Hi I'm a bit uncertain about good practice within IBM DOORS Attribute DXL when it comes to which resources to release?
// I believe the following is correct for assigning the value of a buffer to an attribute of type Text.
Buffer buff = create
buff = "hello"
delete(buff)
obj.attrDXLName = tempStringOf(buff)
delete(buff)
// strings - what is required?
// eg..
string s = "hello"
s = "hello world"
s = null
// Where I am navigating through links, I may be using the following
LinkRef myLinkRef = null
myLinkRef = ...
ModName_ otherModuleHandle = data(SourceVersion myLinkRef)
Module m = ...
delete(otherModuleHandle)
In Attribute DXL, Which handles are known to need to be free'd and whats the best way to release the resource. I've seen delete(otherModuleHandle) being used, but not sure how it works or why it is needed.
I have a suspicion that DOORS DXL does some sort of reference counting in its memory model.
Any thoughts would be greatly appreciated.
I think the code listed will throw several errors?
Example- you can't refer to a buffer after calling delete on that buffer (your line 3).
If you asking about freeing up resources, that's a good practice for attribute dxl (which needs to essentially run the code for each object in the module when the module opens / the attribute is refreshed) - however, I wouldn't bother with setting strings to null. I would clean up used buffers at the end of my script, and I might close open module handles depending on what I was doing with them. On the other hand, I might leave the module handles, especially if I'm opening it multiple other times, as I have occasionally bumped into issues with code that opens / closes modules repeatedly.
Related
Sorry if I had this stupid question...I've been trying to google for answer but couldn't find one. :(
I have a problem assigning a variable to a virtual interface. For example:
Param.sv
...
string MyInput[3];
MyInput[0] = Signal_CLK; //Storing SignalName to in an Array.
MyInput[1] = Signal_Tx;
MyInput[2] = Signal_Rx;
...
MyInterface.sv
...
Signal_CLK = dut.MicroController.Source.clk; //Signal destination
Signal_Tx = dut.MicroController.Tx_01;
Signal_Rx = dut.MicroController.Rx_01;
...
Test.sv
virtual MyInterface my_vif
logic [7:0] read_value;
....
for (i = 0; i <3; i++ )
begin
read_value = my_vif.My_Input[i];
..
//some logic to compare read_value with spec//
..
end
The problem is when compiling, it doesn't translate my_vif.My_Input[0] into my_vif.***dut.MicroController.Source.clk***. Instead, it thinks that the path is my_vif.***My_Input[i]***.
The reason the compiler thinks you are trying to access my_vif.My_Input[i] is because you are. The My_Input[] array is a completely separate string array; not part of the virtual interface. When using the "thing.thing.thing" syntax, the compiler will loyally follow it, so it will expect there to be something called My_Input that has some elements (as its an array) as a member of the interface given by my_vif.
However, looking over youre code, you are trying to have My_Input[i] replaced at compile time, which is very different. The compiler will not run your loop, look in My_Input[i] and find the string "Signal_CLK" and replace that as part of the path to get the path my_vif.Signal_CLK. Nor can it do that at run time.
I dont know of a generic solution to looking over any variables in an interface; though Im also not sure if thats really what you want. IF you provide more details on the rest of your checker, we might be able to help you more.
You cannot use strings to look up identifiers by name within SystemVerilog. There are tool specific and C interfaces that may let you do this, but that would be very inefficient. The best way to do this by using a combination of abstract/concrete classes and the bind construct. See these references: http://events.dvcon.org/2012/proceedings/papers/01P_3.pdf and http://www.doulos.com/knowhow/sysverilog/DVCon08/DVCon08_SysVlog.php
How to clean SSJS (Server Side Javascript) in Domino server after someone used javascript prototype in a nsf?
Mark Roden discovered a huge weakness in XPages SSJS: (thanks to David Leedy for tell me about this and show me the article).
If you have the following SSJS code:
var dummyObj = {}
dummyObj.prototype.NAME = "Johann"
XPages SSJS doesn't care that you uses var (var means the variable must be local) and it makes dummyObj.NAME visible in the whole server with the value Johann. So if another nsf in the same server uses a var with the same name it inherits the whole prototype:
var dummyObj = {}
println(dummyObj.NAME) /*prints "Johann" */
This is a huge bug (one that makes unreliable XPages SSJS IMO). Even if you don't use prototype at all, if someone else in his application do something like this:
String.prototype.split = function(){ return "I broke this method" }
It will broke all applications in the same server that uses the innocent split().
So, the question is: if someone "by mistake" writes the following SSJS (XPages Server Side Javascript) in a NSF:
String.prototype.split = function(){ return "I broke this method" }
How can I fix String.prototype.split() to his original value?
As Mark Roden said, restarting HTTP task doesn't fix it.
///////////////////////////////////////////////////////////
Edit 1: Why I think this is a huge bug:
I'm a Javascript fan but IMHO #MarkyRoden has discovered a huge bug in SSJS. Shims and polyfills aren't really the main problem. Eval is known to be a bad practice but the prototype object is a fundamental element of basic Javascript. It's the standard and preferred way to add methods to Javascript classes, it's also needed for inheritance and all kind of OOP stuff. So you will need some kind of namespace at server level in order to avoid collisions. All this is really bad but the huge problem is that just a line of code in one application can broke all applications in a server. Yes, you can trust in your developers but one of them can write a bad line by mistake and also a Domino server can have hundreds of applications from different software vendors. Set the responsability in code reviews is not a reliable enought procedure. Maybe it's time to have a real javascript engine in SSJS, like V8, Spidermonkey, Chakra or Rhino. As a workaround, I'm thinking in something like Tommy Valand's idea with Rhino in SSJS.
Edit 2: It's even worse. You can do things like:
prototype.importPackage = null
or
prototype.Array = null
As you can see in #SvenHasselbach's article: http://hasselba.ch/blog/?p=1371
Edit 3: IBM: you told me I could use SSJS. COME ONE! PLEASE FIX THIS, it's AWFUL. Please let's officially report this issue to IBM.
You can reset the SSJS interpreter with the following Java code:
FacesContextExImpl fc = (FacesContextExImpl) FacesContextExImpl.getCurrentInstance();
UIViewRootEx2 uiRoot = (UIViewRootEx2) fc.getViewRoot();
JSContext jsContext = uiRoot.getJSInterpreter().getJSContext();
jsContext.getRegistry().init(jsContext);
This reinitializes the registry and all prototype functions.
EDIT: Changed the declaration of fc to the correct type.
EDIT 2:
Here is the SSJS version:
var uiRoot = facesContext.getViewRoot();
var jsContext = uiRoot.getJSInterpreter().getJSContext();
var reg = jsContext.getRegistry();
reg.init( jsContext );
Does I understand you correctly, that you want to clean up the SSJS interpreter to avoid a collision with your own prototype extension?
Just to clarify the answer above: This reinitializes the SSJS interpreter once. And only once.
You have to do this over and over again, because directly after reinitializing, another application on the server can overwrite the prototype functionality again. That's why this is not a real solution, it is an answer to your initial question.
It will have interessting consequences if another application will do the same while your code tries to use your extension...
try to do a Restart Task Http instead
tell http restart will not do a full restart of the http task
I have looking at many threads about the exception "cannot pass a GCHandle across AppDomains" but I still don't get it....
I'm working with an RFID Reader which is driven by a DLL. I don't have source code for this DLL but only a sample to show how to use it.
The sample works great but I have to copy some code in another project to add the reader to the middleware Microsoft Biztalk.
The problem is that the process of Microsoft Biztalk works in another AppDomain. The reader handle events when a tag is read. But when I run it under Microsoft Biztalk I got this annoying exception.
I can't see any solution on how to make it work...
Here is some code that may be interesting :
// Let's connecting the result handlers.
// The reader calls a command-specific result handler if a command is done and the answer is ready to send.
// So let's tell the reader which functions should be called if a result is ready to send.
// result handler for reading EPCs synchronous
Reader.KSRWSetResultHandlerSyncGetEPCs(ResultHandlerSyncGetEPCs);
[...]
var readerErrorCode = Reader.KSRWSyncGetEPCs();
if (readerErrorCode == tKSRWReaderErrorCode.KSRW_REC_NoError)
{
// No error occurs while sending the command to the reader. Let's wait until the result handler was called.
if (ResultHandlerEvent.WaitOne(TimeSpan.FromSeconds(10)))
{
// The reader's work is done and the result handler was called. Let's check the result flag to make sure everything is ok.
if (_readerResultFlag == tKSRWResultFlag.KSRW_RF_NoError)
{
// The command was successfully processed by the reader.
// We'll display the result in the result handler.
}
else
{
// The command can't be proccessed by the reader. To know why check the result flag.
logger.error("Command \"KSRWSyncGetEPCs\" returns with error {0}", _readerResultFlag);
}
}
else
{
// We're getting no answer from the reader within 10 seconds.
logger.error("Command \"KSRWSyncGetEPCs\" timed out");
}
}
[...]
private static void ResultHandlerSyncGetEPCs(object sender, tKSRWResultFlag resultFlag, tKSRWExtendedResultFlag extendedResultFlag, tKSRWEPCListEntry[] epcList)
{
if (Reader == sender)
{
// Let's store the result flag in a global variable to get access from everywhere.
_readerResultFlag = resultFlag;
// Display all available epcs in the antenna field.
Console.ForegroundColor = ConsoleColor.White;
foreach (var resultListEntry in epcList)
{
handleTagEvent(resultListEntry);
}
// Let's set the event so that the calling process knows the command was processed by reader and the result is ready to get processed.
ResultHandlerEvent.Set();
}
}
You are having a problem with the gcroot<> helper class. It is used in the code that nobody can see, inside that DLL. It is frequently used by C++ code that was designed to interop with managed code, gcroot<> stores a reference to a managed object. The class uses the GCHandle type to add the reference. The GCHandle.ToIntPtr() method returns a pointer that the C++ code can store. The operation that fails is GCHandle.FromIntPtr(), used by the C++ code to recover the reference to the object.
There are two basic explanations for getting this exception:
It can be accurate. Which will happen when you initialized the code in the DLL from one AppDomain and use it in another. It isn't clear from the snippet where the Reader class object gets initialized so there are non-zero odds that this is the explanation. Be sure to keep it close to the code that uses the Reader class.
It can be caused by another bug, present in the C++ code inside the DLL. Unmanaged code often suffers from pointer bugs, the kind of bug that can accidentally overwrite memory. If that happens with the field that stores the gcroot<> object then nothing goes wrong for a while. Until the code tries to recover the object reference again. At that point the CLR notices that the corrupted pointer value no longer matches an actual object handle and generates this exception. This is certainly the hard kind of bug to solve since this happens in code you cannot fix and showing the programmer that worked on it a repro for the bug is very difficult, such memory corruption problems never repro well.
Chase bullet #1 first. There are decent odds that Biztalk runs your C# code in a separate AppDomain. And that the DLL gets loaded too soon, before or while the AppDomain is created. Something you can see with SysInternals' ProcMon. Create a repro of this by writing a little test program that creates an AppDomain and runs the test code. If that reproduces the crash then you'll have a very good way to demonstrate the issue to the RFID vendor and some hope that they'll use it and work on a fix.
Having a good working relationship with the RFID reader vendor to get to a resolution is going to be very important. That's never not a problem, always a good reason to go shopping elsewhere.
Can a variable be named with a string or character array, in any language? Basically I want something like:
Var_String = "varname"
Var_String as double
And then I could fill the double varname.
If it helps im trying to make a program that can declare variables on the fly, while running. Even if thats not possible, I am open to workarounds even if they're impractical, although I would prefer that workarounds be in VB6, C++, or PHP, because I know those languages already, but they dont have to be.
Javascript is completely capable of declaring variable names on the fly. A javascript object can be treated "associatively" as a dictionary. Observe:
var testyObject = function()
{
Awesome = "hello";
};
var myObject = new testyObject();
alert(myObject.Awesome); // creates an alert window that says hello
alert(myObject['Awesome']); // the same as above
myObject[myObject.Awesome] = "woo!"; // We just created a property on the object with the name "hello"
alert(myObject.hello); // creates an alert window that says "woo!"
I also believe you can add them to your immediate scope rather than as properties on other objects by using this["whatever you want it named"] = "woo!"; but I'm not certain, someone can correct me on that if such does not work.
You can read more about associative arrays at http://www.quirksmode.org/js/associative.html
The usual way to do something like this is called a hash. You store name/value pairs and given the name, can look up its value. You can generally define them to store any sort of object. In fact, in some languages, objects themselves are essentially hashes with a few extra properties.
You can find more information on wikipedia: http://en.wikipedia.org/wiki/Hash_table
hope you're having a good day.
I have been programming a IRC chatbot in Lua the past few days, and finally I want to start implementing multiple server support into it.
So far, I have created the irc "object" to manage each server, and all that happy stuff - Now, I am having problems with threading.
Lua, as you probably know, doesn't have thread support built-in. LuaLanes and LuaThreads seemed like the closest to what I wanted to use, in terms of libraries. What made me choose LuaLanes is because LuaThreads requires a modified lua core. Plus the "lindas" feature of LuaLanes caught my eye (for later use in plugins)
Anyway, the issue that I'm having is when you generate a lane using function middleman (for example), which then calls another function sqr (for example). if you generate the function like lanes.gen({globals = _G}, middleman), middleman will have access to everything in your current global scope, which is exactly what I want. The problem is, if middleman calls sqr, and sqr uses something from the global scope, it throws an error, almost as if _G suddenly became empty.
Here's some example code I managed to throw together, using my example above:
require 'lanes'
function sqr()
print(5*5)
end
function middleman()
sqr()
end
gen = lanes.gen({globals = _G}, middleman)
print(gen()[1])
Produces an error saying:
tc#box:~$ lua lanestrouble.lua
lua: lanestrouble.lua:4: attempt to call global 'print' (a nil value)
stack traceback:
[C]: in function 'error'
./lanes.lua:190: in function <./lanes.lua:136>
lanestrouble.lua:13: in main chunk
[C]: ?
threading.c 399: pthread_cond_destroy(ref) failed, 16 EBUSY
Aborted
tc#box:~$
(By the way, I'm using linux)
However, if you change line 11 from gen = lanes.gen({globals = _G}, middleman) to gen = lanes.gen({globals = _G}, sqr), it works fine.
I've checked, and the same thing happens if you pass "*" (or any other option for the "libs_str" parameter) to load the default libraries.
I really wish there was something like Java's threading library for Lua, that's how I originally learned to use threads. (I know, not the most ideal environment I suppose)
Thanks, I appreciate help a lot. Especially since this has completely halted my IRC bot development! :(
Making sqr local does the trick. Since it becomes an upvalue of middleman, it is copied to the new lane.
require 'lanes'
local function sqr()
print(5*5)
end
function middleman()
sqr()
end
gen = lanes.gen({globals = _G}, middleman)
print(gen()[1])
But definitely something strange is going on. I mean, even when passing explictly "sqr" and "print" to the new lane, it won't see "print" (when called by "sqr"). It seems to me that something is not working right when serializing functions between lanes. You should contact its maintainer.