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  • Initialisation of Objects Syntax question

    - by Brock Woolf
    When I initialise a struct in C (Node is the struct): struct Node { /* Non-Relevant code */ }; This works: Node *rootNode = new Node(); but so does this: Node *rootNode = new Node; Is there a difference, and what is the difference between using () or not using the brackets? Just off memory, I think the same applies above for C++ object initialisations. What is happening here?

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  • Queue Data structure app crash with front() method

    - by Programer
    I am implementing queue data strcutre but my app gets crashed, I know I am doing something wrong with Node pointer front or front() method of queue class #include <iostream> using namespace std; class Node { public: int get() { return object; }; void set(int object) { this->object = object; }; Node * getNext() { return nextNode; }; void setNext(Node * nextNode) { this->nextNode = nextNode; }; private: int object; Node * nextNode; }; class queue{ private: Node *rear; Node *front; public: int dequeue() { int x = front->get(); Node* p = front; front = front->getNext(); delete p; return x; } void enqueue(int x) { Node* newNode = new Node(); newNode->set(x); newNode->setNext(NULL); rear->setNext(newNode); rear = newNode; } int Front() { return front->get(); } int isEmpty() { return ( front == NULL ); } }; main() { queue q; q.enqueue(2); cout<<q.Front(); system("pause"); }

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  • CSS style refresh in IE after dynamic removal of style link

    - by rybz
    Hi! I've got a problem with the dynamic style manipulation in IE7 (IE8 is fine). Using javascript I need to add and remove the < link / node with the definition of css file. Adding and removing the node as a child of < head / works fine under Firefox. Unfortunately, after removing it in the IE, although The tag is removed properly, the page style does not refresh. In the example below a simple css (makes background green) is appended and removed. After the removal in FF the background turns default, but in IE stays green. index.html <html> <head> </head> <script language="javascript" type="text/javascript"> var node; function append(){ var headID = document.getElementsByTagName("head")[0]; node = document.createElement('link'); node.type = 'text/css'; node.rel = 'stylesheet'; node.href = "s.css"; node.media = 'screen'; headID.appendChild(node); } function remove(){ var headID = document.getElementsByTagName("head")[0]; headID.removeChild(node); } </script> <body> <div onClick="append();"> add </div> <div onClick="remove();"> remove </div> </body> </html> And the style sheet: s.css body { background-color:#00CC33 } Here is the live example: http://rlab.pl/dynamic-style/ Is there a way to get it working?

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  • Skip first entry in Drupal Views Query?

    - by RD
    I've created a view that selects all nodes of type "shoot". But I want it to select all nodes of type "shoot", EXCEPT for the first entry. So, if the normal result is: Node 1 Node 2 Node 3 I want Node 2 Node 3 Node 4 Is that possible?

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  • what is mistakes/errors in this code c++ tell me the correction ??

    - by jeje
    hello all here in this code the compiler print error : 132 C:.... `createlist' undeclared (first use this function) (Each undeclared identifier is reported only once for each function it appears in.) and repeat it again in all calls in main function :( what's the problem ?? plzzzz help me #include<iostream> #include<string> using namespace std; template <typename T> struct Node { T num; struct Node<T> *next; // to craet list nodes void createlist(Node<T> *p) { T data; for( ; ; ) // its containue until user want to stop { cout<<"enter data number or '#' to stop\n"; cin>>data; if(data == '#') { p->next =NULL; break; } else { p->num= data; p->next = new Node<T>; p=p->next; } } } //count list to use it in sort function int countlist (Node<T> *p) { int count=0; while(p->next != NULL) { count++; p=p->next; } return count; } // sort list void sort( Node<T> *p) { Node<T> *p1, *p2; //element 1 & 2 to compare between them int i, j , n; T temp; n= countlist(p); for( i=1; i<n ; i++) { // here every loop time we put the first element in list in p1 and the second in p2 p1=p; p2=p->next; for(j=1; j<=(n-i) ; j++) { if( p1->num > p2->num) { temp=p2->num; p2->num=p1->num; p1->num=temp; } } p1= p1->next; p2= p2->next; } } //add new number in any location the user choose void insertatloc(Node<T> *p) { T n; //read new num int loc; //read the choosen location Node<T> *locadd, *newnum, *temp; cout <<" enter location you want ..! \n"; cin>>loc; locadd=NULL; //make it null to checked if there is location after read it from user ot not while(p->next !=NULL) { if( p->next==loc) { locadd=p; break; } p=p->next; } if (locadd==NULL) {cout<<" cannot find the location\n";} else //if location is right {cout<<" enter new number\n"; // new number to creat also new location for it cin>>n; newnum= new Node/*<T>*/; newnum->num=n; temp= locadd->next; locadd->next=newnum; newnum->next=temp; } locadd->num=sort(locadd); // call sort function } // display all list nodes void displaylist (Node<T> *p) { while (p->next != NULL) { cout<<" the list contain:\n"; cout<<p->num<<endl; p=p->next; } } };//end streuct int main() { cout<<"*** Welcome in Linked List Sheet 2****\n"; // defined pointer for structer Node // that value is the address of first node struct Node<int>*mynodes= new struct Node<int>; // create nodes in mynodes list cout<<"\nCreate nodes in list"; createlist(mynodes); // insert node in location insertatloc(mynodes); /* count the number of all nodes nodescount = countlist(mynodes); cout<<"\nThe number of nodes in list is: "<<nodescount;*/ // sort nodes in list sort(mynodes); // Display nodes cout<<"\nDisplay all nodes in list:\n"; displaylist(mynodes); system("pause"); return 0; }

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  • Drupal Ubercart: error in passing values back to the Content Type after checkout

    - by user512826
    I am trying to set up event registration in a drupal site using Ubercart + the UC Node Checkout Module. I have followed the instructions provided in http://drupaleasy.com/blogs/ultimike/2009/03/event-registration-ubercart. However I seem to be unable to pass the Order ID and Payment Status back to the node. I have created a conditional action that on node checkout executes the following PHP code: I am using the following code to update the node on checkout - but nothing happens: if (isset($order)) { foreach ($order->products as $product) { if (isset($product->data['node_checkout_nid'])) { $node = node_load($product->data['node_checkout_nid']); $node->field_status['0']['value'] = 1; $node->field_orderid['0']['value'] = $order->order_id; node_save($node); } } } I know the conditional action is working because it prints dsm('hello world') messages on node checkout - however when I include a dsm($node) or dsm($product) in the PHP code, they return blank. Also when I go back to my product and click the 'Devel' tab, the 'data' string contains the following characters: a:1:{s:13:"form_build_id";s:37:"form-3ccc03345f4832c69666a89c560de940";} In this link http://www.ubercart.org/forum/support/10951/node_checkout_issue I found someone else with the same issue, but I have been unable to replicate his solution. Can anybody please help? Thanks so much!

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  • Jquery nested div .click event

    - by Sylph
    The link #loadContent will loads tree.html. Upon success loading the content, the script reinitialize some functions which is in tree.html. However, I am unable to get the .click event to function in the loaded content. Index.html <a href="#" id="loadContent">Load</a> <script type="text/javascript"> $(function() { $("#loadContent").click(function() { $.ajax({ url: "tree.html" ,success: function(data) { $('#result').html(data); $("#demo_1").tree({ rules : { use_max_children : false, use_max_depth : false }, callback : { onmove : function (NODE,REF_NODE,TYPE,TREE_OBJ,RB) { alert(TREE_OBJ.get_text(NODE) + " " + TYPE + " " + TREE_OBJ.get_text(REF_NODE)); } } }); } }); }); }); </script> <script type="text/javascript" class="source"> $(function () { $.tree.drag_start = function () { $("#log").append("<br />Drag start "); }; $.tree.drag = function () { $("#log").append(" ."); }; $.tree.drag_end = function () { $("#log").append(" Drag end<br />"); }; $("#demo_1").tree({ rules : { use_max_children : false, use_max_depth : false }, callback : { onmove : function (NODE,REF_NODE,TYPE,TREE_OBJ,RB) { alert(TREE_OBJ.get_text(NODE) + " " + TYPE + " " + TREE_OBJ.get_text(REF_NODE)); } } }); $("#demo_2").tree({ rules : { use_max_children : false, use_max_depth : false }, callback : { onmove : function (NODE,REF_NODE,TYPE,TREE_OBJ,RB) { alert(TREE_OBJ.get_text(NODE) + " " + TYPE + " " + TREE_OBJ.get_text(REF_NODE)); } } }); }); </script> <div class="demo" id="demo_2"> <ul> <li id="phtml_1" class="open"><a href="#"><ins>&nbsp;</ins>Root node 1</a> <ul> <li id="phtml_2"><a href="#"><ins>&nbsp;</ins>Child node 1</a></li> <li id="phtml_3"><a href="#"><ins>&nbsp;</ins>Child node 2</a></li> <li id="phtml_4"><a href="#"><ins>&nbsp;</ins>Some other child node with longer text</a></li> </ul> </li> <li id="phtml_5"><a href="#"><ins>&nbsp;</ins>Root node 2</a></li> </ul> </div> <div id="result"></div><br> <div id="log"></div> Tree.html <div class="demo" id="demo_1"> <ul> <li id="phtml_1" class="open"><a href="#"><ins>&nbsp;</ins>Root node 1</a> <ul> <li id="phtml_2"><a href="#"><ins>&nbsp;</ins>Child node 1</a></li> <li id="phtml_3"><a href="#"><ins>&nbsp;</ins>Child node 2</a></li> <li id="phtml_4"><a href="#"><ins>&nbsp;</ins>Some other child node with longer text</a></li> </ul> </li> <li id="phtml_5"><a href="#"><ins>&nbsp;</ins>Root node 2</a></li> <li><a class="preset_text" id="1">model 1</a> </li> <li><a class="preset_text" id="2">model 2</a></li> </ul> </div> <script type="text/javascript"> $(document).ready(function() { $('.preset_text').click(function(){ var target = $(this).attr("id"); alert(target); }); }); </script> In tree.html, I am unable to get the alert(target). However, If I moved this section out from the "div #demo_1" in tree.html, I am able to receive alert(target). <a class="preset_text" id="1">model 1</a> <a class="preset_text" id="2">model 2</a> How can I get to detect the item clicked in the div demo_1 ? Thanks

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  • adding elements in to the doubly linked list

    - by user329820
    Hi this is my code for main class and doubly linked class and node class but when I run the program ,in the concole will show this"datastructureproject.DoublyLinkedList@19ee1ac" instead of the random numbers .please help me thanks! main class: public class Main { public static int getRandomNumber(double min, double max) { Random random = new Random(); return (int) (random.nextDouble() * (max - min) + min); } public static void main(String[] args) { int j; int i = 0; i = getRandomNumber(10, 10000); DoublyLinkedList listOne = new DoublyLinkedList(); for (j = 0; j <= i / 2; j++) { listOne.add(getRandomNumber(10, 10000)); } System.out.println(listOne); } } doubly linked list class: public class DoublyLinkedList { private Node head ; private Node tail; private long size = 0; public DoublyLinkedList() { head= new Node(0, null, null); tail = new Node(0, head, null); } public void add(int i){ head.setValue(i); Node newNode = new Node(); head.setNext(newNode); newNode.setPrev(head); newNode = head; } } and the node class is like the class that you have seen before (Node prev,Node next,int value)

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  • How to hide canvas content from parent rounded corners in any webkit for Mac?

    - by Jose Rui Santos
    I have a parent div with rounded corners that contains a canvas: <div id="box"> <canvas width="300px" height="300px"></canvas> </div>? #box { width: 150px; height: 150px; background-color: blue; border-radius: 50px; overflow: hidden; }? The canvas renders a red rectangle that overflows the parent. As expected, this is what I get in all browsers: The problem: However, for webkit browsers running in Mac OS lion (I tested Safari 5.1.5 and Chrome 19), the canvas is still visible in the round corners: Interestingly, this problem seems to happen only when the inner element is a canvas. For any other child element, the content is correctly hidden. One workaround would be to apply the same rounded corners to the canvas itself, but unfortunately this is not possible, since I need to animate the canvas relative position. Another workaround that should work, is to redraw the canvas in a clipped region that resembles the rounded corners shape, but I would prefer a cleaner CSS3 solution. So, does one know how to fix this for Safari and Chrome on Mac? EDIT: Problem also happens in Chrome on Win7 jsFiddle here

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  • Understanding linear linked list

    - by ArtWorkAD
    Hi, I have some problems understanding the linear linked list data structure. This is how I define a list element: class Node{ Object data; Node link; public Node(Object pData, Node pLink){ this.data = pData; this.link = pLink; } } To keep it simple we say that a list are linked nodes so we do not need to define a class list (recursion principle). My problem is that I am really confused in understanding how nodes are connected, more precisely the sequence of the nodes when we connect them. Node n1 = new Node(new Integer(2), null); Node n2 = new Node(new Integer(1), n1); What is link? Is it the previous or the next element? Any other suggestions to help me understanding this data structure?

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  • Website displays in chrome perfectly, but not in mozilla or IE

    - by Atharul Khan
    here are the code snippets for the html and css. It works finds in Google chrome, but when I try to display it in mozilla or IE, it shows something completely different. I cannot attach images as I do not have the required reputation. I really appreciate the help. Thank you! HTML <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <meta http-equiv="Content-type" content="text/html; charset=utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1" /> <link rel="stylesheet" type="text/css" href="style.css"> <link rel="shortcut icon" href="ak.png"> <title>Home</title> </head> <body> <div class="Nav"> <nav> <ul class="navigation fade-in2"> <li><a href="#home">Home</a></li> <li><a href="#about">About</a></li> <li><a href="#portfolio">Portfolio</a></li> <li><a href="#shop">Shop</a></li> <li><a href="#blog">Blog</a></li> <li><a href="#contact">Contact</a></li> </ul> </nav> </div> <div class="logo"><a href="#home"><img class="ak fade-in2" src="ak.png"></a></div> <div class="background"><img class="beauty" src="beauty.jpg"></div> <div class="header"> <h1 class="headerName fade-in">DESIGN | DEVELOP | BRAND</h1> <h4 class="service fade-in3"><a href="#portfolio">VIEW PORTFOLIO</a></h4> <h4 class="service fade-in3"><a href="#services">VIEW SERVICES</a></h4> </div> <!--<div class="mainbody"><p>safsdaf</p></div>--> </body> </html> CSS @-webkit-keyframes fadeIn { from { opacity:0; } to { opacity:1; } } @-moz-keyframes fadeIn { from { opacity:0; } to { opacity:1; } } @keyframes fadeIn { from { opacity:0; } to { opacity:1; } } * { padding: 0; margin: 0; } li { display: inline; font-size: 15px; font-family: verdana; } nav { width: 100%; text-align: right; background-color: #222222; padding: 0; margin: 0px; line-height: 47px; position: fixed; z-index: 100; } .ak{ width: 90px; height: 55px; z-index: 101; position: fixed; background: transparent; color: transparent; background-color: transparent; } .Nav a{ text-decoration: none; padding: 15px; } .Nav a:link{ color: #A7A7A7; } .Nav a:visited{ color: #A7A7A7; } .Nav a:hover{ color: #DBDBDB; transition: all 0.3s ease-out 0s; transition-property: all; transition-duration: 0.3s; transition-timing-function: ease-out; transition-delay: 0s; } .header { background-color: rgba(0,0,0, 0.25); width: 100%; height: 626px; text-align: center; position: fixed; z-index: 10; } .background { position: fixed; z-index: 8; } .beauty { width: 100%; height: 626px; } .headerName { font-size: 2.5em; text-align: center; color: #D3D3D3; padding: 180px; padding-bottom: 50px; margin: 0px; letter-spacing: 4px; font-weight: 100; font-family: 'Lato', sans-serif; } .fade-in { opacity:0; /* make things invisible upon start */ -webkit-animation:fadeIn ease-in 1; /* call our keyframe named fadeIn, use animation ease-in and repeat it only 1 time */ -moz-animation:fadeIn ease-in 1; animation:fadeIn ease-in 1; -webkit-animation-fill-mode:forwards; /* this makes sure that after animation is done we remain at the last keyframe value (opacity: 1)*/ -moz-animation-fill-mode:forwards; animation-fill-mode:forwards; -webkit-animation-duration:1s; -moz-animation-duration:1s; animation-duration:1s; -webkit-animation-delay: 0.3s; -moz-animation-delay:0.3s; animation-delay: 0.3s; } .fade-in2 { opacity:0; /* make things invisible upon start */ -webkit-animation:fadeIn ease-in 1; /* call our keyframe named fadeIn, use animation ease-in and repeat it only 1 time */ -moz-animation:fadeIn ease-in 1; animation:fadeIn ease-in 1; -webkit-animation-fill-mode:forwards; /* this makes sure that after animation is done we remain at the last keyframe value (opacity: 1)*/ -moz-animation-fill-mode:forwards; animation-fill-mode:forwards; -webkit-animation-duration:1s; -moz-animation-duration:1s; animation-duration:1s; -webkit-animation-delay: 0.6s; -moz-animation-delay:0.6s; animation-delay: 0.6s; } .fade-in3 { opacity:0; /* make things invisible upon start */ -webkit-animation:fadeIn ease-in 1; /* call our keyframe named fadeIn, use animation ease-in and repeat it only 1 time */ -moz-animation:fadeIn ease-in 1; animation:fadeIn ease-in 1; -webkit-animation-fill-mode:forwards; /* this makes sure that after animation is done we remain at the last keyframe value (opacity: 1)*/ -moz-animation-fill-mode:forwards; animation-fill-mode:forwards; -webkit-animation-duration:1s; -moz-animation-duration:1s; animation-duration:1s; -webkit-animation-delay: 0.9s; -moz-animation-delay:0.9s; animation-delay: 0.9s; } .service{ font-size: 14px; width: 190px; text-align: center; font-family: 'Lato', sans-serif; color: #D3D3D3; border: 2px #A7A7A7 solid; border-color: rgba(255, 255, 255, 0.5); display: inline-block; border-radius: 5px; background-color: transparent; letter-spacing: 2px; } .service a{ text-decoration: none; display: block; padding: 15px 20px; } .service a:link{ color: #D3D3D3; } .service a:visited{ color: #D3D3D3; } .service a:hover{ background-color: rgba(255, 255, 255, 0.15); transition: background-color .15s ease-in; -webkit-transition: background-color .15s ease-in; -moz-transition: background-color .15s ease-in; -o-transition: background-color .15s ease-in; } UPDATE 1: I updated both browsers and it seems the css3 animations work perfectly fine on both browsers. What seems to be the problem is the positioning of the pages UPDATE 2: Here are the links to the different browser screen shots Chrome: https://www.dropbox.com/s/jlpa4vu51kdnews/Chrome.JPG InternetExplorer: https://www.dropbox.com/s/zbchs3su9ahxr0n/IE.JPG Mozilla Firefox: dropbox(.)com/s/fyalnhsha9ktadz/Mozilla.JPG (I can't post the third link because I don't have enough reputation)

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  • Binary Search Tree, cannot do traversal

    - by ihm
    Please see BST codes below. It only outputs "5". what did I do wrong? #include <iostream> class bst { public: bst(const int& numb) : root(new node(numb)) {} void insert(const int& numb) { root->insert(new node(numb), root); } void inorder() { root->inorder(root); } private: class node { public: node(const int& numb) : left(NULL), right(NULL) { value = numb; } void insert(node* insertion, node* position) { if (position == NULL) position = insertion; else if (insertion->value > position->value) insert(insertion, position->right); else if (insertion->value < position->value) insert(insertion, position->left); } void inorder(node* tree) { if (tree == NULL) return; inorder(tree->left); std::cout << tree->value << std::endl; inorder(tree->right); } private: node* left; node* right; int value; }; node* root; }; int main() { bst tree(5); tree.insert(4); tree.insert(2); tree.insert(10); tree.insert(14); tree.inorder(); return 0; }

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  • Understanding of a C Code Required..

    - by RBA
    int Size(struct node* node) { if(node == NULL) { return 0; } else if(node != NULL) { return (Size(node->left) + 1 + Size(node->right)); } } Hi, Can Anybody please post the stack trace for the following piece of code. Lets say if we insert the values 2, 1, 10, 5... Then what could be the stack representation during the recursion process.. Please, its very urgent, and its very confusing too...

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  • Haskell graph data type representation

    - by John Retallack
    I want to represent a graph in Haskell in the following manner: For each node I want to store it's value and a list of adjacent nodes,the problem which i'm having difficulties with is that I want the adjacent nodes to be stored as references to other nodes. For example: I want node ny to be stored as („NY“ (l p)) where l and p are adjacent nodes,and not as („NY“ („London“ „Paris“)). I tried something like this : data Node a = Node { value :: a , neighbors :: [Node a] }deriving (Show) let n1 = Node {value=1, neighbors=[n2]} let n2 = Node {value=1, neighbors=[n1 n3]} let n3 = Node {value=1, neighbors=[n2]} But i get en error in let,What am I doing wrong ?

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  • Following the Thread in OSB

    - by Antony Reynolds
    Threading in OSB The Scenario I recently led an OSB POC where we needed to get high throughput from an OSB pipeline that had the following logic: 1. Receive Request 2. Send Request to External System 3. If Response has a particular value   3.1 Modify Request   3.2 Resend Request to External System 4. Send Response back to Requestor All looks very straightforward and no nasty wrinkles along the way.  The flow was implemented in OSB as follows (see diagram for more details): Proxy Service to Receive Request and Send Response Request Pipeline   Copies Original Request for use in step 3 Route Node   Sends Request to External System exposed as a Business Service Response Pipeline   Checks Response to Check If Request Needs to Be Resubmitted Modify Request Callout to External System (same Business Service as Route Node) The Proxy and the Business Service were each assigned their own Work Manager, effectively giving each of them their own thread pool. The Surprise Imagine our surprise when, on stressing the system we saw it lock up, with large numbers of blocked threads.  The reason for the lock up is due to some subtleties in the OSB thread model which is the topic of this post.   Basic Thread Model OSB goes to great lengths to avoid holding on to threads.  Lets start by looking at how how OSB deals with a simple request/response routing to a business service in a route node. Most Business Services are implemented by OSB in two parts.  The first part uses the request thread to send the request to the target.  In the diagram this is represented by the thread T1.  After sending the request to the target (the Business Service in our diagram) the request thread is released back to whatever pool it came from.  A multiplexor (muxer) is used to wait for the response.  When the response is received the muxer hands off the response to a new thread that is used to execute the response pipeline, this is represented in the diagram by T2. OSB allows you to assign different Work Managers and hence different thread pools to each Proxy Service and Business Service.  In out example we have the “Proxy Service Work Manager” assigned to the Proxy Service and the “Business Service Work Manager” assigned to the Business Service.  Note that the Business Service Work Manager is only used to assign the thread to process the response, it is never used to process the request. This architecture means that while waiting for a response from a business service there are no threads in use, which makes for better scalability in terms of thread usage. First Wrinkle Note that if the Proxy and the Business Service both use the same Work Manager then there is potential for starvation.  For example: Request Pipeline makes a blocking callout, say to perform a database read. Business Service response tries to allocate a thread from thread pool but all threads are blocked in the database read. New requests arrive and contend with responses arriving for the available threads. Similar problems can occur if the response pipeline blocks for some reason, maybe a database update for example. Solution The solution to this is to make sure that the Proxy and Business Service use different Work Managers so that they do not contend with each other for threads. Do Nothing Route Thread Model So what happens if there is no route node?  In this case OSB just echoes the Request message as a Response message, but what happens to the threads?  OSB still uses a separate thread for the response, but in this case the Work Manager used is the Default Work Manager. So this is really a special case of the Basic Thread Model discussed above, except that the response pipeline will always execute on the Default Work Manager.   Proxy Chaining Thread Model So what happens when the route node is actually calling a Proxy Service rather than a Business Service, does the second Proxy Service use its own Thread or does it re-use the thread of the original Request Pipeline? Well as you can see from the diagram when a route node calls another proxy service then the original Work Manager is used for both request pipelines.  Similarly the response pipeline uses the Work Manager associated with the ultimate Business Service invoked via a Route Node.  This actually fits in with the earlier description I gave about Business Services and by extension Route Nodes they “… uses the request thread to send the request to the target”. Call Out Threading Model So what happens when you make a Service Callout to a Business Service from within a pipeline.  The documentation says that “The pipeline processor will block the thread until the response arrives asynchronously” when using a Service Callout.  What this means is that the target Business Service is called using the pipeline thread but the response is also handled by the pipeline thread.  This implies that the pipeline thread blocks waiting for a response.  It is the handling of this response that behaves in an unexpected way. When a Business Service is called via a Service Callout, the calling thread is suspended after sending the request, but unlike the Route Node case the thread is not released, it waits for the response.  The muxer uses the Business Service Work Manager to allocate a thread to process the response, but in this case processing the response means getting the response and notifying the blocked pipeline thread that the response is available.  The original pipeline thread can then continue to process the response. Second Wrinkle This leads to an unfortunate wrinkle.  If the Business Service is using the same Work Manager as the Pipeline then it is possible for starvation or a deadlock to occur.  The scenario is as follows: Pipeline makes a Callout and the thread is suspended but still allocated Multiple Pipeline instances using the same Work Manager are in this state (common for a system under load) Response comes back but all Work Manager threads are allocated to blocked pipelines. Response cannot be processed and so pipeline threads never unblock – deadlock! Solution The solution to this is to make sure that any Business Services used by a Callout in a pipeline use a different Work Manager to the pipeline itself. The Solution to My Problem Looking back at my original workflow we see that the same Business Service is called twice, once in a Routing Node and once in a Response Pipeline Callout.  This was what was causing my problem because the response pipeline was using the Business Service Work Manager, but the Service Callout wanted to use the same Work Manager to handle the responses and so eventually my Response Pipeline hogged all the available threads so no responses could be processed. The solution was to create a second Business Service pointing to the same location as the original Business Service, the only difference was to assign a different Work Manager to this Business Service.  This ensured that when the Service Callout completed there were always threads available to process the response because the response processing from the Service Callout had its own dedicated Work Manager. Summary Request Pipeline Executes on Proxy Work Manager (WM) Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. Route Node Request sent using Proxy WM Thread Proxy WM Thread is released before getting response Muxer is used to handle response Muxer hands off response to Business Service (BS) WM Response Pipeline Executes on Routed Business Service WM Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. No Route Node (Echo functionality) Proxy WM thread released New thread from the default WM used for response pipeline Service Callout Request sent using proxy pipeline thread Proxy thread is suspended (not released) until the response comes back Notification of response handled by BS WM thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. Note this is a very short lived use of the thread After notification by callout BS WM thread that thread is released and execution continues on the original pipeline thread. Route/Callout to Proxy Service Request Pipeline of callee executes on requestor thread Response Pipeline of caller executes on response thread of requested proxy Throttling Request message may be queued if limit reached. Requesting thread is released (route node) or suspended (callout) So what this means is that you may get deadlocks caused by thread starvation if you use the same thread pool for the business service in a route node and the business service in a callout from the response pipeline because the callout will need a notification thread from the same thread pool as the response pipeline.  This was the problem we were having. You get a similar problem if you use the same work manager for the proxy request pipeline and a business service callout from that request pipeline. It also means you may want to have different work managers for the proxy and business service in the route node. Basically you need to think carefully about how threading impacts your proxy services. References Thanks to Jay Kasi, Gerald Nunn and Deb Ayers for helping to explain this to me.  Any errors are my own and not theirs.  Also thanks to my colleagues Milind Pandit and Prasad Bopardikar who travelled this road with me. OSB Thread Model Great Blog Post on Thread Usage in OSB

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  • What are functional-programming ways of implementing Conway's Game of Life

    - by George Mauer
    I recently implemented for fun Conway's Game of Life in Javascript (actually coffeescript but same thing). Since javascript can be used as a functional language I was trying to stay to that end of the spectrum. I was not happy with my results. I am a fairly good OO programmer and my solution smacked of same-old-same-old. So long question short: what is the (pseudocode) functional style of doing it? Here is Pseudocode for my attempt: class Node update: (board) -> get number_of_alive_neighbors from board get this_is_alive from board if this_is_alive and number_of_alive_neighbors < 2 then die if this_is_alive and number_of_alive_neighbors > 3 then die if not this_is_alive and number_of_alive_neighbors == 3 then alive class NodeLocations at: (x, y) -> return node value at x,y of: (node) -> return x,y of node class Board getNeighbors: (node) -> use node_locations to check 8 neighbors around node and return count nodes = for 1..100 new Node state = new NodeState(nodes) locations = new NodeLocations(nodes) board = new Board(locations, state) executeRound: state = clone state accumulated_changes = for n in nodes n.update(board) apply accumulated_changes to state board = new Board(locations, state)

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  • Class hierarchy problem in this social network model

    - by Gerenuk
    I'm trying to design a class system for a social network data model - basically a link/object system. Now I have roughly the following structure (simplified and only relevant methods shown) class Data: "used to handle the data with mongodb" "can link, unlink data and also return other linked data" "is basically a proxy object that only stores _id and accesses mongodb on requests" "it looks like {_id: ..., _out: [id1, id2,...], _inc: [id3, id4, ...]}" def get_node(self, id) "create a new Data object from the underlying mongodb" "each data object can potentially create a reference object to new mongo data" "this is needed when the data returns the linked objects" class Node: """ this class proxies linking calls to .data it includes additional network logic operations whereas Data only contains a basic database solution """ def __init__(self, data): "the infrastructure realization is stored as composition by an included object data" "Node bascially proxies most calls to the infrastructure object data" def get_node(self, data): "creates a new object of class Object or Link depending on data" class Object(Node): "can have multiple connections to Link" class Link(Node): "has one 'in' and one 'out' connection to an Object" This system is working, however maybe wouldn't work outside Python. Note that after reading links Now I have two questions here: 1) I want to infrastructure of the data storage to be replacable. Earlier I had Data as a superclass of Node so that it provided the neccessary calls. But (without dirty Python tricks) you cannot replace the superclass dynamically. Is using composition therefore recommended? The drawback is that I have to proxy most calls (link, unlink etc). Any thoughts? 2) The class Node contains the common method .get_node which is used to built new Object or Link instances after reading out the data. Some attribute of data decided whether the object which is only stored by id should be instantiated as an Object or Link class. The problem here is that Node needs to know about Object and Link in advance, which seems dodgy. Do you see a different solution? Both Object and Link need to instantiate one of all possible types depending on what the find in their linked data. Are there any other ideas how to implement a flexible Object/Link structure where the underlying database storage is isolated?

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  • Graph data structures and journal format for mini-IDE

    - by matec
    Background: I am writing a small/partial IDE. Code is internally converted/parsed into a graph data structure (for fast navigation, syntax-check etc). Functionality to undo/redo (also between sessions) and restoring from crash is implemented by writing to and reading from journal. The journal records modifications to the graph (not to the source). Question: I am hoping for advice on a decision on data-structures and journal format. For the graph I see two possible versions: g-a Graph edges are implemented in the way that one node stores references to other nodes via memory address g-b Every node has an ID. There is an ID-to-memory-address map. Graph uses IDs (instead of addresses) to connect nodes. Moving along an edge from one node to another each time requires lookup in ID-to-address map. And also for the journal: j-a There is a current node (like current working directory in a shell + file-system setting). The journal contains entries like "create new node and connect to current", "connect first child of current node" (relative IDs) j-b Journal uses absolute IDs, e.g. "delete edge 7 - 5", "delete node 5" I could e.g. combine g-a with j-a or combine g-b with j-b. In principle also g-b and j-a should be possible. [My first/original attempt was g-a and a version of j-b that uses addresses, but that turned out to cause severe restrictions: nodes cannot change their addresses (or journal would have to keep track of it), and using journal between two sessions is a mess (or even impossible)] I wonder if variant a or variant b or a combination would be a good idea, what advantages and disadvantages they would have and especially if some variant might be causing troubles later.

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  • Algorithmic problem - quickly finding all #'s where value %x is some given value

    - by Steve B.
    Problem I'm trying to solve, apologies in advance for the length: Given a large number of stored records, each with a unique (String) field S. I'd like to be able to find through an indexed query all records where Hash(S) % N == K for any arbitrary N, K (e.g. given a million strings, find all strings where HashCode(s) % 17 = 5. Is there some way of memoizing this so that we can quickly answer any question of this form without doing the % on every value? The motivation for this is a system of N distributed nodes, where each record has to be assigned to at least one node. The nodes are numbered 0 - (K-1) , and each node has to load up all of the records that match it's number: If we have 3 nodes Node 0 loads all records where Hash % 3 ==0 Node 1 loads all records where Hash % 3 ==1 Node 2 loads all records where Hash % 3 ==2 adding a 4th node, obviously all the assignments have to be recomputed - Node 0 loads all records where Hash % 4 ==0 ... etc I'd like to easily find these records through an indexed query without having to compute the mod individually. The best I've been able to come up with so far: If we take the prime factors of N (p1 * p2 * ... ) if N % M == I then p % M == I % p for all of N's prime factors e.g. 10 nodes : N % 10 == 6 then N % 2 = 0 == 6 %2 N % 5 = 1 == 6 %5 so storing an array of the "%" of N for the first "reasonable" number of primes for my data set should be helpful. For example in the above example we store the hash and the primes HASH PRIMES (array of %2, %3, %5, %7, ... ]) 16 [0 1 1 2 .. ] so looking for N%10 == 6 is equivalent to looking for all values where array[1]==1 and array[2] == 1. However, this breaks at the first prime larger than the highest number I'm storing in the factor table. Is there a better way?

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  • A* PathFinding Not Consistent

    - by RedShft
    I just started trying to implement a basic A* algorithm in my 2D tile based game. All of the nodes are tiles on the map, represented by a struct. I believe I understand A* on paper, as I've gone through some pseudo code, but I'm running into problems with the actual implementation. I've double and tripled checked my node graph, and it is correct, so I believe the issue to be with my algorithm. This issue is, that with the enemy still, and the player moving around, the path finding function will write "No Path" an astounding amount of times and only every so often write "Path Found". Which seems like its inconsistent. This is the node struct for reference: struct Node { bool walkable; //Whether this node is blocked or open vect2 position; //The tile's position on the map in pixels int xIndex, yIndex; //The index values of the tile in the array Node*[4] connections; //An array of pointers to nodes this current node connects to Node* parent; int gScore; int hScore; int fScore; } Here is the rest: http://pastebin.com/cCHfqKTY This is my first attempt at A* so any help would be greatly appreciated.

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  • Big Data – Buzz Words: What is Hadoop – Day 6 of 21

    - by Pinal Dave
    In yesterday’s blog post we learned what is NoSQL. In this article we will take a quick look at one of the four most important buzz words which goes around Big Data – Hadoop. What is Hadoop? Apache Hadoop is an open-source, free and Java based software framework offers a powerful distributed platform to store and manage Big Data. It is licensed under an Apache V2 license. It runs applications on large clusters of commodity hardware and it processes thousands of terabytes of data on thousands of the nodes. Hadoop is inspired from Google’s MapReduce and Google File System (GFS) papers. The major advantage of Hadoop framework is that it provides reliability and high availability. What are the core components of Hadoop? There are two major components of the Hadoop framework and both fo them does two of the important task for it. Hadoop MapReduce is the method to split a larger data problem into smaller chunk and distribute it to many different commodity servers. Each server have their own set of resources and they have processed them locally. Once the commodity server has processed the data they send it back collectively to main server. This is effectively a process where we process large data effectively and efficiently. (We will understand this in tomorrow’s blog post). Hadoop Distributed File System (HDFS) is a virtual file system. There is a big difference between any other file system and Hadoop. When we move a file on HDFS, it is automatically split into many small pieces. These small chunks of the file are replicated and stored on other servers (usually 3) for the fault tolerance or high availability. (We will understand this in the day after tomorrow’s blog post). Besides above two core components Hadoop project also contains following modules as well. Hadoop Common: Common utilities for the other Hadoop modules Hadoop Yarn: A framework for job scheduling and cluster resource management There are a few other projects (like Pig, Hive) related to above Hadoop as well which we will gradually explore in later blog posts. A Multi-node Hadoop Cluster Architecture Now let us quickly see the architecture of the a multi-node Hadoop cluster. A small Hadoop cluster includes a single master node and multiple worker or slave node. As discussed earlier, the entire cluster contains two layers. One of the layer of MapReduce Layer and another is of HDFC Layer. Each of these layer have its own relevant component. The master node consists of a JobTracker, TaskTracker, NameNode and DataNode. A slave or worker node consists of a DataNode and TaskTracker. It is also possible that slave node or worker node is only data or compute node. The matter of the fact that is the key feature of the Hadoop. In this introductory blog post we will stop here while describing the architecture of Hadoop. In a future blog post of this 31 day series we will explore various components of Hadoop Architecture in Detail. Why Use Hadoop? There are many advantages of using Hadoop. Let me quickly list them over here: Robust and Scalable – We can add new nodes as needed as well modify them. Affordable and Cost Effective – We do not need any special hardware for running Hadoop. We can just use commodity server. Adaptive and Flexible – Hadoop is built keeping in mind that it will handle structured and unstructured data. Highly Available and Fault Tolerant – When a node fails, the Hadoop framework automatically fails over to another node. Why Hadoop is named as Hadoop? In year 2005 Hadoop was created by Doug Cutting and Mike Cafarella while working at Yahoo. Doug Cutting named Hadoop after his son’s toy elephant. Tomorrow In tomorrow’s blog post we will discuss Buzz Word – MapReduce. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • 11gR2 ??????????

    - by Allen Gao
    ???????11gR2 GI????????????????????,?10g????,???????GI?????????????1.Ocssd.bin:????????10g??????????,???????(Node Monitoring)????(Group Management)?????????????“??????????”????????2.Cssdagent.bin/Cssdmonitor.bin:?2????11gR2??????????????ocssd.bin??????(Local HeartBeat),??????1??????????????????ocssd.bin???????????,????????ocssd.bin????????,??????,???????????10g??oclsomon/oclsvmon(?????????????)?oprocd????,????11gR2???????—rebootless restart,?????????11.2.0.2????????????,????????????(????????)??????ocssd.bin?????,??????????????,??????????GI stack?????,??GI stack??????????(short disk I/O timeout)??graceful shutdown,????????,??,????????????????????????11gR2 ??????????????1.Ocssd.log2.Cssdagent ? cssdmonitor logs<GI_home>/log/<node_name>/agent/ohasd/oracssdagent_root/oracssdagent_root.log<GI_home>/log/<node_name>/agent/ohasd/oracssdmonitor_root_root/oracssdmonitor_root.log3.Cluster alert log<GI_home>/log/<node_name>/alert<node_name>.log4.OS log5.OSW ?? CHM ????,??????????????????1.???????????????????????????????,??????10g???????????????????????????GI alert log ??,?????node2?2012-08-15 16:30:06.554 [cssd(11011) ]CRS-1612:Network communication with node node1 (1) missing for 50% of timeout interval.  Removal of this node from cluster in 14.510 seconds2012-08-15 16:30:13.586 [cssd(11011) ]CRS-1611:Network communication with node node1 (1) missing for 75% of timeout interval.  Removal of this node from cluster in 7.470 seconds2012-08-15 16:30:18.606 [cssd(11011) ]CRS-1610:Network communication with node node1 (1) missing for 90% of timeout interval.  Removal of this node from cluster in 2.450 seconds2012-08-15 16:30:21.073 [cssd(11011) ]CRS-1632:Node node1 is being removed from the cluster in cluster incarnation 2363798322012-08-15 16:30:21.086 [cssd(11011) ]CRS-1601:CSSD Reconfiguration complete. Active nodes are node2 .?????????????node1?????????????????,???????, node2?? node1 ?????????node1 ???,???node1 ???????????????(????os log ??OSW ????),??node1 ???????node2??node1?????????,????node1??????????,???reconfiguration,????????????,????????????,?11.2.0.2??,??rebootless restart???,node eviction ????????GI stack??,????????????,???node2?node1?????????,node1?ocssd.bin??????(????ocssd.log??)??node1???????????????,??node1??????GI node eviction????2.???????????????,?????10g???????,???????????3.??ocssd.bin ????Cssdagent/Cssdmonitor.bin????????????,??????,????,????oracssdagent_root.log ?oracssdmonitor_root.log ????????2012-07-23 14:09:58.506: [ USRTHRD][1095805248] (:CLSN00111: )clsnproc_needreboot: Impending reboot at 75% of limit 28030; disk timeout 28030, network timeout 26380, last heartbeat from CSSD at epoch seconds 1343023777.410, 21091 milliseconds ago based on invariant clock 269251595; now polling at 100 ms……2012-07-23 14:10:02.704: [ USRTHRD][1095805248] (:CLSN00111: )clsnproc_needreboot: Impending reboot at 90% of limit 28030; disk timeout 28030, network timeout 26380, last heartbeat from CSSD at epoch seconds 1343023777.410, 25291 milliseconds ago based on invariant clock 269251595; now polling at 100 ms……???????????????timeout???28 ???(misscount – reboot time)?4.?????????????????? ??????????????????????,????ocssd.bin??????,?????????????,?????????????ocssd.bin??,????????os???????????OSW??,???? ??????? cpu ???Linux OSWbb v5.0 node1SNAP_INTERVAL 30CPU_COUNT 8OSWBB_ARCHIVE_DEST /osw/archiveprocs -----------memory---------- ---swap-- -----io---- -system-- -----cpu------r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa……zzz ***Mon Aug 30 17:55:21 CST 2012158  6 4200956 923940   7664 19088464    0    0  1296  3574 11153 231579  0 100  0  0  0zzz ***Mon Aug 30 17:55:53 CST 2012135  4 4200956 923760   7812 19089344    0    0     4    45  570 14563  0 100  0  0  0zzz ***Mon Aug 30 17:56:53 CST 2012126  2 4200956 923784   8396 19083620    0    0   196  1121  651 15941  2 98  0  0  0?????????????,????10g??????11gR2????????????????,??????,????????Note 1050693.1 : Troubleshooting 11.2 Clusterware Node Evictions (Reboots)

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