implement seq_trace based context

Author: tsloughter

src/ot_ctx_seqtrace.erl

@@ -25,17 +25,38 @@
          with_value/3]).
 
 -spec get(term()) -> term().
-get(_Key) ->
-    ok.
+get(Key) ->
+    case seq_trace:get_token(label) of
+        {label, Label} ->
+            maps:get(Key, Label, undefined);
+        [] ->
+            undefined
+    end.
 
 -spec get(term(), term()) -> term().
-get(_Key, _Value) ->
-    ok.
+get(Key, Default) ->
+    case seq_trace:get_token(label) of
+        {label, Label} ->
+            maps:get(Key, Label, Default);
+        [] ->
+            undefined
+    end.
 
 -spec with_value(term(), term()) -> ok.
-with_value(_Key, _Value) ->
-    ok.
+with_value(Key, Value) ->
+    case seq_trace:get_token(label) of
+        {label, Label} ->
+            seq_trace:set_token(label, Label#{Key => Value});
+        [] ->
+            seq_trace:set_token(label, #{Key => Value})
+    end.
 
 -spec with_value(term(), term(), fun()) -> ok.
-with_value(_Key, _Value, Fun) ->
-    Fun().
+with_value(Key, Value, Fun) ->
+    Orig = ?MODULE:get(Key),
+    try
+        with_value(Key, Value),
+        Fun()
+    after
+        with_value(Key, Orig)
+    end.

test/opentelemetry_SUITE.erl

@@ -8,15 +8,30 @@
 -include("opentelemetry.hrl").
 
 all() ->
+    [{group, ot_ctx_pdict},
+     {group, ot_ctx_seqtrace}].
+
+all_testcases() ->
     [child_spans, non_default_tracer].
 
+groups() ->
+    [{ot_ctx_pdict, [parallel, shuffle], all_testcases()},
+     {ot_ctx_seqtrace, [parallel, shuffle], all_testcases()}].
+
 init_per_suite(Config) ->
     application:load(opentelemetry),
-    %% set application environment variables
-    {ok, _} = application:ensure_all_started(opentelemetry),
     Config.
 
 end_per_suite(_Config) ->
+    ok.
+
+init_per_group(CtxModule, Config) ->
+    application:set_env(opentelemetry, tracer, {ot_tracer_default, #{span => {ot_span_ets, []},
+                                                                     ctx => {CtxModule, []}}}),
+    {ok, _} = application:ensure_all_started(opentelemetry),
+    Config.
+
+end_per_group(_, _Config) ->
     ok = application:stop(opentelemetry).
 
 init_per_testcase(_, Config) ->