C / C++ / MFC

18-Oct-07 2:37

Hello everyone,

I have noticed a lot of COM samples that the function AddRef and Release function of COM inteface is not synchronized to make it thread safe when dealing with adding/decreasing reference count.

Is it needed to synchronize AddRef and Release? Or the COM runtime underlying implementation handles thread safe issue by itself (i.e. transparent to upper layer COM server developer)

I am using Visual Studio 2005 to develop native (unmanaged C++) COM. No other framework is used (e.g. ATL).

thanks in advance,
George

led mike18-Oct-07 4:28

18-Oct-07 4:28

George_George wrote:
Or the COM runtime underlying implementation handles thread safe issue by itself (i.e. transparent to upper layer COM server developer)

No. There is no thread safety built into COM. That doesn't even make sense. There are Thread Models built into COM. Do some reading on COM and STA or Apartment Thread Model.

I also suggest reading Advanced Windows by Richter to gain a basic understanding of threading issues.

George_George18-Oct-07 4:45

18-Oct-07 4:45

Thanks led mike,

You mean we need to add thread safe synchronization approach to AddRef and Release to make counter value thread safe manually?

regards,
George

led mike18-Oct-07 4:54

18-Oct-07 4:54

George_George wrote:
You mean we need to add thread safe synchronization approach to AddRef and Release to make counter value thread safe manually?

Well you can do it manualy or you can use a library like ATL to do it for you.

George_George18-Oct-07 5:15

18-Oct-07 5:15

Thanks led mike,

Since I implement COM DLL server from scratch, I need to implement thread-safe synchronization approach manually to AddRef and Release. Thanks again.

regards,
George

led mike18-Oct-07 6:11

18-Oct-07 6:11

George_George wrote:
Since I implement COM DLL server from scratch, I need to implement thread-safe synchronization approach manually to AddRef and Release.

Yes, unless of course you are implementing an Apartment model then it doesn't matter since all of the interfaces will only be accessed from a single thread.

George_George18-Oct-07 18:47

18-Oct-07 18:47

Intersted, what is Apartment model?

regards,
George

led mike19-Oct-07 5:08

19-Oct-07 5:08

George_George wrote:
Intersted, what is Apartment model?

This is a nice summary[^]

George_George20-Oct-07 4:18

Problem in generating XML log files

20-Oct-07 4:18

Thanks led!

Good article.

have a good weekend,
George

Charsets , koi8-r

Daniel Kanev7-Mar-17 21:54

Daniel Kanev

7-Mar-17 21:54

Hi,
I want to convert different character encodings like koi8-r to ASCII.
Where can I find information about them?
I can see there are many charsets - utf-8, windows-1251 etc.

Re: Charsets , koi8-r

Nemanja Trifunovic18-Oct-07 2:50

Nemanja Trifunovic

18-Oct-07 2:50

Daniel Kanev wrote:
I want to convert different character encodings like koi8-r to ASCII.

You can't convert kio8-r to ASCII. The former covers Cyrillic alphabet, and the later Latin (the English subset of Latin, really). What exactly do you want to do?

Programming Blog
utf8-cpp

Message Closed

18-Oct-07 3:21

Daniel Kanev

18-Oct-07 3:21

Message Closed

modified 8-Mar-17 3:44am.

Re: Charsets , koi8-r

Nemanja Trifunovic18-Oct-07 3:34

Nemanja Trifunovic

18-Oct-07 3:34

If you want to preserve the cyrillic text, I suggest converting it to some form of Unicode. If you don't know much about it, maybe you can start by reading The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)
[^]

Programming Blog
utf8-cpp

Rocky#18-Oct-07 2:14

Rocky#

18-Oct-07 2:14

Hello every one,

I'm trying to generate log files in XML using MSXML4. Right now I'm trying to get it working correctly in a test application, so that when I get it right I could just implement the same thing in the actual project i need to work on.

This operation is intended to log the calling of functions in the application and the XML it needs to generate should be something like this

<pre>
<CallSequence>
<Call>
<ObjectType>Unit</ObjectType>
<ObjectName>ChemSepUO_382</ObjectName>
<Interface>ICapeUnit</Interface>
<Method>Calculate</Method>
<CallSequence>
<Call>
<ObjectType>Material Object</ObjectType>
<ObjectName>Mix out</ObjectName>
<Interface>ICapeThermoMaterialObject</Interface>
<Method>SetProp</Method>
<Arguments>
<Inputs>
<Row>
<Property>Volume</Property>
<Phase>Overall</Phase>
<Basis>Mole</Basis>
<Calc>Mixture</Calc>
</Row>
<Row>
<Property>My Property</Property>
<Phase>phaseValue</Phase>
<Basis>Molecule</Basis>
<Calc>Mkkkl</Calc>
</Row>

</Inputs>
<Outputs>
<Row>
<Value>0.000018075</Value>
</Row>
</Outputs>
</Arguments>
<ReturnCode>No Error</ReturnCode>
<CallSequence>
<Call>
<ObjectType>Unit</ObjectType>
<ObjectName>ChemSepUO_382</ObjectName>
<Interface>ICapeUnit</Interface>
<Method>Third Level of Recursion</Method>
<ReturnCode>No Error</ReturnCode>
</Call>
</CallSequence>

</Call> ...</pre>

Its the nesting of function calls (callsequence nodes in this case) which is causing the problem. The problem is that in the actual application I dont have access to the code that is calling those functions I need to log. So this nesting looks almost impossible for now.

The XML that is generated right now looks like this where function4 is actually called from Function1 but its not getting nested inside.

<pre><LOG>
<CallSequence>
<Call><MethodName>Function1</MethodName>
<Interface>ICapeThermo</Interface>
</Call>
<Call><MethodName>Function4</MethodName>
<Interface>ICapeThermo</Interface>
</Call>
</CallSequence></LOG></pre>

I'm in real hot water now... looks like I'm completely out of ideas...
Can u give me any idea or help in anyway?

Thanks for your time

Rocky

You can't climb up a ladder with your hands in your pockets.

James R. Twine18-Oct-07 3:12

James R. Twine

18-Oct-07 3:12

   As an aside, who came up with the requirement for using XML for logging? Based on the XML shown above, you have much more XML markup than content. Logging something like a crash/dump is one thing, but this looks like runtime-logging...

   Logging should not be a drain on performance. But XML, and XML combined with MSXML does not exactly scream high-performance...

   Peace!

Rocky#18-Oct-07 19:28

Rocky#

18-Oct-07 19:28

well first of all, thank you so much for answering!

This idea was given by my boss and other seniors and well I think you're right but this task has been given to me n now I gotta do something abt it right?

At the moment this whole call Tree scenario looks pretty vague if u ask me!

Rocky

You can't climb up a ladder with your hands in your pockets.

led mike19-Oct-07 5:13

19-Oct-07 5:13

James R. Twine wrote:
But XML, and XML combined with MSXML does not exactly scream high-performance...

There are all kinds of production loggers that use XML. Performance is not a problem. "Logging" is not actually specific enough to determine what logging mechanism is appropriate.

James R. Twine19-Oct-07 7:09

James R. Twine

19-Oct-07 7:09

   A good and valid point.

   I was merely going on my experience with things that I have and do with on/with. And with these systems, performance does matter and can be a problem, so I cannot take for granted things that other developers get away with.

   Peace!

led mike18-Oct-07 4:25