Implement factory and config for sampling processor (head-based) (ope…

…n-telemetry#186)

* Implement factory and config for sampling processor (head-based)

* Change Config name

processor/tracesamplerprocessor/config.go

@@ -0,0 +1,29 @@
+// 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.
+
+package tracesamplerprocessor
+
+import "github.com/open-telemetry/opentelemetry-service/config/configmodels"
+
+// Config has the configuration guiding the trace sampler processor.
+type Config struct {
+	configmodels.ProcessorSettings `mapstructure:",squash"`
+	// SamplingPercentage is the percentage rate at which traces are going to be sampled. Defaults to zero, i.e.: no sample.
+	// Values greater or equal 100 are treated as "sample all traces".
+	SamplingPercentage float32 `mapstructure:"sampling-percentage"`
+	// HashSeed allows one to configure the hashing seed. This is important in scenarios where multiple layers of collectors
+	// have different sampling rates: if they use the same seed all passing one layer may pass the other even if they have
+	// different sampling rates, configuring different seeds avoids that.
+	HashSeed uint32 `mapstructure:"hash-seed"`
+}

processor/tracesamplerprocessor/config_test.go

@@ -0,0 +1,73 @@
+// 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.
+
+package tracesamplerprocessor
+
+import (
+	"path"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/open-telemetry/opentelemetry-service/config"
+	"github.com/open-telemetry/opentelemetry-service/config/configmodels"
+	"github.com/open-telemetry/opentelemetry-service/processor"
+)
+
+func TestLoadConfig(t *testing.T) {
+	receivers, processors, exporters, err := config.ExampleComponents()
+	assert.Nil(t, err)
+
+	factory := &Factory{}
+	processors[typeStr] = factory
+	cfg, err := config.LoadConfigFile(
+		t, path.Join(".", "testdata", "config.yaml"), receivers, processors, exporters,
+	)
+
+	require.Nil(t, err)
+	require.NotNil(t, cfg)
+
+	p0 := cfg.Processors["trace-sampler"]
+	assert.Equal(t, p0,
+		&Config{
+			ProcessorSettings: configmodels.ProcessorSettings{
+				TypeVal: "trace-sampler",
+				NameVal: "trace-sampler",
+			},
+			SamplingPercentage: 15.3,
+			HashSeed:           22,
+		})
+
+}
+
+func TestLoadConfigEmpty(t *testing.T) {
+	receivers, _, exporters, err := config.ExampleComponents()
+	processors, err := processor.Build(&Factory{})
+	require.NotNil(t, processors)
+	require.NoError(t, err)
+
+	config, err := config.LoadConfigFile(
+		t,
+		path.Join(".", "testdata", "empty.yaml"),
+		receivers,
+		processors,
+		exporters)
+
+	require.Nil(t, err)
+	require.NotNil(t, config)
+	p0 := config.Processors["trace-sampler"]
+	factory := &Factory{}
+	assert.Equal(t, p0, factory.CreateDefaultConfig())
+}

processor/tracesamplerprocessor/factory.go

@@ -0,0 +1,67 @@
+// 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.
+
+package tracesamplerprocessor
+
+import (
+	"go.uber.org/zap"
+
+	"github.com/open-telemetry/opentelemetry-service/config/configerror"
+	"github.com/open-telemetry/opentelemetry-service/config/configmodels"
+	"github.com/open-telemetry/opentelemetry-service/consumer"
+	"github.com/open-telemetry/opentelemetry-service/processor"
+)
+
+const (
+	// The value of "type" trace-samplers in configuration.
+	typeStr = "trace-sampler"
+)
+
+// Factory is the factory for trace-sample processor.
+type Factory struct {
+}
+
+// Type gets the type of the config created by this factory.
+func (f *Factory) Type() string {
+	return typeStr
+}
+
+// CreateDefaultConfig creates the default configuration for processor.
+func (f *Factory) CreateDefaultConfig() configmodels.Processor {
+	return &Config{
+		ProcessorSettings: configmodels.ProcessorSettings{
+			TypeVal: typeStr,
+			NameVal: typeStr,
+		},
+	}
+}
+
+// CreateTraceProcessor creates a trace processor based on this config.
+func (f *Factory) CreateTraceProcessor(
+	logger *zap.Logger,
+	nextConsumer consumer.TraceConsumer,
+	cfg configmodels.Processor,
+) (processor.TraceProcessor, error) {
+	oCfg := cfg.(*Config)
+	return NewTraceProcessor(nextConsumer, *oCfg)
+}
+
+// CreateMetricsProcessor creates a metrics processor based on this config.
+func (f *Factory) CreateMetricsProcessor(
+	logger *zap.Logger,
+	nextConsumer consumer.MetricsConsumer,
+	cfg configmodels.Processor,
+) (processor.MetricsProcessor, error) {
+	return nil, configerror.ErrDataTypeIsNotSupported
+}

processor/tracesamplerprocessor/factory_test.go

@@ -0,0 +1,45 @@
+// 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.
+
+package tracesamplerprocessor
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"go.uber.org/zap"
+
+	"github.com/open-telemetry/opentelemetry-service/exporter/exportertest"
+)
+
+func TestCreateDefaultConfig(t *testing.T) {
+	factory := &Factory{}
+
+	cfg := factory.CreateDefaultConfig()
+	assert.NotNil(t, cfg, "failed to create default config")
+}
+
+func TestCreateProcessor(t *testing.T) {
+	factory := &Factory{}
+
+	cfg := factory.CreateDefaultConfig()
+
+	tp, err := factory.CreateTraceProcessor(zap.NewNop(), exportertest.NewNopTraceExporter(), cfg)
+	assert.NotNil(t, tp)
+	assert.NoError(t, err, "cannot create trace processor")
+
+	mp, err := factory.CreateMetricsProcessor(zap.NewNop(), nil, cfg)
+	assert.Nil(t, mp)
+	assert.Error(t, err, "should not be able to create metric processor")
+}

processor/tracesamplerprocessor/testdata/config.yaml

@@ -0,0 +1,16 @@
+receivers:
+  examplereceiver:
+
+processors:
+  trace-sampler:
+    sampling-percentage: 15.3
+    hash-seed: 22
+
+exporters:
+  exampleexporter:
+
+pipelines:
+  traces:
+    receivers: [examplereceiver]
+    processors: [trace-sampler]
+    exporters: [exampleexporter]

processor/tracesamplerprocessor/testdata/empty.yaml

@@ -0,0 +1,15 @@
+receivers:
+  examplereceiver:
+
+processors:
+  trace-sampler:
+
+
+exporters:
+  exampleexporter:
+
+pipelines:
+  traces:
+    receivers: [examplereceiver]
+    processors: [trace-sampler]
+    exporters: [exampleexporter]

processor/tracesamplerprocessor/tracesamplerprocessor.go

@@ -38,19 +38,8 @@ const (
 	percentageScaleFactor = numHashBuckets / 100.0
 )
 
-// TraceSamplerCfg has the configuration guiding the trace sampler processor.
-type TraceSamplerCfg struct {
-	// SamplingPercentage is the percentage rate at which traces are going to be sampled. Defaults to zero, i.e.: no sample.
-	// Values greater or equal 100 are treated as "sample all traces".
-	SamplingPercentage float32
-	// HashSeed allows one to configure the hashing seed. This is important in scenarios where multiple layers of collectors
-	// have different sampling rates: if they use the same seed all passing one layer may pass the other even if they have
-	// different sampling rates, configuring different seeds avoids that.
-	HashSeed uint32
-}
-
-// InitFromViper updates TraceSamplerCfg according to the viper configuration.
-func (tsc *TraceSamplerCfg) InitFromViper(v *viper.Viper) (*TraceSamplerCfg, error) {
+// InitFromViper updates TraceSampler config according to the viper configuration.
+func (tsc *Config) InitFromViper(v *viper.Viper) (*Config, error) {
 	if v == nil {
 		return nil, errors.New("v is nil")
 	}
@@ -73,7 +62,7 @@ var _ processor.TraceProcessor = (*tracesamplerprocessor)(nil)
 
 // NewTraceProcessor returns a processor.TraceProcessor that will perform head sampling according to the given
 // configuration.
-func NewTraceProcessor(nextConsumer consumer.TraceConsumer, cfg TraceSamplerCfg) (processor.TraceProcessor, error) {
+func NewTraceProcessor(nextConsumer consumer.TraceConsumer, cfg Config) (processor.TraceProcessor, error) {
 	if nextConsumer == nil {
 		return nil, errors.New("nextConsumer is nil")
 	}