cmd/geth, jsre, rpc: run all JS code on the event loop

Some JSRE methods (PrettyPrint, ToVal) bypassed the event loop. All
calls to the JS VM are now wrapped. In order to make this somewhat more
foolproof, the otto VM is now a local variable inside the event loop.

1 files changed, 86 insertions, 149 deletions

diff --git a/jsre/jsre.go b/jsre/jsre.go
index a6dd117a3..3d648f02c 100644
--- a/jsre/jsre.go
+++ b/jsre/jsre.go
@@ -19,9 +19,7 @@ It provides some helper functions to
 - bind native go objects
 */
 type JSRE struct {
-	assetPath string
-	vm        *otto.Otto
-
+	assetPath     string
 	evalQueue     chan *evalReq
 	stopEventLoop chan bool
 	loopWg        sync.WaitGroup
@@ -35,68 +33,37 @@ type jsTimer struct {
 	call     otto.FunctionCall
 }
 
-// evalResult is a structure to store the result of any serialized vm execution
-type evalResult struct {
-	result otto.Value
-	err    error
-}
-
-// evalReq is a serialized vm execution request put in evalQueue and processed by runEventLoop
+// evalReq is a serialized vm execution request processed by runEventLoop.
 type evalReq struct {
-	fn   func(res *evalResult)
+	fn   func(vm *otto.Otto)
 	done chan bool
-	res  evalResult
 }
 
 // runtime must be stopped with Stop() after use and cannot be used after stopping
 func New(assetPath string) *JSRE {
 	re := &JSRE{
-		assetPath: assetPath,
-		vm:        otto.New(),
+		assetPath:     assetPath,
+		evalQueue:     make(chan *evalReq),
+		stopEventLoop: make(chan bool),
 	}
-
-	// load prettyprint func definition
-	re.vm.Run(pp_js)
-	re.vm.Set("loadScript", re.loadScript)
-
-	re.evalQueue = make(chan *evalReq)
-	re.stopEventLoop = make(chan bool)
 	re.loopWg.Add(1)
 	go re.runEventLoop()
-
+	re.Compile("pp.js", pp_js) // load prettyprint func definition
+	re.Set("loadScript", re.loadScript)
 	return re
 }
 
-// this function runs a piece of JS code either in a serialized way (when useEQ is true) or instantly, circumventing the evalQueue
-func (self *JSRE) run(src interface{}, useEQ bool) (value otto.Value, err error) {
-	if useEQ {
-		done := make(chan bool)
-		req := &evalReq{
-			fn: func(res *evalResult) {
-				res.result, res.err = self.vm.Run(src)
-			},
-			done: done,
-		}
-		self.evalQueue <- req
-		<-done
-		return req.res.result, req.res.err
-	} else {
-		return self.vm.Run(src)
-	}
-}
+// This function runs the main event loop from a goroutine that is started
+// when JSRE is created. Use Stop() before exiting to properly stop it.
+// The event loop processes vm access requests from the evalQueue in a
+// serialized way and calls timer callback functions at the appropriate time.
 
-/*
-This function runs the main event loop from a goroutine that is started
- when JSRE is created. Use Stop() before exiting to properly stop it.
-The event loop processes vm access requests from the evalQueue in a
- serialized way and calls timer callback functions at the appropriate time.
-
-Exported functions always access the vm through the event queue. You can
- call the functions of the otto vm directly to circumvent the queue. These
- functions should be used if and only if running a routine that was already
- called from JS through an RPC call.
-*/
+// Exported functions always access the vm through the event queue. You can
+// call the functions of the otto vm directly to circumvent the queue. These
+// functions should be used if and only if running a routine that was already
+// called from JS through an RPC call.
 func (self *JSRE) runEventLoop() {
+	vm := otto.New()
 	registry := map[*jsTimer]*jsTimer{}
 	ready := make(chan *jsTimer)
 
@@ -143,10 +110,10 @@ func (self *JSRE) runEventLoop() {
 		}
 		return otto.UndefinedValue()
 	}
-	self.vm.Set("setTimeout", setTimeout)
-	self.vm.Set("setInterval", setInterval)
-	self.vm.Set("clearTimeout", clearTimeout)
-	self.vm.Set("clearInterval", clearTimeout)
+	vm.Set("setTimeout", setTimeout)
+	vm.Set("setInterval", setInterval)
+	vm.Set("clearTimeout", clearTimeout)
+	vm.Set("clearInterval", clearTimeout)
 
 	var waitForCallbacks bool
 
@@ -166,8 +133,7 @@ loop:
 				arguments = make([]interface{}, 1)
 			}
 			arguments[0] = timer.call.ArgumentList[0]
-			_, err := self.vm.Call(`Function.call.call`, nil, arguments...)
-
+			_, err := vm.Call(`Function.call.call`, nil, arguments...)
 			if err != nil {
 				fmt.Println("js error:", err, arguments)
 			}
@@ -179,10 +145,10 @@ loop:
 					break loop
 				}
 			}
-		case evalReq := <-self.evalQueue:
+		case req := <-self.evalQueue:
 			// run the code, send the result back
-			evalReq.fn(&evalReq.res)
-			close(evalReq.done)
+			req.fn(vm)
+			close(req.done)
 			if waitForCallbacks && (len(registry) == 0) {
 				break loop
 			}
@@ -201,6 +167,14 @@ loop:
 	self.loopWg.Done()
 }
 
+// do schedules the given function on the event loop.
+func (self *JSRE) do(fn func(*otto.Otto)) {
+	done := make(chan bool)
+	req := &evalReq{fn, done}
+	self.evalQueue <- req
+	<-done
+}
+
 // stops the event loop before exit, optionally waits for all timers to expire
 func (self *JSRE) Stop(waitForCallbacks bool) {
 	self.stopEventLoop <- waitForCallbacks
@@ -210,119 +184,78 @@ func (self *JSRE) Stop(waitForCallbacks bool) {
 // Exec(file) loads and runs the contents of a file
 // if a relative path is given, the jsre's assetPath is used
 func (self *JSRE) Exec(file string) error {
-	return self.exec(common.AbsolutePath(self.assetPath, file), true)
-}
-
-// circumvents the eval queue, see runEventLoop
-func (self *JSRE) execWithoutEQ(file string) error {
-	return self.exec(common.AbsolutePath(self.assetPath, file), false)
-}
-
-func (self *JSRE) exec(path string, useEQ bool) error {
-	code, err := ioutil.ReadFile(path)
+	code, err := ioutil.ReadFile(common.AbsolutePath(self.assetPath, file))
 	if err != nil {
 		return err
 	}
-	_, err = self.run(code, useEQ)
+	self.do(func(vm *otto.Otto) { _, err = vm.Run(code) })
 	return err
 }
 
-// assigns value v to a variable in the JS environment
-func (self *JSRE) Bind(name string, v interface{}) (err error) {
-	self.Set(name, v)
-	return
+// Bind assigns value v to a variable in the JS environment
+// This method is deprecated, use Set.
+func (self *JSRE) Bind(name string, v interface{}) error {
+	return self.Set(name, v)
 }
 
-// runs a piece of JS code
-func (self *JSRE) Run(code string) (otto.Value, error) {
-	return self.run(code, true)
+// Run runs a piece of JS code.
+func (self *JSRE) Run(code string) (v otto.Value, err error) {
+	self.do(func(vm *otto.Otto) { v, err = vm.Run(code) })
+	return v, err
 }
 
-// returns the value of a variable in the JS environment
-func (self *JSRE) Get(ns string) (otto.Value, error) {
-	done := make(chan bool)
-	req := &evalReq{
-		fn: func(res *evalResult) {
-			res.result, res.err = self.vm.Get(ns)
-		},
-		done: done,
-	}
-	self.evalQueue <- req
-	<-done
-	return req.res.result, req.res.err
+// Get returns the value of a variable in the JS environment.
+func (self *JSRE) Get(ns string) (v otto.Value, err error) {
+	self.do(func(vm *otto.Otto) { v, err = vm.Get(ns) })
+	return v, err
 }
 
-// assigns value v to a variable in the JS environment
-func (self *JSRE) Set(ns string, v interface{}) error {
-	done := make(chan bool)
-	req := &evalReq{
-		fn: func(res *evalResult) {
-			res.err = self.vm.Set(ns, v)
-		},
-		done: done,
-	}
-	self.evalQueue <- req
-	<-done
-	return req.res.err
+// Set assigns value v to a variable in the JS environment.
+func (self *JSRE) Set(ns string, v interface{}) (err error) {
+	self.do(func(vm *otto.Otto) { err = vm.Set(ns, v) })
+	return err
 }
 
-/*
-Executes a JS script from inside the currently executing JS code.
-Should only be called from inside an RPC routine.
-*/
+// loadScript executes a JS script from inside the currently executing JS code.
 func (self *JSRE) loadScript(call otto.FunctionCall) otto.Value {
 	file, err := call.Argument(0).ToString()
 	if err != nil {
+		// TODO: throw exception
+		return otto.FalseValue()
+	}
+	file = common.AbsolutePath(self.assetPath, file)
+	source, err := ioutil.ReadFile(file)
+	if err != nil {
+		// TODO: throw exception
 		return otto.FalseValue()
 	}
-	if err := self.execWithoutEQ(file); err != nil { // loadScript is only called from inside js
+	if _, err := compileAndRun(call.Otto, file, source); err != nil {
+		// TODO: throw exception
 		fmt.Println("err:", err)
 		return otto.FalseValue()
 	}
-
+	// TODO: return evaluation result
 	return otto.TrueValue()
 }
 
-// uses the "prettyPrint" JS function to format a value
+// PrettyPrint writes v to standard output.
 func (self *JSRE) PrettyPrint(v interface{}) (val otto.Value, err error) {
 	var method otto.Value
-	v, err = self.ToValue(v)
-	if err != nil {
-		return
-	}
-	method, err = self.vm.Get("prettyPrint")
-	if err != nil {
-		return
-	}
-	return method.Call(method, v)
-}
-
-// creates an otto value from a go type (serialized version)
-func (self *JSRE) ToValue(v interface{}) (otto.Value, error) {
-	done := make(chan bool)
-	req := &evalReq{
-		fn: func(res *evalResult) {
-			res.result, res.err = self.vm.ToValue(v)
-		},
-		done: done,
-	}
-	self.evalQueue <- req
-	<-done
-	return req.res.result, req.res.err
-}
-
-// creates an otto value from a go type (non-serialized version)
-func (self *JSRE) ToVal(v interface{}) otto.Value {
-
-	result, err := self.vm.ToValue(v)
-	if err != nil {
-		fmt.Println("Value unknown:", err)
-		return otto.UndefinedValue()
-	}
-	return result
+	self.do(func(vm *otto.Otto) {
+		val, err = vm.ToValue(v)
+		if err != nil {
+			return
+		}
+		method, err = vm.Get("prettyPrint")
+		if err != nil {
+			return
+		}
+		val, err = method.Call(method, val)
+	})
+	return val, err
 }
 
-// evaluates JS function and returns result in a pretty printed string format
+// Eval evaluates JS function and returns result in a pretty printed string format.
 func (self *JSRE) Eval(code string) (s string, err error) {
 	var val otto.Value
 	val, err = self.Run(code)
@@ -336,12 +269,16 @@ func (self *JSRE) Eval(code string) (s string, err error) {
 	return fmt.Sprintf("%v", val), nil
 }
 
-// compiles and then runs a piece of JS code
-func (self *JSRE) Compile(fn string, src interface{}) error {
-	script, err := self.vm.Compile(fn, src)
+// Compile compiles and then runs a piece of JS code.
+func (self *JSRE) Compile(filename string, src interface{}) (err error) {
+	self.do(func(vm *otto.Otto) { _, err = compileAndRun(vm, filename, src) })
+	return err
+}
+
+func compileAndRun(vm *otto.Otto, filename string, src interface{}) (otto.Value, error) {
+	script, err := vm.Compile(filename, src)
 	if err != nil {
-		return err
+		return otto.Value{}, err
 	}
-	self.run(script, true)
-	return nil
+	return vm.Run(script)
 }