setTimeout and sendAsync implemented

added and eval queue for serializing JSRE vm execution

1 files changed, 220 insertions, 13 deletions

diff --git a/jsre/jsre.go b/jsre/jsre.go
index a49422a12..7549b5e1e 100644
--- a/jsre/jsre.go
+++ b/jsre/jsre.go
@@ -3,10 +3,11 @@ package jsre
 import (
 	"fmt"
 	"io/ioutil"
-
-	"github.com/robertkrimen/otto"
+	"sync"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/robertkrimen/otto"
 )
 
 /*
@@ -20,59 +21,261 @@ It provides some helper functions to
 type JSRE struct {
 	assetPath string
 	vm        *otto.Otto
+
+	evalQueue     chan *evalReq
+	stopEventLoop chan bool
+	loopWg        sync.WaitGroup
+}
+
+// jsTimer is a single timer instance with a callback function
+type jsTimer struct {
+	timer    *time.Timer
+	duration time.Duration
+	interval bool
+	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
+type evalReq struct {
+	fn   func(res *evalResult)
+	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,
-		otto.New(),
+		assetPath: assetPath,
+		vm:        otto.New(),
 	}
 
 	// 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()
+
 	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.
+
+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() {
+	registry := map[*jsTimer]*jsTimer{}
+	ready := make(chan *jsTimer)
+
+	newTimer := func(call otto.FunctionCall, interval bool) (*jsTimer, otto.Value) {
+
+		delay, _ := call.Argument(1).ToInteger()
+		if 0 >= delay {
+			delay = 1
+		}
+		timer := &jsTimer{
+			duration: time.Duration(delay) * time.Millisecond,
+			call:     call,
+			interval: interval,
+		}
+		registry[timer] = timer
+
+		timer.timer = time.AfterFunc(timer.duration, func() {
+			ready <- timer
+		})
+
+		value, err := call.Otto.ToValue(timer)
+		if err != nil {
+			panic(err)
+		}
+
+		return timer, value
+	}
+
+	setTimeout := func(call otto.FunctionCall) otto.Value {
+		_, value := newTimer(call, false)
+		return value
+	}
+
+	setInterval := func(call otto.FunctionCall) otto.Value {
+		_, value := newTimer(call, true)
+		return value
+	}
+
+	clearTimeout := func(call otto.FunctionCall) otto.Value {
+		timer, _ := call.Argument(0).Export()
+		if timer, ok := timer.(*jsTimer); ok {
+			timer.timer.Stop()
+			delete(registry, timer)
+		}
+		return otto.UndefinedValue()
+	}
+
+	var waitForCallbacks bool
+
+loop:
+	for {
+		select {
+		case timer := <-ready:
+			// execute callback, remove/reschedule the timer
+			var arguments []interface{}
+			if len(timer.call.ArgumentList) > 2 {
+				tmp := timer.call.ArgumentList[2:]
+				arguments = make([]interface{}, 2+len(tmp))
+				for i, value := range tmp {
+					arguments[i+2] = value
+				}
+			} else {
+				arguments = make([]interface{}, 1)
+			}
+			arguments[0] = timer.call.ArgumentList[0]
+			_, err := self.vm.Call(`Function.call.call`, nil, arguments...)
+
+			if err != nil {
+				break loop
+			}
+			if timer.interval {
+				timer.timer.Reset(timer.duration)
+			} else {
+				delete(registry, timer)
+				if waitForCallbacks && (len(registry) == 0) {
+					break loop
+				}
+			}
+		case evalReq := <-self.evalQueue:
+			// run the code, send the result back
+			self.vm.Set("setTimeout", setTimeout)
+			self.vm.Set("setInterval", setInterval)
+			self.vm.Set("clearTimeout", clearTimeout)
+			self.vm.Set("clearInterval", clearTimeout)
+			evalReq.fn(&evalReq.res)
+			close(evalReq.done)
+			if waitForCallbacks && (len(registry) == 0) {
+				break loop
+			}
+		case waitForCallbacks = <-self.stopEventLoop:
+			if !waitForCallbacks || (len(registry) == 0) {
+				break loop
+			}
+		}
+	}
+
+	for _, timer := range registry {
+		timer.timer.Stop()
+		delete(registry, timer)
+	}
+
+	self.loopWg.Done()
+}
+
+// stops the event loop before exit, optionally waits for all timers to expire
+func (self *JSRE) Stop(waitForCallbacks bool) {
+	self.stopEventLoop <- waitForCallbacks
+	self.loopWg.Wait()
+}
+
 // 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))
+	return self.exec(common.AbsolutePath(self.assetPath, file), true)
 }
 
-func (self *JSRE) exec(path string) error {
+// 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)
 	if err != nil {
 		return err
 	}
-	_, err = self.vm.Run(code)
+	_, err = self.run(code, useEQ)
 	return err
 }
 
+// assigns value v to a variable in the JS environment
 func (self *JSRE) Bind(name string, v interface{}) (err error) {
-	self.vm.Set(name, v)
+	self.Set(name, v)
 	return
 }
 
+// runs a piece of JS code
 func (self *JSRE) Run(code string) (otto.Value, error) {
-	return self.vm.Run(code)
+	return self.run(code, true)
 }
 
+// returns the value of a variable in the JS environment
 func (self *JSRE) Get(ns string) (otto.Value, error) {
-	return self.vm.Get(ns)
+	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
 }
 
+// assigns value v to a variable in the JS environment
 func (self *JSRE) Set(ns string, v interface{}) error {
-	return self.vm.Set(ns, v)
+	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
 }
 
+/*
+Executes a JS script from inside the currently executing JS code.
+Should only be called from inside an RPC routine.
+*/
 func (self *JSRE) loadScript(call otto.FunctionCall) otto.Value {
 	file, err := call.Argument(0).ToString()
 	if err != nil {
 		return otto.FalseValue()
 	}
-	if err := self.Exec(file); err != nil {
+	if err := self.execWithoutEQ(file); err != nil { // loadScript is only called from inside js
 		fmt.Println("err:", err)
 		return otto.FalseValue()
 	}
@@ -80,6 +283,7 @@ func (self *JSRE) loadScript(call otto.FunctionCall) otto.Value {
 	return otto.TrueValue()
 }
 
+// uses the "prettyPrint" JS function to format a value
 func (self *JSRE) PrettyPrint(v interface{}) (val otto.Value, err error) {
 	var method otto.Value
 	v, err = self.vm.ToValue(v)
@@ -93,6 +297,7 @@ func (self *JSRE) PrettyPrint(v interface{}) (val otto.Value, err error) {
 	return method.Call(method, v)
 }
 
+// creates an otto value from a go type
 func (self *JSRE) ToVal(v interface{}) otto.Value {
 	result, err := self.vm.ToValue(v)
 	if err != nil {
@@ -102,6 +307,7 @@ func (self *JSRE) ToVal(v interface{}) otto.Value {
 	return result
 }
 
+// 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)
@@ -115,11 +321,12 @@ 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)
 	if err != nil {
 		return err
 	}
-	self.vm.Run(script)
+	self.run(script, true)
 	return nil
 }