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Diffstat (limited to 'tools/lib/traceevent/Documentation/libtraceevent-field_print.txt')
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diff --git a/tools/lib/traceevent/Documentation/libtraceevent-field_print.txt b/tools/lib/traceevent/Documentation/libtraceevent-field_print.txt new file mode 100644 index 000000000000..9a9df98ac44d --- /dev/null +++ b/tools/lib/traceevent/Documentation/libtraceevent-field_print.txt @@ -0,0 +1,126 @@ +libtraceevent(3) +================ + +NAME +---- +tep_print_field, tep_print_fields, tep_print_num_field, tep_print_func_field - +Print the field content. + +SYNOPSIS +-------- +[verse] +-- +*#include <event-parse.h>* +*#include <trace-seq.h>* + +void *tep_print_field*(struct trace_seq pass:[*]_s_, void pass:[*]_data_, struct tep_format_field pass:[*]_field_); +void *tep_print_fields*(struct trace_seq pass:[*]_s_, void pass:[*]_data_, int _size_, struct tep_event pass:[*]_event_); +int *tep_print_num_field*(struct trace_seq pass:[*]_s_, const char pass:[*]_fmt_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, int _err_); +int *tep_print_func_field*(struct trace_seq pass:[*]_s_, const char pass:[*]_fmt_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, int _err_); +-- + +DESCRIPTION +----------- +These functions print recorded field's data, according to the field's type. + +The _tep_print_field()_ function extracts from the recorded raw _data_ value of +the _field_ and prints it into _s_, according to the field type. + +The _tep_print_fields()_ prints each field name followed by the record's field +value according to the field's type: +[verse] +-- +"field1_name=field1_value field2_name=field2_value ..." +-- +It iterates all fields of the _event_, and calls _tep_print_field()_ for each of +them. + +The _tep_print_num_field()_ function prints a numeric field with given format +string. A search is performed in the _event_ for a field with _name_. If such +field is found, its value is extracted from the _record_ and is printed in the +_s_, according to the given format string _fmt_. If the argument _err_ is +non-zero, and an error occures - it is printed in the _s_. + +The _tep_print_func_field()_ function prints a function field with given format +string. A search is performed in the _event_ for a field with _name_. If such +field is found, its value is extracted from the _record_. The value is assumed +to be a function address, and a search is perform to find the name of this +function. The function name (if found) and its address are printed in the _s_, +according to the given format string _fmt_. If the argument _err_ is non-zero, +and an error occures - it is printed in _s_. + +RETURN VALUE +------------ +The _tep_print_num_field()_ and _tep_print_func_field()_ functions return 1 +on success, -1 in case of an error or 0 if the print buffer _s_ is full. + +EXAMPLE +------- +[source,c] +-- +#include <event-parse.h> +#include <trace-seq.h> +... +struct tep_handle *tep = tep_alloc(); +... +struct trace_seq seq; +trace_seq_init(&seq); +struct tep_event *event = tep_find_event_by_name(tep, "timer", "hrtimer_start"); +... +void process_record(struct tep_record *record) +{ + struct tep_format_field *field_pid = tep_find_common_field(event, "common_pid"); + + trace_seq_reset(&seq); + + /* Print the value of "common_pid" */ + tep_print_field(&seq, record->data, field_pid); + + /* Print all fields of the "hrtimer_start" event */ + tep_print_fields(&seq, record->data, record->size, event); + + /* Print the value of "expires" field with custom format string */ + tep_print_num_field(&seq, " timer expires in %llu ", event, "expires", record, 0); + + /* Print the address and the name of "function" field with custom format string */ + tep_print_func_field(&seq, " timer function is %s ", event, "function", record, 0); + } + ... +-- + +FILES +----- +[verse] +-- +*event-parse.h* + Header file to include in order to have access to the library APIs. +*trace-seq.h* + Header file to include in order to have access to trace sequences related APIs. + Trace sequences are used to allow a function to call several other functions + to create a string of data to use. +*-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 |