update nest: use dispatcher to get lower allocs(4.3.5-rc.0)

proxy/nest.go

@@ -2,14 +2,78 @@ package proxy
 
 import (
 	"bufio"
+	"bytes"
 	"fmt"
 	"ghproxy/config"
 	"io"
 	"strings"
+	"sync"
 
 	"github.com/infinite-iroha/touka"
 )
 
+var (
+	prefixGithub   = []byte("https://github.com")
+	prefixRawUser  = []byte("https://raw.githubusercontent.com")
+	prefixRaw      = []byte("https://raw.github.com")
+	prefixGistUser = []byte("https://gist.githubusercontent.com")
+	prefixGist     = []byte("https://gist.github.com")
+	prefixAPI      = []byte("https://api.github.com")
+	prefixHTTP     = []byte("http://")
+	prefixHTTPS    = []byte("https://")
+)
+
+func EditorMatcherBytes(rawPath []byte, cfg *config.Config) (bool, error) {
+	if bytes.HasPrefix(rawPath, prefixGithub) {
+		return true, nil
+	}
+	if bytes.HasPrefix(rawPath, prefixRawUser) {
+		return true, nil
+	}
+	if bytes.HasPrefix(rawPath, prefixRaw) {
+		return true, nil
+	}
+	if bytes.HasPrefix(rawPath, prefixGistUser) {
+		return true, nil
+	}
+	if bytes.HasPrefix(rawPath, prefixGist) {
+		return true, nil
+	}
+	if cfg.Shell.RewriteAPI {
+		if bytes.HasPrefix(rawPath, prefixAPI) {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
+func modifyURLBytes(url []byte, host []byte, cfg *config.Config) []byte {
+	matched, err := EditorMatcherBytes(url, cfg)
+	if err != nil || !matched {
+		return url
+	}
+
+	var u []byte
+	if bytes.HasPrefix(url, prefixHTTPS) {
+		u = url[len(prefixHTTPS):]
+	} else if bytes.HasPrefix(url, prefixHTTP) {
+		u = url[len(prefixHTTP):]
+	} else {
+		u = url
+	}
+
+	newLen := len(prefixHTTPS) + len(host) + 1 + len(u)
+	newURL := make([]byte, newLen)
+
+	written := 0
+	written += copy(newURL[written:], prefixHTTPS)
+	written += copy(newURL[written:], host)
+	written += copy(newURL[written:], []byte("/"))
+	copy(newURL[written:], u)
+
+	return newURL
+}
+
 func EditorMatcher(rawPath string, cfg *config.Config) (bool, error) {
 	// 匹配 "https://github.com"开头的链接
 	if strings.HasPrefix(rawPath, "https://github.com") {
@@ -64,87 +128,126 @@ func modifyURL(url string, host string, cfg *config.Config) string {
 	return url
 }
 
-// processLinks 处理链接，返回包含处理后数据的 io.Reader
-func processLinks(input io.ReadCloser, host string, cfg *config.Config, c *touka.Context) (readerOut io.Reader, written int64, err error) {
-	pipeReader, pipeWriter := io.Pipe() // 创建 io.Pipe
+var bufferPool = sync.Pool{
+	New: func() interface{} {
+		return new(bytes.Buffer)
+	},
+}
+
+// processLinksStreamingInternal is a link processing function that reads the input line by line.
+// It is memory-safe for large files but less performant due to numerous small allocations.
+func processLinksStreamingInternal(input io.ReadCloser, host string, cfg *config.Config, c *touka.Context) (readerOut io.Reader, written int64, err error) {
+	pipeReader, pipeWriter := io.Pipe()
 	readerOut = pipeReader
 
-	go func() { // 在 Goroutine 中执行写入操作
+	go func() {
 		defer func() {
-			if pipeWriter != nil { // 确保 pipeWriter 关闭，即使发生错误
-				if err != nil {
-					if closeErr := pipeWriter.CloseWithError(err); closeErr != nil { // 如果有错误，传递错误给 reader
-						c.Errorf("pipeWriter close with error failed: %v, original error: %v", closeErr, err)
-					}
-				} else {
-					if closeErr := pipeWriter.Close(); closeErr != nil { // 没有错误，正常关闭
-						c.Errorf("pipeWriter close failed: %v", closeErr)
-						if err == nil { // 如果之前没有错误，记录关闭错误
-							err = closeErr
-						}
-					}
-				}
+			if err != nil {
+				pipeWriter.CloseWithError(err)
+			} else {
+				pipeWriter.Close()
 			}
 		}()
+		defer input.Close()
 
-		defer func() {
-			if err := input.Close(); err != nil {
-				c.Errorf("input close failed: %v", err)
-			}
+		bufReader := bufio.NewReader(input)
+		bufWriter := bufio.NewWriterSize(pipeWriter, 4096)
+		defer bufWriter.Flush()
 
-		}()
-
-		var bufReader *bufio.Reader
-
-		bufReader = bufio.NewReader(input)
-
-		var bufWriter *bufio.Writer
-
-		bufWriter = bufio.NewWriterSize(pipeWriter, 4096) // 使用 pipeWriter
-
-		//确保writer关闭
-		defer func() {
-			if flushErr := bufWriter.Flush(); flushErr != nil {
-				c.Errorf("writer flush failed %v", flushErr)
-				// 如果已经存在错误，则保留。否则，记录此错误。
-				if err == nil {
-					err = flushErr
-				}
-			}
-		}()
-
-		// 使用正则表达式匹配 http 和 https 链接
 		for {
 			line, readErr := bufReader.ReadString('\n')
-			if readErr != nil {
-				if readErr == io.EOF {
-					break // 文件结束
-				}
-				err = fmt.Errorf("读取行错误: %v", readErr) // 传递错误
-				return                                 // Goroutine 中使用 return 返回错误
+			if readErr != nil && readErr != io.EOF {
+				err = fmt.Errorf("read error: %w", readErr)
+				return
 			}
 
-			// 替换所有匹配的 URL
 			modifiedLine := urlPattern.ReplaceAllStringFunc(line, func(originalURL string) string {
-				return modifyURL(originalURL, host, cfg) // 假设 modifyURL 函数已定义
+				return modifyURL(originalURL, host, cfg)
 			})
 
-			n, writeErr := bufWriter.WriteString(modifiedLine)
-			written += int64(n) // 更新写入的字节数
-			if writeErr != nil {
-				err = fmt.Errorf("写入文件错误: %v", writeErr) // 传递错误
-				return                                   // Goroutine 中使用 return 返回错误
+			var n int
+			n, err = bufWriter.WriteString(modifiedLine)
+			written += int64(n)
+			if err != nil {
+				err = fmt.Errorf("write error: %w", err)
+				return
 			}
-		}
 
-		// 在返回之前，再刷新一次 (虽然 defer 中已经有 flush，但这里再加一次确保及时刷新)
-		if flushErr := bufWriter.Flush(); flushErr != nil {
-			if err == nil { // 避免覆盖之前的错误
-				err = flushErr
+			if readErr == io.EOF {
+				break
 			}
-			return // Goroutine 中使用 return 返回错误
 		}
 	}()
 
-	return readerOut, written, nil // 返回 reader 和 written，error 由 Goroutine 通过 pipeWriter.CloseWithError 传递
+	return readerOut, written, nil
+}
+
+// processLinks acts as a dispatcher, choosing the best processing strategy based on file size.
+// It uses a memory-safe streaming approach for large or unknown-size files,
+// and a high-performance buffered approach for smaller files.
+func processLinks(input io.ReadCloser, host string, cfg *config.Config, c *touka.Context, bodySize int) (readerOut io.Reader, written int64, err error) {
+	const sizeThreshold = 256 * 1024 // 256KB
+
+	// Use streaming for large or unknown size files to prevent OOM
+	if bodySize == -1 || bodySize > sizeThreshold {
+		c.Debugf("Using streaming processor for large/unknown size file (%d bytes)", bodySize)
+		return processLinksStreamingInternal(input, host, cfg, c)
+	} else {
+		c.Debugf("Using buffered processor for small file (%d bytes)", bodySize)
+		return processLinksBufferedInternal(input, host, cfg, c)
+	}
+}
+
+// processLinksBufferedInternal a link processing function that reads the entire content into a buffer.
+// It is optimized for performance on smaller files but carries an OOM risk for large files.
+func processLinksBufferedInternal(input io.ReadCloser, host string, cfg *config.Config, c *touka.Context) (readerOut io.Reader, written int64, err error) {
+	pipeReader, pipeWriter := io.Pipe()
+	readerOut = pipeReader
+	hostBytes := []byte(host)
+
+	go func() {
+		// 在 goroutine 退出时, 根据 err 是否为 nil, 带错误或正常关闭 pipeWriter
+		defer func() {
+			if closeErr := input.Close(); closeErr != nil {
+				c.Errorf("input close failed: %v", closeErr)
+			}
+		}()
+		defer func() {
+			if err != nil {
+				if closeErr := pipeWriter.CloseWithError(err); closeErr != nil {
+					c.Errorf("pipeWriter close with error failed: %v", closeErr)
+				}
+			} else {
+				if closeErr := pipeWriter.Close(); closeErr != nil {
+					c.Errorf("pipeWriter close failed: %v", closeErr)
+				}
+			}
+		}()
+
+		buf := bufferPool.Get().(*bytes.Buffer)
+		buf.Reset()
+		defer bufferPool.Put(buf)
+
+		// 将全部输入读入复用的缓冲区
+		if _, err = buf.ReadFrom(input); err != nil {
+			err = fmt.Errorf("reading input failed: %w", err)
+			return
+		}
+
+		// 使用 ReplaceAllFunc 和字节版本辅助函数, 实现准零分配
+		modifiedBytes := urlPattern.ReplaceAllFunc(buf.Bytes(), func(originalURL []byte) []byte {
+			return modifyURLBytes(originalURL, hostBytes, cfg)
+		})
+
+		// 将处理后的字节写回管道
+		var n int
+		n, err = pipeWriter.Write(modifiedBytes)
+		if err != nil {
+			err = fmt.Errorf("writing to pipe failed: %w", err)
+			return
+		}
+		written = int64(n)
+	}()
+
+	return readerOut, written, nil
 }