I'm trying to use a custom ClassLoader in JRuby so my gem's loaded classes don't conflict with any project that requires my gem.
To that end, I can pretty easily create a new URLClassLoader and call loadClass to get my class loaded but what I get back is an unwrapped Java Class that it doesn't seem I can do much with easily.
I'd like to be able to do something like this:
clazz = java_class_loader.loadClass 'org.foo.bar.Class'
wrapped = JRuby.wrap_class clazz
wrapped.static_method 1, 2, 3 # call a static method
wrapped::CONSTANT # get a constant
Any ideas? I've looked all over the JRuby source for a good endpoint and I've tried many of the methods out of JavaSupport like get_proxy_class or likewise to no good effect. I can get and instance of JavaClass from my class but it doesn't seem to do me much good.
Related
Currently facing an issue while writing a similar java class in Jruby.
Example:
In Java:
public class Client extends ClientConnection<ChannelType> {
//do some stuff
}
In Jruby:
class Client < Java::'package_name'::ClientConnection
//do some stuff
end
Don't know how to pass ChannelType class in Jruby code while rewriting the Client class
The short version is, you can't unfortunately.
The JRuby wiki explains it as such here (https://github.com/jruby/jruby/wiki/CallingJavaFromJRuby#beware-of-java-generics):
If a Java class is defined with Java generics, the types are erased during compilation for backwards compatibility. As a result, JRuby will have problems with automatic type conversion. For example, if you have a Map, it will be seen as a simple Map, and JRuby will not be able to determine the correct types using reflection.
I am using Grails 2.2.4 and have a controller endpoint which converts a domain object list to JSON. Under load (as little as 5 concurrent requests) the marshaling performance is very poor. Taking thread dumps the threads are blocked on:
java.lang.ClassLoader.loadClass(ClassLoader.java:291)
There is a single marhsaler registered to marshal all domain objects using reflection and introspection. Realizing that reflection and introspection is slower than direct method calls, I am still seeing unexpected behavior in that the class loader is caller every time and in turn blocking occurs. An example stacktrace is as follows:
java.lang.Thread.State: BLOCKED (on object monitor)
at java.lang.ClassLoader.loadClass(ClassLoader.java:291)
- waiting to lock <785e31830> (a org.grails.plugins.tomcat.ParentDelegatingClassLoader)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at java.beans.Introspector.instantiate(Introspector.java:1470)
at java.beans.Introspector.findExplicitBeanInfo(Introspector.java:431)
at java.beans.Introspector.<init>(Introspector.java:380)
at java.beans.Introspector.getBeanInfo(Introspector.java:167)
at java.beans.Introspector.getBeanInfo(Introspector.java:230)
at java.beans.Introspector.<init>(Introspector.java:389)
at java.beans.Introspector.getBeanInfo(Introspector.java:167)
at java.beans.Introspector.getBeanInfo(Introspector.java:230)
at java.beans.Introspector.<init>(Introspector.java:389)
at java.beans.Introspector.getBeanInfo(Introspector.java:167)
at java.beans.Introspector.getBeanInfo(Introspector.java:230)
at java.beans.Introspector.<init>(Introspector.java:389)
at java.beans.Introspector.getBeanInfo(Introspector.java:167)
at org.springframework.beans.CachedIntrospectionResults.<init>(CachedIntrospectionResults.java:217)
at org.springframework.beans.CachedIntrospectionResults.forClass(CachedIntrospectionResults.java:149)
at org.springframework.beans.BeanWrapperImpl.getCachedIntrospectionResults(BeanWrapperImpl.java:324)
at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:727)
at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:721)
at org.springframework.beans.PropertyAccessor$getPropertyValue.call(Unknown Source)
at com.ngs.id.RestDomainClassMarshaller.extractValue(RestDomainClassMarshaller.groovy:203)
...
...
A simple benchmark loading the same endpoint with the same parameters results in the loadClass call.
I was under the impression the classes would be at least cached by the class loader and not loaded on every method call to get the property to be marshaled.
The code to retrieve the property value is as follows:
BeanWrapper beanWrapper = PropertyAccessorFactory.forBeanPropertyAccess(domainObject);
return beanWrapper.getPropertyValue(property.getName());
Is there a configuration setting that is needed to ensure the classes are only loaded once? or perhaps a different way to get the property that doesn't result in class loading every time? Or perhaps a more performant way to achieve this?
Writing a custom marshaler per domain class would avoid the reflection and introspection but is going to be a lot of repeat code.
Appreciate any input.
So after much digging this is what I found out.
Using the BeanUtils.getPropertyDescriptors and getValue will always try and find a BeanInfo class describing the bean using the class loader. In this case we don't provide BeanInfo classes for our grails domain classes so this call is redundant. I found some information where you can provide a custom BeanInfoFactory to bypass this and exclude your packages but I couldn't find how to configure it with Grails.
Also searching the springframework documentation there is a configuration option you can pass Introspector.IGNORE_ALL_BEANINFO that will tell CachedIntorspectionResults to never look up the bean classes. However this was not available in version 3.1.4 of springframework which was current for grails 2.2.4. The newer versions do appear to have this option.
So, if using BeanUtils you can't by pass this initial lookup on the class loader. However subsequent loaders should be cached by CachedIntrospectionResults. Unfortunately this doesn't happen in our scenario. There looks to be a bug in the test to see if the lookup is cacheable. See more info on this below.
The fix was ultimately to fall back to use pure reflection. Rather than use:
beanWrapper.getPropertyValue(property.getName());
To use:
PropertyDescription pd = BeanUtils.getPropertyDescriptor(domainObject.getClass(), property.getName())
pd.readMethod.invoke(domainObject)
Where the pd is cached.
After fixing this the profiler still showed a lack of caching on CachedIntorspectionResults for the out of the box grails marshaller. This was due to the bad caching implementation in CachedIntrospectionResults. The work around for this was to add the correct class loader to the acceptedClassLoaders in the CachedIntrospectionResults.
public class EnhanceCachedIntrospectionResultsAcceptedClassLoadersListener implements ServletContextListener {
public void contextInitialized(ServletContextEvent event) {
CachedIntrospectionResults.acceptClassLoader(Thread.currentThread().getContextClassLoader().getParent());
}
public void contextDestroyed(ServletContextEvent event) {
CachedIntrospectionResults.clearClassLoader(Thread.currentThread().getContextClassLoader().getParent());
Introspector.flushCaches();
}
}
Note that it was required to add the parent to the accepted class loader list rather than the current class loader. Not sure if this is specific to grails or not but this fixed the issue. I'm not sure if there may be a side effect to this fix.
In summary we went from 10 requests/sec in the original setup to 120 requests/sec after using direct reflection and fixing the CachedIntrospectionResults cache.
However the real eye opened was that if we use a 1-1 marshaller per domain class we were seeing another x2 improvement in performance over the generic marshaller where we test objects for whether they're instances of class etc. We're saving a lot of code with the generic marshaller but there's a lot more work to do to get comparable performance to writing a 1-1 marshaller.
Hopefully this will be useful to someone else who runs into this ...
I'm trying to write a test that needs both Robolectric 2.2 and PowerMock, as the code under test depends on some Android libraries and third party libraries with final classes that I need to mock.
Given that I'm forced to use the Robolectric test runner through:
#RunWith(RobolectricTestRunner.class)
...I cannot use the PowerMock test runner, so I'm trying to go with the PowerMock java agent alternative, without luck so far.
I have setup everything according to this guide but I'm facing a collision problem between classes required by the javaagent library and by robolectric through its dependency with asm-1.4. Both depend on
org.objectweb.asm.ClassVisitor
, but javaagent-1.5.1 ships with its own version where ClassVisitor is an interface while asm-1.4 version for the same namespace is an abstract class, with the corresponding error at runtime:
java.lang.IncompatibleClassChangeError: class org.objectweb.asm.tree.ClassNode has interface org.objectweb.asm.ClassVisitor as super class
I have even tried to modify the javaagent library jar to entirely remove the org.objectew.asm classes in there, but that doesn't work as ClassNotFoundException happens afterwards due to some other classes needed in the org.objectweb.asm package that only ship in the javaagent library jar, and not in the asm one.
Any ideas? According to examples out there the agent seems to work fine with, at least, the Spring test runner.
I had the same problem and while I didn't solve this problem as such, I wanted to share my approach, which removes the need for PowerMock (which is always a good thing in my view): I wanted to mock a call to
Fragment fooFragment = new FooFragment();
So what I did was addanother level of indirection. I created a FragmentProvider class:
public FragmentFactory fragmentFactory = new FragmentFactory();
[...]
Fragment fooFragment = fragmentFactory.getFooFragment();
After i did this, I could just mock out the factory with standard Mockito, like this:
FragmentFactory mockFactory = mock(FragmentFactory.class);
activity.fragmentFactory = mockFactory;
when(mockFactory.getFooFragment()).thenReturn(mockFooFragment);
Background
Okay I'm one of those guys who NEVER asks questions and who can usually find what I need from existing questions or forums....but alas I have spent the last few days trying to figure this one out and have come up with very little existing information.
I am using Flash Builder 4.6 for PHP Premium to build a Flex application that uses the PHP Zend Frameworks's AMF capabilities to map classes from PHP to Flex and to use them as objects to send back and forth instead of using XML or JSON. Right now I am doing it all on a single local machine for ease.
Issue
I am not having trouble mapping my own custom PHP classes into ActionScript/Flex classes but I cannot for the life of me manage to map a DateTime PHP class into an ActionScript Date class. I have read elsewhere that it automatically maps DateTime objects to Date objects but I have never gotten it to work.
Strangely though, I can get it to work if I replace all instances of, in my case, valueObjects.DateTime (the auto-generated ActionScript class) to Date in the _Super_Foo.as class that has the DateTime property. This basically forces Flex to interpret the data of that property as a Date. However, since all the _Super_XXX.as files are files that autogenerated by Flex, it gets rewritten any time I refresh or edit ANY PHP service that Flex is linking to in Flash Builder.
Remarks
I could of course do this the quick and dirty way by keeping the variable as a string (it's coming from MySQL in a DateTime field) and then just create some functions to convert it to a Date object on the client side but I need a more permanent and stable solution.
Example:
<?php
class Foo {
public $id; // int
public $name; // string
public $date; // DateTime
public $bar; // custom object
}
?>
should go to --->
package {
class Foo {
public var id:int;
public var name:String;
public var date:Date; // native class
public var bar:Bar;
}
}
but I am getting
package {
class Foo {
public var id:int;
public var name:String;
public var date:DateTime; // custom class
public var bar:Bar;
}
}
I have tried things such as the following:
in the gateway.php file
$server->setClassMap("Date", "DateTime");
using the Zend_Date object instead
$foo->date = new Zend_Date($blah);
and after trying to map it as well explicitly
$server->setClassMap("Date", "Zend_Date");
the change I currently have working in the _Super_Foo.as file (which gets written over frequently)
private var _internal_date : valueObjects.DateTime; // custom object
to
private var _internal_date : Date; // native object
I just need it to do this automatically like I have read it should.
Well I have to admit, that I usually use BlazeDS on Java and not Zend, but I have had similar problems in transfering Calendar objects (I wanted to prevent loosing the timezone data). For This BlazeDS supported so-called PropertyProxys, which are components that allow to takeover the serialization/deserialization process for certain types.
I would assume that ZEND would support a similar thing. So another option would actually be to make Zend zupport the full Flex type. I have searched a little and it seems that the entire terminology is different in Zend, but I think this stackoverflow article should explain it a little: Zend AMF custom dispatcher
Chris
In my experience, Zend Framework has taught me that it offers many features but many times they don't work exactly how you'd expect. For example:
Recently I was working with a bug in "digitalus-cms" (A blog-like framework built on top of ZF) that it couldn't post new articles with a hyphen in their title name. I tracked it down to Zend_Form_Element::filterName. It uses a regular expression that matches any character that falls into the category of: [^a-zA-Z0-9_\x7f-\xff] then removes it. This ends up removing hyphens from the names of form elements which wound up being the cause of the bug.
If Zend_Amf or Zend_Date doesn't work the way you want it to, find a workaround such as passing a unix timestamp number around so everything works the way it should. Then afterwards, you can write a class to extend off one of Zend's classes. Zend Framework is meant to be extended upon, that's the way the framework was built so you can fix issues like these on your own to get the framework to behave how you want it to. That's the whole point of wrappers. Go ahead, create some of your own wrapper classes and toss in some methods to interact with ZF so you can fine-tune everything.
As far as finding the cause of your issue, all I can tell you is keep on debugging and isolating code so you know what you are passing flex, and how flex responses to that. After you play around with it enough, I'm sure you'll find the culprit.
AmfPHP automatically maps it. http://www.silexlabs.org/amfphp/
I've got a bit of a problem. I'm working in the Castle Windsor IOC Container. Now what i wanted to do is just mess about with some AOP principles and what i specifically want to do is based on a method name perform some logging. I have been looking at Interceptors and at the moment i am using the IInterceptor interface implemented as a class to perform this logging using aspects. The issue is if i want to perform the logging on a specific method then it gets messy as i need to put in some logic into my implemented aspect to check the method name etc...
I have read that you can do all of this using Dynamic Proxies and the IInterceptorSelector interface and the IProxyGenerationHook interface. I have seen a few examples of this done on the net but i am quite confused how this all fits into the Windsor container. I mean i am using the windsor container which in my code is actually a ref to the IWindsorContainer interface to create all my objects. All my configuration is done in code rather than XML.
Firstly does anyone know of a way to perform method specific AOP in the windsor container besides the way i am currently doing it.
Secondly how do i use the Dynamic Proxy in the windsor container ?
Below i have added the code where i am creating my proxy and registering my class with
the interceptors
ProxyGenerator _generator = new ProxyGenerator(new PersistentProxyBuilder());
IInterceptorSelector _selector = new CheckLoggingSelector();
var loggingAspect = new LoggingAspect();
var options = new ProxyGenerationOptions(new LoggingProxyGenerationHook())
{ Selector = _selector };
var proxy = _generator.CreateClassProxy(typeof(TestClass), options, loggingAspect);
TestClass testProxy = proxy as TestClass;
windsorContainer.Register(
Component.For<LoggingAspect>(),
Component.For<CheckLoggingAspect>(),
Component.For<ExceptionCatchAspect>(),
Component.For<ITestClass>()
.ImplementedBy<TestClass>()
.Named("ATestClass")
.Parameters(Parameter.ForKey("Name").Eq("Testing"))
.Proxy.MixIns(testProxy));
The Test Class is below:
public class TestClass : ITestClass
{
public TestClass()
{
}
public string Name
{
get;
set;
}
public void Checkin()
{
Name = "Checked In";
}
}
as for the interceptors they are very simple and just enter a method if the name starts with Check.
Now when i resolve my TestClass from the container i get an error.
{"This is a DynamicProxy2 error: Mixin type TestClassProxy implements IProxyTargetAccessor which is a DynamicProxy infrastructure interface and you should never implement it yourself. Are you trying to mix in an existing proxy?"}
I know i'm using the proxy in the wrong way but as i haven't seen any concrete example in how to use a proxy with the windsor container it's kind of confusing.
I mean if i want to use the LoggingProxyGenerationHook which just tell the interceptors to first for methods that start with the word "check" then is this the correct way to do it or am i completely on the wrong path. I just went down the proxy way as it seems very powerfull and i would like to understand how to use these proxies for future programming efforts.
By using .Interceptors() you already are using Dynamic Proxy. When component has specified interceptors Windsor will create proxy for it, and use these interceptors for it. You can also use method .SelectedWith and .Proxy property to set other options you already know from DynamicProxy.
I just added a website about Windsor AOP to documentation wiki. There's not much there yet, but I (and Mauricio ;) ) will put there all the information you need. Take a look, and let us know if everything is clear, and if something is missing.