feat: unify native API invocation with async callbacks (#1476)

bind/native/invoke.go

@@ -0,0 +1,240 @@
+// Package nativebridge contains transport-neutral behavior shared by the
+// Desktop C FFI and gomobile bridge adapters.
+package nativebridge
+
+import (
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/GopeedLab/gopeed/pkg/rest"
+)
+
+// StopTimeout bounds native shutdown even when an in-process request never returns.
+const StopTimeout = 3 * time.Second
+
+var errNativeBridgeStopping = errors.New("native bridge is stopping")
+
+type invokeRequest struct {
+	method string
+	path   string
+	query  string
+	body   string
+}
+
+type invokeTask struct {
+	id       uint64
+	request  invokeRequest
+	complete func(result string, err error)
+	once     sync.Once
+}
+
+func (t *invokeTask) finish(result string, err error) {
+	t.once.Do(func() {
+		completeCallback(t.complete, result, err)
+	})
+}
+
+// InvokeAsync starts an in-process API request and completes it through the
+// supplied callback. Desktop and mobile adapters share this executor.
+func InvokeAsync(method, path, query, body string, callback func(result string, err error)) {
+	if callback == nil {
+		return
+	}
+	task := invokeTask{
+		request: invokeRequest{
+			method: method,
+			path:   path,
+			query:  query,
+			body:   body,
+		},
+		complete: callback,
+	}
+	if !getInvokeExecutor().submit(task) {
+		completeCallback(callback, "", errNativeBridgeStopping)
+	}
+}
+
+// ResumeInvokes enables request submission after the native runtime starts.
+func ResumeInvokes() {
+	getInvokeExecutor().resume()
+}
+
+// PauseInvokesAndWait prevents new submissions and gives running requests a
+// bounded opportunity to finish before a native runtime is stopped.
+// Requests still pending after StopTimeout are failed and detached so shutdown
+// can continue without invoking their callbacks a second time.
+func PauseInvokesAndWait() bool {
+	return getInvokeExecutor().pauseAndWait(StopTimeout)
+}
+
+// Stop pauses native requests and shuts down the shared runtime, but never
+// keeps the host application waiting longer than StopTimeout. Cleanup that
+// cannot finish within the deadline is allowed to continue in the background.
+func Stop() {
+	stopWithin(getInvokeExecutor(), rest.Stop, StopTimeout)
+}
+
+func stopWithin(executor *invokeExecutor, cleanup func(), timeout time.Duration) {
+	deadline := time.Now().Add(timeout)
+	executor.pauseAndWait(time.Until(deadline))
+
+	stopped := make(chan struct{})
+	go func() {
+		defer close(stopped)
+		cleanup()
+	}()
+
+	remaining := time.Until(deadline)
+	if remaining <= 0 {
+		return
+	}
+	timer := time.NewTimer(remaining)
+	defer timer.Stop()
+	select {
+	case <-stopped:
+	case <-timer.C:
+	}
+}
+
+var (
+	invokeExecutorOnce sync.Once
+	sharedInvoker      *invokeExecutor
+)
+
+func getInvokeExecutor() *invokeExecutor {
+	invokeExecutorOnce.Do(func() {
+		sharedInvoker = newInvokeExecutor(func(request invokeRequest) string {
+			return rest.Dispatch(request.method, request.path, request.query, request.body)
+		})
+	})
+	return sharedInvoker
+}
+
+// invokeExecutor starts every native API request in its own goroutine, matching
+// net/http's request concurrency. It only tracks them to support bounded drain
+// during shutdown; one stuck request must never prevent another from starting.
+type invokeExecutor struct {
+	mu        sync.Mutex
+	closed    bool
+	accepting bool
+	nextID    uint64
+	pending   map[uint64]*invokeTask
+	drained   chan struct{}
+	running   sync.WaitGroup
+	handler   func(invokeRequest) string
+}
+
+func newInvokeExecutor(handler func(invokeRequest) string) *invokeExecutor {
+	drained := make(chan struct{})
+	close(drained)
+	return &invokeExecutor{
+		handler:   handler,
+		accepting: true,
+		pending:   make(map[uint64]*invokeTask),
+		drained:   drained,
+	}
+}
+
+func (e *invokeExecutor) submit(task invokeTask) bool {
+	e.mu.Lock()
+	if e.closed || !e.accepting {
+		e.mu.Unlock()
+		return false
+	}
+	if len(e.pending) == 0 {
+		e.drained = make(chan struct{})
+	}
+	taskID := e.nextID
+	e.nextID++
+	task.id = taskID
+	taskPtr := &task
+	e.pending[taskID] = taskPtr
+	e.running.Add(1)
+	e.mu.Unlock()
+
+	go e.run(taskPtr)
+	return true
+}
+
+func (e *invokeExecutor) resume() {
+	e.mu.Lock()
+	e.accepting = true
+	e.mu.Unlock()
+}
+
+func (e *invokeExecutor) pauseAndWait(timeout time.Duration) bool {
+	e.mu.Lock()
+	e.accepting = false
+	if len(e.pending) == 0 {
+		e.mu.Unlock()
+		return true
+	}
+	drained := e.drained
+	e.mu.Unlock()
+
+	timer := time.NewTimer(timeout)
+	defer timer.Stop()
+	select {
+	case <-drained:
+		return true
+	case <-timer.C:
+	}
+
+	e.mu.Lock()
+	if len(e.pending) == 0 {
+		e.mu.Unlock()
+		return true
+	}
+	pending := make([]*invokeTask, 0, len(e.pending))
+	for _, task := range e.pending {
+		pending = append(pending, task)
+	}
+	e.pending = make(map[uint64]*invokeTask)
+	close(e.drained)
+	e.mu.Unlock()
+
+	for _, task := range pending {
+		task.finish("", errNativeBridgeStopping)
+	}
+	return false
+}
+
+func (e *invokeExecutor) close() {
+	e.mu.Lock()
+	e.closed = true
+	e.accepting = false
+	e.mu.Unlock()
+	e.running.Wait()
+}
+
+func (e *invokeExecutor) run(task *invokeTask) {
+	defer e.running.Done()
+	result, err := e.execute(task.request)
+	task.finish(result, err)
+	e.mu.Lock()
+	if _, exists := e.pending[task.id]; exists {
+		delete(e.pending, task.id)
+		if len(e.pending) == 0 {
+			close(e.drained)
+		}
+	}
+	e.mu.Unlock()
+}
+
+func (e *invokeExecutor) execute(request invokeRequest) (result string, err error) {
+	defer func() {
+		if recovered := recover(); recovered != nil {
+			err = fmt.Errorf("invoke panic: %v", recovered)
+		}
+	}()
+	return e.handler(request), nil
+}
+
+func completeCallback(callback func(string, error), result string, err error) {
+	defer func() {
+		_ = recover()
+	}()
+	callback(result, err)
+}