优化缓存管理

internal/caches/reader_file.go

@@ -0,0 +1,291 @@
+package caches
+
+import (
+	"encoding/binary"
+	"errors"
+	"github.com/iwind/TeaGo/types"
+	"io"
+	"os"
+)
+
+type FileReader struct {
+	fp *os.File
+
+	status       int
+	headerOffset int64
+	headerSize   int
+	bodySize     int64
+	bodyOffset   int64
+}
+
+func NewFileReader(fp *os.File) *FileReader {
+	return &FileReader{fp: fp}
+}
+
+func (this *FileReader) Init() error {
+	isOk := false
+
+	defer func() {
+		if !isOk {
+			_ = this.discard()
+		}
+	}()
+
+	// 读取状态
+	_, err := this.fp.Seek(SizeExpiresAt, io.SeekStart)
+	if err != nil {
+		_ = this.discard()
+		return err
+	}
+	buf := make([]byte, 3)
+	ok, err := this.readToBuff(this.fp, buf)
+	if err != nil {
+		return err
+	}
+	if !ok {
+		return ErrNotFound
+	}
+	status := types.Int(string(buf))
+	if status < 100 || status > 999 {
+		return errors.New("invalid status")
+	}
+	this.status = status
+
+	// URL
+	_, err = this.fp.Seek(SizeExpiresAt+SizeStatus, io.SeekStart)
+	if err != nil {
+		return err
+	}
+
+	bytes4 := make([]byte, 4)
+	ok, err = this.readToBuff(this.fp, bytes4)
+	if err != nil {
+		return err
+	}
+	if !ok {
+		return ErrNotFound
+	}
+	urlLength := binary.BigEndian.Uint32(bytes4)
+
+	// header
+	ok, err = this.readToBuff(this.fp, bytes4)
+	if err != nil {
+		return err
+	}
+	if !ok {
+		return ErrNotFound
+	}
+	headerSize := int(binary.BigEndian.Uint32(bytes4))
+	if headerSize == 0 {
+		return nil
+	}
+	this.headerSize = headerSize
+	this.headerOffset = int64(SizeMeta) + int64(urlLength)
+
+	// body
+	bytes8 := make([]byte, 8)
+	ok, err = this.readToBuff(this.fp, bytes8)
+	if err != nil {
+		return err
+	}
+	if !ok {
+		return ErrNotFound
+	}
+	bodySize := int(binary.BigEndian.Uint64(bytes8))
+	if bodySize == 0 {
+		return nil
+	}
+	this.bodySize = int64(bodySize)
+	this.bodyOffset = this.headerOffset + int64(headerSize)
+
+	isOk = true
+
+	return nil
+}
+
+func (this *FileReader) Status() int {
+	return this.status
+}
+
+func (this *FileReader) HeaderSize() int64 {
+	return int64(this.headerSize)
+}
+
+func (this *FileReader) BodySize() int64 {
+	return this.bodySize
+}
+
+func (this *FileReader) ReadHeader(buf []byte, callback ReaderFunc) error {
+	isOk := false
+
+	defer func() {
+		if !isOk {
+			_ = this.discard()
+		}
+	}()
+
+	_, err := this.fp.Seek(this.headerOffset, io.SeekStart)
+	if err != nil {
+		return err
+	}
+
+	for {
+		n, err := this.fp.Read(buf)
+		if n > 0 {
+			if n < this.headerSize {
+				goNext, e := callback(n)
+				if e != nil {
+					isOk = true
+					return e
+				}
+				if !goNext {
+					break
+				}
+				this.headerSize -= n
+			} else {
+				_, e := callback(this.headerSize)
+				if e != nil {
+					isOk = true
+					return e
+				}
+				break
+			}
+		}
+		if err != nil {
+			if err != io.EOF {
+				return err
+			}
+			break
+		}
+	}
+
+	isOk = true
+
+	return nil
+}
+
+func (this *FileReader) ReadBody(buf []byte, callback ReaderFunc) error {
+	isOk := false
+
+	defer func() {
+		if !isOk {
+			_ = this.discard()
+		}
+	}()
+
+	_, err := this.fp.Seek(this.bodyOffset, io.SeekStart)
+	if err != nil {
+		return err
+	}
+
+	for {
+		n, err := this.fp.Read(buf)
+		if n > 0 {
+			goNext, e := callback(n)
+			if e != nil {
+				isOk = true
+				return e
+			}
+			if !goNext {
+				break
+			}
+		}
+		if err != nil {
+			if err != io.EOF {
+				return err
+			}
+			break
+		}
+	}
+
+	isOk = true
+
+	return nil
+}
+
+func (this *FileReader) ReadBodyRange(buf []byte, start int64, end int64, callback ReaderFunc) error {
+	isOk := false
+
+	defer func() {
+		if !isOk {
+			_ = this.discard()
+		}
+	}()
+
+	offset := start
+	if start < 0 {
+		offset = this.bodyOffset + this.bodySize + end
+		end = this.bodyOffset + this.bodySize - 1
+	} else if end < 0 {
+		offset = this.bodyOffset + start
+		end = this.bodyOffset + this.bodySize - 1
+	} else {
+		offset = this.bodyOffset + start
+		end = this.bodyOffset + end
+	}
+	if offset < 0 || end < 0 || offset > end {
+		isOk = true
+		return ErrInvalidRange
+	}
+	_, err := this.fp.Seek(offset, io.SeekStart)
+	if err != nil {
+		return err
+	}
+
+	for {
+		n, err := this.fp.Read(buf)
+		if n > 0 {
+			n2 := int(end-offset) + 1
+			if n2 <= n {
+				_, e := callback(n2)
+				if e != nil {
+					isOk = true
+					return e
+				}
+				break
+			} else {
+				goNext, e := callback(n)
+				if e != nil {
+					isOk = true
+					return e
+				}
+				if !goNext {
+					break
+				}
+			}
+
+			offset += int64(n)
+			if offset > end {
+				break
+			}
+		}
+		if err != nil {
+			if err != io.EOF {
+				return err
+			}
+			break
+		}
+	}
+
+	isOk = true
+
+	return nil
+}
+
+func (this *FileReader) Close() error {
+	return this.fp.Close()
+}
+
+func (this *FileReader) readToBuff(fp *os.File, buf []byte) (ok bool, err error) {
+	n, err := fp.Read(buf)
+	if err != nil {
+		return false, err
+	}
+	ok = n == len(buf)
+	return
+}
+
+func (this *FileReader) discard() error {
+	_ = this.fp.Close()
+	return os.Remove(this.fp.Name())
+}