refactor: 实现 ConversionEngine 协议转换引擎，替代旧 protocol 包
引入 Canonical Model 和 ProtocolAdapter 架构，支持 OpenAI/Anthropic 协议间 无缝转换，统一 ProxyHandler 替代分散的 OpenAI/Anthropic Handler，简化 ProviderClient 为协议无关的 HTTP 发送器，Provider 新增 protocol 字段。
This commit is contained in:
230
backend/internal/conversion/openai/stream_decoder.go
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230
backend/internal/conversion/openai/stream_decoder.go
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@@ -0,0 +1,230 @@
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package openai
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import (
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"encoding/json"
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"fmt"
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"strings"
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"unicode/utf8"
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"nex/backend/internal/conversion/canonical"
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)
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// StreamDecoder OpenAI 流式解码器
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type StreamDecoder struct {
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messageStarted bool
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openBlocks map[int]string
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textBlockIndex int
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thinkingBlockIndex int
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refusalBlockIndex int
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toolCallIDMap map[int]string
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toolCallNameMap map[int]string
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nextToolCallIdx int
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utf8Remainder []byte
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accumulatedUsage *canonical.CanonicalUsage
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}
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// NewStreamDecoder 创建 OpenAI 流式解码器
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func NewStreamDecoder() *StreamDecoder {
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return &StreamDecoder{
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openBlocks: make(map[int]string),
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toolCallIDMap: make(map[int]string),
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toolCallNameMap: make(map[int]string),
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textBlockIndex: -1,
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thinkingBlockIndex: -1,
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refusalBlockIndex: -1,
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}
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}
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// ProcessChunk 处理原始 SSE chunk
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func (d *StreamDecoder) ProcessChunk(rawChunk []byte) []canonical.CanonicalStreamEvent {
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// 处理 UTF-8 残余
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data := rawChunk
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if len(d.utf8Remainder) > 0 {
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data = append(d.utf8Remainder, rawChunk...)
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d.utf8Remainder = nil
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}
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var events []canonical.CanonicalStreamEvent
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// 解析 SSE data 行
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lines := strings.Split(string(data), "\n")
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for _, line := range lines {
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line = strings.TrimSpace(line)
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if !strings.HasPrefix(line, "data: ") {
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continue
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}
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payload := strings.TrimPrefix(line, "data: ")
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if payload == "[DONE]" {
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events = append(events, d.flushOpenBlocks()...)
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return events
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}
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chunkEvents := d.processDataChunk([]byte(payload))
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events = append(events, chunkEvents...)
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}
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return events
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}
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// Flush 刷新解码器状态
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func (d *StreamDecoder) Flush() []canonical.CanonicalStreamEvent {
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return nil
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}
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// processDataChunk 处理单个 data chunk
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func (d *StreamDecoder) processDataChunk(data []byte) []canonical.CanonicalStreamEvent {
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// 检查 UTF-8 完整性
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if !utf8.Valid(data) {
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validEnd := len(data)
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for !utf8.Valid(data[:validEnd]) {
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validEnd--
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}
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d.utf8Remainder = append(d.utf8Remainder, data[validEnd:]...)
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data = data[:validEnd]
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}
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var chunk StreamChunk
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if err := json.Unmarshal(data, &chunk); err != nil {
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return nil
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}
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var events []canonical.CanonicalStreamEvent
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// 首个 chunk: MessageStart
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if !d.messageStarted {
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events = append(events, canonical.NewMessageStartEvent(chunk.ID, chunk.Model))
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d.messageStarted = true
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}
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for _, choice := range chunk.Choices {
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if choice.Delta == nil {
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continue
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}
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delta := choice.Delta
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// text content
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if delta.Content != nil {
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text := ""
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switch v := delta.Content.(type) {
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case string:
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text = v
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default:
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text = fmt.Sprintf("%v", v)
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}
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if text != "" {
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if _, ok := d.openBlocks[d.textBlockIndex]; !ok || d.textBlockIndex < 0 {
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d.textBlockIndex = d.allocateBlockIndex()
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d.openBlocks[d.textBlockIndex] = "text"
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events = append(events, canonical.NewContentBlockStartEvent(d.textBlockIndex,
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canonical.StreamContentBlock{Type: "text", Text: ""}))
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}
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events = append(events, canonical.NewContentBlockDeltaEvent(d.textBlockIndex,
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canonical.StreamDelta{Type: string(canonical.DeltaTypeText), Text: text}))
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}
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}
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// reasoning_content (非标准)
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if delta.ReasoningContent != "" {
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if _, ok := d.openBlocks[d.thinkingBlockIndex]; !ok || d.thinkingBlockIndex < 0 {
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d.thinkingBlockIndex = d.allocateBlockIndex()
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d.openBlocks[d.thinkingBlockIndex] = "thinking"
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events = append(events, canonical.NewContentBlockStartEvent(d.thinkingBlockIndex,
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canonical.StreamContentBlock{Type: "thinking", Thinking: ""}))
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}
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events = append(events, canonical.NewContentBlockDeltaEvent(d.thinkingBlockIndex,
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canonical.StreamDelta{Type: string(canonical.DeltaTypeThinking), Thinking: delta.ReasoningContent}))
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}
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// refusal
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if delta.Refusal != "" {
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if _, ok := d.openBlocks[d.refusalBlockIndex]; !ok || d.refusalBlockIndex < 0 {
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d.refusalBlockIndex = d.allocateBlockIndex()
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d.openBlocks[d.refusalBlockIndex] = "text"
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events = append(events, canonical.NewContentBlockStartEvent(d.refusalBlockIndex,
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canonical.StreamContentBlock{Type: "text", Text: ""}))
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}
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events = append(events, canonical.NewContentBlockDeltaEvent(d.refusalBlockIndex,
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canonical.StreamDelta{Type: string(canonical.DeltaTypeText), Text: delta.Refusal}))
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}
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// tool_calls
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if len(delta.ToolCalls) > 0 {
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for _, tc := range delta.ToolCalls {
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tcIdx := 0
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if tc.Index != nil {
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tcIdx = *tc.Index
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}
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if tc.ID != "" {
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// 新 tool call block
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d.toolCallIDMap[tcIdx] = tc.ID
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if tc.Function != nil {
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d.toolCallNameMap[tcIdx] = tc.Function.Name
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}
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blockIdx := d.allocateBlockIndex()
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d.openBlocks[blockIdx] = fmt.Sprintf("tool_use_%d", tcIdx)
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name := d.toolCallNameMap[tcIdx]
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events = append(events, canonical.NewContentBlockStartEvent(blockIdx,
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canonical.StreamContentBlock{Type: "tool_use", ID: tc.ID, Name: name}))
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}
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// 查找该 tool call 的 block index
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blockIdx := d.findToolUseBlockIndex(tcIdx)
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if tc.Function != nil && tc.Function.Arguments != "" {
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events = append(events, canonical.NewContentBlockDeltaEvent(blockIdx,
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canonical.StreamDelta{Type: string(canonical.DeltaTypeInputJSON), PartialJSON: tc.Function.Arguments}))
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}
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}
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}
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// finish_reason
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if choice.FinishReason != nil && *choice.FinishReason != "" {
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events = append(events, d.flushOpenBlocks()...)
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sr := mapFinishReason(*choice.FinishReason)
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events = append(events, canonical.NewMessageDeltaEventWithUsage(sr, nil))
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events = append(events, canonical.NewMessageStopEvent())
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}
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}
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// usage chunk (choices 为空)
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if len(chunk.Choices) == 0 && chunk.Usage != nil {
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usage := decodeUsage(chunk.Usage)
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d.accumulatedUsage = &usage
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events = append(events, canonical.NewMessageDeltaEventWithUsage(canonical.StopReasonEndTurn, &usage))
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}
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return events
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}
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// allocateBlockIndex 分配 block 索引
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func (d *StreamDecoder) allocateBlockIndex() int {
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maxIdx := -1
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for k := range d.openBlocks {
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if k > maxIdx {
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maxIdx = k
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}
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}
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return maxIdx + 1
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}
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// findToolUseBlockIndex 查找 tool use block 索引
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func (d *StreamDecoder) findToolUseBlockIndex(tcIdx int) int {
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key := fmt.Sprintf("tool_use_%d", tcIdx)
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for blockIdx, typ := range d.openBlocks {
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if typ == key {
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return blockIdx
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}
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}
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return d.allocateBlockIndex()
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}
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// flushOpenBlocks 关闭所有 open blocks
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func (d *StreamDecoder) flushOpenBlocks() []canonical.CanonicalStreamEvent {
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var events []canonical.CanonicalStreamEvent
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for idx := range d.openBlocks {
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events = append(events, canonical.NewContentBlockStopEvent(idx))
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}
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d.openBlocks = make(map[int]string)
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return events
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}
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