[exporter/awskinesisexporter] fix in compressor crashing under heady …

…load due non-safe thread execution (#32589)

Fixing a bug that made the execution panic when the load was high
enough, specially if the payloads were not very tiny.


**Testing:** 
Executed this with and without the fix locally using heavy load, then
ran it in cloud servers using heavier load and a variety of payloads.

.chloggen/fix_compressor-kinesis-exporter-thread-safe.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: 'bug_fix'
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: awskinesisexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: the compressor was crashing under high load due it not being thread safe.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [32589]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: removed compressor abstraction and each execution has its own buffer (so it's thread safe)
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

exporter/awskinesisexporter/exporter.go

@@ -19,7 +19,6 @@ import (
 	"go.uber.org/zap"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awskinesisexporter/internal/batch"
-	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awskinesisexporter/internal/compress"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awskinesisexporter/internal/producer"
 )
 
@@ -90,16 +89,11 @@ func createExporter(ctx context.Context, c component.Config, log *zap.Logger, op
 		return nil, err
 	}
 
-	compressor, err := compress.NewCompressor(conf.Encoding.Compression)
-	if err != nil {
-		return nil, err
-	}
-
 	encoder, err := batch.NewEncoder(
 		conf.Encoding.Name,
 		batch.WithMaxRecordSize(conf.MaxRecordSize),
 		batch.WithMaxRecordsPerBatch(conf.MaxRecordsPerBatch),
-		batch.WithCompression(compressor),
+		batch.WithCompressionType(conf.Compression),
 	)
 
 	if err != nil {

exporter/awskinesisexporter/internal/batch/batch.go

@@ -29,7 +29,7 @@ type Batch struct {
 	maxBatchSize  int
 	maxRecordSize int
 
-	compression compress.Compressor
+	compressionType string
 
 	records []types.PutRecordsRequestEntry
 }
@@ -54,20 +54,18 @@ func WithMaxRecordSize(size int) Option {
 	}
 }
 
-func WithCompression(compressor compress.Compressor) Option {
+func WithCompressionType(compressionType string) Option {
 	return func(bt *Batch) {
-		if compressor != nil {
-			bt.compression = compressor
-		}
+		bt.compressionType = compressionType
 	}
 }
 
 func New(opts ...Option) *Batch {
 	bt := &Batch{
-		maxBatchSize:  MaxBatchedRecords,
-		maxRecordSize: MaxRecordSize,
-		compression:   compress.NewNoopCompressor(),
-		records:       make([]types.PutRecordsRequestEntry, 0, MaxBatchedRecords),
+		maxBatchSize:    MaxBatchedRecords,
+		maxRecordSize:   MaxRecordSize,
+		compressionType: "none",
+		records:         make([]types.PutRecordsRequestEntry, 0, MaxBatchedRecords),
 	}
 
 	for _, op := range opts {
@@ -78,7 +76,13 @@ func New(opts ...Option) *Batch {
 }
 
 func (b *Batch) AddRecord(raw []byte, key string) error {
-	record, err := b.compression.Do(raw)
+
+	compressor, err := compress.NewCompressor(b.compressionType)
+	if err != nil {
+		return err
+	}
+
+	record, err := compressor(raw)
 	if err != nil {
 		return err
 	}

exporter/awskinesisexporter/internal/compress/compresser.go

@@ -9,77 +9,82 @@ import (
 	"compress/gzip"
 	"compress/zlib"
 	"fmt"
-	"io"
 )
 
-type bufferedResetWriter interface {
-	Write(p []byte) (int, error)
-	Flush() error
-	Reset(newWriter io.Writer)
-	Close() error
-}
-
-type Compressor interface {
-	Do(in []byte) (out []byte, err error)
-}
-
-var _ Compressor = (*compressor)(nil)
-
-type compressor struct {
-	compression bufferedResetWriter
-}
+type Compressor func(in []byte) ([]byte, error)
 
 func NewCompressor(format string) (Compressor, error) {
-	c := &compressor{
-		compression: &noop{},
-	}
 	switch format {
 	case "flate":
-		w, err := flate.NewWriter(nil, flate.BestSpeed)
-		if err != nil {
-			return nil, err
-		}
-		c.compression = w
+		return flateCompressor, nil
 	case "gzip":
-		w, err := gzip.NewWriterLevel(nil, gzip.BestSpeed)
-		if err != nil {
-			return nil, err
-		}
-		c.compression = w
-
+		return gzipCompressor, nil
 	case "zlib":
-		w, err := zlib.NewWriterLevel(nil, zlib.BestSpeed)
-		if err != nil {
-			return nil, err
-		}
-		c.compression = w
+		return zlibCompressor, nil
 	case "noop", "none":
-		// Already the default case
-	default:
-		return nil, fmt.Errorf("unknown compression format: %s", format)
+		return noopCompressor, nil
+	}
+
+	return nil, fmt.Errorf("unknown compression format: %s", format)
+}
+
+func flateCompressor(in []byte) ([]byte, error) {
+	var buf bytes.Buffer
+	w, _ := flate.NewWriter(&buf, flate.BestSpeed)
+	defer w.Close()
+
+	_, err := w.Write(in)
+
+	if err != nil {
+		return nil, err
 	}
 
-	return c, nil
+	err = w.Flush()
+	if err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
 }
 
-func (c *compressor) Do(in []byte) ([]byte, error) {
-	buf := new(bytes.Buffer)
+func gzipCompressor(in []byte) ([]byte, error) {
+	var buf bytes.Buffer
+	w, _ := gzip.NewWriterLevel(&buf, gzip.BestSpeed)
+	defer w.Close()
 
-	c.compression.Reset(buf)
+	_, err := w.Write(in)
 
-	if _, err := c.compression.Write(in); err != nil {
+	if err != nil {
 		return nil, err
 	}
 
-	if err := c.compression.Flush(); err != nil {
+	err = w.Flush()
+	if err != nil {
 		return nil, err
 	}
 
-	if closer, ok := c.compression.(io.Closer); ok {
-		if err := closer.Close(); err != nil {
-			return nil, err
-		}
+	return buf.Bytes(), nil
+}
+
+func zlibCompressor(in []byte) ([]byte, error) {
+	var buf bytes.Buffer
+	w, _ := zlib.NewWriterLevel(&buf, zlib.BestSpeed)
+	defer w.Close()
+
+	_, err := w.Write(in)
+
+	if err != nil {
+		return nil, err
+	}
+
+	err = w.Flush()
+	if err != nil {
+		return nil, err
 	}
 
 	return buf.Bytes(), nil
 }
+
+func noopCompressor(in []byte) ([]byte, error) {
+	return in, nil
+}

exporter/awskinesisexporter/internal/compress/compresser_test.go

@@ -6,6 +6,7 @@ package compress_test
 import (
 	"fmt"
 	"math/rand"
+	"sync"
 	"testing"
 	"time"
 
@@ -35,7 +36,7 @@ func TestCompressorFormats(t *testing.T) {
 			require.NoError(t, err, "Must have a valid compression format")
 			require.NotNil(t, c, "Must have a valid compressor")
 
-			out, err := c.Do([]byte(data))
+			out, err := c([]byte(data))
 			assert.NoError(t, err, "Must not error when processing data")
 			assert.NotNil(t, out, "Must have a valid record")
 		})
@@ -94,8 +95,86 @@ func benchmarkCompressor(b *testing.B, format string, length int) {
 	b.ResetTimer()
 
 	for i := 0; i < b.N; i++ {
-		out, err := compressor.Do(data)
+		out, err := compressor(data)
 		assert.NoError(b, err, "Must not error when processing data")
 		assert.NotNil(b, out, "Must have a valid byte array after")
 	}
 }
+
+// an issue encountered in the past was a crash due race condition in the compressor, so the
+// current implementation creates a new context on each compression request
+// this is a test to check no exceptions are raised for executing concurrent compressions
+func TestCompressorConcurrent(t *testing.T) {
+
+	timeout := time.After(15 * time.Second)
+	done := make(chan bool)
+	go func() {
+		// do your testing
+		concurrentCompressFunc(t)
+		done <- true
+	}()
+
+	select {
+	case <-timeout:
+		t.Fatal("Test didn't finish in time")
+	case <-done:
+	}
+
+}
+
+func concurrentCompressFunc(t *testing.T) {
+	// this value should be way higher to make this test more valuable, but the make of this project uses
+	// max 4 workers, so we had to set this value here
+	numWorkers := 4
+
+	var wg sync.WaitGroup
+	wg.Add(numWorkers)
+
+	errCh := make(chan error, numWorkers)
+	var errMutex sync.Mutex
+
+	// any single format would do it here, since each exporter can be set to use only one at a time
+	// and the concurrent issue that was present in the past was independent of the format
+	compressFunc, err := compress.NewCompressor("gzip")
+
+	if err != nil {
+		errCh <- err
+		return
+	}
+
+	// it is important for the data length to be on the higher side of a record
+	// since it is where the chances of having race conditions are bigger
+	dataLength := 131072
+
+	for j := 0; j < numWorkers; j++ {
+		go func() {
+			defer wg.Done()
+
+			source := rand.NewSource(time.Now().UnixMilli())
+			genRand := rand.New(source)
+
+			data := make([]byte, dataLength)
+			for i := 0; i < dataLength; i++ {
+				data[i] = byte(genRand.Int31())
+			}
+
+			result, localErr := compressFunc(data)
+			if localErr != nil {
+				errMutex.Lock()
+				errCh <- localErr
+				errMutex.Unlock()
+				return
+			}
+
+			_ = result
+		}()
+	}
+
+	wg.Wait()
+
+	close(errCh)
+
+	for err := range errCh {
+		t.Errorf("Error encountered on concurrent compression: %v", err)
+	}
+}