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Diffstat (limited to 'Documentation/libtraceevent-field_find.txt')
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diff --git a/Documentation/libtraceevent-field_find.txt b/Documentation/libtraceevent-field_find.txt new file mode 100644 index 0000000..5e4071c --- /dev/null +++ b/Documentation/libtraceevent-field_find.txt @@ -0,0 +1,118 @@ +libtraceevent(3) +================ + +NAME +---- +tep_find_common_field, tep_find_field, tep_find_any_field - +Search for a field in an event. + +SYNOPSIS +-------- +[verse] +-- +*#include <event-parse.h>* + +struct tep_format_field pass:[*]*tep_find_common_field*(struct tep_event pass:[*]_event_, const char pass:[*]_name_); +struct tep_format_field pass:[*]*tep_find_field*(struct tep_event_ormat pass:[*]_event_, const char pass:[*]_name_); +struct tep_format_field pass:[*]*tep_find_any_field*(struct tep_event pass:[*]_event_, const char pass:[*]_name_); +-- + +DESCRIPTION +----------- +These functions search for a field with given name in an event. The field +returned can be used to find the field content from within a data record. + +The *tep_find_common_field()* function searches for a common field with _name_ +in the _event_. + +The *tep_find_field()* function searches for an event specific field with +_name_ in the _event_. + +The *tep_find_any_field()* function searches for any field with _name_ in the +_event_. + +RETURN VALUE +------------ +The _tep_find_common_field(), *tep_find_field()* and _tep_find_any_field()_ +functions return a pointer to the found field, or NULL in case there is no field +with the requested name. + +EXAMPLE +------- +[source,c] +-- +#include <event-parse.h> +... +void get_htimer_info(struct tep_handle *tep, struct tep_record *record) +{ + struct tep_format_field *field; + struct tep_event *event; + long long softexpires; + int mode; + int pid; + + event = tep_find_event_by_name(tep, "timer", "hrtimer_start"); + + field = tep_find_common_field(event, "common_pid"); + if (field == NULL) { + /* Cannot find "common_pid" field in the event */ + } else { + /* Get pid from the data record */ + pid = tep_read_number(tep, record->data + field->offset, + field->size); + } + + field = tep_find_field(event, "softexpires"); + if (field == NULL) { + /* Cannot find "softexpires" event specific field in the event */ + } else { + /* Get softexpires parameter from the data record */ + softexpires = tep_read_number(tep, record->data + field->offset, + field->size); + } + + field = tep_find_any_field(event, "mode"); + if (field == NULL) { + /* Cannot find "mode" field in the event */ + } else + { + /* Get mode parameter from the data record */ + mode = tep_read_number(tep, record->data + field->offset, + field->size); + } +} +... +-- + +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/libs/libtrace/libtraceevent.git/ |