Add benchmark for filestream input

Now we can quickly compare performance metrics when we make changes to the
filestream implementation without running the whole Filebeat.

filebeat/input/filestream/input_test.go

@@ -0,0 +1,173 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you 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 filestream
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"testing"
+	"time"
+
+	loginp "github.com/elastic/beats/v7/filebeat/input/filestream/internal/input-logfile"
+	v2 "github.com/elastic/beats/v7/filebeat/input/v2"
+	"github.com/elastic/beats/v7/libbeat/beat"
+	"github.com/elastic/beats/v7/libbeat/statestore"
+	"github.com/elastic/beats/v7/libbeat/statestore/storetest"
+	conf "github.com/elastic/elastic-agent-libs/config"
+	"github.com/elastic/elastic-agent-libs/logp"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// runFilestreamBenchmark runs the entire filestream input with the in-memory registry and the test pipeline.
+// `testID` must be unique for each test run
+// `cfg` must be a valid YAML string containing valid filestream configuration
+// `expEventCount` is an expected amount of produced events
+func runFilestreamBenchmark(b *testing.B, testID string, cfg string, expEventCount int) {
+	logger := logp.L()
+	c, err := conf.NewConfigWithYAML([]byte(cfg), cfg)
+	require.NoError(b, err)
+
+	p := Plugin(logger, createTestStore(b))
+	input, err := p.Manager.Create(c)
+	require.NoError(b, err)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	context := v2.Context{
+		Logger:      logger,
+		ID:          testID,
+		Cancelation: ctx,
+	}
+
+	var out []beat.Event
+	connector := newTestPipeline(&out)
+	done := make(chan struct{})
+	go func() {
+		err := input.Run(context, connector)
+		assert.NoError(b, err)
+		done <- struct{}{}
+	}()
+
+	require.Eventually(b, func() bool {
+		return len(out) == expEventCount
+	}, 30*time.Second, 10*time.Millisecond)
+
+	cancel()
+	<-done // for more stable results we should wait until the full shutdown
+}
+
+func generateFile(b *testing.B, lineCount int) string {
+	b.Helper()
+	dir := b.TempDir()
+	file, err := os.CreateTemp(dir, "lines.log")
+	require.NoError(b, err)
+
+	for i := 0; i < lineCount; i++ {
+		fmt.Fprintf(file, "rather mediocre log line message - %d\n", i)
+	}
+	filename := file.Name()
+	err = file.Close()
+	require.NoError(b, err)
+	return filename
+}
+
+func BenchmarkFilestream(b *testing.B) {
+	logp.TestingSetup(logp.ToDiscardOutput())
+	lineCount := 1000
+	filename := generateFile(b, lineCount)
+
+	b.Run("filestream default throughput", func(b *testing.B) {
+		cfg := `
+type: filestream
+prospector.scanner.check_interval: 1s
+paths:
+    - ` + filename + `
+`
+		for i := 0; i < b.N; i++ {
+			runFilestreamBenchmark(b, fmt.Sprintf("default-benchmark-%d", i), cfg, lineCount)
+		}
+	})
+
+	b.Run("filestream fingerprint throughput", func(b *testing.B) {
+		cfg := `
+type: filestream
+prospector.scanner:
+  fingerprint.enabled: true
+  check_interval: 1s
+file_identity.fingerprint: ~
+paths:
+  - ` + filename + `
+`
+		for i := 0; i < b.N; i++ {
+			runFilestreamBenchmark(b, fmt.Sprintf("fp-benchmark-%d", i), cfg, lineCount)
+		}
+	})
+}
+
+func createTestStore(t *testing.B) loginp.StateStore {
+	return &testStore{registry: statestore.NewRegistry(storetest.NewMemoryStoreBackend())}
+}
+
+type testStore struct {
+	registry *statestore.Registry
+}
+
+func (s *testStore) Close() {
+	s.registry.Close()
+}
+
+func (s *testStore) Access() (*statestore.Store, error) {
+	return s.registry.Get("filestream-benchmark")
+}
+
+func (s *testStore) CleanupInterval() time.Duration {
+	return time.Second
+}
+
+func newTestPipeline(out *[]beat.Event) beat.PipelineConnector {
+	return &testPipeline{out: out}
+}
+
+type testPipeline struct {
+	out *[]beat.Event
+}
+
+func (p *testPipeline) ConnectWith(beat.ClientConfig) (beat.Client, error) {
+	return p.Connect()
+}
+func (p *testPipeline) Connect() (beat.Client, error) {
+	return &testClient{out: p.out}, nil
+}
+
+type testClient struct {
+	out *[]beat.Event
+}
+
+func (c *testClient) Publish(event beat.Event) {
+	*c.out = append(*c.out, event)
+}
+
+func (c *testClient) PublishAll(events []beat.Event) {
+	for _, e := range events {
+		c.Publish(e)
+	}
+}
+func (c *testClient) Close() error {
+	return nil
+}