From 7d9649bf0d3acb8b83d966afa945db7f2188b753 Mon Sep 17 00:00:00 2001 From: Richard Musiol Date: Tue, 11 Dec 2018 14:23:17 +0100 Subject: [PATCH] syscall/js: rename js.Callback to js.Func The name "Callback" does not fit to all use cases of js.Callback. This commit changes its name to Func. Accordingly NewCallback gets renamed to FuncOf, which matches ValueOf and TypedArrayOf. The package syscall/js is currently exempt from Go's compatibility promise and js.Callback is already affected by a breaking change in this release cycle. See #28711 for details. Fixes #28711 Change-Id: I2c380970c3822bed6a3893909672c15d0cbe9da3 Reviewed-on: https://go-review.googlesource.com/c/153559 Run-TryBot: Brad Fitzpatrick TryBot-Result: Gobot Gobot Reviewed-by: Brad Fitzpatrick --- misc/wasm/wasm_exec.js | 34 +++++------ src/cmd/vet/all/whitelist/wasm.txt | 2 +- src/net/http/roundtrip_js.go | 12 ++-- src/runtime/lock_js.go | 51 ++++++++--------- src/runtime/rt0_js_wasm.s | 6 +- src/runtime/sys_wasm.s | 4 +- src/syscall/fs_js.go | 2 +- src/syscall/js/callback.go | 92 ------------------------------ src/syscall/js/func.go | 92 ++++++++++++++++++++++++++++++ src/syscall/js/js.go | 2 +- src/syscall/js/js_test.go | 20 +++---- 11 files changed, 158 insertions(+), 159 deletions(-) delete mode 100644 src/syscall/js/callback.go create mode 100644 src/syscall/js/func.go diff --git a/misc/wasm/wasm_exec.js b/misc/wasm/wasm_exec.js index 743eaf70b2..165d567750 100644 --- a/misc/wasm/wasm_exec.js +++ b/misc/wasm/wasm_exec.js @@ -87,8 +87,8 @@ this._exitPromise = new Promise((resolve) => { this._resolveExitPromise = resolve; }); - this._pendingCallback = null; - this._callbackTimeouts = new Map(); + this._pendingEvent = null; + this._scheduledTimeouts = new Map(); this._nextCallbackTimeoutID = 1; const mem = () => { @@ -204,7 +204,7 @@ this.importObject = { go: { // Go's SP does not change as long as no Go code is running. Some operations (e.g. calls, getters and setters) - // may trigger a synchronous callback to Go. This makes Go code get executed in the middle of the imported + // may synchronously trigger a Go event handler. This makes Go code get executed in the middle of the imported // function. A goroutine can switch to a new stack if the current stack is too small (see morestack function). // This changes the SP, thus we have to update the SP used by the imported function. @@ -238,22 +238,22 @@ mem().setInt32(sp + 16, (msec % 1000) * 1000000, true); }, - // func scheduleCallback(delay int64) int32 - "runtime.scheduleCallback": (sp) => { + // func scheduleTimeoutEvent(delay int64) int32 + "runtime.scheduleTimeoutEvent": (sp) => { const id = this._nextCallbackTimeoutID; this._nextCallbackTimeoutID++; - this._callbackTimeouts.set(id, setTimeout( + this._scheduledTimeouts.set(id, setTimeout( () => { this._resume(); }, getInt64(sp + 8) + 1, // setTimeout has been seen to fire up to 1 millisecond early )); mem().setInt32(sp + 16, id, true); }, - // func clearScheduledCallback(id int32) - "runtime.clearScheduledCallback": (sp) => { + // func clearTimeoutEvent(id int32) + "runtime.clearTimeoutEvent": (sp) => { const id = mem().getInt32(sp + 8, true); - clearTimeout(this._callbackTimeouts.get(id)); - this._callbackTimeouts.delete(id); + clearTimeout(this._scheduledTimeouts.get(id)); + this._scheduledTimeouts.delete(id); }, // func getRandomData(r []byte) @@ -420,7 +420,7 @@ _resume() { if (this.exited) { - throw new Error("bad callback: Go program has already exited"); + throw new Error("Go program has already exited"); } this._inst.exports.resume(); if (this.exited) { @@ -428,13 +428,13 @@ } } - _makeCallbackHelper(id) { + _makeFuncWrapper(id) { const go = this; return function () { - const cb = { id: id, this: this, args: arguments }; - go._pendingCallback = cb; + const event = { id: id, this: this, args: arguments }; + go._pendingEvent = event; go._resume(); - return cb.result; + return event.result; }; } } @@ -450,10 +450,10 @@ go.env = Object.assign({ TMPDIR: require("os").tmpdir() }, process.env); go.exit = process.exit; WebAssembly.instantiate(fs.readFileSync(process.argv[2]), go.importObject).then((result) => { - process.on("exit", (code) => { // Node.js exits if no callback is pending + process.on("exit", (code) => { // Node.js exits if no event handler is pending if (code === 0 && !go.exited) { // deadlock, make Go print error and stack traces - go._pendingCallback = { id: 0 }; + go._pendingEvent = { id: 0 }; go._resume(); } }); diff --git a/src/cmd/vet/all/whitelist/wasm.txt b/src/cmd/vet/all/whitelist/wasm.txt index a3f8c291bf..45496ed3f6 100644 --- a/src/cmd/vet/all/whitelist/wasm.txt +++ b/src/cmd/vet/all/whitelist/wasm.txt @@ -12,7 +12,7 @@ runtime/asm_wasm.s: [wasm] rt0_go: use of 8(SP) points beyond argument frame // Calling WebAssembly import. No write from Go assembly. runtime/sys_wasm.s: [wasm] nanotime: RET without writing to 8-byte ret+0(FP) -runtime/sys_wasm.s: [wasm] scheduleCallback: RET without writing to 4-byte ret+8(FP) +runtime/sys_wasm.s: [wasm] scheduleTimeoutEvent: RET without writing to 4-byte ret+8(FP) syscall/js/js_js.s: [wasm] stringVal: RET without writing to 8-byte ret+16(FP) syscall/js/js_js.s: [wasm] valueGet: RET without writing to 8-byte ret+24(FP) syscall/js/js_js.s: [wasm] valueIndex: RET without writing to 8-byte ret+16(FP) diff --git a/src/net/http/roundtrip_js.go b/src/net/http/roundtrip_js.go index 7959816445..1e38b908d3 100644 --- a/src/net/http/roundtrip_js.go +++ b/src/net/http/roundtrip_js.go @@ -93,7 +93,7 @@ func (t *Transport) RoundTrip(req *Request) (*Response, error) { respCh = make(chan *Response, 1) errCh = make(chan error, 1) ) - success := js.NewCallback(func(this js.Value, args []js.Value) interface{} { + success := js.FuncOf(func(this js.Value, args []js.Value) interface{} { result := args[0] header := Header{} // https://developer.mozilla.org/en-US/docs/Web/API/Headers/entries @@ -141,7 +141,7 @@ func (t *Transport) RoundTrip(req *Request) (*Response, error) { return nil }) defer success.Release() - failure := js.NewCallback(func(this js.Value, args []js.Value) interface{} { + failure := js.FuncOf(func(this js.Value, args []js.Value) interface{} { err := fmt.Errorf("net/http: fetch() failed: %s", args[0].String()) select { case errCh <- err: @@ -190,7 +190,7 @@ func (r *streamReader) Read(p []byte) (n int, err error) { bCh = make(chan []byte, 1) errCh = make(chan error, 1) ) - success := js.NewCallback(func(this js.Value, args []js.Value) interface{} { + success := js.FuncOf(func(this js.Value, args []js.Value) interface{} { result := args[0] if result.Get("done").Bool() { errCh <- io.EOF @@ -204,7 +204,7 @@ func (r *streamReader) Read(p []byte) (n int, err error) { return nil }) defer success.Release() - failure := js.NewCallback(func(this js.Value, args []js.Value) interface{} { + failure := js.FuncOf(func(this js.Value, args []js.Value) interface{} { // Assumes it's a TypeError. See // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypeError // for more information on this type. See @@ -258,7 +258,7 @@ func (r *arrayReader) Read(p []byte) (n int, err error) { bCh = make(chan []byte, 1) errCh = make(chan error, 1) ) - success := js.NewCallback(func(this js.Value, args []js.Value) interface{} { + success := js.FuncOf(func(this js.Value, args []js.Value) interface{} { // Wrap the input ArrayBuffer with a Uint8Array uint8arrayWrapper := js.Global().Get("Uint8Array").New(args[0]) value := make([]byte, uint8arrayWrapper.Get("byteLength").Int()) @@ -269,7 +269,7 @@ func (r *arrayReader) Read(p []byte) (n int, err error) { return nil }) defer success.Release() - failure := js.NewCallback(func(this js.Value, args []js.Value) interface{} { + failure := js.FuncOf(func(this js.Value, args []js.Value) interface{} { // Assumes it's a TypeError. See // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypeError // for more information on this type. diff --git a/src/runtime/lock_js.go b/src/runtime/lock_js.go index 98aed8796b..b04ccdb107 100644 --- a/src/runtime/lock_js.go +++ b/src/runtime/lock_js.go @@ -92,7 +92,7 @@ func notetsleepg(n *note, ns int64) bool { delay = 1<<31 - 1 // cap to max int32 } - id := scheduleCallback(delay) + id := scheduleTimeoutEvent(delay) mp := acquirem() notes[n] = gp notesWithTimeout[n] = noteWithTimeout{gp: gp, deadline: deadline} @@ -100,7 +100,7 @@ func notetsleepg(n *note, ns int64) bool { gopark(nil, nil, waitReasonSleep, traceEvNone, 1) - clearScheduledCallback(id) // note might have woken early, clear timeout + clearTimeoutEvent(id) // note might have woken early, clear timeout mp = acquirem() delete(notes, n) delete(notesWithTimeout, n) @@ -134,17 +134,17 @@ func checkTimeouts() { } } -var returnedCallback *g +var returnedEventHandler *g func init() { - // At the toplevel we need an extra goroutine that handles asynchronous callbacks. + // At the toplevel we need an extra goroutine that handles asynchronous events. initg := getg() go func() { - returnedCallback = getg() + returnedEventHandler = getg() goready(initg, 1) gopark(nil, nil, waitReasonZero, traceEvNone, 1) - returnedCallback = nil + returnedEventHandler = nil pause(getcallersp() - 16) }() @@ -152,44 +152,43 @@ func init() { } // beforeIdle gets called by the scheduler if no goroutine is awake. -// If a callback has returned, then we resume the callback handler which -// will pause the execution. +// We resume the event handler (if available) which will pause the execution. func beforeIdle() bool { - if returnedCallback != nil { - goready(returnedCallback, 1) + if returnedEventHandler != nil { + goready(returnedEventHandler, 1) return true } return false } -// pause sets SP to newsp and pauses the execution of Go's WebAssembly code until a callback is triggered. +// pause sets SP to newsp and pauses the execution of Go's WebAssembly code until an event is triggered. func pause(newsp uintptr) -// scheduleCallback tells the WebAssembly environment to trigger a callback after ms milliseconds. -// It returns a timer id that can be used with clearScheduledCallback. -func scheduleCallback(ms int64) int32 +// scheduleTimeoutEvent tells the WebAssembly environment to trigger an event after ms milliseconds. +// It returns a timer id that can be used with clearTimeoutEvent. +func scheduleTimeoutEvent(ms int64) int32 -// clearScheduledCallback clears a callback scheduled by scheduleCallback. -func clearScheduledCallback(id int32) +// clearTimeoutEvent clears a timeout event scheduled by scheduleTimeoutEvent. +func clearTimeoutEvent(id int32) -func handleCallback() { - prevReturnedCallback := returnedCallback - returnedCallback = nil +func handleEvent() { + prevReturnedEventHandler := returnedEventHandler + returnedEventHandler = nil checkTimeouts() - callbackHandler() + eventHandler() - returnedCallback = getg() + returnedEventHandler = getg() gopark(nil, nil, waitReasonZero, traceEvNone, 1) - returnedCallback = prevReturnedCallback + returnedEventHandler = prevReturnedEventHandler pause(getcallersp() - 16) } -var callbackHandler func() +var eventHandler func() -//go:linkname setCallbackHandler syscall/js.setCallbackHandler -func setCallbackHandler(fn func()) { - callbackHandler = fn +//go:linkname setEventHandler syscall/js.setEventHandler +func setEventHandler(fn func()) { + eventHandler = fn } diff --git a/src/runtime/rt0_js_wasm.s b/src/runtime/rt0_js_wasm.s index 8b92fcbdb7..50adbe2225 100644 --- a/src/runtime/rt0_js_wasm.s +++ b/src/runtime/rt0_js_wasm.s @@ -15,7 +15,7 @@ TEXT _rt0_wasm_js(SB),NOSPLIT,$0 Drop // wasm_export_run gets called from JavaScript. It initializes the Go runtime and executes Go code until it needs -// to wait for a callback. It does NOT follow the Go ABI. It has two WebAssembly parameters: +// to wait for an event. It does NOT follow the Go ABI. It has two WebAssembly parameters: // R0: argc (i32) // R1: argv (i32) TEXT wasm_export_run(SB),NOSPLIT,$0 @@ -44,9 +44,9 @@ TEXT wasm_export_run(SB),NOSPLIT,$0 Return // wasm_export_resume gets called from JavaScript. It resumes the execution of Go code until it needs to wait for -// a callback. +// an event. TEXT wasm_export_resume(SB),NOSPLIT,$0 - I32Const $runtime·handleCallback(SB) + I32Const $runtime·handleEvent(SB) I32Const $16 I32ShrU Set PC_F diff --git a/src/runtime/sys_wasm.s b/src/runtime/sys_wasm.s index 3ca844a4c7..6e28656340 100644 --- a/src/runtime/sys_wasm.s +++ b/src/runtime/sys_wasm.s @@ -187,11 +187,11 @@ TEXT ·walltime(SB), NOSPLIT, $0 CallImport RET -TEXT ·scheduleCallback(SB), NOSPLIT, $0 +TEXT ·scheduleTimeoutEvent(SB), NOSPLIT, $0 CallImport RET -TEXT ·clearScheduledCallback(SB), NOSPLIT, $0 +TEXT ·clearTimeoutEvent(SB), NOSPLIT, $0 CallImport RET diff --git a/src/syscall/fs_js.go b/src/syscall/fs_js.go index 58d8216f21..fcc5f038b8 100644 --- a/src/syscall/fs_js.go +++ b/src/syscall/fs_js.go @@ -474,7 +474,7 @@ func fsCall(name string, args ...interface{}) (js.Value, error) { } c := make(chan callResult, 1) - jsFS.Call(name, append(args, js.NewCallback(func(this js.Value, args []js.Value) interface{} { + jsFS.Call(name, append(args, js.FuncOf(func(this js.Value, args []js.Value) interface{} { var res callResult if len(args) >= 1 { // on Node.js 8, fs.utimes calls the callback without any arguments diff --git a/src/syscall/js/callback.go b/src/syscall/js/callback.go deleted file mode 100644 index 7f6540908d..0000000000 --- a/src/syscall/js/callback.go +++ /dev/null @@ -1,92 +0,0 @@ -// Copyright 2018 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// +build js,wasm - -package js - -import "sync" - -var ( - callbacksMu sync.Mutex - callbacks = make(map[uint32]func(Value, []Value) interface{}) - nextCallbackID uint32 = 1 -) - -var _ Wrapper = Callback{} // Callback must implement Wrapper - -// Callback is a Go function that got wrapped for use as a JavaScript callback. -type Callback struct { - Value // the JavaScript function that invokes the Go function - id uint32 -} - -// NewCallback returns a wrapped callback function. -// -// Invoking the callback in JavaScript will synchronously call the Go function fn with the value of JavaScript's -// "this" keyword and the arguments of the invocation. -// The return value of the invocation is the result of the Go function mapped back to JavaScript according to ValueOf. -// -// A callback triggered during a call from Go to JavaScript gets executed on the same goroutine. -// A callback triggered by JavaScript's event loop gets executed on an extra goroutine. -// Blocking operations in the callback will block the event loop. -// As a consequence, if one callback blocks, other callbacks will not be processed. -// A blocking callback should therefore explicitly start a new goroutine. -// -// Callback.Release must be called to free up resources when the callback will not be used any more. -func NewCallback(fn func(this Value, args []Value) interface{}) Callback { - callbacksMu.Lock() - id := nextCallbackID - nextCallbackID++ - callbacks[id] = fn - callbacksMu.Unlock() - return Callback{ - id: id, - Value: jsGo.Call("_makeCallbackHelper", id), - } -} - -// Release frees up resources allocated for the callback. -// The callback must not be invoked after calling Release. -func (c Callback) Release() { - callbacksMu.Lock() - delete(callbacks, c.id) - callbacksMu.Unlock() -} - -// setCallbackHandler is defined in the runtime package. -func setCallbackHandler(fn func()) - -func init() { - setCallbackHandler(handleCallback) -} - -func handleCallback() { - cb := jsGo.Get("_pendingCallback") - if cb == Null() { - return - } - jsGo.Set("_pendingCallback", Null()) - - id := uint32(cb.Get("id").Int()) - if id == 0 { // zero indicates deadlock - select {} - } - callbacksMu.Lock() - f, ok := callbacks[id] - callbacksMu.Unlock() - if !ok { - Global().Get("console").Call("error", "call to closed callback") - return - } - - this := cb.Get("this") - argsObj := cb.Get("args") - args := make([]Value, argsObj.Length()) - for i := range args { - args[i] = argsObj.Index(i) - } - result := f(this, args) - cb.Set("result", result) -} diff --git a/src/syscall/js/func.go b/src/syscall/js/func.go new file mode 100644 index 0000000000..6b7f39b878 --- /dev/null +++ b/src/syscall/js/func.go @@ -0,0 +1,92 @@ +// Copyright 2018 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// +build js,wasm + +package js + +import "sync" + +var ( + funcsMu sync.Mutex + funcs = make(map[uint32]func(Value, []Value) interface{}) + nextFuncID uint32 = 1 +) + +var _ Wrapper = Func{} // Func must implement Wrapper + +// Func is a wrapped Go function to be called by JavaScript. +type Func struct { + Value // the JavaScript function that invokes the Go function + id uint32 +} + +// FuncOf returns a wrapped function. +// +// Invoking the JavaScript function will synchronously call the Go function fn with the value of JavaScript's +// "this" keyword and the arguments of the invocation. +// The return value of the invocation is the result of the Go function mapped back to JavaScript according to ValueOf. +// +// A wrapped function triggered during a call from Go to JavaScript gets executed on the same goroutine. +// A wrapped function triggered by JavaScript's event loop gets executed on an extra goroutine. +// Blocking operations in the wrapped function will block the event loop. +// As a consequence, if one wrapped function blocks, other wrapped funcs will not be processed. +// A blocking function should therefore explicitly start a new goroutine. +// +// Func.Release must be called to free up resources when the function will not be used any more. +func FuncOf(fn func(this Value, args []Value) interface{}) Func { + funcsMu.Lock() + id := nextFuncID + nextFuncID++ + funcs[id] = fn + funcsMu.Unlock() + return Func{ + id: id, + Value: jsGo.Call("_makeFuncWrapper", id), + } +} + +// Release frees up resources allocated for the function. +// The function must not be invoked after calling Release. +func (c Func) Release() { + funcsMu.Lock() + delete(funcs, c.id) + funcsMu.Unlock() +} + +// setEventHandler is defined in the runtime package. +func setEventHandler(fn func()) + +func init() { + setEventHandler(handleEvent) +} + +func handleEvent() { + cb := jsGo.Get("_pendingEvent") + if cb == Null() { + return + } + jsGo.Set("_pendingEvent", Null()) + + id := uint32(cb.Get("id").Int()) + if id == 0 { // zero indicates deadlock + select {} + } + funcsMu.Lock() + f, ok := funcs[id] + funcsMu.Unlock() + if !ok { + Global().Get("console").Call("error", "call to released function") + return + } + + this := cb.Get("this") + argsObj := cb.Get("args") + args := make([]Value, argsObj.Length()) + for i := range args { + args[i] = argsObj.Index(i) + } + result := f(this, args) + cb.Set("result", result) +} diff --git a/src/syscall/js/js.go b/src/syscall/js/js.go index 885723f87d..0893db022d 100644 --- a/src/syscall/js/js.go +++ b/src/syscall/js/js.go @@ -107,7 +107,7 @@ func Global() Value { // | ---------------------- | ---------------------- | // | js.Value | [its value] | // | js.TypedArray | typed array | -// | js.Callback | function | +// | js.Func | function | // | nil | null | // | bool | boolean | // | integers and floats | number | diff --git a/src/syscall/js/js_test.go b/src/syscall/js/js_test.go index b4d2e66faf..c14d2cc24c 100644 --- a/src/syscall/js/js_test.go +++ b/src/syscall/js/js_test.go @@ -300,9 +300,9 @@ func TestZeroValue(t *testing.T) { } } -func TestCallback(t *testing.T) { +func TestFuncOf(t *testing.T) { c := make(chan struct{}) - cb := js.NewCallback(func(this js.Value, args []js.Value) interface{} { + cb := js.FuncOf(func(this js.Value, args []js.Value) interface{} { if got := args[0].Int(); got != 42 { t.Errorf("got %#v, want %#v", got, 42) } @@ -314,10 +314,10 @@ func TestCallback(t *testing.T) { <-c } -func TestInvokeCallback(t *testing.T) { +func TestInvokeFunction(t *testing.T) { called := false - cb := js.NewCallback(func(this js.Value, args []js.Value) interface{} { - cb2 := js.NewCallback(func(this js.Value, args []js.Value) interface{} { + cb := js.FuncOf(func(this js.Value, args []js.Value) interface{} { + cb2 := js.FuncOf(func(this js.Value, args []js.Value) interface{} { called = true return 42 }) @@ -329,15 +329,15 @@ func TestInvokeCallback(t *testing.T) { t.Errorf("got %#v, want %#v", got, 42) } if !called { - t.Error("callback not called") + t.Error("function not called") } } -func ExampleNewCallback() { - var cb js.Callback - cb = js.NewCallback(func(this js.Value, args []js.Value) interface{} { +func ExampleFuncOf() { + var cb js.Func + cb = js.FuncOf(func(this js.Value, args []js.Value) interface{} { fmt.Println("button clicked") - cb.Release() // release the callback if the button will not be clicked again + cb.Release() // release the function if the button will not be clicked again return nil }) js.Global().Get("document").Call("getElementById", "myButton").Call("addEventListener", "click", cb)