_filter_compare, tep_filter_match, tep_event_filtered, +tep_filter_remove_event, tep_filter_strerror, tep_filter_add_filter_str - +Event filter related APIs. + +SYNOPSIS +-------- +[verse] +-- +*#include <event-parse.h>* + +struct tep_event_filter pass:[*]*tep_filter_alloc*(struct tep_handle pass:[*]_tep_); +void *tep_filter_free*(struct tep_event_filter pass:[*]_filter_); +void *tep_filter_reset*(struct tep_event_filter pass:[*]_filter_); +enum tep_errno *tep_filter_add_filter_str*(struct tep_event_filter pass:[*]_filter_, const char pass:[*]_filter_str_); +int *tep_event_filtered*(struct tep_event_filter pass:[*]_filter_, int _event_id_); +int *tep_filter_remove_event*(struct tep_event_filter pass:[*]_filter_, int _event_id_); +enum tep_errno *tep_filter_match*(struct tep_event_filter pass:[*]_filter_, struct tep_record pass:[*]_record_); +int *tep_filter_copy*(struct tep_event_filter pass:[*]_dest_, struct tep_event_filter pass:[*]_source_); +int *tep_filter_compare*(struct tep_event_filter pass:[*]_filter1_, struct tep_event_filter pass:[*]_filter2_); +char pass:[*]*tep_filter_make_string*(struct tep_event_filter pass:[*]_filter_, int _event_id_); +int *tep_filter_strerror*(struct tep_event_filter pass:[*]_filter_, enum tep_errno _err_, char pass:[*]buf, size_t _buflen_); +-- + +DESCRIPTION +----------- +Filters can be attached to traced events. They can be used to filter out various +events when outputting them. Each event can be filtered based on its parameters, +described in the event's format file. This set of functions can be used to +create, delete, modify and attach event filters. + +The _tep_filter_alloc()_ function creates a new event filter. The _tep_ argument +is the trace event parser context. + +The _tep_filter_free()_ function frees an event filter and all resources that it +had used. + +The _tep_filter_reset()_ function removes all rules from an event filter and +resets it. + +The _tep_filter_add_filter_str()_ function adds a new rule to the _filter_. The +_filter_str_ argument is the filter string, that contains the rule. + +The _tep_event_filtered()_ function checks if the event with _event_id_ has +_filter_. + +The _tep_filter_remove_event()_ function removes a _filter_ for an event with +_event_id_. + +The _tep_filter_match()_ function tests if a _record_ matches given _filter_. + +The _tep_filter_copy()_ function copies a _source_ filter into a _dest_ filter. + +The _tep_filter_compare()_ function compares two filers - _filter1_ and _filter2_. + +The _tep_filter_make_string()_ function constructs a string, displaying +the _filter_ contents for given _event_id_. + +The _tep_filter_strerror()_ function copies the _filter_ error buffer into the +given _buf_ with the size _buflen_. If the error buffer is empty, in the _buf_ +is copied a string, describing the error _err_. + +RETURN VALUE +------------ +The _tep_filter_alloc()_ function returns a pointer to the newly created event +filter, or NULL in case of an error. + +The _tep_filter_add_filter_str()_ function returns 0 if the rule was +successfully added or a negative error code. Use _tep_filter_strerror()_ to see +actual error message in case of an error. + +The _tep_event_filtered()_ function returns 1 if the filter is found for given +event, or 0 otherwise. + +The _tep_filter_remove_event()_ function returns 1 if the vent was removed, or +0 if the event was not found. + +The _tep_filter_match()_ function returns _tep_errno_, according to the result: +[verse] +-- +_pass:[TEP_ERRNO__FILTER_MATCH]_ - filter found for event, the record matches. +_pass:[TEP_ERRNO__FILTER_MISS]_ - filter found for event, the record does not match. +_pass:[TEP_ERRNO__FILTER_NOT_FOUND]_ - no filter found for record's event. +_pass:[TEP_ERRNO__NO_FILTER]_ - no rules in the filter. +-- +or any other _tep_errno_, if an error occurred during the test. + +The _tep_filter_copy()_ function returns 0 on success or -1 if not all rules + were copied. + +The _tep_filter_compare()_ function returns 1 if the two filters hold the same +content, or 0 if they do not. + +The _tep_filter_make_string()_ function returns a string, which must be freed +with free(), or NULL in case of an error. + +The _tep_filter_strerror()_ function returns 0 if message was filled +successfully, or -1 in case of an error. + +EXAMPLE +------- +[source,c] +-- +#include <event-parse.h> +... +struct tep_handle *tep = tep_alloc(); +... +char errstr[200]; +int ret; + +struct tep_event_filter *filter = tep_filter_alloc(tep); +struct tep_event_filter *filter1 = tep_filter_alloc(tep); +ret = tep_filter_add_filter_str(filter, "sched/sched_wakeup:target_cpu==1"); +if(ret < 0) { + tep_filter_strerror(filter, ret, errstr, sizeof(errstr)); + /* Failed to add a new rule to the filter, the error string is in errstr */ +} +if (tep_filter_copy(filter1, filter) != 0) { + /* Failed to copy filter in filter1 */ +} +... +if (tep_filter_compare(filter, filter1) != 1) { + /* Both filters are different */ +} +... +void process_record(struct tep_handle *tep, struct tep_record *record) +{ + struct tep_event *event; + char *fstring; + + event = tep_find_event_by_record(tep, record); + + if (tep_event_filtered(filter, event->id) == 1) { + /* The event has filter */ + fstring = tep_filter_make_string(filter, event->id); + if (fstring != NULL) { + /* The filter for the event is in fstring */ + free(fstring); + } + } + + switch (tep_filter_match(filter, record)) { + case TEP_ERRNO__FILTER_MATCH: + /* The filter matches the record */ + break; + case TEP_ERRNO__FILTER_MISS: + /* The filter does not match the record */ + break; + case TEP_ERRNO__FILTER_NOT_FOUND: + /* No filter found for record's event */ + break; + case TEP_ERRNO__NO_FILTER: + /* There are no rules in the filter */ + break + default: + /* An error occurred during the test */ + break; + } + + if (tep_filter_remove_event(filter, event->id) == 1) { + /* The event was removed from the filter */ + } +} + +... +tep_filter_reset(filter); +... +tep_filter_free(filter); +tep_filter_free(filter1); +... +-- + +FILES +----- +[verse] +-- +*event-parse.h* + Header file to include in order to have access to the library APIs. +*-ltraceevent* + Linker switch to add when building a program that uses the library. +-- + +SEE ALSO +-------- +_libtraceevent(3)_, _trace-cmd(1)_ + +AUTHOR +------ +[verse] +-- +*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*. +*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page. +-- +REPORTING BUGS +-------------- +Report bugs to <linux-trace-devel@vger.kernel.org> + +LICENSE +------- +libtraceevent is Free Software licensed under the GNU LGPL 2.1 + +RESOURCES +--------- +https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git |