passage
OpenTraceing API for Erlang
Examples
%% Registers `tracer`
Context = passage_span_context_null,
Sampler = passage_sampler_all:new(),
Reporter = passage_reporter_process:new(self(), span),
ok = passage_tracer_registry:register(tracer, Context, Sampler, Reporter),
%% Starts a root span
RootSpan = passage:start_span(example_root, [{tracer, tracer}]),
%% Starts a child span
ChildSpan = passage:start_span(example_child, [{child_of, RootSpan}]),
%% Finishes spans
passage:finish_span(ChildSpan),
passage:finish_span(RootSpan),
%% Receives the finished spans
receive {span, FinishedChildSpan} -> ok end,
receive {span, FinishedRootSpan} -> ok end.
Process Dictionary Version
%% Registers `tracer`
Context = passage_span_context_null,
Sampler = passage_sampler_all:new(),
Reporter = passage_reporter_process:new(self(), span),
ok = passage_tracer_registry:register(tracer, Context, Sampler, Reporter),
%% Starts a root span
ok = passage_pd:start_span(example_root, [{tracer, tracer}]),
%% Starts a child span
ok = passage_pd:start_span(example_child),
%% Finishes spans
passage_pd:finish_span(), % child
passage_pd:finish_span(), % root
%% Receives the finished spans
receive {span, FinishedChildSpan} -> ok end,
receive {span, FinishedRootSpan} -> ok end.
Parse Transform
-module(example).
-compile({parse_transform, passage_transform}). % Enables `passage_transform'
-passage_trace([{tags, #{foo => bar}}, {eval_tags, #{size => "byte_size(Bin)"}}]).
-spec foo(binary()) -> binary().
foo(Bin) ->
<<"foo", Bin/binary>>.
The above foo function will be transformed as follows:
foo(Bin) ->
try
passage_pd:start_span(
'example:foo/1',
[{tags, #{application => example, module => example, lien => 7, foo => bar}}]),
passage_pd:set_tags(#{process => self(), size => byte_size(Bin)}),
<<"foo", Bin/binary>>
after
passage_pd:finish_span()
end.