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Event Tracer (ET)
Reference Manual
Version 1.4.4.2

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# et_selector

### MODULE

et_selector

### MODULE SUMMARY

Define event transforms and trace patterns

### DESCRIPTION

### EXPORTS

make_pattern(RawPattern) -> TracePattern

Types:

RawPattern = detail_level()
TracePattern = erlang_trace_pattern_match_spec()
detail_level() = min | max | integer(X) when X >= 0, X =< 100

Makes a trace pattern suitable to feed change_pattern/1

Min detail level deactivates tracing of calls to et:trace_me/4,5

Max detail level activates tracing of all calls to et:trace_me/4,5

integer(X) detail level activates tracing of all calls to et:trace_me/4,5 whose detail level argument is lesser than X.

See also erlang:trace_pattern/2 for more info about its match_spec()

change_pattern(Pattern) -> ok

Types:

Pattern = detail_level() | empty_match_spec() | erlang_trace_pattern_match_spec()
detail_level() = min | max | integer(X) when X >= 0, X =< 100
empty_match_spec() = []

Activates/deactivates tracing by changing the current trace pattern.

min detail level deactivates tracing of calls to et:trace_me/4,5

max detail level activates tracing of all calls to et:trace_me/4,5

integer(X) detail level activates tracing of all calls to et:trace_me/4,5 whose detail level argument is lesser than X.

An empty match spec deactivates tracing of calls to et:trace_me/4,5

Other match specs activates tracing of calls to et:trace_me/4,5 accordingly with erlang:trace_pattern/2.

parse_event(Mod, ValidTraceData) -> false | true | {true, Event}

Types:

Mod = module_name() | undefined <v>module_name() = atom() <v>ValidTraceData = erlang_trace_data() | record(event)
erlang_trace_data() = {trace, Pid, Label, Info} | {trace, Pid, Label, Info, Extra} | {trace_ts, Pid, Label, Info, ReportedTS} | {trace_ts, Pid, Label, Info, Extra, ReportedTS} | {seq_trace, Label, Info} | {seq_trace, Label, Info, ReportedTS} | {drop, NumberOfDroppedItems}

Transforms trace data and makes an event record out of it.

See erlang:trace/3 for more info about the semantics of the trace data.

An event record consists of the following fields:

detail_level

  Noise has a high level as opposed to essentials.

trace_ts

  Time when the trace was generated. Same as event_ts if omitted in trace data.

event_ts

  Time when the event record was created.

from

  From actor, such as sender of a message.

to

  To actor, such as receiver of message.

label

  Label intended to provide a brief event summary.

contents

  All nitty gritty details of the event.

See et:trace_me/4and et:trace_me/5 for details.

Returns:

{true, Event}

  where Event is an #event{} record representing the trace data

true

  means that the trace data already is an event record and that it is valid as it is. No transformation is needed.

false

  means that the trace data is uninteresting and should be dropped