feat(proto): add configurable buffer sizes for Redis connections (#3453)

* add configurable buffer sizes for Redis connections

* add MiB to wordlist

* Add description for buffer size parameter

internal/pool/buffer_size_test.go

@@ -0,0 +1,183 @@
+package pool_test
+
+import (
+	"bufio"
+	"context"
+	"net"
+	"unsafe"
+
+	. "github.com/bsm/ginkgo/v2"
+	. "github.com/bsm/gomega"
+
+	"github.com/redis/go-redis/v9/internal/pool"
+	"github.com/redis/go-redis/v9/internal/proto"
+)
+
+var _ = Describe("Buffer Size Configuration", func() {
+	var connPool *pool.ConnPool
+	ctx := context.Background()
+
+	AfterEach(func() {
+		if connPool != nil {
+			connPool.Close()
+		}
+	})
+
+	It("should use default buffer sizes when not specified", func() {
+		connPool = pool.NewConnPool(&pool.Options{
+			Dialer:      dummyDialer,
+			PoolSize:    1,
+			PoolTimeout: 1000,
+		})
+
+		cn, err := connPool.NewConn(ctx)
+		Expect(err).NotTo(HaveOccurred())
+		defer connPool.CloseConn(cn)
+
+		// Check that default buffer sizes are used (0.5MiB)
+		writerBufSize := getWriterBufSizeUnsafe(cn)
+		readerBufSize := getReaderBufSizeUnsafe(cn)
+
+		Expect(writerBufSize).To(Equal(proto.DefaultBufferSize)) // Default 0.5MiB buffer size
+		Expect(readerBufSize).To(Equal(proto.DefaultBufferSize)) // Default 0.5MiB buffer size
+	})
+
+	It("should use custom buffer sizes when specified", func() {
+		customReadSize := 32 * 1024  // 32KB
+		customWriteSize := 64 * 1024 // 64KB
+
+		connPool = pool.NewConnPool(&pool.Options{
+			Dialer:          dummyDialer,
+			PoolSize:        1,
+			PoolTimeout:     1000,
+			ReadBufferSize:  customReadSize,
+			WriteBufferSize: customWriteSize,
+		})
+
+		cn, err := connPool.NewConn(ctx)
+		Expect(err).NotTo(HaveOccurred())
+		defer connPool.CloseConn(cn)
+
+		// Check that custom buffer sizes are used
+		writerBufSize := getWriterBufSizeUnsafe(cn)
+		readerBufSize := getReaderBufSizeUnsafe(cn)
+
+		Expect(writerBufSize).To(Equal(customWriteSize))
+		Expect(readerBufSize).To(Equal(customReadSize))
+	})
+
+	It("should handle zero buffer sizes by using defaults", func() {
+		connPool = pool.NewConnPool(&pool.Options{
+			Dialer:          dummyDialer,
+			PoolSize:        1,
+			PoolTimeout:     1000,
+			ReadBufferSize:  0, // Should use default
+			WriteBufferSize: 0, // Should use default
+		})
+
+		cn, err := connPool.NewConn(ctx)
+		Expect(err).NotTo(HaveOccurred())
+		defer connPool.CloseConn(cn)
+
+		// Check that default buffer sizes are used (0.5MiB)
+		writerBufSize := getWriterBufSizeUnsafe(cn)
+		readerBufSize := getReaderBufSizeUnsafe(cn)
+
+		Expect(writerBufSize).To(Equal(proto.DefaultBufferSize)) // Default 0.5MiB buffer size
+		Expect(readerBufSize).To(Equal(proto.DefaultBufferSize)) // Default 0.5MiB buffer size
+	})
+
+	It("should use 0.5MiB default buffer sizes for standalone NewConn", func() {
+		// Test that NewConn (without pool) also uses 0.5MiB defaults
+		netConn := newDummyConn()
+		cn := pool.NewConn(netConn)
+		defer cn.Close()
+
+		writerBufSize := getWriterBufSizeUnsafe(cn)
+		readerBufSize := getReaderBufSizeUnsafe(cn)
+
+		Expect(writerBufSize).To(Equal(proto.DefaultBufferSize)) // Default 0.5MiB buffer size
+		Expect(readerBufSize).To(Equal(proto.DefaultBufferSize)) // Default 0.5MiB buffer size
+	})
+
+	It("should use 0.5MiB defaults even when pool is created directly without buffer sizes", func() {
+		// Test the scenario where someone creates a pool directly (like in tests)
+		// without setting ReadBufferSize and WriteBufferSize
+		connPool = pool.NewConnPool(&pool.Options{
+			Dialer:      dummyDialer,
+			PoolSize:    1,
+			PoolTimeout: 1000,
+			// ReadBufferSize and WriteBufferSize are not set (will be 0)
+		})
+
+		cn, err := connPool.NewConn(ctx)
+		Expect(err).NotTo(HaveOccurred())
+		defer connPool.CloseConn(cn)
+
+		// Should still get 0.5MiB defaults because NewConnPool sets them
+		writerBufSize := getWriterBufSizeUnsafe(cn)
+		readerBufSize := getReaderBufSizeUnsafe(cn)
+
+		Expect(writerBufSize).To(Equal(proto.DefaultBufferSize)) // Default 0.5MiB buffer size
+		Expect(readerBufSize).To(Equal(proto.DefaultBufferSize)) // Default 0.5MiB buffer size
+	})
+})
+
+// Helper functions to extract buffer sizes using unsafe pointers
+func getWriterBufSizeUnsafe(cn *pool.Conn) int {
+	cnPtr := (*struct {
+		usedAt  int64
+		netConn net.Conn
+		rd      *proto.Reader
+		bw      *bufio.Writer
+		wr      *proto.Writer
+		// ... other fields
+	})(unsafe.Pointer(cn))
+
+	if cnPtr.bw == nil {
+		return -1
+	}
+
+	bwPtr := (*struct {
+		err error
+		buf []byte
+		n   int
+		wr  interface{}
+	})(unsafe.Pointer(cnPtr.bw))
+
+	return len(bwPtr.buf)
+}
+
+func getReaderBufSizeUnsafe(cn *pool.Conn) int {
+	cnPtr := (*struct {
+		usedAt  int64
+		netConn net.Conn
+		rd      *proto.Reader
+		bw      *bufio.Writer
+		wr      *proto.Writer
+		// ... other fields
+	})(unsafe.Pointer(cn))
+
+	if cnPtr.rd == nil {
+		return -1
+	}
+
+	rdPtr := (*struct {
+		rd *bufio.Reader
+	})(unsafe.Pointer(cnPtr.rd))
+
+	if rdPtr.rd == nil {
+		return -1
+	}
+
+	bufReaderPtr := (*struct {
+		buf          []byte
+		rd           interface{}
+		r, w         int
+		err          error
+		lastByte     int
+		lastRuneSize int
+	})(unsafe.Pointer(rdPtr.rd))
+
+	return len(bufReaderPtr.buf)
+}