Integer Pool

[=?Utf-8?B?VHJlY2l1cw==?=]

Hello, Newsgroupians:

I have a method that requires me to specify a client handle when I create
the object. The object prototype is as follows...

void Server.CreateMo nitor(string strName, int nClientHandle);

When I create the monitor, I have specify a client handle. Therefore, when
using other methods that came with the library, all I need to do is specify a
client handle.

I'd like to create a "handle pool" that will allow me to grab an integer
from the pool and pass that into the function. This is synonymous to
creating a handle in Win32; the handle is unique. Does anyone have any good
resources as to where I can find some good information regarding creating a
pool that will do this for me? I've been doing some searching, but all I can
find is "thread pools" and not "handle pools." Perhaps my terminology is
incorrect?

How does Windows do it to create handles and make them unique?

Thank you,


Trecius

[Ashutosh Bhawasinka]

Re: Integer Pool

If there is a direct mapping of the Handle with some value, like it's
type (which is not very clear in your description) you can use a
Dictionary like this

Dictionary<int, inthandles = new Dictionary<int, int>();
or
Dictionary<stri ng, inthandles = new Dictionary<stri ng, int>();

Where the key will be the type of handle and it's value will be the
actual handle
Then you can add/set the handle like this

handles["FileHandle "] = xyz;

and you will retrieve or use it like this
int handle = handles["FileHandle "];

Thanks & Regards,
Ashutosh

Trecius wrote:

Hello, Newsgroupians:
>
I have a method that requires me to specify a client handle when I create
the object. The object prototype is as follows...
>
void Server.CreateMo nitor(string strName, int nClientHandle);
>
When I create the monitor, I have specify a client handle. Therefore, when
using other methods that came with the library, all I need to do is specify a
client handle.
>
I'd like to create a "handle pool" that will allow me to grab an integer
from the pool and pass that into the function. This is synonymous to
creating a handle in Win32; the handle is unique. Does anyone have any good
resources as to where I can find some good information regarding creating a
pool that will do this for me? I've been doing some searching, but all I can
find is "thread pools" and not "handle pools." Perhaps my terminology is
incorrect?
>
How does Windows do it to create handles and make them unique?
>
Thank you,
>
>
Trecius
>

[Peter Duniho]

Re: Integer Pool

On Mon, 03 Nov 2008 10:50:06 -0800, Trecius
<Trecius@discus sions.microsoft .comwrote:

Hello, Newsgroupians:
>
I have a method that requires me to specify a client handle when I create
the object. The object prototype is as follows...
>
void Server.CreateMo nitor(string strName, int nClientHandle);
>
When I create the monitor, I have specify a client handle. Therefore,
when
using other methods that came with the library, all I need to do is
specify a
client handle.
>
[...]
How does Windows do it to create handles and make them unique?

Handles for the unmanaged Windows API are related to the internal data
structures for Windows. They are unique, because they refer to unique
locations in those data structures.

The library design seems suspect to me. It seems to me that if you're
creating an object, like a "monitor" (whatever that is), one of two
scenarios exist: there's a one-to-one mapping between the "nClientHan dle"
and the created "monitor" or there may be multiple "monitor"s for each
"nClientHandle" .

In the former case, it seems to me that the reference to the monitor is
itself the unique identifier you need. In the latter case, then you
either have an instance of an object that's creating the monitor or you
can create some kind of reference object for that purpose. In either
case, the reference to that object can be provided as an appropriate
identifier.

Of course, all of that begs the question as to why you're supplying any
kind of reference or identifier at all. A proper library, when you ask it
to create something, would itself return a reference to that something.
Making the _caller_ come up with the reference seems silly.

Now, all of that would require fixing the library so that you can pass
references (e.g. to Object) instead of an integer. If you've got a
poorly-designed library where that's not an option, then I guess you're
stuck having to come up with a unique integer. Approaches to that include:

Using "unsafe" code you could just convert a reference to an integer, so
that's one option.

Just keep a counter that you increment each time you need a new int; that
gives you 4 billion values before you run out, which in most cases would
be enough.

If 4 billion isn't enough, but you won't ever have nearly that many
integers actually in use at once, then you could maintain a List<intof
"retired" identifiers; as long as there's something in the list, use the
first number available in the list, otherwise increment your counter. The
counter will never go higher than the number of identifiers ever in use at
once (but the length of the List<Twill have to be large enough to
account for the difference between the largest number of identifiers ever
in use at once and the largest retirement of identifiers).

Without more information, it's hard to say what the best approach is.
Except that fixing the library itself is the best solution. :)

Pete

[=?Utf-8?B?VHJlY2l1cw==?=]

Re: Integer Pool

Thank you, but it's not quite what I'm looking for. I may not know the
strName until runtime. For example, if I were to just start the program, and
I have one element. I want to get one item from the pool -- maybe it will be
1. Now I know that no other item can be 1. Next, if I have another element
at run time, I want to get another handle. I call the pool for another
handle, and it gives me one -- maybe it will be 2. Now maybe I'm done with
the first handle and no longer require it, so I release the handle back to
the pool, so if I call the pool for another handle, it may return a 1 to me
because I had already release it.


Trecius

"Ashutosh Bhawasinka" wrote:

If there is a direct mapping of the Handle with some value, like it's
type (which is not very clear in your description) you can use a
Dictionary like this
>
Dictionary<int, inthandles = new Dictionary<int, int>();
or
Dictionary<stri ng, inthandles = new Dictionary<stri ng, int>();
>
Where the key will be the type of handle and it's value will be the
actual handle
Then you can add/set the handle like this
>
handles["FileHandle "] = xyz;
>
and you will retrieve or use it like this
int handle = handles["FileHandle "];
>
Thanks & Regards,
Ashutosh
>
Trecius wrote:

Hello, Newsgroupians:

I have a method that requires me to specify a client handle when I create
the object. The object prototype is as follows...

void Server.CreateMo nitor(string strName, int nClientHandle);

When I create the monitor, I have specify a client handle. Therefore, when
using other methods that came with the library, all I need to do is specify a
client handle.

I'd like to create a "handle pool" that will allow me to grab an integer
from the pool and pass that into the function. This is synonymous to
creating a handle in Win32; the handle is unique. Does anyone have any good
resources as to where I can find some good information regarding creating a
pool that will do this for me? I've been doing some searching, but all I can
find is "thread pools" and not "handle pools." Perhaps my terminology is
incorrect?

How does Windows do it to create handles and make them unique?

Thank you,


Trecius

>

[Ashutosh Bhawasinka]

Re: Integer Pool

Handles are not just any items that you put into a pool and use any
available one.

Each handle (finally) maps to a kernel object in the system. So I am not
sure if your usage is correct.

If all your handles are for a single type of object and you are not
bothered about a particular instance, then you can use a Stack or a
Queue or List to store the handles.


Trecius wrote:

Thank you, but it's not quite what I'm looking for. I may not know the
strName until runtime. For example, if I were to just start the program, and
I have one element. I want to get one item from the pool -- maybe it will be
1. Now I know that no other item can be 1. Next, if I have another element
at run time, I want to get another handle. I call the pool for another
handle, and it gives me one -- maybe it will be 2. Now maybe I'm done with
the first handle and no longer require it, so I release the handle back to
the pool, so if I call the pool for another handle, it may return a 1 to me
because I had already release it.
>
>
Trecius
>
"Ashutosh Bhawasinka" wrote:
>
>

>If there is a direct mapping of the Handle with some value, like it's
>type (which is not very clear in your description) you can use a
>Dictionary like this
>>
>Dictionary<int , inthandles = new Dictionary<int, int>();
>or
>Dictionary<str ing, inthandles = new Dictionary<stri ng, int>();
>>
>Where the key will be the type of handle and it's value will be the
>actual handle
>Then you can add/set the handle like this
>>
>handles["FileHandle "] = xyz;
>>
>and you will retrieve or use it like this
>int handle = handles["FileHandle "];
>>
>Thanks & Regards,
>Ashutosh
>>
>Trecius wrote:
>>

>>Hello, Newsgroupians:
>>>
>>I have a method that requires me to specify a client handle when I create
>>the object. The object prototype is as follows...
>>>
>>void Server.CreateMo nitor(string strName, int nClientHandle);
>>>
>>When I create the monitor, I have specify a client handle. Therefore, when
>>using other methods that came with the library, all I need to do is specify a
>>client handle.
>>>
>>I'd like to create a "handle pool" that will allow me to grab an integer
>>from the pool and pass that into the function. This is synonymous to
>>creating a handle in Win32; the handle is unique. Does anyone have any good
>>resources as to where I can find some good information regarding creating a
>>pool that will do this for me? I've been doing some searching, but all I can
>>find is "thread pools" and not "handle pools." Perhaps my terminology is
>>incorrect?
>>>
>>How does Windows do it to create handles and make them unique?
>>>
>>Thank you,
>>>
>>>
>>Trecius
>>>
>>>

[Peter Duniho]

Re: Integer Pool

On Mon, 03 Nov 2008 11:14:02 -0800, Trecius
<Trecius@discus sions.microsoft .comwrote:

Thank you, but it's not quite what I'm looking for. I may not know the
strName until runtime. For example, if I were to just start the
program, and
I have one element. I want to get one item from the pool -- maybe it
will be
1. Now I know that no other item can be 1. Next, if I have another
element
at run time, I want to get another handle. I call the pool for another
handle, and it gives me one -- maybe it will be 2. Now maybe I'm done
with
the first handle and no longer require it, so I release the handle back
to
the pool, so if I call the pool for another handle, it may return a 1 to
me
because I had already release it.

Here's an implementation of the above, that is basically what I described
as the third proposal in my previous reply:

class IntPool
{
private int _iCur;
private List<int_liReti red = new List<T>();

public int GetNext()
{
int iRet;

if (_liRetired.Cou nt 0)
{
iRet = _liRetired[_liRetired.Coun t - 1];
_liRetired.Remo veAt(_liRetired .Count - 1);
}
else
{
unchecked { iRet = _iCur++ };
if (_iCur == 0)
{
// All 4 billion integers are currently in use!
throw new InvalidOperatio nException("no more ints
available");
}
}

return iRet;
}

public void Retire(int i)
{
_liRetired.Add( i);
}
}

Apologies for typos and minor bugs...I didn't compile this, never mind
test it.

Pete