refactor: 将 Pool 重构为接口，提取 pool 为具体实现

client.go

@@ -20,7 +20,7 @@ import (
 //
 // ctx 取消时会立即中断与 Python 的通信并返回 ctx.Err()。
 // 对于流式输出/双向流，ctx 取消会关闭返回的 channel。
-func Invoke[R any](ctx context.Context, pool *Pool, method string, args ...any) (R, error) {
+func Invoke[R any](ctx context.Context, pool Pool, method string, args ...any) (R, error) {
 	rt := reflect.TypeFor[R]()
 
 	// 查找 chan 类型的输入参数
@@ -89,7 +89,7 @@ func contextErr(ctx context.Context, err error) error {
 	return err
 }
 
-func invokeRegular[R any](ctx context.Context, pool *Pool, method string, args ...any) (R, error) {
+func invokeRegular[R any](ctx context.Context, pool Pool, method string, args ...any) (R, error) {
 	var zero R
 
 	argsJSON, err := json.Marshal(args)
@@ -102,7 +102,7 @@ func invokeRegular[R any](ctx context.Context, pool *Pool, method string, args .
 		return zero, err
 	}
 
-	id := pool.reqID.Add(1)
+	id := pool.nextReqID()
 	stop := watchCtx(ctx, conn, id)
 	defer stop()
 
@@ -136,7 +136,7 @@ func invokeRegular[R any](ctx context.Context, pool *Pool, method string, args .
 	return result, nil
 }
 
-func invokeStreamOut[R any](ctx context.Context, pool *Pool, method string, rt reflect.Type, args ...any) (R, error) {
+func invokeStreamOut[R any](ctx context.Context, pool Pool, method string, rt reflect.Type, args ...any) (R, error) {
 	var zero R
 
 	argsJSON, err := json.Marshal(args)
@@ -149,7 +149,7 @@ func invokeStreamOut[R any](ctx context.Context, pool *Pool, method string, rt r
 		return zero, err
 	}
 
-	id := pool.reqID.Add(1)
+	id := pool.nextReqID()
 	if err := writeMsg(conn, Message{
 		ID:     id,
 		Type:   TypeCall,
@@ -187,7 +187,7 @@ func invokeStreamOut[R any](ctx context.Context, pool *Pool, method string, rt r
 	return ch.Interface().(R), nil
 }
 
-func invokeStreamIn[R any](ctx context.Context, pool *Pool, method string, streamArgIdx int, streamCh reflect.Value, args ...any) (R, error) {
+func invokeStreamIn[R any](ctx context.Context, pool Pool, method string, streamArgIdx int, streamCh reflect.Value, args ...any) (R, error) {
 	var zero R
 
 	jsonArgs := make([]any, len(args))
@@ -204,7 +204,7 @@ func invokeStreamIn[R any](ctx context.Context, pool *Pool, method string, strea
 		return zero, err
 	}
 
-	id := pool.reqID.Add(1)
+	id := pool.nextReqID()
 	stop := watchCtx(ctx, conn, id)
 	defer stop()
 
@@ -265,7 +265,7 @@ func invokeStreamIn[R any](ctx context.Context, pool *Pool, method string, strea
 	return result, nil
 }
 
-func invokeStreamBoth[R any](ctx context.Context, pool *Pool, method string, streamArgIdx int, streamCh reflect.Value, rt reflect.Type, args ...any) (R, error) {
+func invokeStreamBoth[R any](ctx context.Context, pool Pool, method string, streamArgIdx int, streamCh reflect.Value, rt reflect.Type, args ...any) (R, error) {
 	var zero R
 
 	jsonArgs := make([]any, len(args))
@@ -282,7 +282,7 @@ func invokeStreamBoth[R any](ctx context.Context, pool *Pool, method string, str
 		return zero, err
 	}
 
-	id := pool.reqID.Add(1)
+	id := pool.nextReqID()
 	if err := writeMsg(conn, Message{
 		ID:           id,
 		Type:         TypeCall,

pool.go

@@ -72,8 +72,16 @@ func WithStderr(w io.Writer) Option {
 	return func(c *poolConfig) { c.stderr = w }
 }
 
-// Pool 管理多个 Python worker 进程及其连接池
+// Pool 是 Python worker 进程池的接口
-type Pool struct {
+type Pool interface {
+	// Close 关闭所有 worker 进程和连接
+	Close()
+	acquire(ctx context.Context) (net.Conn, *worker, error)
+	nextReqID() uint64
+}
+
+// pool 是 Pool 的具体实现
+type pool struct {
 	workers []*worker
 	idx     atomic.Uint64
 	reqID   atomic.Uint64
@@ -88,7 +96,7 @@ type Pool struct {
 //	    gobridge.WithScriptArgs("worker.py"),
 //	    gobridge.WithWorkDir("./worker"),
 //	)
-func NewPool(script string, opts ...Option) (*Pool, error) {
+func NewPool(script string, opts ...Option) (Pool, error) {
 	cfg := &poolConfig{
 		workers:           2,
 		maxConnsPerWorker: 4,
@@ -114,19 +122,23 @@ func NewPool(script string, opts ...Option) (*Pool, error) {
 		}
 		workers[i] = w
 	}
-	return &Pool{workers: workers}, nil
+	return &pool{workers: workers}, nil
 }
 
 // acquire 以轮询方式从进程池取出一个可用连接
-func (p *Pool) acquire(ctx context.Context) (net.Conn, *worker, error) {
+func (p *pool) acquire(ctx context.Context) (net.Conn, *worker, error) {
 	idx := p.idx.Add(1) % uint64(len(p.workers))
 	w := p.workers[idx]
 	conn, err := w.acquire(ctx)
 	return conn, w, err
 }
 
+func (p *pool) nextReqID() uint64 {
+	return p.reqID.Add(1)
+}
+
 // Close 关闭所有 worker 进程和连接
-func (p *Pool) Close() {
+func (p *pool) Close() {
 	for _, w := range p.workers {
 		w.stop()
 	}