Optimizing a pooling mechanism... - C / C++ / MFC Discussion Boards

Re: strtok - reconstruct string after it finds a token

Renjith Ramachandran27-Dec-02 13:27

Renjith Ramachandran

27-Dec-02 13:27

substring by using strstr()?

~~~~Code the Dreams~~~~~

Where is random() in Visual C++.net ?

HellShrimp4free27-Dec-02 9:52

HellShrimp4free

27-Dec-02 9:52

hi i searched the MSDN but i findout out that the random() function in stdlib.h is not exist.
it seems that it's replaced with srand() and rand() . can anyone explain me how can i use these 2 function or any other to reach random numbers in requested range ? (for example 0 < x < 1000 )

thnx

Re: Where is random() in Visual C++.net ?

Nish Nishant27-Dec-02 10:00

Nish Nishant

27-Dec-02 10:00

See http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclib/html/_crt_rand.asp for an example.

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Re: Where is random() in Visual C++.net ?

HellShrimp4free27-Dec-02 10:11

HellShrimp4free

27-Dec-02 10:11

thanks mr.nishant but it seems that in this example the Range of Figures are not important.
may be i should do something like this :

<br />
int r=1000;<br />
while(1){ r=rand(); if (r<999) break; }

thanks any way.

-=Fight with be Best Die like the Rest=- Big Grin | :-D

Re: Where is random() in Visual C++.net ?

S O S27-Dec-02 10:28

S O S

27-Dec-02 10:28

*cough* modulus *cough* Wink | ;)

Know that good little % operator?
I wonder what this would do:

min + (rand() % (max - min + 1))

Re: Where is random() in Visual C++.net ?

Nick Parker27-Dec-02 11:04

Nick Parker

27-Dec-02 11:04

HellShrimp4free wrote:
but it seems that in this example the Range of Figures are not important.

Correct, in the MSDN example the range isn't important, however you can do the following to limit your range to under 1000:

#include "stdafx.h"

#include <stdlib.h>
#include <stdio.h>
#include <time.h>

#using <mscorlib.dll>
#include <tchar.h>

using namespace System;

// This is the entry point for this application
int _tmain(void)
{
   srand( (unsigned)time( NULL ) );
   for( int i = 0;   i < 10;i++ )
      printf( "  %6d\n", rand()%1000 );
   Console::Read();
}

Nick Parker

You see the Standards change. - Fellow co-worker

Re: Where is random() in Visual C++.net ?

UrbanBlues27-Dec-02 22:11

UrbanBlues

27-Dec-02 22:11

Hi

Those two functions have always been there. In fact I never used (saw ?) the function Random()

Here is how to use them:

// Seed Random-number Generator with Current Time
srand(( unsigned) time(NULL ));

int nRandomData = rand() % 4;

Replace 4 with the Maximum value accepted (1000 in your request)

The call to srand with current time allows the generation of different random sequences. If you start always with the same number, you always got the same sequence ( as far as I remember) ...

HTH

Thierry

Optimizing a pooling mechanism...

Matt Gullett27-Dec-02 9:29

Matt Gullett

27-Dec-02 9:29

I have a Windows NT service which maintains a pool of objects. The purpose of the pool is to improve performance because the objects being pooled require a signifigant amount of time for construction.

At any given time, there can be from 0-N requests for objects from the pool. There are times when the pool will have no requests at all for days. Other times, it will have 1000s of requests an hour/minute. I keep track of # of requests, avg time between requests, first request, last request, time to allocate, time to fill request, peak objects in pool, peak requests per sec/min, # of requests made when pool was exausted.

I am looking for an algorithm that will limit the number of requests that occur when the pool is exausted while not exceeding a maximum pool size or memory usage. There really is not MAX size, but I don't want to just allocate 1000s all the time. My goal would be to have 75-85% of requests filled by the pool with no waiting.

Currently, the algorithm I use is something like this:

(Pseudocode Smile | :)

long lDesiredPoolSize = lMinSize;

// NOTE: I multiply by 1.25 to give myself a 25% cushion

// if the last 5 minutes are more active than the hour, use last 5 minutes
if (lRequestsLast5Minutes > (lRequestsLastHour / 12) && lRequestsLast5Minutes > lDesiredPoolSize)
   lDesiredPoolSize = lRequestsLast5Minutes * 1.25;

// if we are getting many pool-exausted scenarios, base off this
if (lPoolExaustedRequests > lDesiredPoolSize)
   lDesiredPoolSize = lPoolExaustedRequests * 1.25;

// if activity last hour >= activity at peak, use peak
if (lRequestsLastHour >= lRequestsAtPeak)
   lDesiredPoolSize = lRequestsLastHour * 1.25;

// make sure we don't exceed the max
if (lDesiredPoolSize > lMaxPoolSize)
   lDesiredPoolSize = lMaxPoolSize;

// if no requests in past hour, empty pool
if (lRequestsLastHour == 0)
   lDesiredPoolSize = 0;

I just made this up and tinkered with it, but I wonder if anyone in CPland has any more experience with this kind of thing?

CSliderCtrl and textout

ns27-Dec-02 9:01

27-Dec-02 9:01

I get the position of the slider and do a textOut with it. After the slider reaches a 100, and the text says 100, when I slide it back, a part of the last zero doesnt get cleaned off the screen and the textout looks like:

34 ) etc.

How do I make the remnants of the prev numbers go away? I thought of doing an Invalidate() after the textout but then the number totally vanishes (because its not being written out in OnDraw() but in OnHScroll. In HScroll I get the pointer to the scrollbar, so I can GetPos. How would I access this getPos in OnDraw(0 so that I could see the refreshed text?

Appreciate your help,
ns

Re: CSliderCtrl and textout

PJ Arends27-Dec-02 9:41

PJ Arends

27-Dec-02 9:41

Draw a couple spaces after the number? (ie "34 ")

CPUA 0x5041

Sonork 100.11743 Chicken Little

"So it can now be written in stone as a testament to humanities achievments "PJ did Pi at CP"." Colin Davies

Within you lies the power for good - Use it!

Re: CSliderCtrl and textout

ns27-Dec-02 9:45

27-Dec-02 9:45

Wow!

I did 
s.Format("%d    ", position);

and that took care of it!
Thanks!!!

Appreciate your help,
ns

MDI: Single Doc, Multiple Views

Dean Goodman27-Dec-02 9:00

Dean Goodman

27-Dec-02 9:00

I've searched all over (CodeProject and the Internet at large) and I have not been able to find the answer to my problem, so here goes.

I have an MDI app where I would like to be able to open a document and immediately present the user with multiple views of the same document -- one will be the primary view, and I'd like to have two secondary views. I know that the CDocument class has a member function called AddView(), but I don't know where to add my secondary views. Where would I add my other views -- in MainFrm, ChildFrm, or elsewhere? And would using the AddView() member function be the appropriate way of accomplishing what I'm trying to do?

Thanks,

Dean

Re: MDI: Single Doc, Multiple Views

C^hris L^osinger27-Dec-02 10:25

C^hris L^osinger

27-Dec-02 10:25

take a look at: http://www.codeguru.com/doc_view/index.shtml. there are multiple articles there that show how to do multiple views on a single doc.

-c

I'm not the droid you're looking for.

ThumbNailer

CIPAddressCtrl example

ns27-Dec-02 8:18

27-Dec-02 8:18

I know how to do a .Create() and make one, but what does one do after retrieving the address the
user enters? WHich control will accept this address and open the webpage it points to? Is there a sample that shows how the addressctrl communicates this info to the ctrl that actually opens the webpage (which also I need to know about)
Thanks

Appreciate your help,
ns

Activating a window and bringing it to the top

Navin27-Dec-02 7:23

Navin

27-Dec-02 7:23

ARGH - this is killing me. All I am trying to do is take a dialog, bring it to the front, centered, and activated. And I CAN'T for the life of me figure out how to do all three! Here is some code I have tried, in the dialogs, OnInitDialog handler:

BOOL CongratsDlg::OnInitDialog()
{
   ...
   CenterWindow();
   ShowWindow(SW_RESTORE);
// SetWindowPos(&wndTopMost, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);
}

I have tried various parameters in ShowWindow, and I have tried it with the SetWindowPos stuff, and without it... and with it but not ShowWindow... etc.

So what is the magic combination to show and activate a window?

Some background: this is an MFC app. It has no main window - it launches some other app, waits for it to finish, and then pops up this dialog.

Muchas gracias.

Even a broken clock is right twice a day.

Re: Activating a window and bringing it to the top

Navin27-Dec-02 7:28

Navin

27-Dec-02 7:28

Hmm - I may have answered my own question. It seems like if I have the Start menu active at all - even if I activate it long before this dialog comes up, the window won't activate. It seems that in any other situation, the code I have above works.

Ah well.

Even a broken clock is right twice a day.

Re: Activating a window and bringing it to the top

Nish Nishant27-Dec-02 7:28

Nish Nishant

27-Dec-02 7:28

Navin wrote:
So what is the magic combination to show and activate a window?

Try SetForegroundWindow

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Regarding terminology

Nish Nishant27-Dec-02 6:27

Nish Nishant

27-Dec-02 6:27

Hey guys

I just told someone on a forum that CString has an implicit const char* operator. Now I suddenly realized that this is actually wrong grammar or usage or whatever. I mean implicit operators are the ones the compile does for us huh? Like conversion of int to char etc... So I should not have used the word implicit there, right? But then it's not an explicit operator either cause the user need not actually put a cast there. So can someone gimme some info on best usage practices for such stuff, so that I wont confuse other people in future

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Re: Regarding terminology

AlexO27-Dec-02 6:47

AlexO

27-Dec-02 6:47

It is more question of English language, than programming. Stroustrup writes something like "operator const char*() ... provided convenience of an implicit conversion..."(#20.3.7). I understand that as an operator provides some implicit action, but itself cannot be implicit. But again, I am not a native English speaker. Smile | :)

Re: Regarding terminology

Nish Nishant27-Dec-02 6:55

Nish Nishant

27-Dec-02 6:55

Thanks Alex. I guess I'll trust my instincts and use implicit when I feel it's implicit Smile | :)

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Re: Regarding terminology

Michael Dunn27-Dec-02 6:59

Michael Dunn

27-Dec-02 6:59

You should have said "an LPCTSTR operator" Wink | ;)

But seriously, since all operator TYPE() functions can be invoked implicitly, you weren't completely wrong.

--Mike--
If it doesn't move and it should: WD-40. If it moves and it shouldn't: duct tape.

1ClickPicGrabber - Grab & organize pictures from your favorite web pages, with 1 click!
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Sonork-100.19012 Acid_Helm

Re: Regarding terminology

Nish Nishant27-Dec-02 7:23

Nish Nishant

27-Dec-02 7:23

Michael Dunn wrote:
You should have said "an LPCTSTR operator"

Yup Wink | ;-)

I knew you'd say this to me Smile | :)

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

PROGRAM ICONS (portability and configurability)

Anonymous27-Dec-02 6:01

Anonymous

27-Dec-02 6:01

Hi.
Anyone know of a portable way
of doing program icons
(the kind you see when looking in a folder)?

Got an example?

How do I go about making
the program icon a separate file
(so if i edit it, i don't have to recompile)?

Any reading you can point me to, i'd really appreciate it.

message map question

ns27-Dec-02 5:22

27-Dec-02 5:22

So far I'd been making projects with CFormView, so when I wanted to adda handler for the bn_clicked I would just dbl click on the control, say a button, and the ONButtonA type function would be created and automatic messagemap entries made.

Now I have a CView project and am having to add the controls using .Create() so I cant very well dbl click to add the handler automatically. In this case am I responsible for making messagemap entries? Is there no automatic mechanism for this?
Thanks

Appreciate your help,
ns

Re: message map question

valikac27-Dec-02 6:07

valikac

27-Dec-02 6:07

One solution is to add the messages to the message map.

afx_msg BtnHandler()
ON_BN_CLICKED(ID, Handler);

Kuphryn

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.