file_input should not attempt to track lost files on windows (#366)

* WIP - filelog receiver should not attempt to track lost files on windows

* Pull os-specific file handle management into separate struct

operator/builtin/input/file/config.go

@@ -167,6 +167,7 @@ func (c InputConfig) Build(context operator.BuildContext) ([]operator.Operator,
 		firstCheck:            true,
 		cancel:                func() {},
 		knownFiles:            make([]*Reader, 0, 10),
+		roller:                newRoller(),
 		fingerprintSize:       int(c.FingerprintSize),
 		MaxLogSize:            int(c.MaxLogSize),
 		MaxConcurrentFiles:    c.MaxConcurrentFiles,

operator/builtin/input/file/file.go

@@ -47,10 +47,10 @@ type InputOperator struct {
 
 	persister operator.Persister
 
-	knownFiles      []*Reader
-	queuedMatches   []string
-	maxBatchFiles   int
-	lastPollReaders []*Reader
+	knownFiles    []*Reader
+	queuedMatches []string
+	maxBatchFiles int
+	roller        roller
 
 	startAtBeginning bool
 
@@ -70,6 +70,7 @@ func (f *InputOperator) Start(persister operator.Persister) error {
 	f.firstCheck = true
 
 	f.persister = persister
+
 	// Load offsets from disk
 	if err := f.loadLastPollFiles(ctx); err != nil {
 		return fmt.Errorf("read known files from database: %s", err)
@@ -85,9 +86,7 @@ func (f *InputOperator) Start(persister operator.Persister) error {
 func (f *InputOperator) Stop() error {
 	f.cancel()
 	f.wg.Wait()
-	for _, reader := range f.lastPollReaders {
-		reader.Close()
-	}
+	f.roller.cleanup()
 	for _, reader := range f.knownFiles {
 		reader.Close()
 	}
@@ -148,45 +147,17 @@ func (f *InputOperator) poll(ctx context.Context) {
 	readers := f.makeReaders(matches)
 	f.firstCheck = false
 
-	// Detect files that have been rotated out of matching pattern
-	lostReaders := make([]*Reader, 0, len(f.lastPollReaders))
-OUTER:
-	for _, oldReader := range f.lastPollReaders {
-		for _, reader := range readers {
-			if reader.Fingerprint.StartsWith(oldReader.Fingerprint) {
-				continue OUTER
-			}
-		}
-		lostReaders = append(lostReaders, oldReader)
-	}
-
 	var wg sync.WaitGroup
-	for _, reader := range lostReaders {
-		wg.Add(1)
-		go func(r *Reader) {
-			defer wg.Done()
-			r.ReadToEnd(ctx)
-		}(reader)
-	}
-
 	for _, reader := range readers {
 		wg.Add(1)
 		go func(r *Reader) {
 			defer wg.Done()
 			r.ReadToEnd(ctx)
 		}(reader)
 	}
-
-	// Wait until all the reader goroutines are finished
 	wg.Wait()
 
-	// Close all files
-	for _, reader := range f.lastPollReaders {
-		reader.Close()
-	}
-
-	f.lastPollReaders = readers
-
+	f.roller.roll(ctx, readers)
 	f.saveCurrent(readers)
 	f.syncLastPollFiles(ctx)
 }

operator/builtin/input/file/roller.go

@@ -0,0 +1,22 @@
+// Copyright The 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 file
+
+import "context"
+
+type roller interface {
+	roll(context.Context, []*Reader)
+	cleanup()
+}

operator/builtin/input/file/roller_other.go

@@ -0,0 +1,67 @@
+// Copyright The 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.
+
+//go:build !windows
+// +build !windows
+
+package file
+
+import (
+	"context"
+	"sync"
+)
+
+type detectLostFiles struct {
+	oldReaders []*Reader
+}
+
+func newRoller() roller {
+	return &detectLostFiles{[]*Reader{}}
+}
+
+func (r *detectLostFiles) roll(ctx context.Context, readers []*Reader) {
+	// Detect files that have been rotated out of matching pattern
+	lostReaders := make([]*Reader, 0, len(r.oldReaders))
+OUTER:
+	for _, oldReader := range r.oldReaders {
+		for _, reader := range readers {
+			if reader.Fingerprint.StartsWith(oldReader.Fingerprint) {
+				continue OUTER
+			}
+		}
+		lostReaders = append(lostReaders, oldReader)
+	}
+
+	var lostWG sync.WaitGroup
+	for _, reader := range lostReaders {
+		lostWG.Add(1)
+		go func(r *Reader) {
+			defer lostWG.Done()
+			r.ReadToEnd(ctx)
+		}(reader)
+	}
+	lostWG.Wait()
+
+	for _, reader := range r.oldReaders {
+		reader.Close()
+	}
+
+	r.oldReaders = readers
+}
+
+func (r *detectLostFiles) cleanup() {
+	for _, reader := range r.oldReaders {
+		reader.Close()
+	}
+}

operator/builtin/input/file/roller_windows.go

@@ -0,0 +1,36 @@
+// Copyright The 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.
+
+//go:build windows
+// +build windows
+
+package file
+
+import "context"
+
+type closeImmediately struct{}
+
+func newRoller() roller {
+	return &closeImmediately{}
+}
+
+func (r *closeImmediately) roll(_ context.Context, readers []*Reader) {
+	for _, reader := range readers {
+		reader.Close()
+	}
+}
+
+func (r *closeImmediately) cleanup() {
+	return
+}