Merge pull request #261 from qdentity/dvic-refactor-sampler

Refactor otel_sampler to use callbacks for setup, should_sample, and decription

apps/opentelemetry/src/opentelemetry.app.src

@@ -8,7 +8,7 @@
     stdlib,
     opentelemetry_api
    ]},
-  {env, [{sampler, {parent_based, #{root => {always_on, #{}}}}}, % default sampler
+  {env, [{sampler, {parent_based, #{root => always_on}}}, % default sampler
 
          {text_map_propagators, [fun otel_baggage:get_text_map_propagators/0,
                                  fun otel_tracer_default:w3c_propagators/0]},

apps/opentelemetry/src/otel_configuration.erl

@@ -45,7 +45,7 @@ processors(AppEnvOpts) ->
 %% sampler configuration is unique since it has the _ARG that is a sort of
 %% sub-configuration of the sampler config, and isn't a list.
 sampler(AppEnvOpts) ->
-    Sampler = proplists:get_value(sampler, AppEnvOpts, {parent_based, #{root => {always_on, #{}}}}),
+    Sampler = proplists:get_value(sampler, AppEnvOpts, {parent_based, #{root => always_on}}),
 
     Sampler1 = case os:getenv("OTEL_TRACES_SAMPLER") of
                    false ->
@@ -143,22 +143,21 @@ transform(url, Value) ->
     uri_string:parse(Value);
 %% convert sampler string to usable configuration term
 transform(sampler, {"parentbased_always_on", _}) ->
-    {parent_based, #{root => {always_on, #{}}}};
+    {parent_based, #{root => always_on}};
 transform(sampler, {"parentbased_always_off", _}) ->
-    {parent_based, #{root => {always_off, #{}}}};
+    {parent_based, #{root => always_off}};
 transform(sampler, {"always_on", _}) ->
-    {always_on, #{}};
+    always_on;
 transform(sampler, {"always_off", _}) ->
-    {always_off, #{}};
+    always_off;
 transform(sampler, {"traceidratio", false}) ->
     {trace_id_ratio_based, 1.0};
 transform(sampler, {"traceidratio", Probability}) ->
     {trace_id_ratio_based, probability_string_to_float(Probability)};
 transform(sampler, {"parentbased_traceidratio", false}) ->
-    {parentbased_traceidratio, 1.0};
+    {parent_based, #{root => {trace_id_ratio_based, 1.0}}};
 transform(sampler, {"parentbased_traceidratio", Probability}) ->
-    {parent_based,
-     #{root => {trace_id_ratio_based, probability_string_to_float(Probability)}}};
+    {parent_based, #{root => {trace_id_ratio_based, probability_string_to_float(Probability)}}};
 transform(sampler, Value) ->
     Value;
 

apps/opentelemetry/src/otel_sampler.erl

@@ -19,171 +19,78 @@
 %%%-------------------------------------------------------------------------
 -module(otel_sampler).
 
--export([new/3,
-         setup/1,
-         get_description/1,
-         always_on/7,
-         always_off/7,
-         parent_based/7,
-         trace_id_ratio_based/7]).
+-export([description/1, new/1, should_sample/7]).
+
+-export_type([
+    description/0,
+    sampler_config/0,
+    sampler_opts/0,
+    sampling_decision/0,
+    sampling_result/0,
+    t/0
+]).
+
+-callback setup(sampler_opts()) -> sampler_config().
+
+-callback description(sampler_config()) -> description().
+
+-callback should_sample(
+    otel_ctx:t(),
+    opentelemetry:trace_id(),
+    opentelemetry:links(),
+    opentelemetry:span_name(),
+    opentelemetry:span_kind(),
+    opentelemetry:attributes(),
+    sampler_config()
+) -> sampling_result().
 
--include_lib("kernel/include/logger.hrl").
--include_lib("opentelemetry_api/include/opentelemetry.hrl").
 -include("otel_sampler.hrl").
--include("otel_span.hrl").
 
--callback setup(sampler_opts()) -> t().
-
--type sampling_decision() :: ?DROP | ?RECORD_ONLY | ?RECORD_AND_SAMPLE.
--type sampling_result() :: {sampling_decision(), opentelemetry:attributes(), opentelemetry:tracestate()}.
 -type description() :: unicode:unicode_binary().
--type sampler_fun() :: fun((otel_ctx:t(),
-                            opentelemetry:trace_id(),
-                            opentelemetry:links(),
-                            opentelemetry:span_name(),
-                            opentelemetry:span_kind(),
-                            opentelemetry:attributes(),
-                            term()) -> sampling_result()).
--type sampler() :: {sampler_fun(), description(), sampler_opts()}.
+-type sampler_config() :: term().
 -type sampler_opts() :: term().
--opaque t() :: sampler().
--export_type([sampler_fun/0,
-              description/0,
-              sampling_result/0,
-              sampling_decision/0,
-              sampler_opts/0,
-              t/0]).
-
--define(MAX_VALUE, 9223372036854775807). %% 2^63 - 1
-
--spec new(sampler_fun(), description(), sampler_opts()) -> t().
-new(DecisionFunction, Description, SamplerOpts) ->
-    {DecisionFunction, Description, SamplerOpts}.
-
--spec setup(atom() | {atom() | module(), sampler_opts()}) -> t().
-setup({Sampler, Opts}) ->
-    setup(Sampler, Opts);
-setup(Sampler) when is_atom(Sampler) ->
-    setup(Sampler, #{}).
-
-setup(always_on, Opts) ->
-    {fun ?MODULE:always_on/7, description(always_on, Opts), []};
-setup(always_off, Opts) ->
-    {fun ?MODULE:always_off/7, description(always_off, Opts), []};
-setup(parent_based, Opts) ->
-    {Config, Description} = parent_based_config(Opts),
-    {fun ?MODULE:parent_based/7, Description, Config};
-setup(trace_id_ratio_based, Probability) ->
-    IdUpperBound = case Probability of
-                       P when P =:= 0.0 ->
-                           0;
-                       P when P =:= 1.0 ->
-                           ?MAX_VALUE;
-                       P when P >= 0.0 andalso P =< 1.0 ->
-                           P * ?MAX_VALUE
-                   end,
-    {fun ?MODULE:trace_id_ratio_based/7, description(trace_id_ratio_based, Probability), IdUpperBound};
-setup(Sampler, Opts) ->
-    Sampler:setup(Opts).
-
-always_on(Ctx, _TraceId, _Links, _SpanName, _Kind, _Attributes, _Opts) ->
-    {?RECORD_AND_SAMPLE, [], tracestate(Ctx)}.
-
-always_off(Ctx, _TraceId, _Links, _SpanName, _Kind, _Attributes, _Opts) ->
-    {?DROP, [], tracestate(Ctx)}.
-
--spec get_description(sampler()) -> description().
-get_description({_Fun, Description, _Opts}) ->
-    Description.
-
-parent_based_config(Opts=#{root := {RootSampler, RootOpts}})
-  when is_atom(RootSampler)->
-    {RemoteParentSampled, RemoteParentSampledOpts}
-        = maps:get(remote_parent_sampled, Opts, {always_on, #{}}),
-    {RemoteParentNotSampled, RemoteParentNotSampledOpts}
-        = maps:get(remote_parent_not_sampled, Opts, {always_off, #{}}),
-    {LocalParentSampled, LocalParentSampledOpts}
-        = maps:get(local_parent_sampled, Opts, {always_on, #{}}),
-    {LocalParentNotSampled, LocalParentNotSampledOpts}
-        = maps:get(local_parent_not_sampled, Opts, {always_off, #{}}),
-
-    ParentBasedConfig = #{root => setup(RootSampler, RootOpts),
-                          remote_parent_sampled =>
-                              setup(RemoteParentSampled, RemoteParentSampledOpts),
-                          remote_parent_not_sampled =>
-                              setup(RemoteParentNotSampled, RemoteParentNotSampledOpts),
-                          local_parent_sampled =>
-                              setup(LocalParentSampled, LocalParentSampledOpts),
-                          local_parent_not_sampled =>
-                              setup(LocalParentNotSampled, LocalParentNotSampledOpts)},
-    {ParentBasedConfig, description(parent_based, ParentBasedConfig)};
-parent_based_config(Opts) ->
-    ?LOG_INFO("no root opt found for sampler parent_based. always_on will be used for root spans"),
-    parent_based_config(Opts#{root => {always_on, #{}}}).
-
-parent_based(Ctx, TraceId, Links, SpanName, Kind, Attributes, Opts) ->
-    ParentSpanCtx = otel_tracer:current_span_ctx(Ctx),
-    {Sampler, _Description, SamplerOpts} = parent_based_sampler(ParentSpanCtx, Opts),
-    Sampler(Ctx, TraceId, Links, SpanName, Kind, Attributes, SamplerOpts).
-
-%% remote parent sampled
-parent_based_sampler(#span_ctx{trace_flags=TraceFlags,
-                               is_remote=true}, #{remote_parent_sampled := SamplerAndOpts})
-  when ?IS_SAMPLED(TraceFlags) ->
-    SamplerAndOpts;
-%% remote parent not sampled
-parent_based_sampler(#span_ctx{is_remote=true}, #{remote_parent_not_sampled := SamplerAndOpts}) ->
-    SamplerAndOpts;
-%% local parent sampled
-parent_based_sampler(#span_ctx{trace_flags=TraceFlags,
-                               is_remote=false}, #{local_parent_sampled := SamplerAndOpts})
-  when ?IS_SAMPLED(TraceFlags) ->
-    SamplerAndOpts;
-%% local parent not sampled
-parent_based_sampler(#span_ctx{is_remote=false}, #{local_parent_not_sampled := SamplerAndOpts}) ->
-    SamplerAndOpts;
-%% root
-parent_based_sampler(_SpanCtx, #{root := SamplerAndOpts}) ->
-    SamplerAndOpts.
-
-
-trace_id_ratio_based(Ctx, undefined, _, _, _, _, _IdUpperBound) ->
-    {?DROP, [], tracestate(Ctx)};
-trace_id_ratio_based(Ctx, 0, _, _, _, _, _IdUpperBound) ->
-    {?DROP, [], tracestate(Ctx)};
-trace_id_ratio_based(Ctx, TraceId, _, _, _, _, IdUpperBound) ->
-    Lower64Bits = TraceId band ?MAX_VALUE,
-    case erlang:abs(Lower64Bits) < IdUpperBound of
-        true ->
-            {?RECORD_AND_SAMPLE, [], tracestate(Ctx)};
-        false ->
-            {?DROP, [], tracestate(Ctx)}
-    end.
-
-tracestate(Ctx) ->
-    tracestate_(otel_tracer:current_span_ctx(Ctx)).
-
-tracestate_(#span_ctx{tracestate=undefined}) ->
-    [];
-tracestate_(#span_ctx{tracestate=TraceState}) ->
-    TraceState;
-tracestate_(undefined) ->
-    [].
-
-description(always_on, _) ->
-    <<"AlwaysOnSampler">>;
-description(always_off, _) ->
-    <<"AlwaysOffSampler">>;
-description(trace_id_ratio_based, Probability) ->
-    unicode:characters_to_binary(io_lib:format("TraceIdRatioBased{~.6f}", [Probability]));
-description(parent_based, #{root := RootSampler,
-                            remote_parent_sampled := RemoteParentSampler,
-                            remote_parent_not_sampled := RemoteParentNotSampler,
-                            local_parent_sampled := LocalParentSampler,
-                            local_parent_not_sampled := LocalParentNotSampler}) ->
-    <<"ParentBased{root:", (get_description(RootSampler))/binary,
-      ",remoteParentSampled:", (get_description(RemoteParentSampler))/binary,
-      ",remoteParentNotSampled:", (get_description(RemoteParentNotSampler))/binary,
-      ",localParentSampled:", (get_description(LocalParentSampler))/binary,
-      ",localParentNotSampled:", (get_description(LocalParentNotSampler))/binary,
-      "}">>.
+-type builtin_sampler() ::
+    always_on
+    | always_off
+    | {trace_id_ratio_based, float()}
+    | {parent_based, #{
+        remote_parent_sampled => sampler_spec(),
+        remote_parent_not_sampled => sampler_spec(),
+        local_parent_sampled => sampler_spec(),
+        local_parent_not_sampled => sampler_spec(),
+        root => sampler_spec()
+    }}.
+-type sampler_spec() :: builtin_sampler() | {module(), sampler_opts()}.
+-type sampling_decision() :: ?DROP | ?RECORD_ONLY | ?RECORD_AND_SAMPLE.
+-type sampling_result() :: {
+    sampling_decision(), opentelemetry:attributes(), opentelemetry:tracestate()
+}.
+-opaque t() :: {module(), description(), sampler_opts()}.
+
+-spec new(sampler_spec()) -> t().
+new(always_on) ->
+    new({otel_sampler_always_on, #{}});
+new(always_off) ->
+    new({otel_sampler_always_off, #{}});
+new({trace_id_ratio_based, Opts}) ->
+    new({otel_sampler_trace_id_ratio_based, Opts});
+new({parent_based, Opts}) ->
+    new({otel_sampler_parent_based, Opts});
+new({Sampler, Opts}) ->
+    Config = Sampler:setup(Opts),
+    {Sampler, Sampler:description(Config), Config}.
+
+-spec should_sample(
+    t(),
+    otel_ctx:t(),
+    opentelemetry:trace_id(),
+    opentelemetry:links(),
+    opentelemetry:span_name(),
+    opentelemetry:span_kind(),
+    opentelemetry:attributes()
+) -> sampling_result().
+should_sample({Sampler, _, Config}, Ctx, TraceId, Links, SpanName, Kind, Attributes) ->
+    Sampler:should_sample(Ctx, TraceId, Links, SpanName, Kind, Attributes, Config).
+
+-spec description(t()) -> description().
+description({_, Description, _}) -> Description.

apps/opentelemetry/src/otel_sampler_always_off.erl

@@ -0,0 +1,34 @@
+%%%------------------------------------------------------------------------
+%% Copyright 2019, OpenTelemetry Authors
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% @doc
+%% This sampler always decides to neither record nor sample each span.
+%% @end
+%%%-------------------------------------------------------------------------
+-module(otel_sampler_always_off).
+
+-behavior(otel_sampler).
+
+-export([description/1, setup/1, should_sample/7]).
+
+-include_lib("opentelemetry_api/include/opentelemetry.hrl").
+-include("otel_sampler.hrl").
+
+setup(_Opts) -> [].
+
+description(_) -> <<"AlwaysOffSampler">>.
+
+should_sample(Ctx, _TraceId, _Links, _SpanName, _SpanKind, _Attributes, _Opts) ->
+    SpanCtx = otel_tracer:current_span_ctx(Ctx),
+    {?DROP, [], otel_span:tracestate(SpanCtx)}.

apps/opentelemetry/src/otel_sampler_always_on.erl

@@ -0,0 +1,34 @@
+%%%------------------------------------------------------------------------
+%% Copyright 2019, OpenTelemetry Authors
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% @doc
+%% This sampler always decides to record and sample each span.
+%% @end
+%%%-------------------------------------------------------------------------
+-module(otel_sampler_always_on).
+
+-behavior(otel_sampler).
+
+-export([description/1, setup/1, should_sample/7]).
+
+-include_lib("opentelemetry_api/include/opentelemetry.hrl").
+-include("otel_sampler.hrl").
+
+setup(_Opts) -> [].
+
+description(_) -> <<"AlwaysOnSampler">>.
+
+should_sample(Ctx, _TraceId, _Links, _SpanName, _SpanKind, _Attributes, _Opts) ->
+    SpanCtx = otel_tracer:current_span_ctx(Ctx),
+    {?RECORD_AND_SAMPLE, [], otel_span:tracestate(SpanCtx)}.