refactor: share async invoke bridge across native platforms

bind/desktop/invoke_executor.go

@@ -1,123 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"runtime"
-	"sync"
-)
-
-const (
-	minInvokeConcurrency = 4
-	maxInvokeConcurrency = 32
-)
-
-type invokeRequest struct {
-	method string
-	path   string
-	query  string
-	body   string
-}
-
-type invokeTask struct {
-	request  invokeRequest
-	complete func(result string, err error)
-}
-
-// invokeExecutor keeps native API work concurrent without ever rejecting a
-// request because all workers are busy. submit only appends to the waiting
-// queue; callers observe backpressure through the Future completed by the
-// callback rather than by blocking the FFI entry point.
-type invokeExecutor struct {
-	mu      sync.Mutex
-	ready   *sync.Cond
-	queue   []invokeTask
-	closed  bool
-	workers sync.WaitGroup
-	handler func(invokeRequest) string
-}
-
-func invokeConcurrency(cpuCount int) int {
-	concurrency := cpuCount * 2
-	if concurrency < minInvokeConcurrency {
-		return minInvokeConcurrency
-	}
-	if concurrency > maxInvokeConcurrency {
-		return maxInvokeConcurrency
-	}
-	return concurrency
-}
-
-func newInvokeExecutor(workerCount int, handler func(invokeRequest) string) *invokeExecutor {
-	if workerCount < 1 {
-		workerCount = 1
-	}
-	executor := &invokeExecutor{handler: handler}
-	executor.ready = sync.NewCond(&executor.mu)
-	executor.workers.Add(workerCount)
-	for range workerCount {
-		go executor.run()
-	}
-	return executor
-}
-
-func newDefaultInvokeExecutor(handler func(invokeRequest) string) *invokeExecutor {
-	return newInvokeExecutor(invokeConcurrency(runtime.GOMAXPROCS(0)), handler)
-}
-
-func (e *invokeExecutor) submit(task invokeTask) bool {
-	e.mu.Lock()
-	defer e.mu.Unlock()
-	if e.closed {
-		return false
-	}
-	e.queue = append(e.queue, task)
-	e.ready.Signal()
-	return true
-}
-
-func (e *invokeExecutor) close() {
-	e.mu.Lock()
-	e.closed = true
-	e.ready.Broadcast()
-	e.mu.Unlock()
-	e.workers.Wait()
-}
-
-func (e *invokeExecutor) run() {
-	defer e.workers.Done()
-	for {
-		task, ok := e.take()
-		if !ok {
-			return
-		}
-		result, err := e.execute(task.request)
-		task.complete(result, err)
-	}
-}
-
-func (e *invokeExecutor) take() (invokeTask, bool) {
-	e.mu.Lock()
-	defer e.mu.Unlock()
-	for len(e.queue) == 0 && !e.closed {
-		e.ready.Wait()
-	}
-	if len(e.queue) == 0 {
-		return invokeTask{}, false
-	}
-	task := e.queue[0]
-	e.queue[0] = invokeTask{}
-	e.queue = e.queue[1:]
-	if len(e.queue) == 0 {
-		e.queue = nil
-	}
-	return task, true
-}
-
-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
-}

bind/desktop/main.go

@@ -20,29 +20,15 @@ import "C"
 import (
 	"encoding/json"
 	"fmt"
-	"sync"
 	"unsafe"
 
+	nativebridge "github.com/GopeedLab/gopeed/bind/native"
 	"github.com/GopeedLab/gopeed/pkg/rest"
 	"github.com/GopeedLab/gopeed/pkg/rest/model"
 )
 
 func main() {}
 
-var (
-	invokeExecutorOnce sync.Once
-	desktopInvoker     *invokeExecutor
-)
-
-func getInvokeExecutor() *invokeExecutor {
-	invokeExecutorOnce.Do(func() {
-		desktopInvoker = newDefaultInvokeExecutor(func(request invokeRequest) string {
-			return rest.Invoke(request.method, request.path, request.query, request.body)
-		})
-	})
-	return desktopInvoker
-}
-
 //export Start
 func Start(cfg *C.char) (int, *C.char) {
 	var config model.StartConfig
@@ -56,11 +42,13 @@ func Start(cfg *C.char) (int, *C.char) {
 	if err != nil {
 		return 0, C.CString(err.Error())
 	}
+	nativebridge.ResumeInvokes()
 	return realPort, nil
 }
 
 //export Stop
 func Stop() {
+	nativebridge.PauseInvokesAndWait()
 	rest.Stop()
 }
 
@@ -96,16 +84,6 @@ func apiServerResult(state *model.APIServerState, err error) string {
 	return string(data)
 }
 
-//export Invoke
-func Invoke(method *C.char, path *C.char, query *C.char, body *C.char) *C.char {
-	return C.CString(rest.Invoke(
-		C.GoString(method),
-		C.GoString(path),
-		C.GoString(query),
-		C.GoString(body),
-	))
-}
-
 //export InvokeAsync
 func InvokeAsync(
 	method *C.char,
@@ -118,12 +96,6 @@ func InvokeAsync(
 	if callback == 0 {
 		return
 	}
-	request := invokeRequest{
-		method: C.GoString(method),
-		path:   C.GoString(path),
-		query:  C.GoString(query),
-		body:   C.GoString(body),
-	}
 	complete := func(result string, err error) {
 		success := C.int(1)
 		payload := result
@@ -138,9 +110,13 @@ func InvokeAsync(
 			C.CString(payload),
 		)
 	}
-	if !getInvokeExecutor().submit(invokeTask{request: request, complete: complete}) {
-		complete("", fmt.Errorf("invoke executor is closed"))
-	}
+	nativebridge.InvokeAsync(
+		C.GoString(method),
+		C.GoString(path),
+		C.GoString(query),
+		C.GoString(body),
+		complete,
+	)
 }
 
 //export SubscribeTaskEvents

bind/mobile/main.go

@@ -5,6 +5,7 @@ import "C"
 import (
 	"encoding/json"
 
+	nativebridge "github.com/GopeedLab/gopeed/bind/native"
 	"github.com/GopeedLab/gopeed/internal/webview/rpcprovider"
 	"github.com/GopeedLab/gopeed/pkg/rest"
 	"github.com/GopeedLab/gopeed/pkg/rest/model"
@@ -18,10 +19,15 @@ func Start(cfg string) (int, error) {
 	config.ProductionMode = true
 	config.NativeMode = true
 	applyWebViewProvider(&config)
-	return rest.Start(&config)
+	port, err := rest.Start(&config)
+	if err == nil {
+		nativebridge.ResumeInvokes()
+	}
+	return port, err
 }
 
 func Stop() {
+	nativebridge.PauseInvokesAndWait()
 	rest.Stop()
 }
 
@@ -50,8 +56,21 @@ func apiServerResult(state *model.APIServerState, err error) string {
 	return string(data)
 }
 
-func Invoke(method, path, query, body string) string {
-	return rest.Invoke(method, path, query, body)
+type InvokeResultListener interface {
+	OnResult(requestID int64, success bool, payload string)
+}
+
+func InvokeAsync(method, path, query, body string, requestID int64, listener InvokeResultListener) {
+	if listener == nil {
+		return
+	}
+	nativebridge.InvokeAsync(method, path, query, body, func(result string, err error) {
+		if err != nil {
+			listener.OnResult(requestID, false, err.Error())
+			return
+		}
+		listener.OnResult(requestID, true, result)
+	})
 }
 
 type TaskEventListener interface {

bind/native/invoke.go

@@ -0,0 +1,202 @@
+// Package nativebridge contains transport-neutral behavior shared by the
+// Desktop C FFI and gomobile bridge adapters.
+package nativebridge
+
+import (
+	"fmt"
+	"runtime"
+	"sync"
+
+	"github.com/GopeedLab/gopeed/pkg/rest"
+)
+
+const (
+	minInvokeConcurrency = 4
+	maxInvokeConcurrency = 32
+)
+
+type invokeRequest struct {
+	method string
+	path   string
+	query  string
+	body   string
+}
+
+type invokeTask struct {
+	request  invokeRequest
+	complete func(result string, err error)
+}
+
+// InvokeAsync queues 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, "", fmt.Errorf("native bridge is stopping"))
+	}
+}
+
+// ResumeInvokes enables request submission after the native runtime starts.
+func ResumeInvokes() {
+	getInvokeExecutor().resume()
+}
+
+// PauseInvokesAndWait prevents new submissions and waits for every queued or
+// running request to finish before a native runtime is stopped.
+func PauseInvokesAndWait() {
+	getInvokeExecutor().pauseAndWait()
+}
+
+var (
+	invokeExecutorOnce sync.Once
+	sharedInvoker      *invokeExecutor
+)
+
+func getInvokeExecutor() *invokeExecutor {
+	invokeExecutorOnce.Do(func() {
+		sharedInvoker = newDefaultInvokeExecutor(func(request invokeRequest) string {
+			return rest.Dispatch(request.method, request.path, request.query, request.body)
+		})
+	})
+	return sharedInvoker
+}
+
+// invokeExecutor keeps native API work concurrent without rejecting requests
+// when every worker is busy. Additional requests wait in FIFO order and are
+// completed through their callback.
+type invokeExecutor struct {
+	mu        sync.Mutex
+	ready     *sync.Cond
+	queue     []invokeTask
+	closed    bool
+	accepting bool
+	pending   int
+	workers   sync.WaitGroup
+	handler   func(invokeRequest) string
+}
+
+func invokeConcurrency(cpuCount int) int {
+	concurrency := cpuCount * 2
+	if concurrency < minInvokeConcurrency {
+		return minInvokeConcurrency
+	}
+	if concurrency > maxInvokeConcurrency {
+		return maxInvokeConcurrency
+	}
+	return concurrency
+}
+
+func newInvokeExecutor(workerCount int, handler func(invokeRequest) string) *invokeExecutor {
+	if workerCount < 1 {
+		workerCount = 1
+	}
+	executor := &invokeExecutor{handler: handler, accepting: true}
+	executor.ready = sync.NewCond(&executor.mu)
+	executor.workers.Add(workerCount)
+	for range workerCount {
+		go executor.run()
+	}
+	return executor
+}
+
+func newDefaultInvokeExecutor(handler func(invokeRequest) string) *invokeExecutor {
+	return newInvokeExecutor(invokeConcurrency(runtime.GOMAXPROCS(0)), handler)
+}
+
+func (e *invokeExecutor) submit(task invokeTask) bool {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	if e.closed || !e.accepting {
+		return false
+	}
+	e.queue = append(e.queue, task)
+	e.pending++
+	e.ready.Signal()
+	return true
+}
+
+func (e *invokeExecutor) resume() {
+	e.mu.Lock()
+	e.accepting = true
+	e.mu.Unlock()
+}
+
+func (e *invokeExecutor) pauseAndWait() {
+	e.mu.Lock()
+	e.accepting = false
+	for e.pending > 0 {
+		e.ready.Wait()
+	}
+	e.mu.Unlock()
+}
+
+func (e *invokeExecutor) close() {
+	e.mu.Lock()
+	e.closed = true
+	e.ready.Broadcast()
+	e.mu.Unlock()
+	e.workers.Wait()
+}
+
+func (e *invokeExecutor) run() {
+	defer e.workers.Done()
+	for {
+		task, ok := e.take()
+		if !ok {
+			return
+		}
+		result, err := e.execute(task.request)
+		completeCallback(task.complete, result, err)
+		e.mu.Lock()
+		e.pending--
+		if e.pending == 0 {
+			e.ready.Broadcast()
+		}
+		e.mu.Unlock()
+	}
+}
+
+func (e *invokeExecutor) take() (invokeTask, bool) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	for len(e.queue) == 0 && !e.closed {
+		e.ready.Wait()
+	}
+	if len(e.queue) == 0 {
+		return invokeTask{}, false
+	}
+	task := e.queue[0]
+	e.queue[0] = invokeTask{}
+	e.queue = e.queue[1:]
+	if len(e.queue) == 0 {
+		e.queue = nil
+	}
+	return task, true
+}
+
+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)
+}

bind/native/invoke_test.go

@@ -1,6 +1,7 @@
-package main
+package nativebridge
 
 import (
+	"runtime"
 	"strconv"
 	"sync"
 	"sync/atomic"
@@ -100,3 +101,96 @@ func TestInvokeExecutorConvertsPanicsToErrors(t *testing.T) {
 	}
 	executor.close()
 }
+
+func TestInvokeExecutorSurvivesCallbackPanic(t *testing.T) {
+	executor := newInvokeExecutor(1, func(request invokeRequest) string {
+		return request.path
+	})
+	executor.submit(invokeTask{complete: func(string, error) {
+		panic("callback failed")
+	}})
+
+	completed := make(chan string, 1)
+	executor.submit(invokeTask{
+		request: invokeRequest{path: "next"},
+		complete: func(result string, _ error) {
+			completed <- result
+		},
+	})
+	select {
+	case result := <-completed:
+		if result != "next" {
+			t.Fatalf("unexpected result: %q", result)
+		}
+	case <-time.After(time.Second):
+		t.Fatal("worker stopped after callback panic")
+	}
+	executor.close()
+}
+
+func TestInvokeExecutorPausesAndDrains(t *testing.T) {
+	release := make(chan struct{})
+	started := make(chan struct{})
+	executor := newInvokeExecutor(1, func(request invokeRequest) string {
+		if request.path == "running" {
+			close(started)
+			<-release
+		}
+		return request.path
+	})
+	completed := make(chan struct{})
+	if !executor.submit(invokeTask{
+		request: invokeRequest{path: "running"},
+		complete: func(string, error) {
+			close(completed)
+		},
+	}) {
+		t.Fatal("initial task was rejected")
+	}
+	<-started
+
+	drained := make(chan struct{})
+	go func() {
+		executor.pauseAndWait()
+		close(drained)
+	}()
+	deadline := time.Now().Add(time.Second)
+	for {
+		executor.mu.Lock()
+		paused := !executor.accepting
+		executor.mu.Unlock()
+		if paused {
+			break
+		}
+		if time.Now().After(deadline) {
+			t.Fatal("executor did not pause")
+		}
+		runtime.Gosched()
+	}
+	select {
+	case <-drained:
+		t.Fatal("pause returned before the running request completed")
+	default:
+	}
+	if executor.submit(invokeTask{}) {
+		t.Fatal("paused executor accepted a new request")
+	}
+
+	close(release)
+	<-completed
+	select {
+	case <-drained:
+	case <-time.After(time.Second):
+		t.Fatal("pause did not return after pending requests drained")
+	}
+
+	executor.resume()
+	resumed := make(chan struct{})
+	if !executor.submit(invokeTask{complete: func(string, error) {
+		close(resumed)
+	}}) {
+		t.Fatal("resumed executor rejected a request")
+	}
+	<-resumed
+	executor.close()
+}