I have a thread that fetch elements from a std:queue, which are pushed from other threads. My question is how can I fetch elements from the queue in a blocking mode, what I mean is if there are no elements in the queue then the fetch call will block until at least one element is pushed. Of course I want to do it this way to avoid polling.
View 6 RepliesI am trying to create program which will process command line arguments and define which functions should be run, with specific order and specific arguments. This is my first problem:
Code:
// proccessing_args.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <vector>
#include <string>
#include <iostream>
#include <conio.h>
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
[Code] ....
proccessing_argsproccessing_args.cpp(20): error C2143: syntax error : missing ',' before ':'
refers to the line with for. I copied the code form here [URL] .....
I have a paradigm in a loop of queues of a vector,if a condition is true,increase sizes of the queue of that particular queue in the loop of queues, if condition is false, the queuesize is left as such in loop of queues. After this operation i need to search the queue sizes of all queues and enqueue in the shortest queue.
I want to do something like the code given below
#include <vector>
#include <queue>
int min_index = 0;
std::vector<std::queue<int> > q
std::size_t size = q.size();
[Code] ....
How to implement this logic?
will q[i].size=q[i].size+5 increase the queuesize by 5 for the ith queue?
I have an issue where I iterate through devices and make driver API calls. Unfortunately, these calls take too much time and they are interrupting my real-time scheduler. I have 12 cores, of which one is 100% and the others are < 1%.
I'd like to multi-thread this thing. So far, I've replaced:
for (DeviceIterator d = devices.begin(); d != devices.end(); ++d) {
d->Write(words, numwords);
}
with
void* ThreadedWrite(void* p) {
WritePackage* wp = (WritePackage*)p;
wp->device->Write(wp->words, wp->numwords);
delete[] wp->words;
delete wp;
[Code]...
My problem is that this didn't improve performance at all. The main thread still takes too long to execute. Is there something I need to do to prevent the main thread from blocking?
I have a class holding my data strcuture:
// Holding real time option data - should be thread safe
public class OptionRTHolder {
ConcurrentDictionary<double, Quates> book_calls;
ConcurrentDictionary<double, Quates> book_puts;
ConcurrentDictionary<double, List<Single_qoute>> transaction_calls;
ConcurrentDictionary<double, List<Single_qoute>> transaction_puts;
ConcurrentDictionary<double, int> volume_calls;
ConcurrentDictionary<double, int> volume_puts;
DateTime curr_time;
}
I get a stream of data messages, that come in order, each message carries a time and data. I have many threads in paralell pulling messages and in turn update the data strucutre as follows:
Quates and volume data are just overrun (new value overrun former values), also thier size and meta data is fixed (they don't grow post init).
Via the list I have a problem, I would want to lock only the list I am working on. so other lists can update in paralell, what I had in mind was to warp the list in order to warp the add/get calls to make it thread safety, this I think will achieve this goal and I would like to get some assertion from this forum if you may.
Here come my real problem, there are points in time I want to read/copy this structure, during this time I want to block all updating threads as I want to freeze structure in time, is that achiveable ? Idea that I had is to use something like aquire that will get a function (update/read) and a flag that will cause a lock when the read is on...something like that.
My problem: I want to make an application that is going to block the action of some files (It is anticheat files actually).
how do I make code to block the application's action?
Maybe there is another way to do that? I need to use Cheat Engine in game, and anticheat blocks it, so I thought if I'll block the activity of the anticheat it couldn't detect the Cheat Engine...
I wanted to create an asynchronous/non-blocking udp client server application where the client and server were supposed to chat away with each other without waiting for each other's turns. I came to know that this could be done by select()... here is my Server(Mentioning only the communication part):
Code:
fd_set readfds,writefds;
while(1){
FD_ZERO(&readfds);
FD_ZERO(&writefds);
FD_SET(sd,&readfds);
FD_SET(sd,&writefds);
int rv = select(n, &readfds, NULL, NULL, NULL);
[Code] .....
At first on the server side I wrote:
int rv = select(n, &readfds, &writefds, NULL, NULL);
But that led to the printing of an entire empty array on the server console when the server initialised in addition to the fact that communication between the server and client was not proper. removing "&writefds" did remove the redundant data but the improper communication issue still persists...
I am writing an application that needs to temporarily disable the Play/Pause button that appears on multimedia keyboards.
Normally, a key can be blocked quite easily by installing a low level keyboard hook (WH_KEYBOARD_LL) where the KeyboardProc intercepts the key (in this case VK_MEDIA_PLAY_PAUSE) and returns a "1" instead of calling CallNextHookEx. I have tried this with other keys (including the Windows key VK_LWIN) and this works perfectly. I also have no problems with this method under Windows 7 where all keys, including VK_MEDIA_PLAY_PAUSE get blocked.
Windows 8 is a different story. When my application has input focus, everything works as expected, meaning the VK_MEDIA_PLAY_PAUSE key gets blocked and no other application responds to it. However, when my application loses focus, my hook procedure gets called (this was verified by sending out a OutputDebugString) but other applications respond to key even though I return a "1". As soon as my app gets focus again, everything is block as it should.
After some investigation, I found that the multimedia keys not only generate keystrokes but also generate WM_APPCOMMAND messages so I added ShellProc (WH_SHELL) hook with the following hook procedure:
LRESULT __declspec(dllexport)__stdcall CALLBACK ShellProc(int nCode,WPARAM wParam,LPARAM lParam) {
// Do we have to handle this message?
if (nCode == HSHELL_APPCOMMAND) {
OutputDebugStringX(">>>>> HSHELL_APPCOMMAND");
[code]....
This procedure is only getting called when my app has input focus. Whenever I have input focus and return "1" the Play/Pause command gets blocked. As soon as I lose focus the procedure does not get called/hooked.
As I have mentioned, the code works for other keys, just not the multimedia keys.
Alternatively, another way of blocking the multimedia keyboards Play/Pause button?
I have a string (zoneId==176)&&((startTime==100)&&(endTime==1200)) from which i want to fetch value of startTime and endTime in C#.
View 7 Replies View RelatedI am Using a fingerprint Scanner for attendance posting.
finger print reader vendor is essl,model is[URL] The device is connected on lan,It has option to download the users list and attendance list to pendrive in .dat format.
I am looking for fetching these data from device through any of the network computers other than manually copying to pendrive from the device each time.
Is it possible to download data from device through any of the network machines Using C# code ?
I am getting a excel sheet in datatable with some column "Program,Response,T,Timein".There is 3 condition for filtering datatable.
1.fetch unique program.so i got dis.
2.T not equal to "B". I also got dis.
3.Response should be > 5000. I also got dis data in datatable.
Now in Datatable I have same program name presented 3 times with response>5000 nd T<>B.Now I want to fetch only the maximum respnse among 3 of them. so every time my program should be change and for that program I need to pickup max response so How can I do this? for the same I put two loops
for (int i = 0; i < DataFilter.Rows.Count; i++) {
DataRow dr = DataFilter.Rows[i];
DataView dv2 = new DataView();
[Code]....
I am having some column say "Response" column in my Datatable.Now I want to fetch this particular column value and compare this value with the maximum response how to fetch and compare it in C#.net .. This is my code.
for (int i = 0; i < DataFilter.Rows.Count; i++) {
DataRow dr = DataFilter.Rows[i];
DataView dv2 = new DataView();
dv2 = DataFilter.DefaultView;
[Code] ......
i have a spec for fetch the files from server and predict the un-used files from the directory in this situation i am going to fetch the files from server it will return huge files, the problem is the cpu usage will increase while i am fetching large files, so i like to eliminate this scenario.
View 1 Replies View RelatedI fetch maxid row to view in datagridview using the following code :
public static DataTable GetMaximpID() {
string strconn = AlShehabi.Properties.Settings.Default.NewSalariesDBConnectionString;
SqlConnection conn = new SqlConnection(strconn);
if (conn.State == ConnectionState.Closed)
[Code] ....
But I want to fetch all rows inserted and view in datagridview.... For example if user insert 4 rows I want to view them in datagridview after insert them using insertbutton_click....
I want to write my own application which would fetch some data from a web site. I need to parse the HTML code of the web site and get the data.
About the application:A form (main form) that will contain data arranged in rows. Some of the data comes from a web site and some of it comes from a database.The data that comes from the web site needs to be updated every few seconds so I need to keep fetching the data from the web site.The main form will contain a button "add" which when clicked will add a new row. New data can be added to this row by the user.
I am not sure what to use for this. I have been writing the application as a Windows Form Application (Visual C#) but I do not know whether this is the best choice. Should it be a windows form application or web application? Should I use something else?
I have a SSD and I am trying to use it to simulate my program I/O performance, however, IOPS calculated from my program is much much faster than IOMeter.
My SSD is PLEXTOR PX-128M3S, by IOMeter, its max 512B random read IOPS is around 94k (queue depth is 32). However my program (32 windows threads) can reach around 500k 512B IOPS, around 5 times of IOMeter!!! I did data validation but didn't find any error in data fetching. It's because my data fetching in order?
I paste my code belwo (it mainly fetch 512B from file and release it; I did use 4bytes (an int) to validate program logic and didn't find problem).
#include <stdio.h>
#include <Windows.h>
/*
** Purpose: Verify file random read IOPS in comparison with IOMeter
**/
//Global variables
long completeIOs = 0;
long completeBytes = 0;
int threadCount = 32;
unsigned long long length = 1073741824; //4G test file
[Code] ....
What is Function call Overhead and Function Call Stack?
View 2 Replies View RelatedHow to build a FiFO queue without using the STL (done that no problem), get it to dequeue (again, done that no problem). However, to get those extra marks, I need to be able to order it using a priority system.
I've tried ordering the NodeDequeue class that I'll show at the bottom of this post, but I just cannot get it to order appropriately. The closest I have got is everything in order but I lose a Node from the memory completely. So, that's no good.
The most logical idea I have thought of right now is to send the largest number to the back of the queue each time it's iterated, eventually, the largest number will end up at the front.
class PriorityQueue : public Queue {
public:
Node* NodeDequeue(void) {
Node* tmp = front;
Node* seek = tmp->getPrev();
[Code] .....
I'm having a problem with removing an item from a queue. At first in the debugger I got SIGTRAP but I don't get it anymore but the problem still exists. When you try to remove an item from the queue the first nothing happens. Here's the code below compile it and you see what I'm talking about.
Code:
#include <stdio.h>
#include <stdlib.h>
struct Node {
char let;
struct Node *nextNode;
};
[code]....
I have an assignment that needs to display the names of customers to be served according to a sequence. coding to display the names accordingly?
Code:
#include <stdio.h>
#include <stdlib.h>
#define MAXIMUM 20
void create();
[Code].....
This is my output. I have trouble displaying the names of the customers as it outputs null when I try to display my position in queue.
Why is this code not marking that the queue is full.. I'm just including my Add function that verifies if they want to add another number to the queue. The isFull function works fine, have used it on other programs.
template <class T> //Template currSize function
int Queue<T> :: currSize ()
{
return (rear - front + arraylength) % arraylength; //
[Code].....
The output goes all the way down to 1 spot left, lets the user enter the last element. Then it asks if they want to add another.. At this point, when they hit Y, it lets them add it and it says there are 5 spots left!
I'm trying to implement Prim's Algorithm and for that I need to have a decreaseKey method for a priority queue (to update the key value in a priority queue). Can I implement this in the STL Priority Queue?
This is the algorithm I'm following:
for each vertex u in graph G
set key of u to INFINITY
set parent of u to NIL
set key of source vertex to 0
en-queue to priority queue Q all vertices in graph
[Code] .....
I've got a priority queue of items who, from time to time, returns a different comparison result. Any way to re-sort a priority queue who is storing them?
Example:
#include <cstdlib>
struct Random {
bool operator<(const Random&) const { return !(rand()&1); } };
I've been working on a little project and hit a snag. I'm using nodes for a queue and stack class that were created using an existing list node class. I create an object for a student class and I want to enqueue that object.
int main() {
Queue sLine;
Customer stu;
Queue<Student &>
cLine.enqueue(cust);
}
That's basically the coding of it in main. However when I follow the error which says uninitialized reference member ListNode<Student& info>::data;
#ifndef LISTND_H
#define LISTND_H
template< class T > class List;
template< class NODETYPE >
class ListNode {
friend class List< NODETYPE >;
[Code] .....
What I may have been doing wrong? Trying to work within certain contexts.
Is there any possible way to create an STL queue of arrays? I tried
queue<int[]>q;
It didn't work?
what is the empty state of queue?
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