Search Results

Search found 14383 results on 576 pages for 'double checked locking'.

Page 89/576 | < Previous Page | 85 86 87 88 89 90 91 92 93 94 95 96  | Next Page >

• C++: Calculate probability percentage during each iteration

  - by Mur Quirk

  Can't seem to get this to work. The idea is to calculate the percentage of heads and tails after each count, accumulating after each iteration. Except I keep getting nan% for my calculations. Anybody see what I'm doing wrong? void flipCoin(time_t seconds, int flipCount){ vector<int> flips; float headCount = 0; float tailCount = 0; double headProbability = double((headCount/(headCount + tailCount))*100); double tailProbability = double((tailCount/(headCount + tailCount))*100); for (int i=0; i < flipCount; i++) { int flip = rand() % (HEADS - TAILS + 1) + TAILS; flips.push_back(flip); if (flips[i] == 1) { tailCount++; cout << "Tail Percent: " << tailProbability << "%" << endl; }else{ headCount++; cout << "Head Percent: " << headProbability << "%" << endl; } } }

  Read the article

• I want to create a simple function to reset all input values without target input. (Javascript, Jque

  - by question_about_the_problem

  Hi, I want to create a simple function to reset all input values without target input. I don't know how i can do it. Thanks. Here is my sample codes: <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script> <script> function reset_other_inputs(room) { $("input[name^='check_in_date_']").each(function () { if ( $("input[name!='check_in_date_'+room]") ) { this.val(""); } }); $("input[name^='check_out_date_']").each(function () { if ( $("input[name!='check_out_date_'+room]") ) { this.val(""); } }); } </script> <input type="text" name="check_in_date_single" value="single" onClick="reset_other_inputs('single');"> <input type="text" name="check_out_date_single" value="single" onClick="reset_other_inputs('single');"> <input type="text" name="check_in_date_double" value="double" onClick="reset_other_inputs('double');"> <input type="text" name="check_out_date_double" value="double" onClick="reset_other_inputs('double');"> <input type="text" name="check_in_date_triple" value="triple" onClick="reset_other_inputs('triple');"> <input type="text" name="check_out_date_triple" value="triple" onClick="reset_other_inputs('triple');"> <input type="text" name="check_in_date_suite" value="suite" onClick="reset_other_inputs('suite');"> <input type="text" name="check_out_date_suite" value="suite" onClick="reset_other_inputs('suite');">

  Read the article

• Efficient way to call .Sum() on multiple properties

  - by SherCoder

  I have a function that uses Linq to get data from the database and then I call that function in another function to sum all the individual properties using .Sum on each individual property. I was wondering if there is an efficient way to sum all the properties at once rather than calling .Sum() on each individual property. I think the way I am doing as of right now, is very slow (although untested). public OminitureStats GetAvgOmnitureData(int? fnsId, int dateRange) { IQueryable<OminitureStats> query = GetOmnitureDataAsQueryable(fnsId, dateRange); int pageViews = query.Sum(q => q.PageViews); int monthlyUniqueVisitors = query.Sum(q => q.MonthlyUniqueVisitors); int visits = query.Sum(q => q.Visits); double pagesPerVisit = (double)query.Sum(q => q.PagesPerVisit); double bounceRate = (double)query.Sum(q => q.BounceRate); return new OminitureStats(pageViews, monthlyUniqueVisitors, visits, bounceRate, pagesPerVisit); }

  Read the article

• Something missing

  - by DHF

  The error of "} expected" appears at line 5. Why is that? I have included it at line 15. The error of "Declaration missing ;" appears at line 8. Why? There is ";" at the end of the line. #include<iostream> using namespace std; class PEmployee { public: PEmployee(); PEmployee(string employee_name, double initial_salary); void set_salary(double new_salary); double get_salary() const; string get_name() const; private: Person person_data; double salary; }; //line 15 int main() { PEmployee f("Patrick", 1000.00); cout << f.get_name() << " earns a salary of " << f.get_salary() << endl; return 0; } Newbie here, sorry for unclear question

  Read the article

• Enabling Kerberos Authentication for Reporting Services

  - by robcarrol

  Recently, I’ve helped several customers with Kerberos authentication problems with Reporting Services and Analysis Services, so I’ve decided to write this blog post and pull together some useful resources in one place (there are 2 whitepapers in particular that I found invaluable configuring Kerberos authentication, and these can be found in the references section at the bottom of this post). In most of these cases, the problem has manifested itself with the Login failed for User ‘NT Authority\Anonymous’ (“double-hop”) error. By default, Reporting Services uses Windows Integrated Authentication, which includes the Kerberos and NTLM protocols for network authentication. Additionally, Windows Integrated Authentication includes the negotiate security header, which prompts the client to select Kerberos or NTLM for authentication. The client can access reports which have the appropriate permissions by using Kerberos for authentication. Servers that use Kerberos authentication can impersonate those clients and use their security context to access network resources. You can configure Reporting Services to use both Kerberos and NTLM authentication; however this may lead to a failure to authenticate. With negotiate, if Kerberos cannot be used, the authentication method will default to NTLM. When negotiate is enabled, the Kerberos protocol is always used except when: Clients/servers that are involved in the authentication process cannot use Kerberos. The client does not provide the information necessary to use Kerberos. An in-depth discussion of Kerberos authentication is beyond the scope of this post, however when users execute reports that are configured to use Windows Integrated Authentication, their logon credentials are passed from the report server to the server hosting the data source. Delegation needs to be set on the report server and Service Principle Names (SPNs) set for the relevant services. When a user processes a report, the request must go through a Web server on its way to a database server for processing. Kerberos authentication enables the Web server to request a service ticket from the domain controller; impersonate the client when passing the request to the database server; and then restrict the request based on the user’s permissions. Each time a server is required to pass the request to another server, the same process must be used. Kerberos authentication is supported in both native and SharePoint integrated mode, but I’ll focus on native mode for the purpose of this post (I’ll explain configuring SharePoint integrated mode and Kerberos authentication in a future post). Configuring Kerberos avoids the authentication failures due to double-hop issues. These double-hop errors occur when a users windows domain credentials can’t be passed to another server to complete the user’s request. In the case of my customers, users were executing Reporting Services reports that were configured to query Analysis Services cubes on a separate machine using Windows Integrated security. The double-hop issue occurs as NTLM credentials are valid for only one network hop, subsequent hops result in anonymous authentication. The client attempts to connect to the report server by making a request from a browser (or some other application), and the connection process begins with authentication. With NTLM authentication, client credentials are presented to Computer 2. However Computer 2 can’t use the same credentials to access Computer 3 (so we get the Anonymous login error). To access Computer 3 it is necessary to configure the connection string with stored credentials, which is what a number of customers I have worked with have done to workaround the double-hop authentication error. However, to get the benefits of Windows Integrated security, a better solution is to enable Kerberos authentication. Again, the connection process begins with authentication. With Kerberos authentication, the client and the server must demonstrate to one another that they are genuine, at which point authentication is successful and a secure client/server session is established. In the illustration above, the tiers represent the following: Client tier (computer 1): The client computer from which an application makes a request. Middle tier (computer 2): The Web server or farm where the client’s request is directed. Both the SharePoint and Reporting Services server(s) comprise the middle tier (but we’re only concentrating on native deployments just now). Back end tier (computer 3): The Database/Analysis Services server/Cluster where the requested data is stored. In order to enable Kerberos authentication for Reporting Services it’s necessary to configure the relevant SPNs, configure trust for delegation for server accounts, configure Kerberos with full delegation and configure the authentication types for Reporting Services. Service Principle Names (SPNs) are unique identifiers for services and identify the account’s type of service. If an SPN is not configured for a service, a client account will be unable to authenticate to the servers using Kerberos. You need to be a domain administrator to add an SPN, which can be added using the SetSPN utility. For Reporting Services in native mode, the following SPNs need to be registered --SQL Server Service SETSPN -S mssqlsvc/servername:1433 Domain\SQL For named instances, or if the default instance is running under a different port, then the specific port number should be used. --Reporting Services Service SETSPN -S http/servername Domain\SSRS SETSPN -S http/servername.domain.com Domain\SSRS The SPN should be set for the NETBIOS name of the server and the FQDN. If you access the reports using a host header or DNS alias, then that should also be registered SETSPN -S http/www.reports.com Domain\SSRS --Analysis Services Service SETSPN -S msolapsvc.3/servername Domain\SSAS Next, you need to configure trust for delegation, which refers to enabling a computer to impersonate an authenticated user to services on another computer: Location Description Client 1. The requesting application must support the Kerberos authentication protocol. 2. The user account making the request must be configured on the domain controller. Confirm that the following option is not selected: Account is sensitive and cannot be delegated. Servers 1. The service accounts must be trusted for delegation on the domain controller. 2. The service accounts must have SPNs registered on the domain controller. If the service account is a domain user account, the domain administrator must register the SPNs. In Active Directory Users and Computers, verify that the domain user accounts used to access reports have been configured for delegation (the ‘Account is sensitive and cannot be delegated’ option should not be selected): We then need to configure the Reporting Services service account and computer to use Kerberos with full delegation:   We also need to do the same for the SQL Server or Analysis Services service accounts and computers (depending on what type of data source you are connecting to in your reports). Finally, and this is the part that sometimes gets over-looked, we need to configure the authentication type correctly for reporting services to use Kerberos authentication. This is configured in the Authentication section of the RSReportServer.config file on the report server. <Authentication> <AuthenticationTypes>           <RSWindowsNegotiate/> </AuthenticationTypes> <EnableAuthPersistence>true</EnableAuthPersistence> </Authentication> This will enable Kerberos authentication for Internet Explorer. For other browsers, see the link below. The report server instance must be restarted for these changes to take effect. Once these changes have been made, all that’s left to do is test to make sure Kerberos authentication is working properly by running a report from report manager that is configured to use Windows Integrated authentication (either connecting to Analysis Services or SQL Server back-end). Resources: Manage Kerberos Authentication Issues in a Reporting Services Environment http://download.microsoft.com/download/B/E/1/BE1AABB3-6ED8-4C3C-AF91-448AB733B1AF/SSRSKerberos.docx Configuring Kerberos Authentication for Microsoft SharePoint 2010 Products http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=23176 How to: Configure Windows Authentication in Reporting Services http://msdn.microsoft.com/en-us/library/cc281253.aspx RSReportServer Configuration File http://msdn.microsoft.com/en-us/library/ms157273.aspx#Authentication Planning for Browser Support http://msdn.microsoft.com/en-us/library/ms156511.aspx

  Read the article

• readonly keyword

  - by nmarun

  This is something new that I learned about the readonly keyword. Have a look at the following class: 1: public class MyClass 2: { 3: public string Name { get; set; } 4: public int Age { get; set; } 5:  6: private readonly double Delta; 7:  8: public MyClass() 9: { 10: Initializer(); 11: } 12:  13: public MyClass(string name = "", int age = 0) 14: { 15: Name = name; 16: Age = age; 17: Initializer(); 18: } 19:  20: private void Initializer() 21: { 22: Delta = 0.2; 23: } 24: } I have a couple of public properties and a private readonly member. There are two constructors – one that doesn’t take any parameters and the other takes two parameters to initialize the public properties. I’m also calling the Initializer method in both constructors to initialize the readonly member. Now when I build this, the code breaks and the Error window says: “A readonly field cannot be assigned to (except in a constructor or a variable initializer)” Two things after I read this message: It’s such a negative statement. I’d prefer something like: “A readonly field can be assigned to (or initialized) only in a constructor or through a variable initializer” But in my defense, I AM assigning it in a constructor (only indirectly). All I’m doing is creating a method that does it and calling it in a constructor. Turns out, .net was not ‘frameworked’ this way. We need to have the member initialized directly in the constructor. If you have multiple constructors, you can just use the ‘this’ keyword on all except the default constructors to call the default constructor. This default constructor can then initialize your readonly members. This will ensure you’re not repeating the code in multiple places. A snippet of what I’m talking can be seen below: 1: public class Person 2: { 3: public int UniqueNumber { get; set; } 4: public string Name { get; set; } 5: public int Age { get; set; } 6: public DateTime DateOfBirth { get; set; } 7: public string InvoiceNumber { get; set; } 8:  9: private readonly string Alpha; 10: private readonly int Beta; 11: private readonly double Delta; 12: private readonly double Gamma; 13:  14: public Person() 15: { 16: Alpha = "FDSA"; 17: Beta = 2; 18: Delta = 3.0; 19: Gamma = 0.0989; 20: } 21:  22: public Person(int uniqueNumber) : this() 23: { 24: UniqueNumber = uniqueNumber; 25: } 26: } See the syntax in line 22 and you’ll know what I’m talking about. So the default constructor gets called before the one in line 22. These are known as constructor initializers and they allow one constructor to call another. The other ‘myth’ I had about readonly members is that you can set it’s value only once. This was busted as well (I recall Adam and Jamie’s show). Say you’ve initialized the readonly member through a variable initializer. You can over-write this value in any of the constructors any number of times. 1: public class Person 2: { 3: public int UniqueNumber { get; set; } 4: public string Name { get; set; } 5: public int Age { get; set; } 6: public DateTime DateOfBirth { get; set; } 7: public string InvoiceNumber { get; set; } 8:  9: private readonly string Alpha = "asdf"; 10: private readonly int Beta = 15; 11: private readonly double Delta = 0.077; 12: private readonly double Gamma = 1.0; 13:  14: public Person() 15: { 16: Alpha = "FDSA"; 17: Beta = 2; 18: Delta = 3.0; 19: Gamma = 0.0989; 20: } 21:  22: public Person(int uniqueNumber) : this() 23: { 24: UniqueNumber = uniqueNumber; 25: Beta = 3; 26: } 27:  28: public Person(string name, DateTime dob) : this() 29: { 30: Name = name; 31: DateOfBirth = dob; 32:  33: Alpha = ";LKJ"; 34: Gamma = 0.0898; 35: } 36:  37: public Person(int uniqueNumber, string name, int age, DateTime dob, string invoiceNumber) : this() 38: { 39: UniqueNumber = uniqueNumber; 40: Name = name; 41: Age = age; 42: DateOfBirth = dob; 43: InvoiceNumber = invoiceNumber; 44:  45: Alpha = "QWER"; 46: Beta = 5; 47: Delta = 1.0; 48: Gamma = 0.0; 49: } 50: } In the above example, every constructor over-writes the values for the readonly members. This is perfectly valid. There is a possibility that based on the way the object is instantiated, the readonly member will have a different value. Well, that’s all I have for today and read this as it’s on a related topic.

  Read the article

• Move penetrating OBB out of another OBB to resolve collision

  - by Milo

  I'm working on collision resolution for my game. I just need a good way to get an object out of another object if it gets stuck. In this case a car. Here is a typical scenario. The red car is in the green object. How do I correctly get it out so the car can slide along the edge of the object as it should. I tried: if(buildings.size() > 0) { Entity e = buildings.get(0); Vector2D vel = new Vector2D(); vel.x = vehicle.getVelocity().x; vel.y = vehicle.getVelocity().y; vel.normalize(); while(vehicle.getRect().overlaps(e.getRect())) { vehicle.setCenter(vehicle.getCenterX() - vel.x * 0.1f, vehicle.getCenterY() - vel.y * 0.1f); } colided = true; } But that does not work too well. Is there some sort of vector I could calculate to use as the vector to move the car away from the object? Thanks Here is my OBB2D class: public class OBB2D { // Corners of the box, where 0 is the lower left. private Vector2D corner[] = new Vector2D[4]; private Vector2D center = new Vector2D(); private Vector2D extents = new Vector2D(); private RectF boundingRect = new RectF(); private float angle; //Two edges of the box extended away from corner[0]. private Vector2D axis[] = new Vector2D[2]; private double origin[] = new double[2]; public OBB2D(Vector2D center, float w, float h, float angle) { set(center,w,h,angle); } public OBB2D(float left, float top, float width, float height) { set(new Vector2D(left + (width / 2), top + (height / 2)),width,height,0.0f); } public void set(Vector2D center,float w, float h,float angle) { Vector2D X = new Vector2D( (float)Math.cos(angle), (float)Math.sin(angle)); Vector2D Y = new Vector2D((float)-Math.sin(angle), (float)Math.cos(angle)); X = X.multiply( w / 2); Y = Y.multiply( h / 2); corner[0] = center.subtract(X).subtract(Y); corner[1] = center.add(X).subtract(Y); corner[2] = center.add(X).add(Y); corner[3] = center.subtract(X).add(Y); computeAxes(); extents.x = w / 2; extents.y = h / 2; computeDimensions(center,angle); } private void computeDimensions(Vector2D center,float angle) { this.center.x = center.x; this.center.y = center.y; this.angle = angle; boundingRect.left = Math.min(Math.min(corner[0].x, corner[3].x), Math.min(corner[1].x, corner[2].x)); boundingRect.top = Math.min(Math.min(corner[0].y, corner[1].y),Math.min(corner[2].y, corner[3].y)); boundingRect.right = Math.max(Math.max(corner[1].x, corner[2].x), Math.max(corner[0].x, corner[3].x)); boundingRect.bottom = Math.max(Math.max(corner[2].y, corner[3].y),Math.max(corner[0].y, corner[1].y)); } public void set(RectF rect) { set(new Vector2D(rect.centerX(),rect.centerY()),rect.width(),rect.height(),0.0f); } // Returns true if other overlaps one dimension of this. private boolean overlaps1Way(OBB2D other) { for (int a = 0; a < axis.length; ++a) { double t = other.corner[0].dot(axis[a]); // Find the extent of box 2 on axis a double tMin = t; double tMax = t; for (int c = 1; c < corner.length; ++c) { t = other.corner[c].dot(axis[a]); if (t < tMin) { tMin = t; } else if (t > tMax) { tMax = t; } } // We have to subtract off the origin // See if [tMin, tMax] intersects [0, 1] if ((tMin > 1 + origin[a]) || (tMax < origin[a])) { // There was no intersection along this dimension; // the boxes cannot possibly overlap. return false; } } // There was no dimension along which there is no intersection. // Therefore the boxes overlap. return true; } //Updates the axes after the corners move. Assumes the //corners actually form a rectangle. private void computeAxes() { axis[0] = corner[1].subtract(corner[0]); axis[1] = corner[3].subtract(corner[0]); // Make the length of each axis 1/edge length so we know any // dot product must be less than 1 to fall within the edge. for (int a = 0; a < axis.length; ++a) { axis[a] = axis[a].divide((axis[a].length() * axis[a].length())); origin[a] = corner[0].dot(axis[a]); } } public void moveTo(Vector2D center) { Vector2D centroid = (corner[0].add(corner[1]).add(corner[2]).add(corner[3])).divide(4.0f); Vector2D translation = center.subtract(centroid); for (int c = 0; c < 4; ++c) { corner[c] = corner[c].add(translation); } computeAxes(); computeDimensions(center,angle); } // Returns true if the intersection of the boxes is non-empty. public boolean overlaps(OBB2D other) { if(right() < other.left()) { return false; } if(bottom() < other.top()) { return false; } if(left() > other.right()) { return false; } if(top() > other.bottom()) { return false; } if(other.getAngle() == 0.0f && getAngle() == 0.0f) { return true; } return overlaps1Way(other) && other.overlaps1Way(this); } public Vector2D getCenter() { return center; } public float getWidth() { return extents.x * 2; } public float getHeight() { return extents.y * 2; } public void setAngle(float angle) { set(center,getWidth(),getHeight(),angle); } public float getAngle() { return angle; } public void setSize(float w,float h) { set(center,w,h,angle); } public float left() { return boundingRect.left; } public float right() { return boundingRect.right; } public float bottom() { return boundingRect.bottom; } public float top() { return boundingRect.top; } public RectF getBoundingRect() { return boundingRect; } public boolean overlaps(float left, float top, float right, float bottom) { if(right() < left) { return false; } if(bottom() < top) { return false; } if(left() > right) { return false; } if(top() > bottom) { return false; } return true; } };

  Read the article

• Finding the normal of OBB face with an OBB penetrating

  - by Milo

  Below is an illustration: I have an OBB in an OBB (see below for OBB2D code if needed). What I need to determine is, what face it is in, and what direction do I point the normal? The goal is to get the OBB out of the OBB so the normal needs to face outward of the OBB. How could I go about: Finding what face the line is penetrating given the 4 corners of the OBB and the class below: if we define dx=x2-x1 and dy=y2-y1, then the normals are (-dy, dx) and (dy, -dx). Which normal points outward of the OBB? Thanks public class OBB2D { // Corners of the box, where 0 is the lower left. private Vector2D corner[] = new Vector2D[4]; private Vector2D center = new Vector2D(); private Vector2D extents = new Vector2D(); private RectF boundingRect = new RectF(); private float angle; //Two edges of the box extended away from corner[0]. private Vector2D axis[] = new Vector2D[2]; private double origin[] = new double[2]; public OBB2D(Vector2D center, float w, float h, float angle) { set(center,w,h,angle); } public OBB2D(float left, float top, float width, float height) { set(new Vector2D(left + (width / 2), top + (height / 2)),width,height,0.0f); } public void set(Vector2D center,float w, float h,float angle) { Vector2D X = new Vector2D( (float)Math.cos(angle), (float)Math.sin(angle)); Vector2D Y = new Vector2D((float)-Math.sin(angle), (float)Math.cos(angle)); X = X.multiply( w / 2); Y = Y.multiply( h / 2); corner[0] = center.subtract(X).subtract(Y); corner[1] = center.add(X).subtract(Y); corner[2] = center.add(X).add(Y); corner[3] = center.subtract(X).add(Y); computeAxes(); extents.x = w / 2; extents.y = h / 2; computeDimensions(center,angle); } private void computeDimensions(Vector2D center,float angle) { this.center.x = center.x; this.center.y = center.y; this.angle = angle; boundingRect.left = Math.min(Math.min(corner[0].x, corner[3].x), Math.min(corner[1].x, corner[2].x)); boundingRect.top = Math.min(Math.min(corner[0].y, corner[1].y),Math.min(corner[2].y, corner[3].y)); boundingRect.right = Math.max(Math.max(corner[1].x, corner[2].x), Math.max(corner[0].x, corner[3].x)); boundingRect.bottom = Math.max(Math.max(corner[2].y, corner[3].y),Math.max(corner[0].y, corner[1].y)); } public void set(RectF rect) { set(new Vector2D(rect.centerX(),rect.centerY()),rect.width(),rect.height(),0.0f); } // Returns true if other overlaps one dimension of this. private boolean overlaps1Way(OBB2D other) { for (int a = 0; a < axis.length; ++a) { double t = other.corner[0].dot(axis[a]); // Find the extent of box 2 on axis a double tMin = t; double tMax = t; for (int c = 1; c < corner.length; ++c) { t = other.corner[c].dot(axis[a]); if (t < tMin) { tMin = t; } else if (t > tMax) { tMax = t; } } // We have to subtract off the origin // See if [tMin, tMax] intersects [0, 1] if ((tMin > 1 + origin[a]) || (tMax < origin[a])) { // There was no intersection along this dimension; // the boxes cannot possibly overlap. return false; } } // There was no dimension along which there is no intersection. // Therefore the boxes overlap. return true; } //Updates the axes after the corners move. Assumes the //corners actually form a rectangle. private void computeAxes() { axis[0] = corner[1].subtract(corner[0]); axis[1] = corner[3].subtract(corner[0]); // Make the length of each axis 1/edge length so we know any // dot product must be less than 1 to fall within the edge. for (int a = 0; a < axis.length; ++a) { axis[a] = axis[a].divide((axis[a].length() * axis[a].length())); origin[a] = corner[0].dot(axis[a]); } } public void moveTo(Vector2D center) { Vector2D centroid = (corner[0].add(corner[1]).add(corner[2]).add(corner[3])).divide(4.0f); Vector2D translation = center.subtract(centroid); for (int c = 0; c < 4; ++c) { corner[c] = corner[c].add(translation); } computeAxes(); computeDimensions(center,angle); } // Returns true if the intersection of the boxes is non-empty. public boolean overlaps(OBB2D other) { if(right() < other.left()) { return false; } if(bottom() < other.top()) { return false; } if(left() > other.right()) { return false; } if(top() > other.bottom()) { return false; } if(other.getAngle() == 0.0f && getAngle() == 0.0f) { return true; } return overlaps1Way(other) && other.overlaps1Way(this); } public Vector2D getCenter() { return center; } public float getWidth() { return extents.x * 2; } public float getHeight() { return extents.y * 2; } public void setAngle(float angle) { set(center,getWidth(),getHeight(),angle); } public float getAngle() { return angle; } public void setSize(float w,float h) { set(center,w,h,angle); } public float left() { return boundingRect.left; } public float right() { return boundingRect.right; } public float bottom() { return boundingRect.bottom; } public float top() { return boundingRect.top; } public RectF getBoundingRect() { return boundingRect; } public boolean overlaps(float left, float top, float right, float bottom) { if(right() < left) { return false; } if(bottom() < top) { return false; } if(left() > right) { return false; } if(top() > bottom) { return false; } return true; } };

  Read the article

• The code works but when using printf it gives me a weird answer. Help please [closed]

  - by user71458

  //Programmer-William Chen //Seventh Period Computer Science II //Problem Statement - First get the elapsed times and the program will find the //split times for the user to see. // //Algorithm- First the programmer makes the prototype and calls them in the //main function. The programmer then asks the user to input lap time data. //Secondly, you convert the splits into seconds and subtract them so you can //find the splits. Then the average is all the lap time's in seconds. Finally, //the programmer printf all the results for the user to see. #include <iostream> #include <stdlib.h> #include <math.h> #include <conio.h> #include <stdio.h> using namespace std; void thisgetsElapsedTimes( int &m1, int &m2, int &m3, int &m4, int &m5, int &s1, int &s2, int &s3, int &s4, int &s5); //this is prototype void thisconvertstoseconds ( int &m1, int &m2, int &m3, int &m4, int &m5, int &s1, int &s2, int &s3, int &s4, int &s5, int &split1, int &split2, int &split3, int &split4, int &split5);//this too void thisfindsSplits(int &m1, int &m2, int &m3, int &m4, int &m5, int &split1, int &split2, int &split3, int &split4, int &split5, int &split6, int &split7, int &split8, int &split9, int &split10);// this is part of prototype void thisisthesecondconversation (int &split1M, int &split2M, int &split3M, int &split4M, int &split5M, int &split1S,int &split2S, int &split3S, int &split4S, int &split5S, int &split1, int &split2, int &split3, int &split4, int &split5);//this gets a value void thisfindstheaverage(double &average, int &split1, int &split2, int &split3, int &split4, int &split5);//and this void thisprintsstuff( int &split1M, int &split2M, int &split3M, int &split4M, int &split5M, int &split1S, int &split2S, int &split3S, int &split4S, int &split5S, double &average); //this prints int main(int argc, char *argv[]) { int m1, m2, m3, m4, m5, s1, s2, s3, s4, s5, split1, split2, split3, split4, split5, split1M, split2M, split3M, split4M, split5M, split1S, split2S, split3S, split4S, split5S; int split6, split7, split8, split9, split10; double average; char thistakescolon; thisgetsElapsedTimes ( m1, m2, m3, m4, m5, s1, s2, s3, s4, s5); thisconvertstoseconds ( m1, m2, m3, m4, m5, s1, s2, s3, s4, s5, split1, split2, split3, split4, split5); thisfindsSplits ( m1, m2, m3, m4, m5, split1, split2, split3, split4, split5, split6, split7, split8, split9, split10); thisisthesecondconversation ( split1M, split2M, split3M, split4M, split5M, split1S, split2S, split3S, split4S, split5S, split1, split2, split3, split4, split5); thisfindstheaverage ( average, split1, split2, split3, split4, split5); thisprintsstuff ( split1M, split2M, split3M, split4M, split5M, split1S, split2S, split3S, split4S, split5S, average); // these are calling statements and they call from the main function to the other functions. system("PAUSE"); return 0; } void thisgetsElapsedTimes(int &m1, int &m2, int &m3, int &m4, int &m5, int &s1, int &s2, int &s3, int &s4, int &s5) { char thistakescolon; cout << "Enter the elapsed time:" << endl; cout << " Kilometer 1 "; cin m1 thistakescolon s1; cout << " Kilometer 2 "; cin m2 thistakescolon s2; cout << " Kilometer 3 " ; cin m3 thistakescolon s3; cout << " Kilometer 4 "; cin m4 thistakescolon s4; cout << " Kilometer 5 "; cin m5 thistakescolon s5; // this gets the data required to get the results needed for the user to see // . } void thisconvertstoseconds (int &m1, int &m2, int &m3, int &m4, int &m5, int &s1, int &s2, int &s3, int &s4, int &s5, int &split1, int &split2, int &split3, int &split4, int &split5) { split1 = (m1 * 60) + s1;//this converts for minutes to seconds for m1 split2 = (m2 * 60) + s2;//this converts for minutes to seconds for m2 split3 = (m3 * 60) + s3;//this converts for minutes to seconds for m3 split4 = (m4 * 60) + s4;//this converts for minutes to seconds for m4 split5 = (m5 * 60) + s5;//this converts for minutes to seconds for m5 } void thisfindsSplits (int &m1, int &m2, int &m3, int &m4, int &m5,int &split1, int &split2, int &split3, int &split4, int &split5, int &split6, int &split7, int &split8, int &split9, int &split10)//this is function heading { split6 = split1; //this is split for the first lap. split7 = split2 - split1;//this is split for the second lap. split8 = split3 - split2;//this is split for the third lap. split9 = split4 - split3;//this is split for the fourth lap. split10 = split5 - split4;//this is split for the fifth lap. } void thisfindstheaverage(double &average, int &split1, int &split2, int &split3, int &split4, int &split5) { average = (split1 + split2 + split3 + split4 + split5)/5; // this finds the average from all the splits in seconds } void thisisthesecondconversation (int &split1M, int &split2M, int &split3M, int &split4M, int &split5M, int &split1S,int &split2S, int &split3S, int &split4S, int &split5S, int &split1, int &split2, int &split3, int &split4, int &split5) { split1M = split1 * 60; //this finds the split times split1S = split1M - split1 * 60; //then this finds split2M = split2 * 60; //and all of this split2S = split2M - split2 * 60; //does basically split3M = split3 * 60; //the same thing split3S = split3M - split3 * 60; //all of it split4M = split4 * 60; //it's also a split4S = split4M - split4 * 60; //function split5M = split5 * 60; //and it finds the splits split5S = split5M - split5 * 60; //for each lap. } void thisprintsstuff (int &split1M, int &split2M, int &split3M, int &split4M, int &split5M, int &split1S, int &split2S, int &split3S, int &split4S, int &split5S, double &average)// this is function heading { printf("\n kilometer 1 %d" , ":02%d",'split1M','split1S'); printf("\n kilometer 2 %d" , ":02%d",'split2M','split2S'); printf("\n kilometer 3 %d" , ":02%d",'split3M','split3S'); printf("\n kilometer 4 %d" , ":02%d",'split4M','split4S'); printf("\n kilometer 5 %d" , ":02%d",'split5M','split5S'); printf("\n your average pace is ",'average',"per kilometer \n", "William Chen\n"); // this printf so the programmer // can allow the user to see // the results from the data gathered. }

  Read the article

• Problem Implementing Texture on Libgdx Mesh of Randomized Terrain

  - by BrotherJack

  I'm having problems understanding how to apply a texture to a non-rectangular object. The following code creates textures such as this: from the debug renderer I think I've got the physical shape of the "earth" correct. However, I don't know how to apply a texture to it. I have a 50x50 pixel image (in the environment constructor as "dirt.png"), that I want to apply to the hills. I have a vague idea that this seems to involve the mesh class and possibly a ShapeRenderer, but the little i'm finding online is just confusing me. Bellow is code from the class that makes and regulates the terrain and the code in a separate file that is supposed to render it (but crashes on the mesh.render() call). Any pointers would be appreciated. public class Environment extends Actor{ Pixmap sky; public Texture groundTexture; Texture skyTexture; double tankypos; //TODO delete, temp public Tank etank; //TODO delete, temp int destructionRes; // how wide is a static pixel private final float viewWidth; private final float viewHeight; private ChainShape terrain; public Texture dirtTexture; private World world; public Mesh terrainMesh; private static final String LOG = Environment.class.getSimpleName(); // Constructor public Environment(Tank tank, FileHandle sfileHandle, float w, float h, int destructionRes) { world = new World(new Vector2(0, -10), true); this.destructionRes = destructionRes; sky = new Pixmap(sfileHandle); viewWidth = w; viewHeight = h; skyTexture = new Texture(sky); terrain = new ChainShape(); genTerrain((int)w, (int)h, 6); Texture tankSprite = new Texture(Gdx.files.internal("TankSpriteBase.png")); Texture turretSprite = new Texture(Gdx.files.internal("TankSpriteTurret.png")); tank = new Tank(0, true, tankSprite, turretSprite); Rectangle tankrect = new Rectangle(300, (int)tankypos, 44, 45); tank.setRect(tankrect); BodyDef terrainDef = new BodyDef(); terrainDef.type = BodyType.StaticBody; terrainDef.position.set(0, 0); Body terrainBody = world.createBody(terrainDef); FixtureDef fixtureDef = new FixtureDef(); fixtureDef.shape = terrain; terrainBody.createFixture(fixtureDef); BodyDef tankDef = new BodyDef(); Rectangle rect = tank.getRect(); tankDef.type = BodyType.DynamicBody; tankDef.position.set(0,0); tankDef.position.x = rect.x; tankDef.position.y = rect.y; Body tankBody = world.createBody(tankDef); FixtureDef tankFixture = new FixtureDef(); PolygonShape shape = new PolygonShape(); shape.setAsBox(rect.width*WORLD_TO_BOX, rect.height*WORLD_TO_BOX); fixtureDef.shape = shape; dirtTexture = new Texture(Gdx.files.internal("dirt.png")); etank = tank; } private void genTerrain(int w, int h, int hillnessFactor){ int width = w; int height = h; Random rand = new Random(); //min and max bracket the freq's of the sin/cos series //The higher the max the hillier the environment int min = 1; //allocating horizon for screen width Vector2[] horizon = new Vector2[width+2]; horizon[0] = new Vector2(0,0); double[] skyline = new double[width]; //TODO skyline necessary as an array? //ratio of amplitude of screen height to landscape variation double r = (int) 2.0/5.0; //number of terms to be used in sine/cosine series int n = 4; int[] f = new int[n*2]; //calculating omegas for sine series for(int i = 0; i < n*2 ; i ++){ f[i] = rand.nextInt(hillnessFactor - min + 1) + min; } //amp is the amplitude of the series int amp = (int) (r*height); double lastPoint = 0.0; for(int i = 0 ; i < width; i ++){ skyline[i] = 0; for(int j = 0; j < n; j++){ skyline[i] += ( Math.sin( (f[j]*Math.PI*i/height) ) + Math.cos(f[j+n]*Math.PI*i/height) ); } skyline[i] *= amp/(n*2); skyline[i] += (height/2); skyline[i] = (int)skyline[i]; //TODO Possible un-necessary float to int to float conversions tankypos = skyline[i]; horizon[i+1] = new Vector2((float)i, (float)skyline[i]); if(i == width) lastPoint = skyline[i]; } horizon[width+1] = new Vector2(800, (float)lastPoint); terrain.createChain(horizon); terrain.createLoop(horizon); //I have no idea if the following does anything useful :( terrainMesh = new Mesh(true, (width+2)*2, (width+2)*2, new VertexAttribute(Usage.Position, (width+2)*2, "a_position")); float[] vertices = new float[(width+2)*2]; short[] indices = new short[(width+2)*2]; for(int i=0; i < (width+2); i+=2){ vertices[i] = horizon[i].x; vertices[i+1] = horizon[i].y; indices[i] = (short)i; indices[i+1] = (short)(i+1); } terrainMesh.setVertices(vertices); terrainMesh.setIndices(indices); } Here is the code that is (supposed to) render the terrain. @Override public void render(float delta) { Gdx.gl.glClearColor(1, 1, 1, 1); Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); // tell the camera to update its matrices. camera.update(); // tell the SpriteBatch to render in the // coordinate system specified by the camera. backgroundStage.draw(); backgroundStage.act(delta); uistage.draw(); uistage.act(delta); batch.begin(); debugRenderer.render(this.ground.getWorld(), camera.combined); batch.end(); //Gdx.graphics.getGL10().glEnable(GL10.GL_TEXTURE_2D); ground.dirtTexture.bind(); ground.terrainMesh.render(GL10.GL_TRIANGLE_FAN); //I'm particularly lost on this ground.step(); }

  Read the article

• Issues with signal handling [closed]

  - by user34790

  I am trying to actually study the signal handling behavior in multiprocess system. I have a system where there are three signal generating processes generating signals of type SIGUSR1 and SIGUSR1. I have two handler processes that handle a particular type of signal. I have another monitoring process that also receives the signals and then does its work. I have a certain issue. Whenever my signal handling processes generate a signal of a particular type, it is sent to the process group so it is received by the signal handling processes as well as the monitoring processes. Whenever the signal handlers of monitoring and signal handling processes are called, I have printed to indicate the signal handling. I was expecting a uniform series of calls for the signal handlers of the monitoring and handling processes. However, looking at the output I could see like at the beginning the monitoring and signal handling processes's signal handlers are called uniformly. However, after I could see like signal handler processes handlers being called in a burst followed by the signal handler of monitoring process being called in a burst. Here is my code and output #include <iostream> #include <sys/types.h> #include <sys/wait.h> #include <sys/time.h> #include <signal.h> #include <cstdio> #include <stdlib.h> #include <sys/ipc.h> #include <sys/shm.h> #define NUM_SENDER_PROCESSES 3 #define NUM_HANDLER_PROCESSES 4 #define NUM_SIGNAL_REPORT 10 #define MAX_SIGNAL_COUNT 100000 using namespace std; volatile int *usrsig1_handler_count; volatile int *usrsig2_handler_count; volatile int *usrsig1_sender_count; volatile int *usrsig2_sender_count; volatile int *lock_1; volatile int *lock_2; volatile int *lock_3; volatile int *lock_4; volatile int *lock_5; volatile int *lock_6; //Used only by the monitoring process volatile int monitor_count; volatile int usrsig1_monitor_count; volatile int usrsig2_monitor_count; double time_1[NUM_SIGNAL_REPORT]; double time_2[NUM_SIGNAL_REPORT]; //Used only by the main process int total_signal_count; //For shared memory int shmid; const int shareSize = sizeof(int) * (10); double timestamp() { struct timeval tp; gettimeofday(&tp, NULL); return (double)tp.tv_sec + tp.tv_usec / 1000000.; } pid_t senders[NUM_SENDER_PROCESSES]; pid_t handlers[NUM_HANDLER_PROCESSES]; pid_t reporter; void signal_catcher_1(int); void signal_catcher_2(int); void signal_catcher_int(int); void signal_catcher_monitor(int); void signal_catcher_main(int); void terminate_processes() { //Kill the child processes int status; cout << "Time up terminating the child processes" << endl; for(int i=0; i<NUM_SENDER_PROCESSES; i++) { kill(senders[i],SIGKILL); } for(int i=0; i<NUM_HANDLER_PROCESSES; i++) { kill(handlers[i],SIGKILL); } kill(reporter,SIGKILL); //Wait for the child processes to finish for(int i=0; i<NUM_SENDER_PROCESSES; i++) { waitpid(senders[i], &status, 0); } for(int i=0; i<NUM_HANDLER_PROCESSES; i++) { waitpid(handlers[i], &status, 0); } waitpid(reporter, &status, 0); } int main(int argc, char *argv[]) { if(argc != 2) { cout << "Required parameters missing. " << endl; cout << "Option 1 = 1 which means run for 30 seconds" << endl; cout << "Option 2 = 2 which means run until 100000 signals" << endl; exit(0); } int option = atoi(argv[1]); pid_t pid; if(option == 2) { if(signal(SIGUSR1, signal_catcher_main) == SIG_ERR) { perror("1"); exit(1); } if(signal(SIGUSR2, signal_catcher_main) == SIG_ERR) { perror("2"); exit(1); } } else { if(signal(SIGUSR1, SIG_IGN) == SIG_ERR) { perror("1"); exit(1); } if(signal(SIGUSR2, SIG_IGN) == SIG_ERR) { perror("2"); exit(1); } } if(signal(SIGINT, signal_catcher_int) == SIG_ERR) { perror("3"); exit(1); } /////////////////////////////////////////////////////////////////////////////////////// ////////////////////// Initializing the shared memory ///////////////////////////////// /////////////////////////////////////////////////////////////////////////////////////// cout << "Initializing the shared memory" << endl; if ((shmid=shmget(IPC_PRIVATE,shareSize,IPC_CREAT|0660))< 0) { perror("shmget fail"); exit(1); } usrsig1_handler_count = (int *) shmat(shmid, NULL, 0); usrsig2_handler_count = usrsig1_handler_count + 1; usrsig1_sender_count = usrsig2_handler_count + 1; usrsig2_sender_count = usrsig1_sender_count + 1; lock_1 = usrsig2_sender_count + 1; lock_2 = lock_1 + 1; lock_3 = lock_2 + 1; lock_4 = lock_3 + 1; lock_5 = lock_4 + 1; lock_6 = lock_5 + 1; //Initialize them to be zero *usrsig1_handler_count = 0; *usrsig2_handler_count = 0; *usrsig1_sender_count = 0; *usrsig2_sender_count = 0; *lock_1 = 0; *lock_2 = 0; *lock_3 = 0; *lock_4 = 0; *lock_5 = 0; *lock_6 = 0; cout << "End of initializing the shared memory" << endl; ///////////////////////////////////////////////////////////////////////////////////////////// /////////////////// End of initializing the shared memory /////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////////////////////// /////////////////////////////Registering the signal handlers/////////////////////////////// /////////////////////////////////////////////////////////////////////////////////////////// cout << "Registering the signal handlers" << endl; for(int i=0; i<NUM_HANDLER_PROCESSES; i++) { if((pid = fork()) == 0) { if(i%2 == 0) { struct sigaction action; action.sa_handler = signal_catcher_1; sigset_t block_mask; action.sa_flags = 0; sigaction(SIGUSR1,&action,NULL); if(signal(SIGUSR2, SIG_IGN) == SIG_ERR) { perror("2"); exit(1); } } else { if(signal(SIGUSR1 ,SIG_IGN) == SIG_ERR) { perror("1"); exit(1); } struct sigaction action; action.sa_handler = signal_catcher_2; action.sa_flags = 0; sigaction(SIGUSR2,&action,NULL); } if(signal(SIGINT, SIG_DFL) == SIG_ERR) { perror("2"); exit(1); } while(true) { pause(); } exit(0); } else { //cout << "Registerd the handler " << pid << endl; handlers[i] = pid; } } cout << "End of registering the signal handlers" << endl; ///////////////////////////////////////////////////////////////////////////////////////////////////// ////////////////////////////End of registering the signal handlers ////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////////////////////////////////////// ///////////////////////////Registering the monitoring process ////////////////////////////////////// //////////////////////////////////////////////////////////////////////////////////////////////////// cout << "Registering the monitoring process" << endl; if((pid = fork()) == 0) { struct sigaction action; action.sa_handler = signal_catcher_monitor; sigemptyset(&action.sa_mask); sigset_t block_mask; sigemptyset(&block_mask); sigaddset(&block_mask,SIGUSR1); sigaddset(&block_mask,SIGUSR2); action.sa_flags = 0; action.sa_mask = block_mask; sigaction(SIGUSR1,&action,NULL); sigaction(SIGUSR2,&action,NULL); if(signal(SIGINT, SIG_DFL) == SIG_ERR) { perror("2"); exit(1); } while(true) { pause(); } exit(0); } else { cout << "Monitor's pid is " << pid << endl; reporter = pid; } cout << "End of registering the monitoring process" << endl; ///////////////////////////////////////////////////////////////////////////////////////////////////// ////////////////////////End of registering the monitoring process//////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////////////////////////// //Sleep to make sure that the monitor and handler processes are well initialized and ready to handle signals sleep(5); ////////////////////////////////////////////////////////////////////////////////////////////////////// //////////////////////////Registering the signal generators/////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////////////////////////// cout << "Registering the signal generators" << endl; for(int i=0; i<NUM_SENDER_PROCESSES; i++) { if((pid = fork()) == 0) { if(signal(SIGUSR1, SIG_IGN) == SIG_ERR) { perror("1"); exit(1); } if(signal(SIGUSR2, SIG_IGN) == SIG_ERR) { perror("2"); exit(1); } if(signal(SIGINT, SIG_DFL) == SIG_ERR) { perror("2"); exit(1); } srand(i); while(true) { int signal_id = rand()%2 + 1; if(signal_id == 1) { killpg(getpgid(getpid()), SIGUSR1); while(__sync_lock_test_and_set(lock_4,1) != 0) { } (*usrsig1_sender_count)++; *lock_4 = 0; } else { killpg(getpgid(getpid()), SIGUSR2); while(__sync_lock_test_and_set(lock_5,1) != 0) { } (*usrsig2_sender_count)++; *lock_5=0; } int r = rand()%10 + 1; double s = (double)r/100; sleep(s); } exit(0); } else { //cout << "Registered the sender " << pid << endl; senders[i] = pid; } } //cout << "End of registering the signal generators" << endl; ///////////////////////////////////////////////////////////////////////////////////////////////////// //////////////////////////End of registering the signal generators/////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////////////////////////// //Either sleep for 30 seconds and terminate the program or if the number of signals generated reaches 10000, terminate the program if(option = 1) { sleep(90); terminate_processes(); } else { while(true) { if(total_signal_count >= MAX_SIGNAL_COUNT) { terminate_processes(); } else { sleep(0.001); } } } } void signal_catcher_1(int the_sig) { while(__sync_lock_test_and_set(lock_1,1) != 0) { } (*usrsig1_handler_count) = (*usrsig1_handler_count) + 1; cout << "Signal Handler 1 " << *usrsig1_handler_count << endl; __sync_lock_release(lock_1); } void signal_catcher_2(int the_sig) { while(__sync_lock_test_and_set(lock_2,1) != 0) { } (*usrsig2_handler_count) = (*usrsig2_handler_count) + 1; __sync_lock_release(lock_2); } void signal_catcher_main(int the_sig) { while(__sync_lock_test_and_set(lock_6,1) != 0) { } total_signal_count++; *lock_6 = 0; } void signal_catcher_int(int the_sig) { for(int i=0; i<NUM_SENDER_PROCESSES; i++) { kill(senders[i],SIGKILL); } for(int i=0; i<NUM_HANDLER_PROCESSES; i++) { kill(handlers[i],SIGKILL); } kill(reporter,SIGKILL); exit(3); } void signal_catcher_monitor(int the_sig) { cout << "Monitoring process " << *usrsig1_handler_count << endl; } Here is the initial segment of output Monitoring process 0 Monitoring process 0 Monitoring process 0 Monitoring process 0 Signal Handler 1 1 Monitoring process 2 Signal Handler 1 2 Signal Handler 1 3 Signal Handler 1 4 Monitoring process 4 Monitoring process Signal Handler 1 6 Signal Handler 1 7 Monitoring process 7 Monitoring process 8 Monitoring process 8 Signal Handler 1 9 Monitoring process 9 Monitoring process 9 Monitoring process 10 Signal Handler 1 11 Monitoring process 11 Monitoring process 12 Signal Handler 1 13 Signal Handler 1 14 Signal Handler 1 15 Signal Handler 1 16 Signal Handler 1 17 Signal Handler 1 18 Monitoring process 19 Signal Handler 1 20 Monitoring process 20 Signal Handler 1 21 Monitoring process 21 Monitoring process 21 Monitoring process 22 Monitoring process 22 Monitoring process 23 Signal Handler 1 24 Signal Handler 1 25 Monitoring process 25 Signal Handler 1 27 Signal Handler 1 28 Signal Handler 1 29 Here is the segment when the signal handler processes signal handlers are called in a burst Signal Handler 1 456 Signal Handler 1 457 Signal Handler 1 458 Signal Handler 1 459 Signal Handler 1 460 Signal Handler 1 461 Signal Handler 1 462 Signal Handler 1 463 Signal Handler 1 464 Signal Handler 1 465 Signal Handler 1 466 Signal Handler 1 467 Signal Handler 1 468 Signal Handler 1 469 Signal Handler 1 470 Signal Handler 1 471 Signal Handler 1 472 Signal Handler 1 473 Signal Handler 1 474 Signal Handler 1 475 Signal Handler 1 476 Signal Handler 1 477 Signal Handler 1 478 Signal Handler 1 479 Signal Handler 1 480 Signal Handler 1 481 Signal Handler 1 482 Signal Handler 1 483 Signal Handler 1 484 Signal Handler 1 485 Signal Handler 1 486 Signal Handler 1 487 Signal Handler 1 488 Signal Handler 1 489 Signal Handler 1 490 Signal Handler 1 491 Signal Handler 1 492 Signal Handler 1 493 Signal Handler 1 494 Signal Handler 1 495 Signal Handler 1 496 Signal Handler 1 497 Signal Handler 1 498 Signal Handler 1 499 Signal Handler 1 500 Signal Handler 1 501 Signal Handler 1 502 Signal Handler 1 503 Signal Handler 1 504 Signal Handler 1 505 Signal Handler 1 506 Here is the segment when the monitoring processes signal handlers are called in a burst Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Why isn't it uniform afterwards. Why are they called in a burst?

  Read the article

• jtreg update, March 2012

  - by jjg

  There is a new update for jtreg 4.1, b04, available. The primary changes have been to support faster and more reliable test runs, especially for tests in the jdk/ repository. [ For users inside Oracle, there is preliminary direct support for gathering code coverage data using jcov while running tests, and for generating a coverage report when all the tests have been run. ] -- jtreg can be downloaded from the OpenJDK jtreg page: http://openjdk.java.net/jtreg/. Scratch directories On platforms like Windows, if a test leaves a file open when the test is over, that can cause a problem for downstream tests, because the scratch directory cannot be emptied beforehand. This is addressed in agentvm mode by discarding any agents using that scratch directory and starting new agents using a new empty scratch directory. Successive directives use suffices _1, _2, etc. If you see such directories appearing in the work directory, that is an indication that files were left open in the preceding directory in the series. Locking support Some tests use shared system resources such as fixed port numbers. This causes a problem when running tests concurrently. So, you can now mark a directory such that all the tests within all such directories will be run sequentially, even if you use -concurrency:N on the command line to run the rest of the tests in parallel. This is seen as a short term solution: it is recommended that tests not use shared system resources whenever possible. If you are running multiple instances of jtreg on the same machine at the same time, you can use a new option -lock:file to specify a file to be used for file locking; otherwise, the locking will just be within the JVM used to run jtreg. "autovm mode" By default, if no options to the contrary are given on the command line, tests will be run in othervm mode. Now, a test suite can be marked so that the default execution mode is "agentvm" mode. In conjunction with this, you can now mark a directory such that all the tests within that directory will be run in "othervm" mode. Conceptually, this is equivalent to putting /othervm on every appropriate action on every test in that directory and any subdirectories. This is seen as a short term solution: it is recommended tests be adapted to use agentvm mode, or use "@run main/othervm" explicitly. Info in test result files The user name and jtreg version info are now stored in the properties near the beginning of the .jtr file. Build The makefiles used to build and test jtreg have been reorganized and simplified. jtreg is now using JT Harness version 4.4. Other jtreg provides access to GNOME_DESKTOP_SESSION_ID when set. jtreg ensures that shell tests are given an absolute path for the JDK under test. jtreg now honors the "first sentence rule" for the description given by @summary. jtreg saves the default locale before executing a test in samevm or agentvm mode, and restores it afterwards. Bug fixes jtreg tried to execute a test even if the compilation failed in agentvm mode because of a JVM crash. jtreg did not correctly handle the -compilejdk option. Acknowledgements Thanks to Alan, Amy, Andrey, Brad, Christine, Dima, Max, Mike, Sherman, Steve and others for their help, suggestions, bug reports and for testing this latest version.

  Read the article

• Faster Memory Allocation Using vmtasks

  - by Steve Sistare

  You may have noticed a new system process called "vmtasks" on Solaris 11 systems: % pgrep vmtasks 8 % prstat -p 8 PID USERNAME SIZE RSS STATE PRI NICE TIME CPU PROCESS/NLWP 8 root 0K 0K sleep 99 -20 9:10:59 0.0% vmtasks/32 What is vmtasks, and why should you care? In a nutshell, vmtasks accelerates creation, locking, and destruction of pages in shared memory segments. This is particularly helpful for locked memory, as creating a page of physical memory is much more expensive than creating a page of virtual memory. For example, an ISM segment (shmflag & SHM_SHARE_MMU) is locked in memory on the first shmat() call, and a DISM segment (shmflg & SHM_PAGEABLE) is locked using mlock() or memcntl(). Segment operations such as creation and locking are typically single threaded, performed by the thread making the system call. In many applications, the size of a shared memory segment is a large fraction of total physical memory, and the single-threaded initialization is a scalability bottleneck which increases application startup time. To break the bottleneck, we apply parallel processing, harnessing the power of the additional CPUs that are always present on modern platforms. For sufficiently large segments, as many of 16 threads of vmtasks are employed to assist an application thread during creation, locking, and destruction operations. The segment is implicitly divided at page boundaries, and each thread is given a chunk of pages to process. The per-page processing time can vary, so for dynamic load balancing, the number of chunks is greater than the number of threads, and threads grab chunks dynamically as they finish their work. Because the threads modify a single application address space in compressed time interval, contention on locks protecting VM data structures locks was a problem, and we had to re-scale a number of VM locks to get good parallel efficiency. The vmtasks process has 1 thread per CPU and may accelerate multiple segment operations simultaneously, but each operation gets at most 16 helper threads to avoid monopolizing CPU resources. We may reconsider this limit in the future. Acceleration using vmtasks is enabled out of the box, with no tuning required, and works for all Solaris platform architectures (SPARC sun4u, SPARC sun4v, x86). The following tables show the time to create + lock + destroy a large segment, normalized as milliseconds per gigabyte, before and after the introduction of vmtasks: ISM system ncpu before after speedup ------ ---- ------ ----- ------- x4600 32 1386 245 6X X7560 64 1016 153 7X M9000 512 1196 206 6X T5240 128 2506 234 11X T4-2 128 1197 107 11x DISM system ncpu before after speedup ------ ---- ------ ----- ------- x4600 32 1582 265 6X X7560 64 1116 158 7X M9000 512 1165 152 8X T5240 128 2796 198 14X (I am missing the data for T4 DISM, for no good reason; it works fine). The following table separates the creation and destruction times: ISM, T4-2 before after ------ ----- create 702 64 destroy 495 43 To put this in perspective, consider creating a 512 GB ISM segment on T4-2. Creating the segment would take 6 minutes with the old code, and only 33 seconds with the new. If this is your Oracle SGA, you save over 5 minutes when starting the database, and you also save when shutting it down prior to a restart. Those minutes go directly to your bottom line for service availability.

  Read the article

• Adding Polynomials (Linked Lists)......Bug Help

  - by Brian

  I have written a program that creates nodes that in this class are parts of polynomials and then the two polynomials get added together to become one polynomial (list of nodes). All my code compiles so the only problem I am having is that the nodes are not inserting into the polynomial via the insert method I have in polynomial.java and when running the program it does create nodes and displays them in the 2x^2 format but when it comes to add the polynomials together it displays o as the polynomials, so if anyone can figure out whats wrong and what I can do to fix it it would be much appreciated. Here is the code: import java.util.Scanner; class Polynomial{ public termNode head; public Polynomial() { head = null; } public boolean isEmpty() { return (head == null); } public void display() { if (head == null) System.out.print("0"); else for(termNode cur = head; cur != null; cur = cur.getNext()) { System.out.println(cur); } } public void insert(termNode newNode) { termNode prev = null; termNode cur = head; while (cur!=null && (newNode.compareTo(cur)<0)) { prev = null; cur = cur.getNext(); } if (prev == null) { newNode.setNext(head); head = newNode; } else { newNode.setNext(cur); prev.setNext(newNode); } } public void readPolynomial(Scanner kb) { boolean done = false; double coefficient; int exponent; termNode term; head = null; //UNLINK ANY PREVIOUS POLYNOMIAL System.out.println("Enter 0 and 0 to end."); System.out.print("coefficient: "); coefficient = kb.nextDouble(); System.out.println(coefficient); System.out.print("exponent: "); exponent = kb.nextInt(); System.out.println(exponent); done = (coefficient == 0 && exponent == 0); while(!done) { Polynomial poly = new Polynomial(); term = new termNode(coefficient,exponent); System.out.println(term); poly.insert(term); System.out.println("Enter 0 and 0 to end."); System.out.print("coefficient: "); coefficient = kb.nextDouble(); System.out.println(coefficient); System.out.print("exponent: "); exponent = kb.nextInt(); System.out.println(exponent); done = (coefficient==0 && exponent==0); } } public static Polynomial add(Polynomial p, Polynomial q) { Polynomial r = new Polynomial(); double coefficient; int exponent; termNode first = p.head; termNode second = q.head; termNode sum = r.head; termNode term; while (first != null && second != null) { if (first.getExp() == second.getExp()) { if (first.getCoeff() != 0 && second.getCoeff() != 0); { double addCoeff = first.getCoeff() + second.getCoeff(); term = new termNode(addCoeff,first.getExp()); sum.setNext(term); first.getNext(); second.getNext(); } } else if (first.getExp() < second.getExp()) { sum.setNext(second); term = new termNode(second.getCoeff(),second.getExp()); sum.setNext(term); second.getNext(); } else { sum.setNext(first); term = new termNode(first.getNext()); sum.setNext(term); first.getNext(); } } while (first != null) { sum.setNext(first); } while (second != null) { sum.setNext(second); } return r; } } Here is my Node class: class termNode implements Comparable { private int exp; private double coeff; private termNode next; public termNode(double coefficient, int exponent) { coeff = coefficient; exp = exponent; next = null; } public termNode(termNode inTermNode) { coeff = inTermNode.coeff; exp = inTermNode.exp; } public void setData(double coefficient, int exponent) { coefficient = coeff; exponent = exp; } public double getCoeff() { return coeff; } public int getExp() { return exp; } public void setNext(termNode link) { next = link; } public termNode getNext() { return next; } public String toString() { if (exp == 0) { return(coeff + " "); } else if (exp == 1) { return(coeff + "x"); } else { return(coeff + "x^" + exp); } } public int compareTo(Object other) { if(exp ==((termNode) other).exp) return 0; else if(exp < ((termNode) other).exp) return -1; else return 1; } } And here is my Test class to run the program. import java.util.Scanner; class PolyTest{ public static void main(String [] args) { Scanner kb = new Scanner(System.in); Polynomial r; Polynomial p = new Polynomial(); System.out.println("Enter first polynomial."); p.readPolynomial(kb); Polynomial q = new Polynomial(); System.out.println(); System.out.println("Enter second polynomial."); q.readPolynomial(kb); r = Polynomial.add(p,q); System.out.println(); System.out.print("The sum of "); p.display(); System.out.print(" and "); q.display(); System.out.print(" is "); r.display(); } }

  Read the article

• Unexpected ArrayIndexOutOfBoundsException in JavaFX application, refering to no array

  - by Eugene

  I have the following code: public void setContent(Importer3D importer) { if (DEBUG) { System.out.println("Initialization of Mesh's arrays"); } coords = importer.getCoords(); texCoords = importer.getTexCoords(); faces = importer.getFaces(); if (DEBUG) { System.out.println("Applying Mesh's arrays"); } mesh = new TriangleMesh(); mesh.getPoints().setAll(coords); mesh.getTexCoords().setAll(texCoords); mesh.getFaces().setAll(faces); if (DEBUG) { System.out.println("Initialization of the material"); } initMaterial(); if (DEBUG) { System.out.println("Setting the MeshView"); } meshView.setMesh(mesh); meshView.setMaterial(material); meshView.setDrawMode(DrawMode.FILL); if (DEBUG) { System.out.println("Adding to 3D scene"); } root3d.getChildren().clear(); root3d.getChildren().add(meshView); if (DEBUG) { System.out.println("3D model is ready!"); } } The Imporeter3D class part: private void load(File file) { stlLoader = new STLLoader(file); } public float[] getCoords() { return stlLoader.getCoords(); } public float[] getTexCoords() { return stlLoader.getTexCoords(); } public int[] getFaces() { return stlLoader.getFaces(); } The STLLoader: public class STLLoader{ public STLLoader(File file) { stlFile = new STLFile(file); loadManager = stlFile.loadManager; pointsArray = new PointsArray(stlFile); texCoordsArray = new TexCoordsArray(); } public float[] getCoords() { return pointsArray.getPoints(); } public float[] getTexCoords() { return texCoordsArray.getTexCoords(); } public int[] getFaces() { return pointsArray.getFaces(); } private STLFile stlFile; private PointsArray pointsArray; private TexCoordsArray texCoordsArray; private FacesArray facesArray; public SimpleBooleanProperty finished = new SimpleBooleanProperty(false); public LoadManager loadManager;} PointsArray file: public class PointsArray { public PointsArray(STLFile stlFile) { this.stlFile = stlFile; initPoints(); } private void initPoints() { ArrayList<Double> pointsList = stlFile.getPoints(); ArrayList<Double> uPointsList = new ArrayList<>(); faces = new int[pointsList.size()*2]; int n = 0; for (Double d : pointsList) { if (uPointsList.indexOf(d) == -1) { uPointsList.add(d); } faces[n] = uPointsList.indexOf(d); faces[++n] = 0; n++; } int i = 0; points = new float[uPointsList.size()]; for (Double d : uPointsList) { points[i] = d.floatValue(); i++; } } public float[] getPoints() { return points; } public int[] getFaces() { return faces; } private float[] points; private int[] faces; private STLFile stlFile; public static boolean DEBUG = true; } And STLFile: ArrayList<Double> coords = new ArrayList<>(); double temp; private void readV(STLParser parser) { for (int n = 0; n < 3; n++) { if(!(parser.ttype==STLParser.TT_WORD && parser.sval.equals("vertex"))) { System.err.println("Format Error:expecting 'vertex' on line " + parser.lineno()); } else { if (parser.getNumber()) { temp = parser.nval; coords.add(temp); if(DEBUG) { System.out.println("Vertex:"); System.out.print("X=" + temp + " "); } if (parser.getNumber()) { temp = parser.nval; coords.add(temp); if(DEBUG) { System.out.print("Y=" + temp + " "); } if (parser.getNumber()) { temp = parser.nval; coords.add(temp); if(DEBUG) { System.out.println("Z=" + temp + " "); } readEOL(parser); } else System.err.println("Format Error: expecting coordinate on line " + parser.lineno()); } else System.err.println("Format Error: expecting coordinate on line " + parser.lineno()); } else System.err.println("Format Error: expecting coordinate on line " + parser.lineno()); } if (n < 2) { try { parser.nextToken(); } catch (IOException e) { System.err.println("IO Error on line " + parser.lineno() + ": " + e.getMessage()); } } } } public ArrayList<Double> getPoints() { return coords; } As a result of all of this code, I expected to get 3d model in MeshView. But the present result is very strange: everything works and in DEBUG mode I get 3d model is ready! from setContent(), and then unexpected ArrayIndexOutOfBoundsException: File readed Initialization of Mesh's arrays Applying Mesh's arrays Initialization of the material Setting the MeshView Adding to 3D scene 3D model is ready! java.lang.ArrayIndexOutOfBoundsException: Array index out of range: 32252 at com.sun.javafx.collections.ObservableFloatArrayImpl.rangeCheck(ObservableFloatArrayImpl.java:276) at com.sun.javafx.collections.ObservableFloatArrayImpl.get(ObservableFloatArrayImpl.java:184) at javafx.scene.shape.TriangleMesh.computeBounds(TriangleMesh.java:262) at javafx.scene.shape.MeshView.impl_computeGeomBounds(MeshView.java:151) at javafx.scene.Node.updateGeomBounds(Node.java:3497) at javafx.scene.Node.getGeomBounds(Node.java:3450) at javafx.scene.Node.getLocalBounds(Node.java:3432) at javafx.scene.Node.updateTxBounds(Node.java:3510) at javafx.scene.Node.getTransformedBounds(Node.java:3350) at javafx.scene.Node.updateBounds(Node.java:516) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.SubScene.updateBounds(SubScene.java:556) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.Parent.updateBounds(Parent.java:1668) at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2309) at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:329) at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:479) at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:459) at com.sun.javafx.tk.quantum.QuantumToolkit$13.run(QuantumToolkit.java:326) at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95) at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) at com.sun.glass.ui.win.WinApplication.access$300(WinApplication.java:39) at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:101) at java.lang.Thread.run(Thread.java:724) Exception in thread "JavaFX Application Thread" java.lang.ArrayIndexOutOfBoundsException: Array index out of range: 32252 at com.sun.javafx.collections.ObservableFloatArrayImpl.rangeCheck(ObservableFloatArrayImpl.java:276) at com.sun.javafx.collections.ObservableFloatArrayImpl.get(ObservableFloatArrayImpl.java:184) The stranger thing is that this stack doesn't stop until I close the program. And moreover it doesn't point to any my array. What is this? And why does it happen?

  Read the article

• Incorrect output on changing sequence of declarations

  - by max

  Writing C++ code to implement Sutherland-Hodgeman polygon clipping. This order of declaration of these 2 statements gives correct output, reverse does not. int numberOfVertices = 5; Point pointList[] = { {50,50}, {200,300}, {310,110}, {130,90}, {70,40} }; I am passing the polygon vertex set to clippers in order - LEFT, RIGHT, TOP, BOTTOM. The exact error which comes when the declarations are reversed is that the bottom clipper, produces an empty set of vertices so no polygon is displayed after clipping. Correct: Incorrent: Confirmed by outputting the number of vertices produced after each pass: Correct: Incorrect: What is the reason for this error? Code: #include <iostream> #include <GL/glut.h> #define MAXVERTICES 10 #define LEFT 0 #define RIGHT 1 #define TOP 2 #define BOTTOM 3 using namespace std; /* Clipping window */ struct Window { double xmin; double xmax; double ymin; double ymax; }; struct Point { double x; double y; }; /* If I interchange these two lines, the code doesn't work. */ /**************/ int numberOfVertices = 5; Point pointList[] = { {50,50}, {200,300}, {310,110}, {130,90}, {70,40} }; /**************/ const Window w = { 100, 400, 60, 200 }; /* Checks whether a point is inside or outside a window side */ int isInside(Point p, int side) { switch(side) { case LEFT: return p.x >= w.xmin; case RIGHT: return p.x <= w.xmax; case TOP: return p.y <= w.ymax; case BOTTOM: return p.y >= w.ymin; } } /* Calculates intersection of a segment and a window side */ Point intersection(Point p1, Point p2, int side) { Point temp; double slope, intercept; bool infinite; /* Find slope and intercept of segment, taking care of inf slope */ if(p2.x - p1.x != 0) { slope = (p2.y - p1.y) / (p2.x - p1.x); infinite = false; } else { infinite = true; } intercept = p1.y - p1.x * slope; /* Calculate intersections */ switch(side) { case LEFT: temp.x = w.xmin; temp.y = temp.x * slope + intercept; break; case RIGHT: temp.x = w.xmax; temp.y = temp.x * slope + intercept; break; case TOP: temp.y = w.ymax; temp.x = infinite ? p1.x : (temp.y - intercept) / slope; break; case BOTTOM: temp.y = w.ymin; temp.x = infinite ? p1.x : (temp.y - intercept) / slope; break; } return temp; } /* Clips polygon against a side, updating the point list (called once for each side) */ void clipAgainstSide(int sideToClip) { int i, j=0; Point s,p; Point outputList[MAXVERTICES]; /* Main algorithm */ s = pointList[numberOfVertices-1]; for(i=0 ; i<numberOfVertices ; i++) { p = pointList[i]; if(isInside(p, sideToClip)) { /* p inside */ if(!isInside(s, sideToClip)) { /* p inside, s outside */ outputList[j] = intersection(p, s, sideToClip); j++; } outputList[j] = p; j++; } else if(isInside(s, sideToClip)) { /* s inside, p outside */ outputList[j] = intersection(s, p, sideToClip); j++; } s = p; } /* Updating number of points and point list */ numberOfVertices = j; /* ERROR: In last call with BOTTOM argument, numberOfVertices becomes 0 */ /* all earlier 3 calls have correct output */ cout<<numberOfVertices<<endl; for(i=0 ; i<numberOfVertices ; i++) { pointList[i] = outputList[i]; } } void SutherlandHodgemanPolygonClip() { clipAgainstSide(LEFT); clipAgainstSide(RIGHT); clipAgainstSide(TOP); clipAgainstSide(BOTTOM); } void init() { glClearColor(1,1,1,0); glMatrixMode(GL_PROJECTION); gluOrtho2D(0,1000,0,500); } void display() { glClear(GL_COLOR_BUFFER_BIT); /* Displaying ORIGINAL box and polygon */ glColor3f(0,0,1); glBegin(GL_LINE_LOOP); glVertex2i(w.xmin, w.ymin); glVertex2i(w.xmin, w.ymax); glVertex2i(w.xmax, w.ymax); glVertex2i(w.xmax, w.ymin); glEnd(); glColor3f(1,0,0); glBegin(GL_LINE_LOOP); for(int i=0 ; i<numberOfVertices ; i++) { glVertex2i(pointList[i].x, pointList[i].y); } glEnd(); /* Clipping */ SutherlandHodgemanPolygonClip(); /* Displaying CLIPPED box and polygon, 500px right */ glColor3f(0,0,1); glBegin(GL_LINE_LOOP); glVertex2i(w.xmin+500, w.ymin); glVertex2i(w.xmin+500, w.ymax); glVertex2i(w.xmax+500, w.ymax); glVertex2i(w.xmax+500, w.ymin); glEnd(); glColor3f(1,0,0); glBegin(GL_LINE_LOOP); for(int i=0 ; i<numberOfVertices ; i++) { glVertex2i(pointList[i].x+500, pointList[i].y); } glEnd(); glFlush(); } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutInitWindowSize(1000,500); glutCreateWindow("Sutherland-Hodgeman polygon clipping"); init(); glutDisplayFunc(display); glutMainLoop(); return 0; }

  Read the article

• ADO.NET DataTable/DataRow Thread Safety

  - by Allen E. Scharfenberg

  Introduction A user reported to me this morning that he was having an issue with inconsistent results (namely, column values sometimes coming out null when they should not be) of some parallel execution code that we provide as part of an internal framework. This code has worked fine in the past and has not been tampered with lately, but it got me to thinking about the following snippet: Code Sample lock (ResultTable) { newRow = ResultTable.NewRow(); } newRow["Key"] = currentKey; foreach (KeyValuePair<string, object> output in outputs) { object resultValue = output.Value; newRow[output.Name] = resultValue != null ? resultValue : DBNull.Value; } lock (ResultTable) { ResultTable.Rows.Add(newRow); } (No guarantees that that compiles, hand-edited to mask proprietery information.) Explanation We have this cascading type of locking code other places in our system, and it works fine, but this is the first instance of cascading locking code that I have come across that interacts with ADO .NET. As we all know, members of framework objects are usually not thread safe (which is the case in this situation), but the cascading locking should ensure that we are not reading and writing to ResultTable.Rows concurrently. We are safe, right? Hypothesis Well, the cascading lock code does not ensure that we are not reading from or writing to ResultTable.Rows at the same time that we are assigning values to columns in the new row. What if ADO .NET uses some kind of buffer for assigning column values that is not thread safe--even when different object types are involved (DataTable vs. DataRow)? Has anyone run into anything like this before? I thought I would ask here at StackOverflow before beating my head against this for hours on end :) Conclusion Well, the consensus appears to be that changing the cascading lock to a full lock has resolved the issue. That is not the result that I expected, but the full lock version has not produced the issue after many, many, many tests. The lesson: be wary of cascading locks used on APIs that you do not control. Who knows what may be going on under the covers!

  Read the article

• optimistic and pessimistic locks

  - by billmce

  Working on my first php/Codeigniter project and I’ve scoured the ‘net for information on locking access to editing data and haven’t found very much information. I expect it to be a fairly regular occurrence for 2 users to attempt to edit the same form simultaneously. My experience (in the stateful world of BBx, filePro, and other RAD apps) is that the data being edited is locked using a pessimistic lock—one user has access to the edit form at the time. The second user basically has to wait for the first to finish. I understand this can be done using Ajax sending XMLHttpRequests to maintain a ‘lock’ database. The php world, lacking state, seems to prefer optimistic locking. If I understand it correctly it works like this: both users get to access the data and they each record a ‘before changes’ version of the data. Before saving their changes, the data is once again retrieved and compared the ‘before changes’ version. If the two versions are identical then the users changes are written. If they are different; the user is shown what has changed since he/she started editing and some mechanism is added to resolve the differences—or the user is shown a ‘Sorry, try again’ message. I’m interested in any experience people here have had with implementing both pessimistic and optimistic locking. If there are any libraries, tools, or ‘how-to’s available I’m appreciate a link. Thanks

  Read the article

• .NET List Thread-Safe Implementation Suggestion needed

  - by Bamboo

  .Net List class isn't thread safe. I hope to achieve the minimal lock needed and yet still fulfilling the requirement such that as for reading, phantom record is allowed, and for writing, they must be thread-safe so there won't be any lost updates. So I have something like public static List<string> list = new List<string>(); In Methods that have **List.Add**/**List.Remove** , I always lock to assure thread safety lock (lockHelper) { list.Add(obj); or list.Remove(obj); } In Methods that requires **List Reading** I don't care about phantom record so I go ahead to read without any locking. In this case. Return a bool by checking whether a string had been added. if (list.Count() != 0) { return list.Contains("some string") } All I did was locking write accesses, and allow read accesses to go through without any locking. Is my thread safety idea valid? I understand there is List size expansion. Will it be ok? My guess is that when a List is expanding, it may uses a temp. list. This is ok becasue the temp list size will always have a boundary, and .Net class is well implemented, ie. there shouldn't be any indexOutOfBound or circular reference problems when reading was caught in updates.

  Read the article

• C#/.NET Little Wonders: The ConcurrentDictionary

  - by James Michael Hare

  Once again we consider some of the lesser known classes and keywords of C#.  In this series of posts, we will discuss how the concurrent collections have been developed to help alleviate these multi-threading concerns.  Last week’s post began with a general introduction and discussed the ConcurrentStack<T> and ConcurrentQueue<T>.  Today's post discusses the ConcurrentDictionary<T> (originally I had intended to discuss ConcurrentBag this week as well, but ConcurrentDictionary had enough information to create a very full post on its own!).  Finally next week, we shall close with a discussion of the ConcurrentBag<T> and BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. Recap As you'll recall from the previous post, the original collections were object-based containers that accomplished synchronization through a Synchronized member.  While these were convenient because you didn't have to worry about writing your own synchronization logic, they were a bit too finely grained and if you needed to perform multiple operations under one lock, the automatic synchronization didn't buy much. With the advent of .NET 2.0, the original collections were succeeded by the generic collections which are fully type-safe, but eschew automatic synchronization.  This cuts both ways in that you have a lot more control as a developer over when and how fine-grained you want to synchronize, but on the other hand if you just want simple synchronization it creates more work. With .NET 4.0, we get the best of both worlds in generic collections.  A new breed of collections was born called the concurrent collections in the System.Collections.Concurrent namespace.  These amazing collections are fine-tuned to have best overall performance for situations requiring concurrent access.  They are not meant to replace the generic collections, but to simply be an alternative to creating your own locking mechanisms. Among those concurrent collections were the ConcurrentStack<T> and ConcurrentQueue<T> which provide classic LIFO and FIFO collections with a concurrent twist.  As we saw, some of the traditional methods that required calls to be made in a certain order (like checking for not IsEmpty before calling Pop()) were replaced in favor of an umbrella operation that combined both under one lock (like TryPop()). Now, let's take a look at the next in our series of concurrent collections!For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here. ConcurrentDictionary – the fully thread-safe dictionary The ConcurrentDictionary<TKey,TValue> is the thread-safe counterpart to the generic Dictionary<TKey, TValue> collection.  Obviously, both are designed for quick – O(1) – lookups of data based on a key.  If you think of algorithms where you need lightning fast lookups of data and don’t care whether the data is maintained in any particular ordering or not, the unsorted dictionaries are generally the best way to go. Note: as a side note, there are sorted implementations of IDictionary, namely SortedDictionary and SortedList which are stored as an ordered tree and a ordered list respectively.  While these are not as fast as the non-sorted dictionaries – they are O(log2 n) – they are a great combination of both speed and ordering -- and still greatly outperform a linear search. Now, once again keep in mind that if all you need to do is load a collection once and then allow multi-threaded reading you do not need any locking.  Examples of this tend to be situations where you load a lookup or translation table once at program start, then keep it in memory for read-only reference.  In such cases locking is completely non-productive. However, most of the time when we need a concurrent dictionary we are interleaving both reads and updates.  This is where the ConcurrentDictionary really shines!  It achieves its thread-safety with no common lock to improve efficiency.  It actually uses a series of locks to provide concurrent updates, and has lockless reads!  This means that the ConcurrentDictionary gets even more efficient the higher the ratio of reads-to-writes you have. ConcurrentDictionary and Dictionary differences For the most part, the ConcurrentDictionary<TKey,TValue> behaves like it’s Dictionary<TKey,TValue> counterpart with a few differences.  Some notable examples of which are: Add() does not exist in the concurrent dictionary. This means you must use TryAdd(), AddOrUpdate(), or GetOrAdd().  It also means that you can’t use a collection initializer with the concurrent dictionary. TryAdd() replaced Add() to attempt atomic, safe adds. Because Add() only succeeds if the item doesn’t already exist, we need an atomic operation to check if the item exists, and if not add it while still under an atomic lock. TryUpdate() was added to attempt atomic, safe updates. If we want to update an item, we must make sure it exists first and that the original value is what we expected it to be.  If all these are true, we can update the item under one atomic step. TryRemove() was added to attempt atomic, safe removes. To safely attempt to remove a value we need to see if the key exists first, this checks for existence and removes under an atomic lock. AddOrUpdate() was added to attempt an thread-safe “upsert”. There are many times where you want to insert into a dictionary if the key doesn’t exist, or update the value if it does.  This allows you to make a thread-safe add-or-update. GetOrAdd() was added to attempt an thread-safe query/insert. Sometimes, you want to query for whether an item exists in the cache, and if it doesn’t insert a starting value for it.  This allows you to get the value if it exists and insert if not. Count, Keys, Values properties take a snapshot of the dictionary. Accessing these properties may interfere with add and update performance and should be used with caution. ToArray() returns a static snapshot of the dictionary. That is, the dictionary is locked, and then copied to an array as a O(n) operation.  GetEnumerator() is thread-safe and efficient, but allows dirty reads. Because reads require no locking, you can safely iterate over the contents of the dictionary.  The only downside is that, depending on timing, you may get dirty reads. Dirty reads during iteration The last point on GetEnumerator() bears some explanation.  Picture a scenario in which you call GetEnumerator() (or iterate using a foreach, etc.) and then, during that iteration the dictionary gets updated.  This may not sound like a big deal, but it can lead to inconsistent results if used incorrectly.  The problem is that items you already iterated over that are updated a split second after don’t show the update, but items that you iterate over that were updated a split second before do show the update.  Thus you may get a combination of items that are “stale” because you iterated before the update, and “fresh” because they were updated after GetEnumerator() but before the iteration reached them. Let’s illustrate with an example, let’s say you load up a concurrent dictionary like this: 1: // load up a dictionary. 2: var dictionary = new ConcurrentDictionary<string, int>(); 3:  4: dictionary["A"] = 1; 5: dictionary["B"] = 2; 6: dictionary["C"] = 3; 7: dictionary["D"] = 4; 8: dictionary["E"] = 5; 9: dictionary["F"] = 6; Then you have one task (using the wonderful TPL!) to iterate using dirty reads: 1: // attempt iteration in a separate thread 2: var iterationTask = new Task(() => 3: { 4: // iterates using a dirty read 5: foreach (var pair in dictionary) 6: { 7: Console.WriteLine(pair.Key + ":" + pair.Value); 8: } 9: }); And one task to attempt updates in a separate thread (probably): 1: // attempt updates in a separate thread 2: var updateTask = new Task(() => 3: { 4: // iterates, and updates the value by one 5: foreach (var pair in dictionary) 6: { 7: dictionary[pair.Key] = pair.Value + 1; 8: } 9: }); Now that we’ve done this, we can fire up both tasks and wait for them to complete: 1: // start both tasks 2: updateTask.Start(); 3: iterationTask.Start(); 4:  5: // wait for both to complete. 6: Task.WaitAll(updateTask, iterationTask); Now, if I you didn’t know about the dirty reads, you may have expected to see the iteration before the updates (such as A:1, B:2, C:3, D:4, E:5, F:6).  However, because the reads are dirty, we will quite possibly get a combination of some updated, some original.  My own run netted this result: 1: F:6 2: E:6 3: D:5 4: C:4 5: B:3 6: A:2 Note that, of course, iteration is not in order because ConcurrentDictionary, like Dictionary, is unordered.  Also note that both E and F show the value 6.  This is because the output task reached F before the update, but the updates for the rest of the items occurred before their output (probably because console output is very slow, comparatively). If we want to always guarantee that we will get a consistent snapshot to iterate over (that is, at the point we ask for it we see precisely what is in the dictionary and no subsequent updates during iteration), we should iterate over a call to ToArray() instead: 1: // attempt iteration in a separate thread 2: var iterationTask = new Task(() => 3: { 4: // iterates using a dirty read 5: foreach (var pair in dictionary.ToArray()) 6: { 7: Console.WriteLine(pair.Key + ":" + pair.Value); 8: } 9: }); The atomic Try…() methods As you can imagine TryAdd() and TryRemove() have few surprises.  Both first check the existence of the item to determine if it can be added or removed based on whether or not the key currently exists in the dictionary: 1: // try add attempts an add and returns false if it already exists 2: if (dictionary.TryAdd("G", 7)) 3: Console.WriteLine("G did not exist, now inserted with 7"); 4: else 5: Console.WriteLine("G already existed, insert failed."); TryRemove() also has the virtue of returning the value portion of the removed entry matching the given key: 1: // attempt to remove the value, if it exists it is removed and the original is returned 2: int removedValue; 3: if (dictionary.TryRemove("C", out removedValue)) 4: Console.WriteLine("Removed C and its value was " + removedValue); 5: else 6: Console.WriteLine("C did not exist, remove failed."); Now TryUpdate() is an interesting creature.  You might think from it’s name that TryUpdate() first checks for an item’s existence, and then updates if the item exists, otherwise it returns false.  Well, note quite... It turns out when you call TryUpdate() on a concurrent dictionary, you pass it not only the new value you want it to have, but also the value you expected it to have before the update.  If the item exists in the dictionary, and it has the value you expected, it will update it to the new value atomically and return true.  If the item is not in the dictionary or does not have the value you expected, it is not modified and false is returned. 1: // attempt to update the value, if it exists and if it has the expected original value 2: if (dictionary.TryUpdate("G", 42, 7)) 3: Console.WriteLine("G existed and was 7, now it's 42."); 4: else 5: Console.WriteLine("G either didn't exist, or wasn't 7."); The composite Add methods The ConcurrentDictionary also has composite add methods that can be used to perform updates and gets, with an add if the item is not existing at the time of the update or get. The first of these, AddOrUpdate(), allows you to add a new item to the dictionary if it doesn’t exist, or update the existing item if it does.  For example, let’s say you are creating a dictionary of counts of stock ticker symbols you’ve subscribed to from a market data feed: 1: public sealed class SubscriptionManager 2: { 3: private readonly ConcurrentDictionary<string, int> _subscriptions = new ConcurrentDictionary<string, int>(); 4:  5: // adds a new subscription, or increments the count of the existing one. 6: public void AddSubscription(string tickerKey) 7: { 8: // add a new subscription with count of 1, or update existing count by 1 if exists 9: var resultCount = _subscriptions.AddOrUpdate(tickerKey, 1, (symbol, count) => count + 1); 10:  11: // now check the result to see if we just incremented the count, or inserted first count 12: if (resultCount == 1) 13: { 14: // subscribe to symbol... 15: } 16: } 17: } Notice the update value factory Func delegate.  If the key does not exist in the dictionary, the add value is used (in this case 1 representing the first subscription for this symbol), but if the key already exists, it passes the key and current value to the update delegate which computes the new value to be stored in the dictionary.  The return result of this operation is the value used (in our case: 1 if added, existing value + 1 if updated). Likewise, the GetOrAdd() allows you to attempt to retrieve a value from the dictionary, and if the value does not currently exist in the dictionary it will insert a value.  This can be handy in cases where perhaps you wish to cache data, and thus you would query the cache to see if the item exists, and if it doesn’t you would put the item into the cache for the first time: 1: public sealed class PriceCache 2: { 3: private readonly ConcurrentDictionary<string, double> _cache = new ConcurrentDictionary<string, double>(); 4:  5: // adds a new subscription, or increments the count of the existing one. 6: public double QueryPrice(string tickerKey) 7: { 8: // check for the price in the cache, if it doesn't exist it will call the delegate to create value. 9: return _cache.GetOrAdd(tickerKey, symbol => GetCurrentPrice(symbol)); 10: } 11:  12: private double GetCurrentPrice(string tickerKey) 13: { 14: // do code to calculate actual true price. 15: } 16: } There are other variations of these two methods which vary whether a value is provided or a factory delegate, but otherwise they work much the same. Oddities with the composite Add methods The AddOrUpdate() and GetOrAdd() methods are totally thread-safe, on this you may rely, but they are not atomic.  It is important to note that the methods that use delegates execute those delegates outside of the lock.  This was done intentionally so that a user delegate (of which the ConcurrentDictionary has no control of course) does not take too long and lock out other threads. This is not necessarily an issue, per se, but it is something you must consider in your design.  The main thing to consider is that your delegate may get called to generate an item, but that item may not be the one returned!  Consider this scenario: A calls GetOrAdd and sees that the key does not currently exist, so it calls the delegate.  Now thread B also calls GetOrAdd and also sees that the key does not currently exist, and for whatever reason in this race condition it’s delegate completes first and it adds its new value to the dictionary.  Now A is done and goes to get the lock, and now sees that the item now exists.  In this case even though it called the delegate to create the item, it will pitch it because an item arrived between the time it attempted to create one and it attempted to add it. Let’s illustrate, assume this totally contrived example program which has a dictionary of char to int.  And in this dictionary we want to store a char and it’s ordinal (that is, A = 1, B = 2, etc).  So for our value generator, we will simply increment the previous value in a thread-safe way (perhaps using Interlocked): 1: public static class Program 2: { 3: private static int _nextNumber = 0; 4:  5: // the holder of the char to ordinal 6: private static ConcurrentDictionary<char, int> _dictionary 7: = new ConcurrentDictionary<char, int>(); 8:  9: // get the next id value 10: public static int NextId 11: { 12: get { return Interlocked.Increment(ref _nextNumber); } 13: } Then, we add a method that will perform our insert: 1: public static void Inserter() 2: { 3: for (int i = 0; i < 26; i++) 4: { 5: _dictionary.GetOrAdd((char)('A' + i), key => NextId); 6: } 7: } Finally, we run our test by starting two tasks to do this work and get the results… 1: public static void Main() 2: { 3: // 3 tasks attempting to get/insert 4: var tasks = new List<Task> 5: { 6: new Task(Inserter), 7: new Task(Inserter) 8: }; 9:  10: tasks.ForEach(t => t.Start()); 11: Task.WaitAll(tasks.ToArray()); 12:  13: foreach (var pair in _dictionary.OrderBy(p => p.Key)) 14: { 15: Console.WriteLine(pair.Key + ":" + pair.Value); 16: } 17: } If you run this with only one task, you get the expected A:1, B:2, ..., Z:26.  But running this in parallel you will get something a bit more complex.  My run netted these results: 1: A:1 2: B:3 3: C:4 4: D:5 5: E:6 6: F:7 7: G:8 8: H:9 9: I:10 10: J:11 11: K:12 12: L:13 13: M:14 14: N:15 15: O:16 16: P:17 17: Q:18 18: R:19 19: S:20 20: T:21 21: U:22 22: V:23 23: W:24 24: X:25 25: Y:26 26: Z:27 Notice that B is 3?  This is most likely because both threads attempted to call GetOrAdd() at roughly the same time and both saw that B did not exist, thus they both called the generator and one thread got back 2 and the other got back 3.  However, only one of those threads can get the lock at a time for the actual insert, and thus the one that generated the 3 won and the 3 was inserted and the 2 got discarded.  This is why on these methods your factory delegates should be careful not to have any logic that would be unsafe if the value they generate will be pitched in favor of another item generated at roughly the same time.  As such, it is probably a good idea to keep those generators as stateless as possible. Summary The ConcurrentDictionary is a very efficient and thread-safe version of the Dictionary generic collection.  It has all the benefits of type-safety that it’s generic collection counterpart does, and in addition is extremely efficient especially when there are more reads than writes concurrently. Tweet Technorati Tags: C#, .NET, Concurrent Collections, Collections, Little Wonders, Black Rabbit Coder,James Michael Hare

  Read the article

• jQuery, array form radio button name problem.

  - by borayeris

  <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>click div to select hidden options</title> <script type="text/javascript" src="jquery-1.4.4.js"></script> <style type="text/css"> .clickDiv { width:50px; height:50px; cursor:crosshair; } .red {border:1px #000 solid;} .green {border:1px #000 solid;} .redBG {background:#F00;} .greenBG {background:#0F0;} </style> <script type="text/javascript"> $(function() { $('div.clickDiv.red').click(function(){ var secilenMadde=$(this).attr('madde'); $('div#write').text(secilenMadde); $('input[name='+secilenMadde+'][value=red]').attr('checked', 'checked'); $('div.clickDiv.red[madde='+secilenMadde+']').addClass('redBG'); $('div.clickDiv.green[madde='+secilenMadde+']').removeClass('greenBG'); }); $('div.clickDiv.green').click(function(){ var secilenMadde=$(this).attr('madde'); $('div#write').text(secilenMadde); $('input[name='+secilenMadde+'][value=green]').attr('checked', 'checked'); $('div.clickDiv.green[madde='+secilenMadde+']').addClass('greenBG'); $('div.clickDiv.red[madde='+secilenMadde+']').removeClass('redBG'); }); }); </script> </head> <body> <div id="write"></div> <form id="formId" name="formName" method="post"> <table> <tr> <td><div class="clickDiv red" madde="line1"></div></td> <td><div class="clickDiv green" madde="line1"></div></td> </tr> <tr> <td><div class="clickDiv red" madde="line2"></div></td> <td><div class="clickDiv green" madde="line2"></div></td> </tr> </table> <label for="line1red"><input id="line1red" type="radio" name="line1" value="red" /> Red</label> <label for="line1green"><input id="line1green" type="radio" name="line1" value="green" /> Green</label><br /> <label for="line2red"><input type="radio" name="line2" value="red" /> Red</label> <label for="line2green"><input type="radio" name="line2" value="green" /> Green</label> </form> </body> </html> This works. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>click div to select hidden options</title> <script type="text/javascript" src="jquery-1.4.4.js"></script> <style type="text/css"> .clickDiv { width:50px; height:50px; cursor:crosshair; } .red {border:1px #000 solid;} .green {border:1px #000 solid;} .redBG {background:#F00;} .greenBG {background:#0F0;} </style> <script type="text/javascript"> $(function() { $('div.clickDiv.red').click(function(){ var secilenMadde=$(this).attr('madde'); $('div#write').text(secilenMadde); $('input[name='+secilenMadde+'][value=red]').attr('checked', 'checked'); $('div.clickDiv.red[madde='+secilenMadde+']').addClass('redBG'); $('div.clickDiv.green[madde='+secilenMadde+']').removeClass('greenBG'); }); $('div.clickDiv.green').click(function(){ var secilenMadde=$(this).attr('madde'); $('div#write').text(secilenMadde); $('input[name='+secilenMadde+'][value=green]').attr('checked', 'checked'); $('div.clickDiv.green[madde='+secilenMadde+']').addClass('greenBG'); $('div.clickDiv.red[madde='+secilenMadde+']').removeClass('redBG'); }); }); </script> </head> <body> <div id="write"></div> <form id="formId" name="formName" method="post"> <table> <tr> <td><div class="clickDiv red" madde="line[1]"></div></td> <td><div class="clickDiv green" madde="line[1]"></div></td> </tr> <tr> <td><div class="clickDiv red" madde="line[2]"></div></td> <td><div class="clickDiv green" madde="line[2]"></div></td> </tr> </table> <label for="line1red"><input id="line1red" type="radio" name="line[1]" value="red" /> Red</label> <label for="line1green"><input id="line1green" type="radio" name="line[1]" value="green" /> Green</label><br /> <label for="line2red"><input type="radio" name="line[2]" value="red" /> Red</label> <label for="line2green"><input type="radio" name="line[2]" value="green" /> Green</label> </form> </body> </html> This doesn't. I need input names as an array but it breaks my script. Why?

  Read the article

• Outlook 2007 - slow loading messages, etc

  - by studiohack

  Outlook 2007 is slow to load messages...Why is this, and what can I do to speed it up? Currently have about 850 messages in the Inbox folder, and the preview pane turned off, thus I view messages by double-clicking. This is where it gets slow, when I double click, it brings up a new window with everything but the actual message loaded. Solutions? Thanks! (running Windows 7)

  Read the article

• Mac OS X: Finder view options?

  - by trolle3000

  Hi there. In OS X 10.6, Finder usually looks something like this: The Finder window looks like that when you double-click on most folders or drives. However, whenever I mount a Truecrypt Volume and double-click that, it looks like this: Is there any way to default to the first view option for all types of folders? I tried view options in Finder, but it didn't seem to work.

  Read the article

• Problem with hp laser jet 1018

  - by dbf

  Hi! I'm using WinXP SP3 and HP LJ 1018. When I send 80 pages to pring as double side (directly or via FinePrint) only about 10 pages (at one side) are printed, I don't get any pages more and "Continue" button in double-side print dialog is disabled. Is it possible to fix it? Thanks!

  Read the article

• Outlook 2007 - slow loading messages

  - by studiohack

  Outlook 2007 is slow to load messages...Why is this, and what can I do to speed it up? Currently have about 850 messages in the Inbox folder, and the preview pane turned off, thus I view messages by double-clicking. This is where it gets slow, when I double click, it brings up a new window with everything but the actual message loaded, which then takes several more seconds to appear. Solutions? Thanks! (running Windows 7)

  Read the article

< Previous Page | 85 86 87 88 89 90 91 92 93 94 95 96  | Next Page >