Is there a way to get the current source location (SourceSection) from java?
e.g. a js script executed via context.eval() calls a java method, the java method logs the current js script name+line
PolyglotException has a getSourceLocation() that provide this information. also stack traces from polyglot seems to contains information about the source location e.g. at :program(Unnamed:2:23-53)
I know you asked this a long time ago, but I have just seen it for the first time.
Here is a way to get to the current location easily:
static StackFrame getCurrentLocation() {
PolyglotException e = Context.getCurrent().asValue(new RuntimeException()).as(PolyglotException.class);
for (StackFrame frame: e.getPolyglotStackTrace()) {
if (frame.isGuestFrame()) {
return frame;
}
}
return null;
}
Here is a full runnable example:
public class Test {
public static void main(String[] args) {
try (Context context = Context.newBuilder().allowHostAccess(HostAccess.ALL).build()) {
context.getBindings("js").putMember("test", new Test());
Source source = Source.newBuilder("js", "test.callback()", "mysource.js").buildLiteral();
context.eval(source);
}
}
public void callback() {
System.out.println(getCurrentLocation());
}
static StackFrame getCurrentLocation() {
PolyglotException e = Context.getCurrent().asValue(new RuntimeException()).as(PolyglotException.class);
for (StackFrame frame: e.getPolyglotStackTrace()) {
if (frame.isGuestFrame()) {
return frame;
}
}
return null;
}
}
This prints:
<js> :program(mysource.js:1:0-14)
Hacky solution: You could pass the new Error().stack as an argument to your java function to get a stack trace. Given
public class A {
public A() {}
public void foo(String x) {
System.out.println("MY ARGUMENT IS: " + x);
}
}
you can
$GRAALVM_HOME/bin/js --jvm --vm.cp=.
> function bar() { var x = new (Java.type("A"))(); x.foo(new Error().stack) }
> bar()
MY ARGUMENT IS: Error
at bar (<shell>:6:1:56)
at <shell>:7:1:1
I've found a solution, but I'm still not sure if it is good or bad one. but at the moment it's the only one that seems to work.
Basically, I need to add a bunch of --add-opens to java args:
--add-opens org.graalvm.truffle/com.oracle.truffle.api=ALL-UNNAMED
--add-opens org.graalvm.truffle/com.oracle.truffle.api.frame=ALL-UNNAMED
--add-opens org.graalvm.truffle/com.oracle.truffle.api.nodes=ALL-UNNAMED
--add-opens org.graalvm.truffle/com.oracle.truffle.api.source=ALL-UNNAMED
And then using the Truffle runtime I'm able to get the caller frame and SourceSelection
Truffle.getRuntime().getCallerFrame().getCallNode().getEncapsulatingSourceSection()
Related
To prevent the XY problem, I'll start from the beginning:
I have a non-blocking SOAP client which I wrapped it to make the return type Mono<T> (By default it accepts callback. I can elaborate on this if needed).
Now I want to do (given ID):
1. Get the code by ID
2. Do something with the code
3. After that, get Foo and Bar and create FooBar
What I wrote was:
public class MyService {
private final MySoapClient soapClient;
public Mono<FooBarDto> doSomething(String id) {
return Mono.just(id)
.flatMap(soapClient::getCode) // returns Mono<String>
.flatMap(code ->
soapClient.doSomething(code) // returns Mono<Void>
.then(getFooBar(id, code))); // See this
}
private Mono<FooBarDto> getFooBar(String id, String code) {
return Mono.zip(
soapClient.getFoo(code), // returns Mono<Foo>
soapClient.getBar(code) // returns Mono<Bar>
).map(tuple2 -> toFooBarDto(id, tuple2));
}
private FooBarDto toFooBarDto(String id, Tuple2<Foo, Bar> tuple2) {
return FooBarDto.builder()/* set properties */.build();
}
}
Now the problem is, because methods of the SOAP client are not lazy (the moment you call them they start the process), the semantic of then won't work here. Meaning I want to get Foo and Bar when doSomething is done. They all start together.
I tried to change it fix it by changing then to flatMap, but made it even worse. The getFooBar never got called. (1. Can someone please explain why?).
So what I ended up doing was to wrap SOAP calls again to make them lazy:
public class MySoapClient {
private final AutoGeneratedSoapClient client;
Mono<Foo> getFoo(GetFooRequest request) {
return Mono.just(request).flatMap(this::doGetMsisdnByIccid);
}
private Mono<Foo> doGetFoo(GetFooRequest request) {
val handler = new AsyncHandler<GetFooRequest>();
client.getFoo(request, handler);
return Mono.fromFuture(handler.future);
}
private static class AsyncHandler<T> implements javax.xml.ws.AsyncHandler<T> {
private final CompletableFuture<T> future = new CompletableFuture<>();
#Override
public void handleResponse(Response<T> res) {
try {
future.complete(res.get());
} catch (Exception e) {
future.completeExceptionally(e);
}
}
}
}
Is there any better way to do it? Specifically:
2. Using CompeletableFuture and the callback.
3. Making methods lazy in the SOAP client.
I tried to change it fix it by changing then to flatMap, but made it
even worse. The getFooBar never got called. (1. Can someone please
explain why?)
I think a Mono<Void> always completes empty (or error), so subsequent flatMap is never called.
Using CompeletableFuture and the callback.
Making methods lazy in the SOAP client.
To make the call lazy you can do one of the followings:
1, You can use Mono.fromFuture which accepts a supplier:
private Mono<Foo> doGetFoo(GetFooRequest request) {
return Mono.fromFuture(() -> {
val handler = new AsyncHandler<GetFooRequest>();
client.getFoo(request, handler);
return handler.future;
});
}
2, You can use Mono.defer:
private Mono<Foo> doGetFoo(GetFooRequest request) {
return Mono.defer(() -> {
val handler = new AsyncHandler<GetFooRequest>();
client.getFoo(request, handler);
return Mono.fromFuture(handler.future);
});
}
3, You can get rid of CompletableFuture and use Mono.create instead, something like this:
private Mono<Foo> doGetFoo(GetFooRequest request) {
return Mono.create(sink -> {
AsyncHandler<Foo> handler = response ->
{
try
{
sink.success(response.get());
} catch (Exception e)
{
sink.error(e);
}
};
client.getFoo(request, handler);
});
}
If you do any of these it will be safe to use then method and it will work as expected.
I am trying to get callable classes to work in dart, but I have ran into a few issues. First thing I realized is that a normal function
myFunc() {
return 'myFunc';
}
Function.apply(myFunc,null);
is not working as a callable.
Then I realized that if I do
final myFunc = () => 'myFunc';
Function.apply(myFunc,null);
this works.
So now I am trying it out with classes
class Cars {
call(Map<Symbol,dynamic> args) {
return "ride";
}
const Cars();
}
final cars = Cars();
final jobs = {cars.hashCode :cars};
void main() {
int code = cars.hashCode;
print(Function.apply(jobs[code],null));
}
but in DartPad I get the following error
Uncaught exception:
NoSuchMethodError: method not found: 'call'
Receiver: Closure 'call$1' of Instance of 'Cars'
Arguments: []
are there some restrictions on the call method? Or how it works with Function.apply() that I am not finding in the docs?
Thanks.
Your first example works fine for me, but your program needs an entry point:
myFunc() {
return 'myFunc';
}
void main() {
print(Function.apply(myFunc, null));
}
In your class example, your call method requires a Map, but you're passing null. There is no call method with zero arguments, hence the method not found: 'call' error.
One way to fix it is by adding an empty Map to the parameter list in Function.apply:
class Cars {
call(Map<Symbol,dynamic> args) {
return "ride";
}
const Cars();
}
final cars = Cars();
final jobs = {cars.hashCode :cars};
void main() {
int code = cars.hashCode;
print(Function.apply(jobs[code], [Map<Symbol,dynamic>()]));
}
It's worth noting that you can call any method on a class with any number of arguments:
class Car {
go(int speed, int wheels) {
print('$speed mph, $wheels wheels');
}
}
void main() {
var car = Car();
Function.apply(car.go, [50, 4]);
}
I am developing in a Grails application. What I want to do is to lock the request/response, create a promise, and let someone else resolve it, that is somewhere else in the code, and then flush the response.
What I find really strange is that the Promise promise = task {} interface has no method that resembles resolve or similar.
I need to lock the response until someone resolves the promise, which is a global/static property set in development mode.
Promise interface:
http://grails.org/doc/latest/api/grails/async/Promise.html
I have looked at the GPars doc and can't find anything there that resembles a resolve method.
How can I create a promise, that locks the response or request, and then flushes the response when someone resolves it?
You can call get() on the promise which will block until whatever the task is doing completes, but I imagine what that is not what you want. What you want seems to be equivalent to a GPars DataflowVariable:
http://gpars.org/1.0.0/javadoc/groovyx/gpars/dataflow/DataflowVariable.html
Which allows using the left shift operator to resolve the value from another thread. Currently there is no way to use the left shift operator via Grails directly, but since Grails' promise API is just a layer over GPars this can probably be accomplished by using the GPars API directly with something like:
import org.grails.async.factory.gpars.*
import groovyx.gpars.dataflow.*
import static grails.async.Promise.*
def myAction() {
def dataflowVar = new DataflowVariable()
task {
// do some calculation and resolve data flow variable
def expensiveData = ...
dataflowVar << expensiveData
}
return new GParsPromise(dataflowVar)
}
It took me quite some time to get around this and have a working answer.
I must say that it appears as if Grails is quite a long way of making this work properly.
task { }
will always execute immediatly, so the call is not put on hold until dispatch() or whatever is invoked which is a problem.
Try this to see:
public def test() {
def dataflowVar = new groovyx.gpars.dataflow.DataflowVariable()
task {
// do some calculation and resolve data flow variable
println '1111111111111111111111111111111111111111111111111111'
//dataflowVar << expensiveData
}
return new org.grails.async.factory.gpars.GparsPromise(dataflowVar);
}
If you are wondering what this is for, it is to make the lesscss refresh automatically in grails, which is a problem when you are using import statements in less. When the file is touched, the lesscss compiler will trigger a recompilation, and only when it is done should it respond to the client.
On the client side I have some javascript that keeps replacing the last using the refresh action here:
In my controller:
/**
* Refreshes link resources. refresh?uri=/resource/in/web-app/such/as/empty.less
*/
public def refresh() {
return LessRefresh.stackRequest(request, params.uri);
}
A class written for this:
import grails.util.Environment
import grails.util.Holders
import javax.servlet.AsyncContext
import javax.servlet.AsyncEvent
import javax.servlet.AsyncListener
import javax.servlet.http.HttpServletRequest
/**
* #Author SecretService
*/
class LessRefresh {
static final Map<String, LessRefresh> FILES = new LinkedHashMap<String, LessRefresh>();
String file;
Boolean touched
List<AsyncContext> asyncContexts = new ArrayList<AsyncContext>();
String text;
public LessRefresh(String file) {
this.file = file;
}
/** Each request will be put on hold in a stack until dispatchAll below is called when the recompilation of the less file finished **/
public static AsyncContext stackRequest(HttpServletRequest request, String file) {
if ( !LessRefresh.FILES[file] ) {
LessRefresh.FILES[file] = new LessRefresh(file);
}
return LessRefresh.FILES[file].handleRequest(request);
}
public AsyncContext handleRequest(HttpServletRequest request) {
if ( Environment.current == Environment.DEVELOPMENT ) {
// We only touch it once since we are still waiting for the less compiler to finish from previous edits and recompilation
if ( !touched ) {
touched = true
touchFile(file);
}
AsyncContext asyncContext = request.startAsync();
asyncContext.setTimeout(10000)
asyncContexts.add (asyncContext);
asyncContext.addListener(new AsyncListener() {
#Override
void onComplete(AsyncEvent event) throws IOException {
event.getSuppliedResponse().writer << text;
}
#Override
void onTimeout(AsyncEvent event) throws IOException {
}
#Override
void onError(AsyncEvent event) throws IOException {
}
#Override
void onStartAsync(AsyncEvent event) throws IOException {
}
});
return asyncContext;
}
return null;
}
/** When recompilation is done, dispatchAll is called from LesscssResourceMapper.groovy **/
public void dispatchAll(String text) {
this.text = text;
if ( asyncContexts ) {
// Process all
while ( asyncContexts.size() ) {
AsyncContext asyncContext = asyncContexts.remove(0);
asyncContext.dispatch();
}
}
touched = false;
}
/** A touch of the lessfile will trigger a recompilation **/
int count = 0;
void touchFile(String uri) {
if ( Environment.current == Environment.DEVELOPMENT ) {
File file = getWebappFile(uri);
if (file && file.exists() ) {
++count;
if ( count < 5000 ) {
file << ' ';
}
else {
count = 0
file.write( file.getText().trim() )
}
}
}
}
static File getWebappFile(String uri) {
new File( Holders.getServletContext().getRealPath( uri ) )
}
}
In LesscssResourceMapper.groovy of the lesscsss-recources plugin:
...
try {
lessCompiler.compile input, target
// Update mapping entry
// We need to reference the new css file from now on
resource.processedFile = target
// Not sure if i really need these
resource.sourceUrlExtension = 'css'
resource.contentType = 'text/css'
resource.tagAttributes?.rel = 'stylesheet'
resource.updateActualUrlFromProcessedFile()
// ==========================================
// Call made here!
// ==========================================
LessRefresh.FILES[resource.sourceUrl.toString()]?.dispatchAll( target.getText() );
} catch (LessException e) {
log.error("error compiling less file: ${originalFile}", e)
}
...
In the index.gsp file:
<g:set var="uri" value="${"${App.files.root}App/styles/empty.less"}"/>
<link media="screen, projection" rel="stylesheet" type="text/css" href="${r.resource(uri:uri)}" refresh="${g.createLink(controller:'home', action:'refresh', params:[uri:uri])}" resource="true">
JavaScript method refreshResources to replace the previous link href=...
/**
* Should only be used in development mode
*/
function refreshResources(o) {
o || (o = {});
var timeoutBegin = o.timeoutBegin || 1000;
var intervalRefresh = o.intervalRefresh || 1000;
var timeoutBlinkAvoid = o.timeoutBlinkAvoid || 400 ;
var maxErrors = o.maxErrors || 200 ;
var xpath = 'link[resource][type="text/css"]';
// Find all link[resource]
$(xpath).each(function(i, element) {
refresh( $(element) );
});
function refresh(element) {
var parent = element.parent();
var next = element.next();
var outer = element.clone().attr('href', '').wrap('<p>').parent().html();
var uri = element.attr('refresh');
var errorCount = 0;
function replaceLink() {
var link = $(outer);
link.load(function () {
// The link has been successfully added! Now remove the other ones, then do again
errorCount = 0;
// setTimeout needed to avoid blinking, we allow duplicates for a few milliseconds
setTimeout(function() {
var links = parent.find(xpath + '[refresh="'+uri+'"]');
var i = 0;
// Remove all but this one
while ( i < links.length - 1 ) {
links[i++].remove();
}
replaceLinkTimeout();
}, timeoutBlinkAvoid );
});
link.error(function(event, handler) {
console.log('Error refreshing: ' + outer );
++errorCount;
if ( errorCount < maxErrors ) {
// Load error, it happens. Remove this & redo!
link.remove();
replaceLink();
}
else {
console.log('Refresh: Aborting!')
}
});
link.attr('href', urlRandom(uri)).get(0);
link.insertBefore(next); // Insert just after
}
function urlRandom(uri) {
return uri + "&rand=" + Math.random();
}
function replaceLinkTimeout() {
setTimeout(function() {
replaceLink();
}, intervalRefresh ) ;
}
// Waith 1s before triggering the interval
setTimeout(function() {
replaceLinkTimeout();
}, timeoutBegin);
}
};
Comments
I am unsure why Javascript style promises have not been added to the Grails stack.
You can not render or stuff like that in the onComplete. render, redirect and what not are not available.
Something tells me that Grails and Promises/Futures are not there yet. The design of the GPars libraries seems not take into account of the core features which is to resolve later. At least it is not simple to do so.
It would be great if the dispatch() method actually could be invoked with some paramaters to pass from the resolving context. I am able to go around this using static properties.
I might continue to write my own solution and possibly contribute with a more fitting solutions around the AsyncContext class, but for now, this is enough for me.
I just wanted to refresh my less resources automatically.
Phew...
EDIT:
I made it to support several number of files. It is complete now!
I was wondering if is possible to create an instance of a generic type in Dart. In other languages like Java you could work around this using reflection, but I'm not sure if this is possible in Dart.
I have this class:
class GenericController <T extends RequestHandler> {
void processRequest() {
T t = new T(); // ERROR
}
}
I tried mezonis approach with the Activator and it works. But it is an expensive approach as it uses mirrors, which requires you to use "mirrorsUsed" if you don't want to have a 2-4MB js file.
This morning I had the idea to use a generic typedef as generator and thus get rid of reflection:
You define a method type like this: (Add params if necessary)
typedef S ItemCreator<S>();
or even better:
typedef ItemCreator<S> = S Function();
Then in the class that needs to create the new instances:
class PagedListData<T>{
...
ItemCreator<T> creator;
PagedListData(ItemCreator<T> this.creator) {
}
void performMagic() {
T item = creator();
...
}
}
Then you can instantiate the PagedList like this:
PagedListData<UserListItem> users
= new PagedListData<UserListItem>(()=> new UserListItem());
You don't lose the advantage of using generic because at declaration time you need to provide the target class anyway, so defining the creator method doesn't hurt.
You can use similar code:
import "dart:mirrors";
void main() {
var controller = new GenericController<Foo>();
controller.processRequest();
}
class GenericController<T extends RequestHandler> {
void processRequest() {
//T t = new T();
T t = Activator.createInstance(T);
t.tellAboutHimself();
}
}
class Foo extends RequestHandler {
void tellAboutHimself() {
print("Hello, I am 'Foo'");
}
}
abstract class RequestHandler {
void tellAboutHimself();
}
class Activator {
static createInstance(Type type, [Symbol constructor, List
arguments, Map<Symbol, dynamic> namedArguments]) {
if (type == null) {
throw new ArgumentError("type: $type");
}
if (constructor == null) {
constructor = const Symbol("");
}
if (arguments == null) {
arguments = const [];
}
var typeMirror = reflectType(type);
if (typeMirror is ClassMirror) {
return typeMirror.newInstance(constructor, arguments,
namedArguments).reflectee;
} else {
throw new ArgumentError("Cannot create the instance of the type '$type'.");
}
}
}
I don't know if this is still useful to anyone. But I have found an easy workaround. In the function you want to initialize the type T, pass an extra argument of type T Function(). This function should return an instance of T. Now whenever you want to create object of T, call the function.
class foo<T> {
void foo(T Function() creator) {
final t = creator();
// use t
}
}
P.S. inspired by Patrick's answer
2022 answer
Just came across this problem and found out that although instantiating using T() is still not possible, you can get the constructor of an object easier with SomeClass.new in dart>=2.15.
So what you could do is:
class MyClass<T> {
final T Function() creator;
MyClass(this.creator);
T getGenericInstance() {
return creator();
}
}
and when using it:
final myClass = MyClass<SomeOtherClass>(SomeOtherClass.new)
Nothing different but looks cleaner imo.
Here's my work around for this sad limitation
class RequestHandler {
static final _constructors = {
RequestHandler: () => RequestHandler(),
RequestHandler2: () => RequestHandler2(),
};
static RequestHandler create(Type type) {
return _constructors[type]();
}
}
class RequestHandler2 extends RequestHandler {}
class GenericController<T extends RequestHandler> {
void processRequest() {
//T t = new T(); // ERROR
T t = RequestHandler.create(T);
}
}
test() {
final controller = GenericController<RequestHandler2>();
controller.processRequest();
}
Sorry but as far as I know, a type parameter cannot be used to name a constructor in an instance creation expression in Dart.
Working with FLutter
typedef S ItemCreator<S>();
mixin SharedExtension<T> {
T getSPData(ItemCreator<T> creator) async {
return creator();
}
}
Abc a = sharedObj.getSPData(()=> Abc());
P.S. inspired by Patrick
simple like that.
import 'dart:mirrors';
void main(List<String> args) {
final a = A<B>();
final b1 = a.getInstance();
final b2 = a.getInstance();
print('${b1.value}|${b1.text}|${b1.hashCode}');
print('${b2.value}|${b2.text}|${b2.hashCode}');
}
class A<T extends B> {
static int count = 0;
T getInstance() {
return reflectClass(T).newInstance(
Symbol(''),
['Text ${++count}'],
{Symbol('value'): count},
).reflectee;
}
}
class B {
final int value;
final String text;
B(this.text, {required this.value});
}
Inspired by Patrick's answer, this is the factory I ended up with.
class ServiceFactory<T> {
static final Map<Type, dynamic> _cache = <String, dynamic>{};
static T getInstance<T>(T Function() creator) {
String typeName = T.toString();
return _cache.putIfAbsent(typeName, () => creator());
}
}
Then I would use it like this.
final authClient = ServiceFactory.getInstance<AuthenticationClient>(() => AuthenticationClient());
Warning: Erik made a very good point in the comment below that the same type name can exist in multiple packages and that will cause issues. As much as I dislike to force the user to pass in a string key (that way it's the consumer's responsibility to ensuring the uniqueness of the type name), that might be the only way.
I've just recently started using Rhino-Etl for very simple ETL processes and have had great success with it. I have a slightly more complicated scenario to address now and I didn't find the ConventionInputCommandOperation behaving the way I expected.
I've done up a very simplified example of what I'm trying to do. Basically I have two systems involved and I don't know what I want to get from system 2 until I first query system 1. I thought registering an InputOperation immediately after another InputOperation would behave like a loop. So that each row in operation 1 would be fed to operation 2. The below code fails with "Failed to execute operation DetailReader: Must declare the scalar variable #PlanetAbbrv." So my question is how are you meant to handle situations where the input operation is dependent a previous input operation?
Thanks,
Brian
using System;
using Rhino.Etl.Core;
using Rhino.Etl.Core.ConventionOperations;
namespace ETLTest
{
class Program
{
static void Main()
{
new MainProcess().Execute();
Console.ReadLine();
}
}
public class MainProcess : EtlProcess
{
protected override void Initialize()
{
Register(new MainReader());
Register(new DetailReader());
}
protected override void PostProcessing()
{
foreach (var exception in GetAllErrors())
{
throw exception;
}
}
}
public class MainReader : ConventionInputCommandOperation
{
public MainReader() : base("Galactic1")
{
Command = #"select * from Planet";
}
}
public class DetailReader : ConventionInputCommandOperation
{
public DetailReader() : base("Galactic2")
{
Command = #"select * from Delivery where DeliveryPlanetAbbrv = #PlanetAbbrv";
}
}
}
You'll need to have your DetailReader select all rows (take out the where operation).
Then use a JoinOperation to match the details to the main information.
Register(new JoinPlanets()
.Right(new MainReader())
.Left(new DetailReader()));
public class JoinPlanets: JoinOperation
{
protected override Row MergeRows(Row leftRow, Row rightRow)
{
Row row = leftRow.Clone();
foreach (var column in leftRow.Columns)
row[column] = leftRow[column];
return row;
}
protected override void SetupJoinConditions()
{
FullOuterJoin.Left("PlanetAbbrv")
.Right("DeliveryPlanetAbbrv");
}
}