WIP: VMSplice/STDOUT consumer

.goreleaser.yaml

@@ -19,7 +19,7 @@ builds:
 archives:
   - format: binary
     name_template: >-
-      {{ .ProjectName }}_{{ title .Os }}_
+      {{ .ProjectName }}_{{ tolower .Os }}_
       {{- if eq .Arch "amd64" }}x86_64
       {{- else if eq .Arch "386" }}i386
       {{- else }}{{ .Arch }}{{end -}}

pkg/config/config.go

@@ -20,6 +20,8 @@ const (
 	ConsumerFile         = "file"
 	ConsumerTarExtractor = "tar-extractor"
 	ConsumerNull         = "null"
+	ConsumerVMSplice     = "vmsplice"
+	ConsumerSTDOut       = "stdout"
 )
 
 var (
@@ -162,6 +164,10 @@ func GetConsumer() (consumer.Consumer, error) {
 		return &consumer.TarExtractor{}, nil
 	case ConsumerNull:
 		return &consumer.NullWriter{}, nil
+	case ConsumerVMSplice:
+		return &consumer.VMSpliceConsumer{}, nil
+	case ConsumerSTDOut:
+		return &consumer.StdoutConsumer{}, nil
 	default:
 		return nil, fmt.Errorf("invalid consumer specified: %s", consumerName)
 	}

pkg/consumer/darwin_vmsplice.go

@@ -0,0 +1,21 @@
+//go:build darwin
+
+package consumer
+
+import (
+	"io"
+
+	"github.com/replicate/pget/pkg/logging"
+)
+
+var _ Consumer = &VMSpliceConsumer{}
+
+type VMSpliceConsumer struct {
+}
+
+func (v VMSpliceConsumer) Consume(reader io.Reader, destPath string) error {
+	logger := logging.GetLogger()
+	logger.Warn().Msg("'vmsplice' is not supported on darwin, falling back to StdoutConsumer")
+	return StdoutConsumer{}.Consume(reader, destPath)
+
+}

pkg/consumer/linux_vmsplice.go

@@ -0,0 +1,44 @@
+//go:build linux
+
+package consumer
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"syscall"
+	"unsafe"
+
+	"github.com/dustin/go-humanize"
+)
+
+var _ Consumer = &VMSpliceConsumer{}
+
+type VMSpliceConsumer struct{}
+
+func (v VMSpliceConsumer) Consume(reader io.Reader, destPath string) error {
+	// Create the buffer once and reuse it, this is zero additional allocations
+	buffer := make([]byte, humanize.MiByte)
+	for {
+		length, err := reader.Read(buffer)
+		if err != nil {
+			if err == io.EOF {
+				return nil
+			}
+			return fmt.Errorf("error reading from reader: %w", err)
+		}
+		if length > 0 {
+			_, _, err := syscall.Syscall6(
+				syscall.SYS_VMSPLICE,
+				os.Stdout.Fd(),
+				uintptr(unsafe.Pointer(
+					&syscall.Iovec{
+						Base: &buffer[0],
+						Len:  uint64(length),
+					})), 1, 0, 0, 0)
+			if err != 0 {
+				return fmt.Errorf("error splicing %s to stdout: %w", buffer, err)
+			}
+		}
+	}
+}

pkg/consumer/stdout.go

@@ -0,0 +1,20 @@
+package consumer
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+var _ Consumer = &StdoutConsumer{}
+
+type StdoutConsumer struct {
+}
+
+func (s StdoutConsumer) Consume(reader io.Reader, destPath string) error {
+	_, err := io.Copy(os.Stdout, reader)
+	if err != nil {
+		return fmt.Errorf("error writing to stdout: %w", err)
+	}
+	return nil
+}