Add buffer pool for memfs

io/fs/mem.go

@@ -105,17 +105,60 @@ func (f *memFile) Seek(offset int64, whence int) (int64, error) {
 }
 
 func (f *memFile) Close() error {
-	if f.data == nil {
+	if f.r == nil {
 		return io.EOF
 	}
 
 	f.r = nil
-	f.data.Reset()
-	f.data = nil
 
 	return nil
 }
 
+func (f *memFile) free() {
+	f.Close()
+
+	if f.data == nil {
+		return
+	}
+
+	pool.Put(f.data)
+
+	f.data = nil
+}
+
+type fileDataPool struct {
+	pool sync.Pool
+}
+
+var pool *fileDataPool = nil
+
+func NewFileDataPool() *fileDataPool {
+	p := &fileDataPool{
+		pool: sync.Pool{
+			New: func() any {
+				return &bytes.Buffer{}
+			},
+		},
+	}
+
+	return p
+}
+
+func (p *fileDataPool) Get() *bytes.Buffer {
+	buf := p.pool.Get().(*bytes.Buffer)
+	buf.Reset()
+
+	return buf
+}
+
+func (p *fileDataPool) Put(buf *bytes.Buffer) {
+	p.pool.Put(buf)
+}
+
+func init() {
+	pool = NewFileDataPool()
+}
+
 type memFilesystem struct {
 	metadata map[string]string
 	metaLock sync.RWMutex
@@ -315,7 +358,7 @@ func (fs *memFilesystem) Files() int64 {
 func (fs *memFilesystem) Open(path string) File {
 	path = fs.cleanPath(path)
 
-	file, ok := fs.storage.LoadAndCopy(path)
+	file, ok := fs.storage.Load(path)
 	if !ok {
 		return nil
 	}
@@ -323,24 +366,26 @@ func (fs *memFilesystem) Open(path string) File {
 	newFile := &memFile{
 		memFileInfo: memFileInfo{
 			name:    file.name,
+			size:    file.size,
+			dir:     file.dir,
 			lastMod: file.lastMod,
 			linkTo:  file.linkTo,
 		},
+		data: file.data,
 	}
 
 	if len(file.linkTo) != 0 {
-		file.Close()
+		file, ok := fs.storage.Load(file.linkTo)
-
-		file, ok = fs.storage.LoadAndCopy(file.linkTo)
 		if !ok {
 			return nil
 		}
+
+		newFile.lastMod = file.lastMod
+		newFile.data = file.data
+		newFile.size = file.size
 	}
 
-	newFile.lastMod = file.lastMod
+	newFile.r = bytes.NewReader(newFile.data.Bytes())
-	newFile.data = file.data
-	newFile.size = file.size
-	newFile.r = bytes.NewReader(file.data.Bytes())
 
 	return newFile
 }
@@ -348,22 +393,22 @@ func (fs *memFilesystem) Open(path string) File {
 func (fs *memFilesystem) ReadFile(path string) ([]byte, error) {
 	path = fs.cleanPath(path)
 
-	file, ok := fs.storage.LoadAndCopy(path)
+	file, ok := fs.storage.Load(path)
 	if !ok {
 		return nil, ErrNotExist
 	}
 
 	if len(file.linkTo) != 0 {
-		file.Close()
+		file, ok = fs.storage.Load(file.linkTo)
-
-		file, ok = fs.storage.LoadAndCopy(file.linkTo)
 		if !ok {
 			return nil, ErrNotExist
 		}
 	}
 
-	defer file.Close()
+	data := make([]byte, file.data.Len())
-	return file.data.Bytes(), nil
+	copy(data, file.data.Bytes())
+
+	return data, nil
 }
 
 func (fs *memFilesystem) Symlink(oldname, newname string) error {
@@ -403,7 +448,7 @@ func (fs *memFilesystem) Symlink(oldname, newname string) error {
 	defer fs.sizeLock.Unlock()
 
 	if replaced {
-		oldFile.Close()
+		oldFile.free()
 		fs.currentSize -= oldFile.size
 	}
 
@@ -456,7 +501,7 @@ func (fs *memFilesystem) WriteFileReader(path string, r io.Reader, sizeHint int)
 			size:    0,
 			lastMod: time.Now(),
 		},
-		data: &bytes.Buffer{},
+		data: pool.Get(),
 	}
 
 	if sizeHint > 0 && sizeHint < 5*1024*1024 {
@@ -471,7 +516,7 @@ func (fs *memFilesystem) WriteFileReader(path string, r io.Reader, sizeHint int)
 			"error":          err,
 		}).Warn().Log("Incomplete file")
 
-		newFile.Close()
+		newFile.free()
 
 		return -1, false, fmt.Errorf("incomplete file")
 	}
@@ -488,7 +533,7 @@ func (fs *memFilesystem) WriteFileReader(path string, r io.Reader, sizeHint int)
 	defer fs.sizeLock.Unlock()
 
 	if replace {
-		oldFile.Close()
+		oldFile.free()
 
 		fs.currentSize -= oldFile.size
 	}
@@ -521,13 +566,26 @@ func (fs *memFilesystem) WriteFileSafe(path string, data []byte) (int64, bool, e
 func (fs *memFilesystem) AppendFileReader(path string, r io.Reader, sizeHint int) (int64, error) {
 	path = fs.cleanPath(path)
 
-	file, hasFile := fs.storage.LoadAndCopy(path)
+	file, hasFile := fs.storage.Load(path)
 	if !hasFile {
 		size, _, err := fs.WriteFileReader(path, r, sizeHint)
 		return size, err
 	}
 
-	size, err := copyToBufferFromReader(file.data, r, 8*1024)
+	newFile := &memFile{
+		memFileInfo: memFileInfo{
+			name:    path,
+			dir:     false,
+			size:    0,
+			lastMod: time.Now(),
+		},
+		data: pool.Get(),
+	}
+
+	newFile.data.Grow(file.data.Len())
+	newFile.data.Write(file.data.Bytes())
+
+	size, err := copyToBufferFromReader(newFile.data, r, 8*1024)
 	if err != nil {
 		fs.logger.WithFields(log.Fields{
 			"path":           path,
@@ -535,18 +593,22 @@ func (fs *memFilesystem) AppendFileReader(path string, r io.Reader, sizeHint int
 			"error":          err,
 		}).Warn().Log("Incomplete file")
 
-		file.Close()
+		newFile.free()
 
 		return -1, fmt.Errorf("incomplete file")
 	}
 
 	file.size += size
 
-	fs.storage.Store(path, file)
+	oldFile, replace := fs.storage.Store(path, newFile)
 
 	fs.sizeLock.Lock()
 	defer fs.sizeLock.Unlock()
 
+	if replace {
+		oldFile.free()
+	}
+
 	fs.currentSize += size
 
 	fs.logger.Debug().WithFields(log.Fields{
@@ -583,7 +645,7 @@ func (fs *memFilesystem) Purge(size int64) int64 {
 		fs.currentSize -= f.size
 		fs.sizeLock.Unlock()
 
-		f.Close()
+		f.free()
 
 		fs.logger.WithFields(log.Fields{
 			"path":           f.name,
@@ -643,7 +705,7 @@ func (fs *memFilesystem) Rename(src, dst string) error {
 	defer fs.sizeLock.Unlock()
 
 	if replace {
-		dstFile.Close()
+		dstFile.free()
 
 		fs.currentSize -= dstFile.size
 	}
@@ -663,13 +725,12 @@ func (fs *memFilesystem) Copy(src, dst string) error {
 		return os.ErrInvalid
 	}
 
-	srcFile, ok := fs.storage.LoadAndCopy(src)
+	srcFile, ok := fs.storage.Load(src)
 	if !ok {
 		return ErrNotExist
 	}
 
 	if srcFile.dir {
-		srcFile.Close()
 		return ErrNotExist
 	}
 
@@ -680,9 +741,12 @@ func (fs *memFilesystem) Copy(src, dst string) error {
 			size:    srcFile.size,
 			lastMod: time.Now(),
 		},
-		data: srcFile.data,
+		data: pool.Get(),
 	}
 
+	dstFile.data.Grow(srcFile.data.Len())
+	dstFile.data.Write(srcFile.data.Bytes())
+
 	f, replace := fs.storage.Store(dst, dstFile)
 
 	if !replace {
@@ -693,7 +757,7 @@ func (fs *memFilesystem) Copy(src, dst string) error {
 	defer fs.sizeLock.Unlock()
 
 	if replace {
-		f.Close()
+		f.free()
 		fs.currentSize -= f.size
 	}
 
@@ -761,7 +825,7 @@ func (fs *memFilesystem) Remove(path string) int64 {
 func (fs *memFilesystem) remove(path string) int64 {
 	file, ok := fs.storage.Delete(path)
 	if ok {
-		file.Close()
+		file.free()
 
 		fs.dirs.Remove(path)
 
@@ -851,7 +915,7 @@ func (fs *memFilesystem) RemoveList(path string, options ListOptions) ([]string,
 
 		fs.dirs.Remove(file.name)
 
-		file.Close()
+		file.free()
 	}
 
 	fs.sizeLock.Lock()

io/fs/mem_storage.go

@@ -21,10 +21,6 @@ type memStorage interface {
 	// i.e. all changes to the file will be reflected on the storage.
 	Load(key string) (value *memFile, ok bool)
 
-	// LoadAndCopy loads a file from the storage. The returned file is a copy
-	// and can be modified without modifying the file on the storage.
-	LoadAndCopy(key string) (value *memFile, ok bool)
-
 	// Has checks whether a file exists at path.
 	Has(key string) bool
 
@@ -68,33 +64,6 @@ func (m *mapOfStorage) Load(key string) (*memFile, bool) {
 	return m.files.Load(key)
 }
 
-func (m *mapOfStorage) LoadAndCopy(key string) (*memFile, bool) {
-	token := m.lock.RLock()
-	defer m.lock.RUnlock(token)
-
-	v, ok := m.files.Load(key)
-	if !ok {
-		return nil, false
-	}
-
-	f := &memFile{
-		memFileInfo: memFileInfo{
-			name:    v.name,
-			size:    v.size,
-			dir:     v.dir,
-			lastMod: v.lastMod,
-			linkTo:  v.linkTo,
-		},
-		r: nil,
-	}
-
-	if v.data != nil {
-		f.data = bytes.NewBuffer(v.data.Bytes())
-	}
-
-	return f, true
-}
-
 func (m *mapOfStorage) Has(key string) bool {
 	token := m.lock.RLock()
 	defer m.lock.RUnlock(token)

io/fs/mem_test.go

@@ -48,6 +48,34 @@ func TestWriteWhileRead(t *testing.T) {
 	require.Equal(t, []byte("xxxxx"), data)
 }
 
+func TestCopy(t *testing.T) {
+	fs, err := NewMemFilesystem(MemConfig{})
+	require.NoError(t, err)
+
+	_, _, err = fs.WriteFile("/foobar", []byte("xxxxx"))
+	require.NoError(t, err)
+
+	data, err := fs.ReadFile("/foobar")
+	require.NoError(t, err)
+
+	require.Equal(t, []byte("xxxxx"), data)
+
+	err = fs.Copy("/foobar", "/barfoo")
+	require.NoError(t, err)
+
+	data, err = fs.ReadFile("/barfoo")
+	require.NoError(t, err)
+
+	require.Equal(t, []byte("xxxxx"), data)
+
+	fs.Remove("/foobar")
+
+	data, err = fs.ReadFile("/barfoo")
+	require.NoError(t, err)
+
+	require.Equal(t, []byte("xxxxx"), data)
+}
+
 func BenchmarkMemStorages(b *testing.B) {
 	storages := []string{
 		"map",

io/fs/memtest/.gitignore

@@ -0,0 +1 @@
+memtest

io/fs/memtest/memtest.go

@@ -0,0 +1,220 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	gorand "math/rand/v2"
+	"os"
+	"os/signal"
+	"runtime"
+	"runtime/debug"
+	"strconv"
+	"sync"
+	"time"
+
+	"github.com/datarhei/core/v16/io/fs"
+	"github.com/datarhei/core/v16/math/rand"
+
+	"github.com/google/gops/agent"
+)
+
+func main() {
+	oStorage := "mapof"
+	oWriters := 500
+	oReaders := 1000
+	oFiles := 15
+	oInterval := 1 // seconds
+	oSize := 2     // megabytes
+	oLimit := false
+
+	flag.StringVar(&oStorage, "storage", "mapof", "type of mem storage implementation (mapof, map, swiss)")
+	flag.IntVar(&oWriters, "writers", 500, "number of concurrent writers")
+	flag.IntVar(&oReaders, "readers", 1000, "number of concurrent readers")
+	flag.IntVar(&oFiles, "files", 15, "number of files to keep per writer")
+	flag.IntVar(&oInterval, "interval", 1, "interval for writing files in seconds")
+	flag.IntVar(&oSize, "size", 2048, "size of files to write in kilobytes")
+	flag.BoolVar(&oLimit, "limit", false, "set memory limit")
+
+	flag.Parse()
+
+	estimatedSize := float64(oWriters*oFiles*oSize) / 1024 / 1024
+
+	fmt.Printf("Expecting effective memory consumption of %.1fGB\n", estimatedSize)
+
+	if oLimit {
+		fmt.Printf("Setting memory limit to %.1fGB\n", estimatedSize*1.5)
+		debug.SetMemoryLimit(int64(estimatedSize * 1.5))
+	}
+
+	memfs, err := fs.NewMemFilesystem(fs.MemConfig{
+		Storage: oStorage,
+	})
+
+	if err != nil {
+		log.Fatalf("acquiring new memfs: %s", err.Error())
+	}
+
+	err = agent.Listen(agent.Options{
+		Addr:                   ":9000",
+		ReuseSocketAddrAndPort: true,
+	})
+
+	if err != nil {
+		log.Fatalf("starting agent: %s", err.Error())
+	}
+
+	fmt.Printf("Started agent on :9000\n")
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	wgWriter := sync.WaitGroup{}
+
+	for i := 0; i < oWriters; i++ {
+		fmt.Printf("%4d / %4d writer started\r", i+1, oWriters)
+
+		wgWriter.Add(1)
+
+		go func(ctx context.Context, memfs fs.Filesystem, index int, nfiles int64, interval time.Duration) {
+			defer wgWriter.Done()
+
+			jitter := gorand.IntN(200)
+			interval += time.Duration(jitter) * time.Millisecond
+
+			sequence := int64(0)
+
+			buf := bytes.NewBufferString(rand.StringAlphanumeric(oSize * (1024 + jitter - 100)))
+			r := bytes.NewReader(buf.Bytes())
+
+			ticker := time.NewTicker(interval)
+			defer ticker.Stop()
+
+			for {
+				select {
+				case <-ctx.Done():
+					return
+				case <-ticker.C:
+					path := fmt.Sprintf("/foobar/test_%d_%06d.dat", index, sequence)
+
+					// Write file to memfs
+					r.Seek(0, io.SeekStart)
+					memfs.WriteFileReader(path, r, -1)
+
+					// Delete file from memfs
+					if sequence-nfiles >= 0 {
+						path = fmt.Sprintf("/foobar/test_%d_%06d.dat", index, sequence-nfiles)
+						memfs.Remove(path)
+					}
+
+					path = fmt.Sprintf("/foobar/test_%d.last", index)
+					memfs.WriteFile(path, []byte(strconv.FormatInt(sequence, 10)))
+
+					sequence++
+				}
+			}
+		}(ctx, memfs, i, int64(oFiles), time.Duration(oInterval)*time.Second)
+	}
+
+	fmt.Printf("\n")
+
+	wgReader := sync.WaitGroup{}
+
+	if oReaders > 0 {
+		for i := 0; i < oReaders; i++ {
+			fmt.Printf("%4d / %4d reader started\r", i+1, oReaders)
+
+			wgReader.Add(1)
+
+			go func(ctx context.Context, memfs fs.Filesystem, interval time.Duration) {
+				defer wgReader.Done()
+
+				buf := bytes.Buffer{}
+
+				jitter := gorand.IntN(200)
+				interval += time.Duration(jitter) * time.Millisecond
+
+				ticker := time.NewTicker(interval)
+				defer ticker.Stop()
+
+				for {
+					select {
+					case <-ctx.Done():
+						return
+					case <-ticker.C:
+						index := gorand.IntN(oWriters)
+
+						path := fmt.Sprintf("/foobar/test_%d.list", index)
+						data, err := memfs.ReadFile(path)
+						if err != nil {
+							continue
+						}
+
+						sequence, err := strconv.ParseUint(string(data), 10, 64)
+						if err != nil {
+							continue
+						}
+
+						path = fmt.Sprintf("/foobar/test_%d_%06d.dat", index, sequence)
+						file := memfs.Open(path)
+
+						buf.ReadFrom(file)
+						buf.Reset()
+					}
+				}
+			}(ctx, memfs, time.Duration(oInterval)*time.Second)
+		}
+
+		fmt.Printf("\n")
+	}
+
+	go func(ctx context.Context, memfs fs.Filesystem) {
+		ticker := time.NewTicker(2 * time.Second)
+		defer ticker.Stop()
+
+		nMallocs := uint64(0)
+
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-ticker.C:
+				m := runtime.MemStats{}
+				runtime.ReadMemStats(&m)
+
+				size, _ := memfs.Size()
+				fmt.Printf("%5.1fGB ", float64(size)/1024/1024/1024)
+
+				listfiles := 0
+				listsize := int64(0)
+				files := memfs.List("/", fs.ListOptions{})
+				for _, f := range files {
+					listsize += f.Size()
+				}
+				listfiles = len(files)
+
+				fmt.Printf("(%7d files with %5.1fGB) ", listfiles, float64(listsize)/1024/1024/1024)
+
+				fmt.Printf("alloc=%5.1fGB (%8.1fGB) sys=%5.1fGB idle=%5.1fGB inuse=%5.1fGB mallocs=%d objects=%d\n", float64(m.HeapAlloc)/1024/1024/1024, float64(m.TotalAlloc)/1024/1024/1024, float64(m.HeapSys)/1024/1024/1024, float64(m.HeapIdle)/1024/1024/1024, float64(m.HeapInuse)/1024/1024/1024, m.Mallocs-nMallocs, m.Mallocs-m.Frees)
+
+				nMallocs = m.Mallocs
+			}
+		}
+	}(ctx, memfs)
+
+	quit := make(chan os.Signal, 1)
+	signal.Notify(quit, os.Interrupt)
+	<-quit
+
+	cancel()
+
+	fmt.Printf("Waiting for readers to stop ...\n")
+	wgReader.Wait()
+
+	fmt.Printf("Waiting for writers to stop ...\n")
+	wgWriter.Wait()
+
+	fmt.Printf("Done\n")
+}