refactor: 0.1.0-beta

cursor-backend/capture.go

@@ -0,0 +1,95 @@
+// capture.go 在不影响上游转发的前提下截取有限大小的 HTTP 流。
+package main
+
+import (
+	"bytes"
+	"encoding/hex"
+	"io"
+	"sync"
+)
+
+// captureReadCloser 包装响应体并并发安全地累计诊断副本。
+type captureReadCloser struct {
+	source    io.ReadCloser
+	mu        sync.Mutex
+	buffer    bytes.Buffer
+	limit     int
+	size      int64
+	truncated bool
+	done      bool
+	onChunk   func([]byte)
+	onDone    func(captured []byte, size int64, truncated bool, readErr error)
+}
+
+// newCaptureReadCloser 创建带分块和完成回调的捕获读取器。
+func newCaptureReadCloser(
+	source io.ReadCloser,
+	limit int,
+	onChunk func([]byte),
+	onDone func(captured []byte, size int64, truncated bool, readErr error),
+) *captureReadCloser {
+	return &captureReadCloser{
+		source:  source,
+		limit:   limit,
+		onChunk: onChunk,
+		onDone:  onDone,
+	}
+}
+
+// Read 转发读取结果并保存不超过限制的副本。
+func (reader *captureReadCloser) Read(payload []byte) (int, error) {
+	read, err := reader.source.Read(payload)
+	if read > 0 {
+		chunk := payload[:read]
+		reader.mu.Lock()
+		reader.size += int64(read)
+		remaining := reader.limit - reader.buffer.Len()
+		if remaining > 0 {
+			captured := read
+			if captured > remaining {
+				captured = remaining
+			}
+			_, _ = reader.buffer.Write(chunk[:captured])
+		}
+		if reader.buffer.Len() >= reader.limit && reader.size > int64(reader.buffer.Len()) {
+			reader.truncated = true
+		}
+		reader.mu.Unlock()
+		if reader.onChunk != nil {
+			reader.onChunk(append([]byte(nil), chunk...))
+		}
+	}
+	if err != nil {
+		reader.finish(err)
+	}
+	return read, err
+}
+
+// Close 关闭原始响应体并保证完成回调只执行一次。
+func (reader *captureReadCloser) Close() error {
+	err := reader.source.Close()
+	reader.finish(err)
+	return err
+}
+
+// finish 固化捕获快照并在锁外调用完成回调。
+func (reader *captureReadCloser) finish(readErr error) {
+	reader.mu.Lock()
+	if reader.done {
+		reader.mu.Unlock()
+		return
+	}
+	reader.done = true
+	captured := append([]byte(nil), reader.buffer.Bytes()...)
+	size := reader.size
+	truncated := reader.truncated
+	reader.mu.Unlock()
+	if reader.onDone != nil {
+		reader.onDone(captured, size, truncated, readErr)
+	}
+}
+
+// rawHex 把捕获字节编码为便于 JSON 持久化的十六进制文本。
+func rawHex(payload []byte) string {
+	return hex.EncodeToString(payload)
+}