修复热点数据从文件系统转移到内存时可能不完整的Bug/实现部分Partial Content功能

internal/caches/writer_partial_file.go

@@ -0,0 +1,173 @@
+// Copyright 2022 Liuxiangchao iwind.liu@gmail.com. All rights reserved.
+
+package caches
+
+import (
+	"encoding/binary"
+	"github.com/iwind/TeaGo/types"
+	"io"
+	"os"
+	"strings"
+	"sync"
+)
+
+type PartialFileWriter struct {
+	rawWriter  *os.File
+	key        string
+	headerSize int64
+	bodySize   int64
+	expiredAt  int64
+	endFunc    func()
+	once       sync.Once
+
+	isNew      bool
+	isPartial  bool
+	bodyOffset int64
+}
+
+func NewPartialFileWriter(rawWriter *os.File, key string, expiredAt int64, isNew bool, isPartial bool, bodyOffset int64, endFunc func()) *PartialFileWriter {
+	return &PartialFileWriter{
+		key:        key,
+		rawWriter:  rawWriter,
+		expiredAt:  expiredAt,
+		endFunc:    endFunc,
+		isNew:      isNew,
+		isPartial:  isPartial,
+		bodyOffset: bodyOffset,
+	}
+}
+
+// WriteHeader 写入数据
+func (this *PartialFileWriter) WriteHeader(data []byte) (n int, err error) {
+	if !this.isNew {
+		return
+	}
+	n, err = this.rawWriter.Write(data)
+	this.headerSize += int64(n)
+	if err != nil {
+		_ = this.Discard()
+	}
+	return
+}
+
+// WriteHeaderLength 写入Header长度数据
+func (this *PartialFileWriter) WriteHeaderLength(headerLength int) error {
+	bytes4 := make([]byte, 4)
+	binary.BigEndian.PutUint32(bytes4, uint32(headerLength))
+	_, err := this.rawWriter.Seek(SizeExpiresAt+SizeStatus+SizeURLLength, io.SeekStart)
+	if err != nil {
+		_ = this.Discard()
+		return err
+	}
+	_, err = this.rawWriter.Write(bytes4)
+	if err != nil {
+		_ = this.Discard()
+		return err
+	}
+	return nil
+}
+
+// Write 写入数据
+func (this *PartialFileWriter) Write(data []byte) (n int, err error) {
+	n, err = this.rawWriter.Write(data)
+	this.bodySize += int64(n)
+	if err != nil {
+		_ = this.Discard()
+	}
+	return
+}
+
+// WriteAt 在指定位置写入数据
+func (this *PartialFileWriter) WriteAt(data []byte, offset int64) error {
+	if this.bodyOffset == 0 {
+		this.bodyOffset = SizeMeta + int64(len(this.key)) + this.headerSize
+	}
+	_, err := this.rawWriter.WriteAt(data, this.bodyOffset+offset)
+	return err
+}
+
+// WriteBodyLength 写入Body长度数据
+func (this *PartialFileWriter) WriteBodyLength(bodyLength int64) error {
+	bytes8 := make([]byte, 8)
+	binary.BigEndian.PutUint64(bytes8, uint64(bodyLength))
+	_, err := this.rawWriter.Seek(SizeExpiresAt+SizeStatus+SizeURLLength+SizeHeaderLength, io.SeekStart)
+	if err != nil {
+		_ = this.Discard()
+		return err
+	}
+	_, err = this.rawWriter.Write(bytes8)
+	if err != nil {
+		_ = this.Discard()
+		return err
+	}
+	return nil
+}
+
+// Close 关闭
+func (this *PartialFileWriter) Close() error {
+	defer this.once.Do(func() {
+		this.endFunc()
+	})
+
+	var path = this.rawWriter.Name()
+
+	if this.isNew {
+		err := this.WriteHeaderLength(types.Int(this.headerSize))
+		if err != nil {
+			_ = this.rawWriter.Close()
+			_ = os.Remove(path)
+			return err
+		}
+		err = this.WriteBodyLength(this.bodySize)
+		if err != nil {
+			_ = this.rawWriter.Close()
+			_ = os.Remove(path)
+			return err
+		}
+	}
+
+	err := this.rawWriter.Close()
+	if err != nil {
+		_ = os.Remove(path)
+	} else if !this.isPartial {
+		err = os.Rename(path, strings.Replace(path, ".tmp", "", 1))
+		if err != nil {
+			_ = os.Remove(path)
+		}
+	}
+
+	return err
+}
+
+// Discard 丢弃
+func (this *PartialFileWriter) Discard() error {
+	defer this.once.Do(func() {
+		this.endFunc()
+	})
+
+	_ = this.rawWriter.Close()
+
+	err := os.Remove(this.rawWriter.Name())
+	return err
+}
+
+func (this *PartialFileWriter) HeaderSize() int64 {
+	return this.headerSize
+}
+
+func (this *PartialFileWriter) BodySize() int64 {
+	return this.bodySize
+}
+
+func (this *PartialFileWriter) ExpiredAt() int64 {
+	return this.expiredAt
+}
+
+func (this *PartialFileWriter) Key() string {
+	return this.key
+}
+
+// ItemType 获取内容类型
+func (this *PartialFileWriter) ItemType() ItemType {
+	return ItemTypeFile
+}