feature (plg_backend_local): speed improvements on linux

server/plugin/plg_backend_local/direct_linux.go

@@ -0,0 +1,92 @@
+package plg_backend_local
+
+import (
+	"errors"
+	"io"
+	"os"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	directChunk   = 16 * 1024 * 1024
+	directAlign   = 4096
+	directMinSize = 8 * 1024 * 1024
+)
+
+type direct struct {
+	f    *os.File
+	ch   chan []byte
+	done chan struct{}
+	err  error
+	cur  []byte
+}
+
+func NewDirect(f *os.File, fs os.FileInfo) io.ReadCloser {
+	if fs.Size() < directMinSize {
+		return f
+	}
+	flags, err := unix.FcntlInt(f.Fd(), unix.F_GETFL, 0)
+	if err != nil {
+		return f
+	} else if _, err = unix.FcntlInt(f.Fd(), unix.F_SETFL, flags|unix.O_DIRECT); err != nil {
+		return f
+	}
+	return &direct{f: f, done: make(chan struct{})}
+}
+
+func (this *direct) Seek(offset int64, whence int) (int64, error) {
+	if this.ch != nil {
+		return 0, errors.New("seek not supported after read")
+	}
+	return this.f.Seek(offset, whence)
+}
+
+func (this *direct) Read(p []byte) (int, error) {
+	if this.ch == nil {
+		this.ch = make(chan []byte)
+		go this.fill()
+	}
+	for len(this.cur) == 0 {
+		b, ok := <-this.ch
+		if !ok {
+			return 0, this.err
+		}
+		this.cur = b
+	}
+	n := copy(p, this.cur)
+	this.cur = this.cur[n:]
+	return n, nil
+}
+
+func (this *direct) fill() {
+	defer close(this.ch)
+	buf, next := alignedBuffer(directChunk), alignedBuffer(directChunk)
+	start, err := this.f.Seek(0, io.SeekCurrent)
+	pos := start - start%directAlign
+	for err == nil {
+		var n int
+		n, err = this.f.ReadAt(buf, pos)
+		skip := min(max(start-pos, 0), int64(n))
+		select {
+		case this.ch <- buf[skip:n]:
+		case <-this.done:
+			return
+		}
+		pos += int64(n)
+		buf, next = next, buf
+	}
+	this.err = err
+}
+
+func alignedBuffer(size int) []byte {
+	b := make([]byte, size+directAlign)
+	off := directAlign - int(uintptr(unsafe.Pointer(&b[0]))%directAlign)
+	return b[off : off+size]
+}
+
+func (this *direct) Close() error {
+	close(this.done)
+	return this.f.Close()
+}

server/plugin/plg_backend_local/direct_other.go

@@ -0,0 +1,12 @@
+//go:build !linux
+
+package plg_backend_local
+
+import (
+	"io"
+	"os"
+)
+
+func NewDirect(f *os.File, fs os.FileInfo) io.ReadCloser {
+	return f
+}

server/plugin/plg_backend_local/index.go

@@ -1,11 +1,13 @@
 package plg_backend_local
 
 import (
-	. "github.com/mickael-kerjean/filestash/server/common"
-	"golang.org/x/crypto/bcrypt"
 	"io"
 	"os"
 	"os/user"
+
+	. "github.com/mickael-kerjean/filestash/server/common"
+
+	"golang.org/x/crypto/bcrypt"
 )
 
 func init() {
@@ -112,7 +114,7 @@ func (this Local) Cat(path string) (io.ReadCloser, error) {
 		f.Close()
 		return nil, ErrNotFound
 	}
-	return f, nil
+	return NewDirect(f, fs), nil
 }
 
 func (this Local) Mkdir(path string) error {