优化Partial Content内容缓存，现在可以使用“部分文件缓存+部分回源”的方式提供内容

internal/nodes/http_request_cache_partial.go

@@ -0,0 +1,86 @@
+// Copyright 2024 GoEdge CDN goedge.cdn@gmail.com. All rights reserved. Official site: https://goedge.cn .
+
+package nodes
+
+import (
+	"github.com/TeaOSLab/EdgeNode/internal/caches"
+	"github.com/iwind/TeaGo/types"
+	"io"
+	"net/http"
+)
+
+// HTTPRequestPartialReader 分区文件读取器
+type HTTPRequestPartialReader struct {
+	req    *HTTPRequest
+	offset int64
+	resp   *http.Response
+
+	cacheReader caches.Reader
+	cacheWriter caches.Writer
+}
+
+// NewHTTPRequestPartialReader 构建新的分区文件读取器
+// req 当前请求
+// offset 读取位置
+// reader 当前缓存读取器
+func NewHTTPRequestPartialReader(req *HTTPRequest, offset int64, reader caches.Reader) *HTTPRequestPartialReader {
+	return &HTTPRequestPartialReader{
+		req:         req,
+		offset:      offset,
+		cacheReader: reader,
+	}
+}
+
+// 读取内容
+func (this *HTTPRequestPartialReader) Read(p []byte) (n int, err error) {
+	if this.resp == nil {
+		_ = this.cacheReader.Close()
+
+		this.req.RawReq.Header.Set("Range", "bytes="+types.String(this.offset)+"-")
+		var resp = this.req.doReverseProxy(false)
+		if resp == nil {
+			err = io.ErrUnexpectedEOF
+			return
+		}
+		this.resp = resp
+
+		this.prepareCacheWriter()
+	}
+
+	n, err = this.resp.Body.Read(p)
+
+	// 写入到缓存
+	if n > 0 && this.cacheWriter != nil {
+		_ = this.cacheWriter.WriteAt(this.offset, p[:n])
+		this.offset += int64(n)
+	}
+
+	return
+}
+
+// Close 关闭读取器
+func (this *HTTPRequestPartialReader) Close() error {
+	if this.cacheWriter != nil {
+		_ = this.cacheWriter.Close()
+	}
+
+	if this.resp != nil && this.resp.Body != nil {
+		return this.resp.Body.Close()
+	}
+
+	return nil
+}
+
+// 准备缓存写入器
+func (this *HTTPRequestPartialReader) prepareCacheWriter() {
+	var storage = this.req.writer.cacheStorage
+	if storage == nil {
+		return
+	}
+
+	var cacheKey = this.req.cacheKey + caches.SuffixPartial
+	writer, err := storage.OpenWriter(cacheKey, this.cacheReader.ExpiresAt(), this.cacheReader.Status(), int(this.cacheReader.HeaderSize()), this.cacheReader.BodySize(), -1, true)
+	if err == nil {
+		this.cacheWriter = writer
+	}
+}