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• Oracle GoldenGate 12c - Leading Enterprise Replication

  - by Doug Reid

  Oracle GoldenGate 12c released  on October 17th and includes several new cutting edge features that firmly establishes GoldenGate's leader position in the data replication space.   In fact, this release more than doubles the performance of data delivery, supports Oracle's new multitenant database feature,  it's more secure, has more options for high availability, and has made great strides to simplify the configuration and deployment of the product.     Read through the press release if you haven't already and do not miss the quote from Cern's Eva Dafonte Perez, regarding Oracle GoldenGate 12c "….performs five times faster compared to previous GoldenGate versions and simplifies the management of a multi-tier environment" There are a variety of new and improved features in the Oracle GoldenGate 12c.  Here are the highlights: Optimized for Oracle Database 12c -  GoldenGate 12c is custom tailored to the unique capabilities of Oracle database 12c and out of the box GoldenGate 12c supports multitenant (pluggable database (PDB)) and non-consolidated deployments of Oracle Database 12c.   The naming convention used by database 12c is now in three parts (PDB-name, schema-name, and object name).  We have made changes to the GoldenGate capture process to support the new naming convention and streamlined the whole process so a single GoldenGate capture process is being used at the container level rather than at each individual PDB.  By having the capture process at the container level resource usage and the number of processes are reduced. To view a conceptual architecture diagram click here. Integrated Delivery for the Oracle Database - Leveraging a lightweight streaming API built exclusively for Oracle GoldenGate 12c, this process distributes load, auto tunes the degree of parallelism, scales better, and delivers blinding rates of changed data delivery to the Oracle database.  One of the goals for Oracle GoldenGate 12c was to reduce IT costs by simplifying the configuration and reduce the time to manage complex infrastructures.  In previous versions of Oracle GoldenGate, customers would split transaction loads by grouping tables into multiple different delivery processes (click here to view the previous method). Each delivery process executed independently and without any interaction or knowledge of other delivery processes.  This setup was complicated to configure and time consuming as the developer needed in-depth knowledge of the source and target schemas and the transaction profile. With GoldenGate 12c and Integrated Delivery we have made it easier to configure and faster to deploy.  To view a conceptual architecture diagram of integrated delivery click here Coordinated Delivery for Non-Oracle Databases - Coordinated Delivery orchestrates high-speed apply processes and simplifies the configuration of GoldenGate for non-Oracle targets. In Oracle GoldenGate 12c a single delivery process is used with multiple threads (click here) and key events, such as primary key updates, event markers, DDL, etc, are coordinated between the various threads to insure that the transactions are applied in the same sequence as they were captured, all while delivery improved performance.  Replication Between On-Premises and Cloud-Based systems. - The trend for business to utilize both on-premises and cloud-based systems is rising and businesses need to replicate data back and forth.   GoldenGate 12c can be configured in a variety of ways to provide real-time replication when unrestricted or restricted (limited ports or HTTP tunneling) networks are between on-premises and cloud-based systems.    Expanded Heterogeneity - It wouldn't be a GoldenGate release without new and improved platform support.   Release 1 includes support for MySQL 5.6 and Sybase 15.7.   Upcoming in the next release GoldenGate, support will be expanded for MS SQL Server, DB2, and Teradata. Tighter Security - Oracle GoldenGate 12c is integrated with the Oracle wallet to shield usernames and passwords using strong encryption and aliases.   Customers accustomed to using the Oracle Wallet with other Oracle products will instantly be familiar with how to use this great new feature Expanded Oracle Application and Technology Support -   GoldenGate can be used along with Oracle Coherence to enable real-time changed data feeds to the Coherence cache using Toplink and the Oracle GoldenGate JMS adapter.     Plus,  Oracle Advanced Customer Services (ACS) now offers a low downtime E-Business Suite platform and database migrations using GoldenGate as the enabling technology.  Keep tuned for more blogs on the new features and the upcoming launch webcast where we will go into these new features in more detail.   In the mean time make sure to read through our white paper "Oracle GoldenGate 12c Release 1 New Features Overview"

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• Best Method For Evaluating Existing Software or New Software

  How many of us have been faced with having to decide on an off-the-self or a custom built component, application, or solution to integrate in to an existing system or to be the core foundation of a new system? What is the best method for evaluating existing software or new software still in the design phase? One of the industry preferred methodologies to use is the Active Reviews for Intermediate Designs (ARID) evaluation process.  ARID is a hybrid mixture of the Active Design Review (ADR) methodology and the Architectural Tradeoff Analysis Method (ATAM). So what is ARID? ARD’s main goal is to ensure quality, detailed designs in software. One way in which it does this is by empowering reviewers by assigning generic open ended survey questions. This approach attempts to remove the possibility for allowing the standard answers such as “Yes” or “No”. The ADR process ignores the “Yes”/”No” questions due to the fact that they can be leading based on how the question is asked. Additionally these questions tend to receive less thought in comparison to more open ended questions. Common Active Design Review Questions What possible exceptions can occur in this component, application, or solution? How should exceptions be handled in this component, application, or solution? Where should exceptions be handled in this component, application, or solution? How should the component, application, or solution flow based on the design? What is the maximum execution time for every component, application, or solution? What environments can this component, application, or solution? What data dependencies does this component, application, or solution have? What kind of data does this component, application, or solution require? Ok, now I know what ARID is, how can I apply? Let’s imagine that your organization is going to purchase an off-the-shelf (OTS) solution for its customer-relationship management software. What process would we use to ensure that the correct purchase is made? If we use ARID, then we will have a series of 9 steps broken up by 2 phases in order to ensure that the correct OTS solution is purchases. Phase 1 Identify the Reviewers Prepare the Design Briefing Prepare the Seed Scenarios Prepare the Materials When identifying reviewers for a design it is preferred that they be pulled from a candidate pool comprised of developers that are going to implement the design. The believe is that developers actually implementing the design will have more a vested interest in ensuring that the design is correct prior to the start of code. Design debriefing consist of a summary of the design, examples of the design solving real world examples put in to use and should be no longer than two hours typically. The primary goal of this briefing is to adequately summarize the design so that the review members could actually implement the design. In the example of purchasing an OTS product I would attempt to review my briefing prior to its distribution with the review facilitator to ensure that nothing was excluded that should have not been. This practice will also allow me to test the length of the briefing to ensure that can be delivered in an appropriate about of time. Seed Scenarios are designed to illustrate conceptualized scenarios when applied with a set of sample data. These scenarios can then be used by the reviewers in the actual evaluation of the software, All materials needed for the evaluation should be prepared ahead of time so that they can be reviewed prior to and during the meeting. Materials Included: Presentation Seed Scenarios Review Agenda Phase 2 Present ARID Present Design Brainstorm and prioritize scenarios Apply scenarios Summarize Prior to the start of any ARID review meeting the Facilitator should define the remaining steps of ARID so that all the participants know exactly what they are doing prior to the start of the review process. Once the ARID rules have been laid out, then the lead designer presents an overview of the design which typically takes about two hours. During this time no questions about the design or rational are allowed to be asked by the review panel as a standard, but they are written down for use latter in the process. After the presentation the list of compiled questions is then summarized and sent back to the lead designer as areas that need to be addressed further. In the example of purchasing an OTS product issues could arise regarding security, the implementation needed or even if this is this the correct product to solve the needed solution. After the Design presentation a brainstorming and prioritize scenarios process begins by reducing the seed scenarios down to just the highest priority scenarios.  These will then be used to test the design for suitability. Once the selected scenarios have been defined the reviewers apply the examples provided in the presentation to the scenarios. The intended output of this process is to provide code or pseudo code that makes use of the examples provided while solving the selected seed scenarios. As a standard rule, the designers of the systems are not allowed to help the review board unless they all become stuck. When this occurs it is documented and along with the reason why the designer needed to help the review panel back on track. Once all of the scenarios have been completed the review facilitator reviews with the group issues that arise during the process. Then the reviewers will be polled as to efficacy of the review experience. References: Clements, Paul., Kazman, Rick., Klien, Mark. (2002). Evaluating Software Architectures: Methods and Case Studies Indianapolis, IN: Addison-Wesley

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• Platformer Starter Kit - Collision Issues

  - by Cyral

  I'm having trouble with my game that is based off the XNA Platformer starter kit. My game uses smaller tiles (16x16) then the original (32x40) which I'm thinking may be having an effect on collision (Being it needs to be more precise). Standing on the edge of a tile and jumping causes the player to move off the the tile when he lands. And 80% of the time, when the player lands, he goes flying though SOLID tiles in a diagonal fashion. This is very annoying as it is almost impossible to test other features, when spawning and jumping will result in the player landing in another part of the level or falling off the edge completely. The code is as follows: /// <summary> /// Updates the player's velocity and position based on input, gravity, etc. /// </summary> public void ApplyPhysics(GameTime gameTime) { float elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds; Vector2 previousPosition = Position; // Base velocity is a combination of horizontal movement control and // acceleration downward due to gravity. velocity.X += movement * MoveAcceleration * elapsed; velocity.Y = MathHelper.Clamp(velocity.Y + GravityAcceleration * elapsed, -MaxFallSpeed, MaxFallSpeed); velocity.Y = DoJump(velocity.Y, gameTime); // Apply pseudo-drag horizontally. if (IsOnGround) velocity.X *= GroundDragFactor; else velocity.X *= AirDragFactor; // Prevent the player from running faster than his top speed. velocity.X = MathHelper.Clamp(velocity.X, -MaxMoveSpeed, MaxMoveSpeed); // Apply velocity. Position += velocity * elapsed; Position = new Vector2((float)Math.Round(Position.X), (float)Math.Round(Position.Y)); // If the player is now colliding with the level, separate them. HandleCollisions(); // If the collision stopped us from moving, reset the velocity to zero. if (Position.X == previousPosition.X) velocity.X = 0; if (Position.Y == previousPosition.Y) velocity.Y = 0; } /// <summary> /// Detects and resolves all collisions between the player and his neighboring /// tiles. When a collision is detected, the player is pushed away along one /// axis to prevent overlapping. There is some special logic for the Y axis to /// handle platforms which behave differently depending on direction of movement. /// </summary> private void HandleCollisions() { // Get the player's bounding rectangle and find neighboring tiles. Rectangle bounds = BoundingRectangle; int leftTile = (int)Math.Floor((float)bounds.Left / Tile.Width); int rightTile = (int)Math.Ceiling(((float)bounds.Right / Tile.Width)) - 1; int topTile = (int)Math.Floor((float)bounds.Top / Tile.Height); int bottomTile = (int)Math.Ceiling(((float)bounds.Bottom / Tile.Height)) - 1; // Reset flag to search for ground collision. isOnGround = false; // For each potentially colliding tile, for (int y = topTile; y <= bottomTile; ++y) { for (int x = leftTile; x <= rightTile; ++x) { // If this tile is collidable, ItemCollision collision = Level.GetCollision(x, y); if (collision != ItemCollision.Passable) { // Determine collision depth (with direction) and magnitude. Rectangle tileBounds = Level.GetBounds(x, y); Vector2 depth = RectangleExtensions.GetIntersectionDepth(bounds, tileBounds); if (depth != Vector2.Zero) { float absDepthX = Math.Abs(depth.X); float absDepthY = Math.Abs(depth.Y); // Resolve the collision along the shallow axis. if (absDepthY < absDepthX || collision == ItemCollision.Platform) { // If we crossed the top of a tile, we are on the ground. if (previousBottom <= tileBounds.Top) isOnGround = true; // Ignore platforms, unless we are on the ground. if (collision == ItemCollision.Impassable || IsOnGround) { // Resolve the collision along the Y axis. Position = new Vector2(Position.X, Position.Y + depth.Y); // Perform further collisions with the new bounds. bounds = BoundingRectangle; } } else if (collision == ItemCollision.Impassable) // Ignore platforms. { // Resolve the collision along the X axis. Position = new Vector2(Position.X + depth.X, Position.Y); // Perform further collisions with the new bounds. bounds = BoundingRectangle; } } } } } // Save the new bounds bottom. previousBottom = bounds.Bottom; } It also tends to jitter a little bit sometimes, I'm solved some of this with some fixes I found here on stackexchange, But Ive only seen one other case of the flying though blocks problem. This question seems to have a similar problem in the video, but mine is more crazy. Again this is a very annoying bug! Any help would be greatly appreciated! EDIT: Speed stuff // Constants for controling horizontal movement private const float MoveAcceleration = 13000.0f; private const float MaxMoveSpeed = 1750.0f; private const float GroundDragFactor = 0.48f; private const float AirDragFactor = 0.58f; // Constants for controlling vertical movement private const float MaxJumpTime = 0.35f; private const float JumpLaunchVelocity = -3500.0f; private const float GravityAcceleration = 3400.0f; private const float MaxFallSpeed = 550.0f; private const float JumpControlPower = 0.14f;

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• Windows in StreamInsight: Hopping vs. Snapshot

  - by Roman Schindlauer

  Three weeks ago, we explained the basic concept of windows in StreamInsight: defining sets of events that serve as arguments for set-based operations, like aggregations. Today, we want to discuss the so-called Hopping Windows and compare them with Snapshot Windows. We will compare these two, because they can serve similar purposes with different behaviors; we will discuss the remaining window type, Count Windows, another time. Hopping (and its syntactic-sugar-sister Tumbling) windows are probably the most straightforward windowing concept in StreamInsight. A hopping window is defined by its length, and the offset from one window to the next. They are aligned with some absolute point on the timeline (which can also be given as a parameter to the window) and create sets of events. The diagram below shows an example of a hopping window with length of 1h and hop size (the offset) of 15 minutes, hence creating overlapping windows:   Two aspects in this diagram are important: Since this window is overlapping, an event can fall into more than one windows. If an (interval) event spans a window boundary, its lifetime will be clipped to the window, before it is passed to the set-based operation. That’s the default and currently only available window input policy. (This should only concern you if you are using a time-sensitive user-defined aggregate or operator.) The set-based operation will be applied to each of these sets, yielding a result. This result is: A single scalar value in case of built-in or user-defined aggregates. A subset of the input payloads, in case of the TopK operator. Arbitrary events, when using a user-defined operator. The timestamps of the result are almost always the ones of the windows. Only the user-defined  operator can create new events with timestamps. (However, even these event lifetimes are subject to the window’s output policy, which is currently always to clip to the window end.) Let’s assume we were calculating the sum over some payload field: var result = from window in source.HoppingWindow( TimeSpan.FromHours(1), TimeSpan.FromMinutes(15), HoppingWindowOutputPolicy.ClipToWindowEnd) select new { avg = window.Avg(e => e.Value) }; Now each window is reflected by one result event:   As you can see, the window definition defines the output frequency. No matter how many or few events we got from the input, this hopping window will produce one result every 15 minutes – except for those windows that do not contain any events at all, because StreamInsight window operations are empty-preserving (more about that another time). The “forced” output for every window can become a performance issue if you have a real-time query with many events in a wide group & apply – let me explain: imagine you have a lot of events that you group by and then aggregate within each group – classical streaming pattern. The hopping window produces a result in each group at exactly the same point in time for all groups, since the window boundaries are aligned with the timeline, not with the event timestamps. This means that the query output will become very bursty, delivering the results of all the groups at the same point in time. This becomes especially obvious if the events are long-lasting, spanning multiple windows each, so that the produced result events do not change their value very often. In such a case, a snapshot window can remedy. Snapshot windows are more difficult to explain than hopping windows: they represent those periods in time, when no event changes occur. In other words, if you mark all event start and and times on your timeline, then you are looking at all snapshot window boundaries:   If your events are never overlapping, the snapshot window will not make much sense. It is commonly used together with timestamp modification, which make it a very powerful tool. Or as Allan Mitchell expressed in in a recent tweet: “I used to look at SnapshotWindow() with disdain. Now she is my mistress, the one I turn to in times of trouble and need”. Let’s look at a simple example: I want to compute the average of some value in my events over the last minute. I don’t want this output be produced at fixed intervals, but at soon as it changes (that’s the true event-driven spirit!). The snapshot window will include all currently active event at each point in time, hence we need to extend our original events’ lifetimes into the future: Applying the Snapshot window on these events, it will appear to be “looking back into the past”: If you look at the result produced in this diagram, you can easily prove that, at each point in time, the current event value represents the average of all original input event within the last minute. Here is the LINQ representation of that query, applying the lifetime extension before the snapshot window: var result = from window in source .AlterEventDuration(e => TimeSpan.FromMinutes(1)) .SnapshotWindow(SnapshotWindowOutputPolicy.Clip) select new { avg = window.Avg(e => e.Value) }; With more complex modifications of the event lifetimes you can achieve many more query patterns. For instance “running totals” by keeping the event start times, but snapping their end times to some fixed time, like the end of the day. Each snapshot then “sees” all events that have happened in the respective time period so far. Regards, The StreamInsight Team

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• Microsoft BUILD 2013 Day 1&ndash;Keynote

  - by Tim Murphy

  Originally posted on: http://geekswithblogs.net/tmurphy/archive/2013/06/27/microsoft-build-2013-day-1ndashkeynote.aspx This one is going to be a little long because the keynote was jam-packed so bare with me. The keynote for the first day of BUILD 2013 was kicked off by Steve Balmer.  He made it very clear that Microsoft’s focus is on accelerating its time to market with products and product updates.  His quote was that “Rapid release” is the new norm.  He continued by showing off several new Lumias that have been buzzing around the internet for a while and announce that Sprint will now be carrying the HTC 8XT and Samsung ATIV. Balmer is known for repeating words or phrase for affect.  This time it was “Rapid release, rapid release” and “Touch, touch, touch, touch, touch, …”.  This was fun, but even more fun was when he announce that all attendees would receive an Acer Iconia 8” tablet. SCORE! The next subject Balmer focused on is new apps.  The three new ones were Flipboard, Facebook and NFL Fantasy Football.  I liked the first two because these are ones that people coming from other platforms are missing.  The NFL app is great just because it targets a demographic that can be fanatical.  If these types of apps keep coming than the missing app argument goes away. While many Negative Nancy’s are describing Windows 8.1 as Windows 180 Steve Balmer chose to call it a “refined blend” as in a coffee that has been improved with a new mix.  This includes more multi-tasking options and leveraging Bing straight throughout the entire ecosystem. He ended this first section by explaining that this will also bring more Bing development opportunities to the community. Steve Balmer was followed by Julie Larson-Green who spent her time on stage selling us on Windows 8 all over again from my point of view.  Something that I would not have thought was needed until I had listened to some other attendees who had a number of concerns and complaints.  She showed a number of new gestures that will come with Windows 8.1, and while they were cool I was left wondering if they really improved the experience.  I guess only time will tell. I did like the fact that it the UI implementation to bring up “All Apps” now mirrors that of Windows Phone.  The consistency is a big step forward that I hope to see continue.  The cool factor went up from there as she swiped content from a desktop (mega-tablet) to the XBox One.  This seamless experience I believe is what is really needed for any future platform to be relevant. I was much more enthused by the presentation of Antoine Leblond who humbled us by letting us know that there are 5k new API.  How that can be or how anyone would ever use all of them is another question.  His announcement was that the Visual Studio 2013 preview would be available today along with the Windows 8.1 bits.  One of the features of VS2013 that he demonstrated is the power consumption profiler.  With battery life being a key factor with consumer consumption devices this is a welcome addition. He didn’t limit his presentation to VS2013 features though.  He showed how the Store has been redesigned to enable better search and discoverability of apps and how Win 8.1 can perform multiple screen scales depending on the resolution of the device automatically.  The last feature he demoed was the real time video streaming API which he made sure we understood by attaching a Surface to a little robot.  Oh, but there was one more thing.  Antoine and Julie announce that all attendees would also be getting Surface Pros.  BONUS! How much more could there be?  Gurdeep Singh Pall was about to pile on.  He introduced us to Bing as a platform (BaaP?).  He said if they (Microsoft) could do something with and API that is good 3rd party developers can do something that is dynamite and showed us some of the tools they had produced.  These included natural user interface improvements such as voice commands that looked to put Siri to shame.  Add to that 3D, OCR and translation capabilities and the future looks to be full of opportunities. Balmer then came out to show us one last thing.  Project Spark is a game design environment that will be available for Windows 8.1, XBox 360 and XBox One.  All I can say is that if my kids get their hands on this they are going to be able to learn some of what dad does in a much more enjoyable way. At the end of it all I was both exhausted and energized by what I saw.  What could they have possibly left for the day 2 keynote?  I hear it will feature Scott Hanselman.  If that is right we are in for a treat.  See you there. del.icio.us Tags: BUILD 2013,Windows 8.1,Winodws Phone,XAML,Keynote,Bing,Visual Studio 2013,Project Spark

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• Data management in unexpected places

  - by Ashok_Ora

  Normal 0 false false false EN-US X-NONE X-NONE Data management in unexpected places When you think of network switches, routers, firewall appliances, etc., it may not be obvious that at the heart of these kinds of solutions is an engine that can manage huge amounts of data at very high throughput with low latencies and high availability. Consider a network router that is processing tens (or hundreds) of thousands of network packets per second. So what really happens inside a router? Packets are streaming in at the rate of tens of thousands per second. Each packet has multiple attributes, for example, a destination, associated SLAs etc. For each packet, the router has to determine the address of the next “hop” to the destination; it has to determine how to prioritize this packet. If it’s a high priority packet, then it has to be sent on its way before lower priority packets. As a consequence of prioritizing high priority packets, lower priority data packets may need to be temporarily stored (held back), but addressed fairly. If there are security or privacy requirements associated with the data packet, those have to be enforced. You probably need to keep track of statistics related to the packets processed (someone’s sure to ask). You have to do all this (and more) while preserving high availability i.e. if one of the processors in the router goes down, you have to have a way to continue processing without interruption (the customer won’t be happy with a “choppy” VoIP conversation, right?). And all this has to be achieved without ANY intervention from a human operator – the router is most likely to be in a remote location – it must JUST CONTINUE TO WORK CORRECTLY, even when bad things happen. How is this implemented? As soon as a packet arrives, it is interpreted by the receiving software. The software decodes the packet headers in order to determine the destination, kind of packet (e.g. voice vs. data), SLAs associated with the “owner” of the packet etc. It looks up the internal database of “rules” of how to process this packet and handles the packet accordingly. The software might choose to hold on to the packet safely for some period of time, if it’s a low priority packet. Ah – this sounds very much like a database problem. For each packet, you have to minimally · Look up the most efficient next “hop” towards the destination. The “most efficient” next hop can change, depending on latency, availability etc. · Look up the SLA and determine the priority of this packet (e.g. voice calls get priority over data ftp) · Look up security information associated with this data packet. It may be necessary to retrieve the context for this network packet since a network packet is a small “slice” of a session. The context for the “header” packet needs to be stored in the router, in order to make this work. · If the priority of the packet is low, then “store” the packet temporarily in the router until it is time to forward the packet to the next hop. · Update various statistics about the packet. In most cases, you have to do all this in the context of a single transaction. For example, you want to look up the forwarding address and perform the “send” in a single transaction so that the forwarding address doesn’t change while you’re sending the packet. So, how do you do all this? Berkeley DB is a proven, reliable, high performance, highly available embeddable database, designed for exactly these kinds of usage scenarios. Berkeley DB is a robust, reliable, proven solution that is currently being used in these scenarios. First and foremost, Berkeley DB (or BDB for short) is very very fast. It can process tens or hundreds of thousands of transactions per second. It can be used as a pure in-memory database, or as a disk-persistent database. BDB provides high availability – if one board in the router fails, the system can automatically failover to another board – no manual intervention required. BDB is self-administering – there’s no need for manual intervention in order to maintain a BDB application. No need to send a technician to a remote site in the middle of nowhere on a freezing winter day to perform maintenance operations. BDB is used in over 200 million deployments worldwide for the past two decades for mission-critical applications such as the one described here. You have a choice of spending valuable resources to implement similar functionality, or, you could simply embed BDB in your application and off you go! I know what I’d do – choose BDB, so I can focus on my business problem. What will you do? /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

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• Subterranean IL: The ThreadLocal type

  - by Simon Cooper

  I came across ThreadLocal<T> while I was researching ConcurrentBag. To look at it, it doesn't really make much sense. What's all those extra Cn classes doing in there? Why is there a GenericHolder<T,U,V,W> class? What's going on? However, digging deeper, it's a rather ingenious solution to a tricky problem. Thread statics Declaring that a variable is thread static, that is, values assigned and read from the field is specific to the thread doing the reading, is quite easy in .NET: [ThreadStatic] private static string s_ThreadStaticField; ThreadStaticAttribute is not a pseudo-custom attribute; it is compiled as a normal attribute, but the CLR has in-built magic, activated by that attribute, to redirect accesses to the field based on the executing thread's identity. TheadStaticAttribute provides a simple solution when you want to use a single field as thread-static. What if you want to create an arbitary number of thread static variables at runtime? Thread-static fields can only be declared, and are fixed, at compile time. Prior to .NET 4, you only had one solution - thread local data slots. This is a lesser-known function of Thread that has existed since .NET 1.1: LocalDataStoreSlot threadSlot = Thread.AllocateNamedDataSlot("slot1"); string value = "foo"; Thread.SetData(threadSlot, value); string gettedValue = (string)Thread.GetData(threadSlot); Each instance of LocalStoreDataSlot mediates access to a single slot, and each slot acts like a separate thread-static field. As you can see, using thread data slots is quite cumbersome. You need to keep track of LocalDataStoreSlot objects, it's not obvious how instances of LocalDataStoreSlot correspond to individual thread-static variables, and it's not type safe. It's also relatively slow and complicated; the internal implementation consists of a whole series of classes hanging off a single thread-static field in Thread itself, using various arrays, lists, and locks for synchronization. ThreadLocal<T> is far simpler and easier to use. ThreadLocal ThreadLocal provides an abstraction around thread-static fields that allows it to be used just like any other class; it can be used as a replacement for a thread-static field, it can be used in a List<ThreadLocal<T>>, you can create as many as you need at runtime. So what does it do? It can't just have an instance-specific thread-static field, because thread-static fields have to be declared as static, and so shared between all instances of the declaring type. There's something else going on here. The values stored in instances of ThreadLocal<T> are stored in instantiations of the GenericHolder<T,U,V,W> class, which contains a single ThreadStatic field (s_value) to store the actual value. This class is then instantiated with various combinations of the Cn types for generic arguments. In .NET, each separate instantiation of a generic type has its own static state. For example, GenericHolder<int,C0,C1,C2> has a completely separate s_value field to GenericHolder<int,C1,C14,C1>. This feature is (ab)used by ThreadLocal to emulate instance thread-static fields. Every time an instance of ThreadLocal is constructed, it is assigned a unique number from the static s_currentTypeId field using Interlocked.Increment, in the FindNextTypeIndex method. The hexadecimal representation of that number then defines the specific Cn types that instantiates the GenericHolder class. That instantiation is therefore 'owned' by that instance of ThreadLocal. This gives each instance of ThreadLocal its own ThreadStatic field through a specific unique instantiation of the GenericHolder class. Although GenericHolder has four type variables, the first one is always instantiated to the type stored in the ThreadLocal<T>. This gives three free type variables, each of which can be instantiated to one of 16 types (C0 to C15). This puts an upper limit of 4096 (163) on the number of ThreadLocal<T> instances that can be created for each value of T. That is, there can be a maximum of 4096 instances of ThreadLocal<string>, and separately a maximum of 4096 instances of ThreadLocal<object>, etc. However, there is an upper limit of 16384 enforced on the total number of ThreadLocal instances in the AppDomain. This is to stop too much memory being used by thousands of instantiations of GenericHolder<T,U,V,W>, as once a type is loaded into an AppDomain it cannot be unloaded, and will continue to sit there taking up memory until the AppDomain is unloaded. The total number of ThreadLocal instances created is tracked by the ThreadLocalGlobalCounter class. So what happens when either limit is reached? Firstly, to try and stop this limit being reached, it recycles GenericHolder type indexes of ThreadLocal instances that get disposed using the s_availableIndices concurrent stack. This allows GenericHolder instantiations of disposed ThreadLocal instances to be re-used. But if there aren't any available instantiations, then ThreadLocal falls back on a standard thread local slot using TLSHolder. This makes it very important to dispose of your ThreadLocal instances if you'll be using lots of them, so the type instantiations can be recycled. The previous way of creating arbitary thread-static variables, thread data slots, was slow, clunky, and hard to use. In comparison, ThreadLocal can be used just like any other type, and each instance appears from the outside to be a non-static thread-static variable. It does this by using the CLR type system to assign each instance of ThreadLocal its own instantiated type containing a thread-static field, and so delegating a lot of the bookkeeping that thread data slots had to do to the CLR type system itself! That's a very clever use of the CLR type system.

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• My rhythm game runs choppy even with high frame rate

  - by felipedrl

  I'm coding a rhythm game and the game runs smoothly with uncapped fps. But when I try to cap it around 60 the game updates in little chunks, like hiccups, as if it was skipping frames or at a very low frame rate. The reason I need to cap frame rate is because in some computers I tested, the fps varies a lot (from ~80 - ~250 fps) and those drops are noticeable and degrade response time. Since this is a rhythm game this is very important. This issue is driving me crazy. I've spent a few weeks already on it and still can't figure out the problem. I hope someone more experienced than me could shed some light on it. I'll try to put here all the hints I've tried along with two pseudo codes for game loops I tried, so I apologize if this post gets too lengthy. 1st GameLoop: const uint UPDATE_SKIP = 1000 / 60; uint nextGameTick = SDL_GetTicks(); while(isNotDone) { // only false when a QUIT event is generated! if (processEvents()) { if (SDL_GetTicks() > nextGameTick) { update(UPDATE_SKIP); render(); nextGameTick += UPDATE_SKIP; } } } 2nd Game Loop: const uint UPDATE_SKIP = 1000 / 60; while (isNotDone) { LARGE_INTEGER startTime; QueryPerformanceCounter(&startTime); // process events will return false in case of a QUIT event processed if (processEvents()) { update(frameTime); render(); } LARGE_INTEGER endTime; do { QueryPerformanceCounter(&endTime); frameTime = static_cast<uint>((endTime.QuadPart - startTime.QuadPart) * 1000.0 / frequency.QuadPart); } while (frameTime < UPDATE_SKIP); } [1] At first I thought it was a timer resolution problem. I was using SDL_GetTicks, but even when I switched to QueryPerformanceCounter, supposedly less granular, I saw no difference. [2] Then I thought it could be due to a rounding error in my position computation and since game updates are smaller in high FPS that would be less noticeable. Indeed there is an small error, but from my tests I realized that it is not enough to produce the position jumps I'm getting. Also, another intriguing factor is that if I enable vsync I'll get smooth updates @60fps regardless frame cap code. So why not rely on vsync? Because some computers can force a disable on gfx card config. [3] I started printing the maximum and minimum frame time measured in 1sec span, in the hope that every a few frames one would take a long time but still not enough to drop my fps computation. It turns out that, with frame cap code I always get frame times in the range of [16, 18]ms, and still, the game "does not moves like jagger". [4] My process' priority is set to HIGH (Windows doesn't allow me to set REALTIME for some reason). As far as I know there is only one thread running along with the game (a sound callback, which I really don't have access to it). I'm using AudiereLib. I then disabled Audiere by removing it from the project and still got the issue. Maybe there are some others threads running and one of them is taking too long to come back right in between when I measured frame times, I don't know. Is there a way to know which threads are attached to my process? [5] There are some dynamic data being created during game run. But It is a little bit hard to remove it to test. Maybe I'll have to try harder this one. Well, as I told you I really don't know what to try next. Anything, I mean, anything would be of great help. What bugs me more is why at 60fps & vsync enabled I get an smooth update and at 60fps & no vsync I don't. Is there a way to implement software vsync? I mean, query display sync info? Thanks in advance. I appreciate the ones that got this far and yet again I apologize for the long post. Best Regards from a fellow coder.

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• k-d tree implementation [closed]

  - by user466441

  when i run my code and debugged,i got this error - this 0x00093584 {_Myproxy=0x00000000 _Mynextiter=0x00000000 } std::_Iterator_base12 * const - _Myproxy 0x00000000 {_Mycont=??? _Myfirstiter=??? } std::_Container_proxy * _Mycont CXX0017: Error: symbol "" not found _Myfirstiter CXX0030: Error: expression cannot be evaluated + _Mynextiter 0x00000000 {_Myproxy=??? _Mynextiter=??? } std::_Iterator_base12 * but i dont know what does it means,code is this #include<iostream> #include<vector> #include<algorithm> using namespace std; struct point { float x,y; }; vector<point>pointleft(4); vector<point>pointright(4); //we are going to implement two comparison function for x and y coordinates,we need it in calculation of median (we should sort vector //by x or y according to depth informaton,is depth even or odd. bool sortby_X(point &a,point &b) { return a.x<b.x; } bool sortby_Y(point &a,point &b) { return a.y<b.y; } //so i am going to implement to median finding algorithm,one for finding median by x and another find median by y point medianx(vector<point>points) { point temp; sort(points.begin(),points.end(),sortby_X); temp=points[(points.size()/2)]; return temp; } point mediany(vector<point>points) { point temp; sort(points.begin(),points.end(),sortby_Y); temp=points[(points.size()/2)]; return temp; } //now construct basic tree structure struct Tree { float x,y; Tree(point a) { x=a.x; y=a.y; } Tree *left; Tree *right; }; Tree * build_kd( Tree *root,vector<point>points,int depth) { point temp; if(points.size()==1)// that point is as a leaf { if(root==NULL) root=new Tree(points[0]); return root; } if(depth%2==0) { temp=medianx(points); root=new Tree(temp); for(int i=0;i<points.size();i++) { if (points[i].x<temp.x) pointleft[i]=points[i]; else pointright[i]=points[i]; } } else { temp=mediany(points); root=new Tree(temp); for(int i=0;i<points.size();i++) { if(points[i].y<temp.y) pointleft[i]=points[i]; else pointright[i]=points[i]; } } return build_kd(root->left,pointleft,depth+1); return build_kd(root->right,pointright,depth+1); } void print(Tree *root) { while(root!=NULL) { cout<<root->x<<" " <<root->y; print(root->left); print(root->right); } } int main() { int depth=0; Tree *root=NULL; vector<point>points(4); float x,y; int n=4; for(int i=0;i<n;i++) { cin>>x>>y; points[i].x=x; points[i].y=y; } root=build_kd(root,points,depth); print(root); return 0; } i am trying ti implement in c++ this pseudo code tuple function build_kd_tree(int depth, set points): if points contains only one point: return that point as a leaf. if depth is even: Calculate the median x-value. Create a set of points (pointsLeft) that have x-values less than the median. Create a set of points (pointsRight) that have x-values greater than or equal to the median. else: Calculate the median y-value. Create a set of points (pointsLeft) that have y-values less than the median. Create a set of points (pointsRight) that have y-values greater than or equal to the median. treeLeft = build_kd_tree(depth + 1, pointsLeft) treeRight = build_kd_tree(depth + 1, pointsRight) return(median, treeLeft, treeRight) please help me what this error means?

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• Is it feasible and useful to auto-generate some code of unit tests?

  - by skiwi

  Earlier today I have come up with an idea, based upon a particular real use case, which I would want to have checked for feasability and usefulness. This question will feature a fair chunk of Java code, but can be applied to all languages running inside a VM, and maybe even outside. While there is real code, it uses nothing language-specific, so please read it mostly as pseudo code. The idea Make unit testing less cumbersome by adding in some ways to autogenerate code based on human interaction with the codebase. I understand this goes against the principle of TDD, but I don't think anyone ever proved that doing TDD is better over first creating code and then immediatly therafter the tests. This may even be adapted to be fit into TDD, but that is not my current goal. To show how it is intended to be used, I'll copy one of my classes here, for which I need to make unit tests. public class PutMonsterOnFieldAction implements PlayerAction { private final int handCardIndex; private final int fieldMonsterIndex; public PutMonsterOnFieldAction(final int handCardIndex, final int fieldMonsterIndex) { this.handCardIndex = Arguments.requirePositiveOrZero(handCardIndex, "handCardIndex"); this.fieldMonsterIndex = Arguments.requirePositiveOrZero(fieldMonsterIndex, "fieldCardIndex"); } @Override public boolean isActionAllowed(final Player player) { Objects.requireNonNull(player, "player"); Hand hand = player.getHand(); Field field = player.getField(); if (handCardIndex >= hand.getCapacity()) { return false; } if (fieldMonsterIndex >= field.getMonsterCapacity()) { return false; } if (field.hasMonster(fieldMonsterIndex)) { return false; } if (!(hand.get(handCardIndex) instanceof MonsterCard)) { return false; } return true; } @Override public void performAction(final Player player) { Objects.requireNonNull(player); if (!isActionAllowed(player)) { throw new PlayerActionNotAllowedException(); } Hand hand = player.getHand(); Field field = player.getField(); field.setMonster(fieldMonsterIndex, (MonsterCard)hand.play(handCardIndex)); } } We can observe the need for the following tests: Constructor test with valid input Constructor test with invalid inputs isActionAllowed test with valid input isActionAllowed test with invalid inputs performAction test with valid input performAction test with invalid inputs My idea mainly focuses on the isActionAllowed test with invalid inputs. Writing these tests is not fun, you need to ensure a number of conditions and you check whether it really returns false, this can be extended to performAction, where an exception needs to be thrown in that case. The goal of my idea is to generate those tests, by indicating (through GUI of IDE hopefully) that you want to generate tests based on a specific branch. The implementation by example User clicks on "Generate code for branch if (handCardIndex >= hand.getCapacity())". Now the tool needs to find a case where that holds. (I haven't added the relevant code as that may clutter the post ultimately) To invalidate the branch, the tool needs to find a handCardIndex and hand.getCapacity() such that the condition >= holds. It needs to construct a Player with a Hand that has a capacity of at least 1. It notices that the capacity private int of Hand needs to be at least 1. It searches for ways to set it to 1. Fortunately it finds a constructor that takes the capacity as an argument. It uses 1 for this. Some more work needs to be done to succesfully construct a Player instance, involving the creation of objects that have constraints that can be seen by inspecting the source code. It has found the hand with the least capacity possible and is able to construct it. Now to invalidate the test it will need to set handCardIndex = 1. It constructs the test and asserts it to be false (the returned value of the branch) What does the tool need to work? In order to function properly, it will need the ability to scan through all source code (including JDK code) to figure out all constraints. Optionally this could be done through the javadoc, but that is not always used to indicate all constraints. It could also do some trial and error, but it pretty much stops if you cannot attach source code to compiled classes. Then it needs some basic knowledge of what the primitive types are, including arrays. And it needs to be able to construct some form of "modification trees". The tool knows that it needs to change a certain variable to a different value in order to get the correct testcase. Hence it will need to list all possible ways to change it, without using reflection obviously. What this tool will not replace is the need to create tailored unit tests that tests all kinds of conditions when a certain method actually works. It is purely to be used to test methods when they invalidate constraints. My questions: Is creating such a tool feasible? Would it ever work, or are there some obvious problems? Would such a tool be useful? Is it even useful to automatically generate these testcases at all? Could it be extended to do even more useful things? Does, by chance, such a project already exist and would I be reinventing the wheel? If not proven useful, but still possible to make such thing, I will still consider it for fun. If it's considered useful, then I might make an open source project for it depending on the time. For people searching more background information about the used Player and Hand classes in my example, please refer to this repository. At the time of writing the PutMonsterOnFieldAction has not been uploaded to the repo yet, but this will be done once I'm done with the unit tests.

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• Windows 8/Surface Lunch Event Summary

  - by Tim Murphy

  Today was a big day for Microsoft with two separate launch event.  The first for Windows 8 and all of it’s hardware partners.  The second was specifically to introduce the Microsoft Windows 8 Surface tablet.  Below are some of the take-aways I got from the webcasts. Windows 8 Launch The three general area that Microsoft focused on were the release of the OS itself, the public unveiling of the Windows Store and the new devices available from its hardware partners. The release of the OS focused on the fact that it will be available at mid-night tonight for both new PCs and for upgrades.  I can’t say that this interested me that much since it was already known to most people.  I think what they did show well was how easy the OS really is to use. The Windows Store is also not a new feature to those of us who have been running the pre-release versions of Windows 8 or have owned Windows Phone 7 for the past 2 years.  What was interesting is that the Windows Store launches with more apps available than any other platforms store at their respective launch.  I think this says a lot about how Microsoft focuses on the ability of developers to create software and make it available.  The of course were sure to emphasize that the Windows Store has better monetary terms for developers than its competitors. The also showed off the fact that XBox Music streaming is available for to all Windows 8 user for free.  Couple this with the Bing suite of apps that give you news, weather, sports and finance right out of the box and I think most people will find the environment a joy to use. I think the hardware demo, while quick and furious, really show where Windows shine: CHOICE!  They made a statement that over 1000 devices have been certified for Windows 8.  They showed tablets, laptops, desktops, all-in-ones and convertibles.  Since these devices have industry standard connectors they give a much wider variety of accessories and devices that you can use with them. Steve Balmer then came on stage and tried to see how many times he could use the “magical”.  He focused on how the Windows 8 OS is designed to integrate with SkyDrive, Skype and Outlook.com.  He also enforced that they think Windows 8 is the best choice for the Enterprise when it comes to protecting data and integrating across devices including Windows Phone 8. With that we were left to wait for the second event of the day. Surface Launch The second event of the day started with kids with magnets.  Ok, they were adults, but who doesn’t like playing with magnets.  Steven Sinofsky detached and reattached the Surface keyboard repeatedly, clearly enjoying himself.  It turns out that there are 4 magnets in the cover, 2 for alignment and 2 as connectors. They then went to giving us the details on the display.  The 10.6” display is optically bonded to the case and is optimized to reduce glare.  I think this came through very well in the demonstrations. The properties of the case were also a great selling point.  The VaporMg allowed them to drop the device on stage, on purpose, and continue working.  Of course they had to bring out the skate boards made from Surface devices. “It just has to feel right” was the reason they gave for many of their design decisions from the weight and size of the device to the way the kickstand and camera work together.  While this gave you the feeling that the whole process was trial and error you could tell that a lot of science went into the specs.  This included making sure that the magnets were strong enough to hold the cover on and still have a 3 year old remove the cover without effort. I am glad that they also decided the a USB port would be part of the spec since it give so many options.  They made the point that this allows Surface to leverage over 420 million existing devices.  That works for me. The last feature that I really thought was important was the microSD port.  Begin stuck with the onboard memory has been an aggravation of mine with many of the devices in the market today. I think they did job of really getting the audience to understand why you want this platform and this particular device.  Using personal examples like creating a video of a birthday party and being in it or the fact that the device was being used to live blog the event and control the lights and presentation.  They showed very well that it was not only fun but very capable of getting real work done.  Handing out tablets to the crowd didn’t hurt either.  In the end I really wanted a Surface even though I really have no need for one on a daily basis.  Great job Microsoft! del.icio.us Tags: Windows 8,Win8,Windows 8 Luanch

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• SPARC T4 ??????: SPARC T4 ??????????!!

  - by user13138700

  ?? 2011 ? 9 ?? SPARC T4 CPU ???????? SPARC T4 ????????????????2011??10?????????????????????????? ????????????????????SPARC T4 ?????????????????????????????????????????????????????????? SPARC T4 CPU ???? SPARC T4 ?????????????????????????????????? ??????????????????????4/4, 4/5, 4/6 ? 3???????? Oracle Open World 2012 ???????? Oracle Open World 2012 Tokyo ?? Oracle ?????&????? ??? Oracle Solaris ????????????·????????? SPARC&Solaris ??????????????SPARC&Solaris ????????????????????????????????????????????????????????????????????????? Oracle OpenWorld Tokyo 2012 ???? URL http://www.oracle.com/openworld/jp-ja/index.html ?????? 7264 ??????????????? ????Oracle Open World 2012 Tokyo ?????????????????????????SPARC T4 ????? ????????????????? SPARC T4 ????????? SPARC T3 ????????(S2??)??????????????????????????(S3??)??????????????????? ???????" T " ???????????????(?)?????? SPARC T1/T2/T3 ???????????????????????????(????????)????????????????????????? ?SPARC T4 ????????????????????????????? ?SPARC T4 ???????DB?????????????????????????????? ???????????????? ????????????????????????????????????????????? ???? SPARC T3 ???????????????????????????2???????????? ????????????????????????????????????????????????????? ?????????????? SPARC T4 ????????????????????????????????????SPARC T4 ????????? SPARC T4 ??????????????????????????????????????????? ?????????????? T4 ??????????????????? SPARC ???????????????????????????????????????????????????????????????????&??????????? ?????????????????????????????????????????????????????????Web?????????????DB?????????????????????????????????????? (????????????) ???????????? SPARC T4 ????????????????????????????? < T4 ???????? > ??? SPARC ??(S3??)??? x5??????????????????? x2????????????????????? Crypto (?????)?????????? ?????????????????????????/???????????????? ?????? 1, 2,& 4 ??????????? < T4 ????? ??????? > 8x SPARC S3 ?? (64????/???) 4MB ?? L3 ????? (8???/16???) 8x9 ????? 4x DDR3 ??????????? @6.4Gbps 6x ?????????? @9.6Gbps 2x8 PCIe 2.0 (5GTS) 2x10Gb XAUI ??????? < S3???????????? > ALU : Arithmetic Logic Unit BRU : Branch Logic Unit FGU : Flouting-point Graphics Unit IRF : Integer Register File FRF : Flouting-point Register File WRF : Working Register File MMU : Memory Management Unit LSU : Load Store Unit Crypto(SPU) : Streaming Processing Unit TRU : Trap Logic Unit < S3????????? > ????? 8????/?? ?????? Out-of-Order ?? 16???????????????? ????????????? ???????????? ??????? ????????? 64???? ITLB ? 128???? DTLB 64KB 4??? L1 ?????????????? 128KB 8??? ???? L2 ????? < T4 ???????? vs T3 ???????? > T4 ????????????? Out-Of-Order ???? Pick ???????? In-Order ?? Pick ?????? Commit ??????? Out-Of-Order ?? Commit ?????? In-Order ?? < T4 ?????????? > ???????????vs????????????????????????????? ????????Active??????????????????? ???????????????????????? ??????????????????? < T4vsT1/T2/T3 ??????? > SPARC T4 ???? T3????????Web??????????? DB?????????????????????????????? ????????????????????SPARC T4 ?????&Solaris ?????????????(????????)??????????????????????????????????????????????????????????!!? ????Oracle Open World 2012 Tokyo ????????????????SPARC T4 ?????????????????????? 4/4, 4/5, 4/6 ?3????????????????????????????????????????????????????????????????????????????????????? ????????????????? URL http://www.oracle.com/openworld/jp-ja/exhibit/index.html

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• PHP SimpleXML recursive function to list children and attibutes

  - by Phill Pafford

  I need some help on the SimpleXML calls for a recursive function that lists the elements name and attributes. Making a XML config file system but each script will have it's own config file as well as a new naming convention. So what I need is an easy way to map out all the elements that have attributes, so like in example 1 I need a simple way to call all the processes but I don't know how to do this without hard coding the elements name is the function call. Is there a way to recursively call a function to match a child element name? I did see the xpath functionality but I don't see how to use this for attributes. Any ideas? Also does the XML in the examples look correct? can I structure my XML like this? Example 1: <application> <processes> <process id="123" name="run batch A" /> <process id="122" name="run batch B" /> <process id="129" name="run batch C" /> </processes> <connections> <databases> <database usr="test" pss="test" hst="test" dbn="test" /> </databases> <shells> <ssh usr="test" pss="test" hst="test-2" /> <ssh usr="test" pss="test" hst="test-1" /> </shells> </connections> </application> Example 2: <config> <queues> <queue id="1" name="test" /> <queue id="2" name="production" /> <queue id="3" name="error" /> </queues> </config> Pseudo code: // Would return matching process id getProcess($process_id) { return the process attributes as array that are in the XML } // Would return matching DBN (database name) getDatabase($database_name) { return the database attributes as array that are in the XML } // Would return matching SSH Host getSSHHost($ssh_host) { return the ssh attributes as array that are in the XML } // Would return matching SSH User getSSHUser($ssh_user) { return the ssh attributes as array that are in the XML } // Would return matching Queue getQueue($queue_id) { return the queue attributes as array that are in the XML } EDIT: Can I pass two parms? on the first method you have suggested @Gordon public function findProcessById($id, $name) { $attr = false; $el = $this->xml->xpath("//process[@id='$id']"); // How do I also filter by the name? if($el && count($el) === 1) { $attr = (array) $el[0]->attributes(); $attr = $attr['@attributes']; } return $attr; }

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• One-to-one Mapping issue with NHibernate/Fluent: Foreign Key not updateing

  - by Trevor

  Summary: Parent and Child class. One to one relationship between the Parent and Child. Parent has a FK property which references the primary key of the Child. Code as follows: public class NHTestParent { public virtual Guid NHTestParentId { get; set; } public virtual Guid ChildId { get { return ChildRef.NHTestChildId; } set { } } public virtual string ParentName { get; set; } protected NHTestChild _childRef; public virtual NHTestChild ChildRef { get { if (_childRef == null) _childRef = new NHTestChild(); return _childRef; } set { _childRef = value; } } } public class NHTestChild { public virtual Guid NHTestChildId { get; set; } public virtual string ChildName { get; set; } } With the following Fluent mappings: Parent Mapping Id(x => x.NHTestParentId); Map(x => x.ParentName); Map(x => x.ChildId); References(x => x.ChildRef, "ChildId").Cascade.All(); Child Mapping: Id(x => x.NHTestChildId); Map(x => x.ChildName); If I do something like (pseudo code) ... HTestParent parent = new NHTestParent(); parent.ParentName = "Parent 1"; parent.ChildRef.ChildName = "Child 1"; nhibernateSession.SaveOrUpdate(aParent); Commit; ... I get an error: "Invalid index 3 for this SqlParameterCollection with Count=3" If I change the parent 'References' line as follows (i.e. provide the name of the child property I'm pointing at): References(x => x.ChildRef, "ChildId").PropertyRef("NHTestChildId").Cascade.All(); I get the error: "Unable to resolve property: NHTestChildId" So, I tried the 'HasOne()' reference setting, as follows: HasOne<NHTestChild>(x => x.ChildRef).ForeignKey("ChildId").Cascade.All().Fetch.Join(); This results in the save working, but the load fails to find the child. If I inspect the SQL Nhibernate produces I can see that NHibernate is assuming the Primary key of the parent is the link to the child (i.e. load join condition is "parent.NHTestParentId = child.NHTestChildId). The 'ForeignKey' specified appears to be ignored. I can set any value and no error occurs - the join just always fails and no child is returned. I've tried a number of slight variations on the above. It seems like it should be a simple thing to achieve. Any ideas?

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• Access Violation Using memcpy or Assignment to an Array in a Struct

  - by Synetech inc.

  Hi, I wrote a program last night that worked just fine but when I refactored it today to make it more extensible, I ended up with a problem. The original version had a hard-coded array of bytes. After some processing, some bytes were written into the array and then some more processing was done. To avoid hard-coding the pattern, I put the array in a structure so that I could add some related data and create an array of them. However now, I cannot write to the array in the structure. Here’s a pseudo-code example: main() { char pattern[]="\x32\x33\x12\x13\xba\xbb"; PrintData(pattern); pattern[2]='\x65'; PrintData(pattern); } That one works but this one does not: struct ENTRY { char* pattern; int somenum; }; main() { ENTRY Entries[] = { {"\x32\x33\x12\x13\xba\xbb\x9a\xbc", 44} , {"\x12\x34\x56\x78", 555} }; PrintData(Entries[0].pattern); Entries[0].pattern[2]='\x65'; //0xC0000005 exception!!! :( PrintData(Entries[0].pattern); } The second version causes an access violation exception on the assignment. I’m sure it’s because the second version allocates memory differently, but I’m starting to get a headache trying to figure out what’s what or how to get fix this. (I’m currently working around it by dynamically allocating a buffer of the same size as the pattern array, copying the pattern to the new buffer, making the changes to the buffer, using the buffer in the place of the pattern array, and then trying to remember to free the—temporary—buffer.) (Specifically, the original version cast the pattern array—+offset—to a DWORD* and assigned a DWORD constant to it to overwrite the four target bytes. The new version cannot do that since the length of the source is unknown—may not be four bytes—so it uses memcpy instead. I’ve checked and re-checked and have made sure that the pointers to memcpy are correct, but I still get an access violation. I use memcpy instead of str(n)cpy because I am using plain chars (as an array of bytes), not Unicode chars and ignoring the null-terminator. Using an assignment as above causes the same problem.) Any ideas? Thanks a lot.

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• How to debug nondeterministic access violation crash?

  - by Special Touch

  Our C#/COM/C++ application is crashing and I need help debugging it. Running with gflags enabled and WinDbg attached, we determined the crashes are caused by an access violation, but we haven't been able to narrow it down any more than that. We are not seeing the issue on all machines; there are a couple of machines that seem to reproduce the issue frequently but not deterministically. We have observed the application crash from simply switching away from the application (say, Alt-Tab) and then back. Output from WinDbg is below. We have been trying to systematically comment out areas of code that could be causing the problem, but we haven't had much success yet. Any suggestions on what debugging steps or tools we should try? !analyze -v EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff) ExceptionAddress: 1a584ff2 (+0x1a584ff1) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 1a584ff2 Attempt to read from address 1a584ff2 PROCESS_NAME: ProcessFiles.exe ERROR_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%08lx referenced memory at 0x%08lx. The memory could not be %s. EXCEPTION_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%08lx referenced memory at 0x%08lx. The memory could not be %s. EXCEPTION_PARAMETER1: 00000000 EXCEPTION_PARAMETER2: 1a584ff2 READ_ADDRESS: 1a584ff2 FOLLOWUP_IP: Ed20+1a584ff1 1a584ff2 ?? ??? NTGLOBALFLAG: 2000000 APPLICATION_VERIFIER_FLAGS: 0 IP_MODULE_UNLOADED: Ed20+1a584ff1 1a584ff2 ?? ??? MANAGED_STACK: (TransitionMU) 0EC6F6F4 7B1D8CCE System_Windows_Forms_ni!System.Windows.Forms.Application+ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32, Int32, Int32)+0x24e 0EC6F790 7B1D8937 System_Windows_Forms_ni!System.Windows.Forms.Application+ThreadContext.RunMessageLoopInner(Int32, System.Windows.Forms.ApplicationContext)+0x177 0EC6F7E4 7B1D8781 System_Windows_Forms_ni!System.Windows.Forms.Application+ThreadContext.RunMessageLoop(Int32, System.Windows.Forms.ApplicationContext)+0x61 0EC6F814 7B195911 System_Windows_Forms_ni!System.Windows.Forms.Application.Run(System.Windows.Forms.Form)+0x31 0EC6F828 0969D97A Extract_Utilities_Forms!Extract.Utilities.Forms.VerificationForm`1[[System.__Canon, mscorlib]].A(System.Object)+0x23a 0EC6F8C0 79A00EEE mscorlib_ni!System.Threading.ThreadHelper.ThreadStart_Context(System.Object)+0x72a25e 0EC6F8CC 792E019F mscorlib_ni!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)+0x6f 0EC6F8E4 797DB48A mscorlib_ni!System.Threading.ThreadHelper.ThreadStart(System.Object)+0x4a (TransitionUM) LAST_CONTROL_TRANSFER: from 7e418734 to 1a584ff2 FAULTING_THREAD: ffffffff ADDITIONAL_DEBUG_TEXT: Followup set based on attribute [ip_not_executable] from Frame:[0] on thread:[e30] BUGCHECK_STR: APPLICATION_FAULT_BAD_INSTRUCTION_PTR_INVALID_POINTER_READ_WRONG_SYMBOLS_WINDOW_HOOK PRIMARY_PROBLEM_CLASS: BAD_INSTRUCTION_PTR DEFAULT_BUCKET_ID: BAD_INSTRUCTION_PTR STACK_TEXT: 7b1d8cce System_Windows_Forms_ni!System.Windows.Forms.Application+ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop+0xc 7b1d8937 System_Windows_Forms_ni!System.Windows.Forms.Application+ThreadContext.RunMessageLoopInner+0x0 7b1d8781 System_Windows_Forms_ni!System.Windows.Forms.Application+ThreadContext.RunMessageLoop+0x0 7b195911 System_Windows_Forms_ni!System.Windows.Forms.Application.Run+0x31 0969d97a Extract_Utilities_Forms!Extract.Utilities.Forms.VerificationForm`1[[System.__Canon, mscorlib]].A+0x23a 79a00eee mscorlib_ni!System.Threading.ThreadHelper.ThreadStart_Context+0x72a25e 792e019f mscorlib_ni!System.Threading.ExecutionContext.Run+0x6f 797db48a mscorlib_ni!System.Threading.ThreadHelper.ThreadStart+0x4a STACK_COMMAND: .ecxr ; ~~[e30] ; .frame 0 ; ** Pseudo Context ** ; kb FAILED_INSTRUCTION_ADDRESS: Ed20+1a584ff1 1a584ff2 ?? ??? SYMBOL_NAME: Ed20 FOLLOWUP_NAME: MachineOwner MODULE_NAME: Ed20 IMAGE_NAME: Ed20 DEBUG_FLR_IMAGE_TIMESTAMP: 0 FAILURE_BUCKET_ID: BAD_INSTRUCTION_PTR_c0000005_Ed20!Unloaded BUCKET_ID: APPLICATION_FAULT_BAD_INSTRUCTION_PTR_INVALID_POINTER_READ_WRONG_SYMBOLS_WINDOW_HOOK_BAD_IP_Ed20 Followup: MachineOwner

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• 2d trajectory planning of a spaceship with physics.

  - by egarcia

  I'm implementing a 2D game with ships in space. In order to do it, I'm using LÖVE, which wraps Box2D with Lua. But I believe that my question can be answered by anyone with a greater understanding of physics than myself - so pseudo code is accepted as a response. My problem is that I don't know how to move my spaceships properly on a 2D physics-enabled world. More concretely: A ship of mass m is located at an initial position {x, y}. It has an initial velocity vector of {vx, vy} (can be {0,0}). The objective is a point in {xo,yo}. The ship has to reach the objective having a velocity of {vxo, vyo} (or near it), following the shortest trajectory. There's a function called update(dt) that is called frequently (i.e. 30 times per second). On this function, the ship can modify its position and trajectory, by applying "impulses" to itself. The magnitude of the impulses is binary: you can either apply it in a given direction, or not to apply it at all). In code, it looks like this: def Ship:update(dt) m = self:getMass() x,y = self:getPosition() vx,vy = self.getLinearVelocity() xo,yo = self:getTargetPosition() vxo,vyo = self:getTargetVelocity() thrust = self:getThrust() if(???) angle = ??? self:applyImpulse(math.sin(angle)*thrust, math.cos(angle)*thrust)) end end The first ??? is there to indicate that in some occasions (I guess) it would be better to "not to impulse" and leave the ship "drift". The second ??? part consists on how to calculate the impulse angle on a given dt. We are in space, so we can ignore things like air friction. Although it would be very nice, I'm not looking for someone to code this for me; I put the code there so my problem is clearly understood. What I need is an strategy - a way of attacking this. I know some basic physics, but I'm no expert. For example, does this problem have a name? That sort of thing. Thanks a lot.

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• SQL Server 2008: FileStream Insertion Failure w/ .NET 3.5SP1

  - by James Alexander

  I've configured a db w/ a FileStream group and have a table w/ File type on it. When attempting to insert a streamed file and after I create the table row, my query to read the filepath out and the buffer returns a null file path. I can't seem to figure out why though. Here is the table creation script: /****** Object: Table [dbo].[JobInstanceFile] Script Date: 03/22/2010 18:05:36 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO SET ANSI_PADDING ON GO CREATE TABLE [dbo].[JobInstanceFile]( [JobInstanceFileId] [int] IDENTITY(1,1) NOT NULL, [JobInstanceId] [int] NOT NULL, [File] [varbinary](max) FILESTREAM NULL, [FileId] [uniqueidentifier] ROWGUIDCOL NOT NULL, [Created] [datetime] NOT NULL, CONSTRAINT [PK_JobInstanceFile] PRIMARY KEY CLUSTERED ( [JobInstanceFileId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] FILESTREAM_ON [JobInstanceFilesGroup], UNIQUE NONCLUSTERED ( [FileId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] FILESTREAM_ON [JobInstanceFilesGroup] GO SET ANSI_PADDING OFF GO ALTER TABLE [dbo].[JobInstanceFile] ADD DEFAULT (newid()) FOR [FileId] GO Here's my proc I call to create the row before streaming the file: /****** Object: StoredProcedure [dbo].[JobInstanceFileCreate] Script Date: 03/22/2010 18:06:23 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO create proc [dbo].[JobInstanceFileCreate] @JobInstanceId int, @Created datetime as insert into JobInstanceFile (JobInstanceId, FileId, Created) values (@JobInstanceId, newid(), @Created) select scope_identity() GO And lastly, here's the code I'm using: public int CreateJobInstanceFile(int jobInstanceId, string filePath) { using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConsumerMarketingStoreFiles"].ConnectionString)) using (var fileStream = new FileStream(filePath, FileMode.Open)) { connection.Open(); var tran = connection.BeginTransaction(IsolationLevel.ReadCommitted); try { //create the JobInstanceFile instance var command = new SqlCommand("JobInstanceFileCreate", connection) { Transaction = tran }; command.CommandType = CommandType.StoredProcedure; command.Parameters.AddWithValue("@JobInstanceId", jobInstanceId); command.Parameters.AddWithValue("@Created", DateTime.Now); int jobInstanceFileId = Convert.ToInt32(command.ExecuteScalar()); //read out the filestream transaction context to stream the file for storage command.CommandText = "select [File].PathName(), GET_FILESTREAM_TRANSACTION_CONTEXT() from JobInstanceFile where JobInstanceFileId = @JobInstanceFileId"; command.CommandType = CommandType.Text; command.Parameters.AddWithValue("@JobInstanceFileId", jobInstanceFileId); using (SqlDataReader dr = command.ExecuteReader()) { dr.Read(); //get the file path we're writing out to string writePath = dr.GetString(0); using (var writeStream = new SqlFileStream(writePath, (byte[])dr.GetValue(1), FileAccess.ReadWrite)) { //copy from one stream to another byte[] bytes = new byte[65536]; int numBytes; while ((numBytes = fileStream.Read(bytes, 0, 65536)) 0) writeStream.Write(bytes, 0, numBytes); } } tran.Commit(); return jobInstanceFileId; } catch (Exception e) { tran.Rollback(); throw e; } } } Can someone please let me know what I'm doing wrong. In the code, the following expression is returning null for the file path and shouldn't be: //get the file path we're writing out to string writePath = dr.GetString(0); The server is different then the computer the code is running on but the necessary shares appear to be in order and I have also run the following: EXEC sp_configure filestream_access_level, 2 Any help would be greatly appreciated. Thanks!

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• Objective-c - How to serialize audio file into small packets that can be played?

  - by vfn

  Hi there, So, I would like to get a sound file and convert it in packets, and send it to another computer. I would like that the other computer be able to play the packets as they arrive. I am using AVAudioPlayer to try to play this packets, but I couldn't find a proper way to serialize the data on the peer1 that the peer2 can play. The scenario is, peer1 has a audio file, split the audio file in many small packets, put them on a NSData and send them to peer2. Peer 2 receive the packets and play one by one, as they arrive. Does anyone have know how to do this? or even if it is possible? EDIT: Here it is some piece of code to illustrate what I would like to achieve. // This code is part of the peer1, the one who sends the data - (void)sendData { int packetId = 0; NSString *soundFilePath = [[NSBundle mainBundle] pathForResource:@"myAudioFile" ofType:@"wav"]; NSData *soundData = [[NSData alloc] initWithContentsOfFile:soundFilePath]; NSMutableArray *arraySoundData = [[NSMutableArray alloc] init]; // Spliting the audio in 2 pieces // This is only an illustration // The idea is to split the data into multiple pieces // dependin on the size of the file to be sent NSRange soundRange; soundRange.length = [soundData length]/2; soundRange.location = 0; [arraySoundData addObject:[soundData subdataWithRange:soundRange]]; soundRange.length = [soundData length]/2; soundRange.location = [soundData length]/2; [arraySoundData addObject:[soundData subdataWithRange:soundRange]]; for (int i=0; i // This is the code on peer2 that would receive an play the piece of audio on each packet - (void) receiveData:(NSData *)data { NSKeyedUnarchiver* unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; if ([unarchiver containsValueForKey:PACKET_ID]) NSLog(@"DECODED PACKET_ID: %i", [unarchiver decodeIntForKey:PACKET_ID]); if ([unarchiver containsValueForKey:PACKET_SOUND_DATA]) { NSLog(@"DECODED sound"); NSData *sound = (NSData *)[unarchiver decodeObjectForKey:PACKET_SOUND_DATA]; if (sound == nil) { NSLog(@"sound is nil!"); } else { NSLog(@"sound is not nil!"); AVAudioPlayer *audioPlayer = [AVAudioPlayer alloc]; if ([audioPlayer initWithData:sound error:nil]) { [audioPlayer prepareToPlay]; [audioPlayer play]; } else { [audioPlayer release]; NSLog(@"Player couldn't load data"); } } } [unarchiver release]; } So, here is what I am trying to achieve...so, what I really need to know is how to create the packets, so peer2 can play the audio. It would be a kind of streaming. Yes, for now I am not worried about the order that the packet are received or played...I only need to get the sound sliced and them be able to play each piece, each slice, without need to wait for the whole file be received by peer2. Thanks!

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• Is this (Lock-Free) Queue Implementation Thread-Safe?

  - by Hosam Aly

  I am trying to create a lock-free queue implementation in Java, mainly for personal learning. The queue should be a general one, allowing any number of readers and/or writers concurrently. Would you please review it, and suggest any improvements/issues you find? Thank you. import java.util.concurrent.atomic.AtomicReference; public class LockFreeQueue<T> { private static class Node<E> { E value; volatile Node<E> next; Node(E value) { this.value = value; } } private AtomicReference<Node<T>> head, tail; public LockFreeQueue() { // have both head and tail point to a dummy node Node<T> dummyNode = new Node<T>(null); head = new AtomicReference<Node<T>>(dummyNode); tail = new AtomicReference<Node<T>>(dummyNode); } /** * Puts an object at the end of the queue. */ public void putObject(T value) { Node<T> newNode = new Node<T>(value); Node<T> prevTailNode = tail.getAndSet(newNode); prevTailNode.next = newNode; } /** * Gets an object from the beginning of the queue. The object is removed * from the queue. If there are no objects in the queue, returns null. */ public T getObject() { Node<T> headNode, valueNode; // move head node to the next node using atomic semantics // as long as next node is not null do { headNode = head.get(); valueNode = headNode.next; // try until the whole loop executes pseudo-atomically // (i.e. unaffected by modifications done by other threads) } while (valueNode != null && !head.compareAndSet(headNode, valueNode)); T value = (valueNode != null ? valueNode.value : null); // release the value pointed to by head, keeping the head node dummy if (valueNode != null) valueNode.value = null; return value; }

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• Can I Number a GroupTemplate or ItemTemplate?

  - by Atomiton

  I would like to use a GroupTemplate to separate a list of items into groups. However, I need each Group to be numbered sequentially so I can link to them and implement some JS paging. I'm binding to an IEnumerable Here's some pseudo code. I would like the output to look like this: <a href="#group1">Go to Group 1<a> <a href="#group2">Go to Group 2<a> <a href="#group3">Go to Group 3<a> <ul id="group1"> <li>Item</li> <li>Item</li> <li>Item</li> </ul> <ul id="group2"> <li>Item</li> <li>Item</li> <li>Item</li> </ul> <ul id="group3"> <li>Item</li> <li>Item</li> <li>Item</li> </ul> Is this easy to do in a ListView, using GroupTemplate and ItemTemplate? <asp:ListView ID="lv" runat="server" GroupPlaceholderID="groupPlaceholder"> <LayoutTemplate> <asp:PlaceHolder ID="groupPlaceholder" runat="server"></asp:PlaceHolder> </LayoutTemplate> <GroupTemplate> <ul id="<!-- group-n goes here -->"> <asp:PlaceHolder ID="itemPlaceholder" runat="server"></asp:PlaceHolder> </ul> </GroupTemplate> <ItemTemplate> <li>Item</li> </ItemTemplate> </asp:ListView> I can get the number of groups to do the links at the top from the Datasource and basic math, but how do I get id="groupN" number into the template?

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• How to maximize http.sys file upload performance

  - by anelson

  I'm building a tool that transfers very large streaming data sets (possibly on the order of terabytes in a single stream; routinely in the tens of gigabytes) from one server to another. The client portion of the tool will read blocks from the source disk, and send them over the network. The server side will read these blocks off the network and write them to a file on the server disk. Right now I'm trying to decide which transport to use. Options are raw TCP, and HTTP. I really, REALLY want to be able to use HTTP. The HttpListener (or WCF if I want to go that route) make it easy to plug in to the HTTP Server API (http.sys), and I can get things like authentication and SSL for free. The problem right now is performance. I wrote a simple test harness that sends 128K blocks of NULL bytes using the BeginWrite/EndWrite async I/O idiom, with async BeginRead/EndRead on the server side. I've modified this test harness so I can do this with either HTTP PUT operations via HttpWebRequest/HttpListener, or plain old socket writes using TcpClient/TcpListener. To rule out issues with network cards or network pathways, both the client and server are on one machine and communicate over localhost. On my 12-core Windows 2008 R2 test server, the TCP version of this test harness can push bytes at 450MB/s, with minimal CPU usage. On the same box, the HTTP version of the test harness runs between 130MB/s and 200MB/s depending upon how I tweak it. In both cases CPU usage is low, and the vast majority of what CPU usage there is is kernel time, so I'm pretty sure my usage of C# and the .NET runtime is not the bottleneck. The box has two 6-core Xeon X5650 processors, 24GB of single-ranked DDR3 RAM, and is used exclusively by me for my own performance testing. I already know about HTTP client tweaks like ServicePointManager.MaxServicePointIdleTime, ServicePointManager.DefaultConnectionLimit, ServicePointManager.Expect100Continue, and HttpWebRequest.AllowWriteStreamBuffering. Does anyone have any ideas for how I can get HTTP.sys performance beyond 200MB/s? Has anyone seen it perform this well on any environment?

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• LSP packet modify

  - by kellogs

  Hello, anybody care to share some insights on how to use LSP for packet modifying ? I am using the non IFS subtype and I can see how (pseudo?) packets first enter WSPRecv. But how do I modify them ? My inquiry is about one single HTTP response that causes WSPRecv to be called 3 times :((. I need to modify several parts of this response, but since it comes in 3 slices, it is pretty hard to modify it accordingly. And, maybe on other machines or under different conditions (such as high traffic) there would only be one sole WSPRecv call, or maybe 10 calls. What is the best way to work arround this (please no NDIS :D), and how to properly change the buffer (lpBuffers-buf) by increasing it ? int WSPAPI WSPRecv( SOCKET s, LPWSABUF lpBuffers, DWORD dwBufferCount, LPDWORD lpNumberOfBytesRecvd, LPDWORD lpFlags, LPWSAOVERLAPPED lpOverlapped, LPWSAOVERLAPPED_COMPLETION_ROUTINE lpCompletionRoutine, LPWSATHREADID lpThreadId, LPINT lpErrno ) { LPWSAOVERLAPPEDPLUS ProviderOverlapped = NULL; SOCK_INFO *SocketContext = NULL; int ret = SOCKET_ERROR; *lpErrno = NO_ERROR; // // Find our provider socket corresponding to this one // SocketContext = FindAndRefSocketContext(s, lpErrno); if ( NULL == SocketContext ) { dbgprint( "WSPRecv: FindAndRefSocketContext failed!" ); goto cleanup; } // // Check for overlapped I/O // if ( NULL != lpOverlapped ) { /*bla bla .. not interesting in my case*/ } else { ASSERT( SocketContext->Provider->NextProcTable.lpWSPRecv ); SetBlockingProvider(SocketContext->Provider); ret = SocketContext->Provider->NextProcTable.lpWSPRecv( SocketContext->ProviderSocket, lpBuffers, dwBufferCount, lpNumberOfBytesRecvd, lpFlags, lpOverlapped, lpCompletionRoutine, lpThreadId, lpErrno); SetBlockingProvider(NULL); //is this the place to modify packet length and contents ? if (strstr(lpBuffers->buf, "var mapObj = null;")) { int nLen = strlen(lpBuffers->buf) + 200; /*CHAR *szNewBuf = new CHAR[]; CHAR *pIndex; pIndex = strstr(lpBuffers->buf, "var mapObj = null;"); nLen = strlen(strncpy(szNewBuf, lpBuffers->buf, (pIndex - lpBuffers->buf) * sizeof (CHAR))); nLen = strlen(strncpy(szNewBuf + nLen * sizeof(CHAR), "var com = null;\r\n", 17 * sizeof(CHAR))); pIndex += 18 * sizeof(CHAR); nLen = strlen(strncpy(szNewBuf + nLen * sizeof(CHAR), pIndex, 1330 * sizeof (CHAR))); nLen = strlen(strncpy(szNewBuf + nLen * sizeof(CHAR), "if (com == null)\r\n" \ "com = new ActiveXObject(\"InterCommJS.Gateway\");\r\n" \ "com.lat = latitude;\r\n" \ "com.lon = longitude;\r\n}", 111 * sizeof (CHAR))); pIndex = strstr(szNewBuf, "Content-Length:"); pIndex += 16 * sizeof(CHAR); strncpy(pIndex, "1465", 4 * sizeof(CHAR)); lpBuffers->buf = szNewBuf; lpBuffers->len += 128;*/ } if ( SOCKET_ERROR != ret ) { SocketContext->BytesRecv += *lpNumberOfBytesRecvd; } } cleanup: if ( NULL != SocketContext ) DerefSocketContext( SocketContext, lpErrno ); return ret; } Thank you

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• Bind listbox in WPF with grouping

  - by Michael Stoll

  Hi, I've got a collection of ViewModels and want to bind a ListBox to them. Doing some investigation I found this. So my ViewModel look like this (Pseudo Code) interface IItemViewModel { string DisplayName { get; } } class AViewModel : IItemViewModel { string DisplayName { return "foo"; } } class BViewModel : IItemViewModel { string DisplayName { return "foo"; } } class ParentViewModel { IEnumerable<IItemViewModel> Items { get { return new IItemViewModel[] { new AItemViewModel(), new BItemViewModel() } } } } class GroupViewModel { static readonly GroupViewModel GroupA = new GroupViewModel(0); static readonly GroupViewModel GroupB = new GroupViewModel(1); int GroupIndex; GroupViewModel(int groupIndex) { this.GroupIndex = groupIndex; } string DisplayName { get { return "This is group " + GroupIndex.ToString(); } } } class ItemGroupTypeConverter : IValueConverter { object Convert(object value, Type targetType, object parameter, CultureInfo culture) { if (value is AItemViewModel) return GroupViewModel.GroupA; else return GroupViewModel.GroupB; } } And this XAML <UserControl.Resources> <vm:ItemsGroupTypeConverter x:Key="ItemsGroupTypeConverter "/> <CollectionViewSource x:Key="GroupedItems" Source="{Binding Items}"> <CollectionViewSource.GroupDescriptions> <PropertyGroupDescription Converter="{StaticResource ItemsGroupTypeConverter }"/> </CollectionViewSource.GroupDescriptions> </CollectionViewSource> </UserControl.Resources> <ListBox ItemsSource="{Binding Source={StaticResource GroupedItems}}"> <ListBox.GroupStyle> <GroupStyle> <GroupStyle.HeaderTemplate> <DataTemplate> <TextBlock Text="{Binding DisplayName}" FontWeight="bold" /> </DataTemplate> </GroupStyle.HeaderTemplate> </GroupStyle> </ListBox.GroupStyle> <ListBox.ItemTemplate> <DataTemplate> <TextBlock Text="{Binding DisplayName}" /> </DataTemplate> </ListBox.ItemTemplate> </ListBox> This works somehow, exept of the fact that the binding of the HeaderTemplate does not work. Anyhow I'd prefer omitting the TypeConverter and the CollectionViewSource. Isn't there a way to use a property of the ViewModel for Grouping? I know that in this sample scenario it would be easy to replace the GroupViewModel with a string an have it working, but that's not an option. So how can I bind the HeaderTemplate to the GroupViewModel?

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• velocity vector

  - by wanderer

  Hi, I am trying to simulate a collision. The collision is shown here http://www.freeimagehosting.net/image.php?c5ae01b476.jpg A particle falls down on a sphere and a collision between sphere and particle takes place. The sphere always remain stationary and the collision itself is not elastic. So if the particle falls directly n top of sphere, the velocity of particle will become zero. I was trying to set the velocity of particle to be zero after the collision. But that does not give good simulation when the collision does not occur on top of sphere but along the side of sphere. So now after the collision i need to make sure that the particle has a velocity which is orthogonal to the vector of the point of collision from the center of sphere. The velocity along the vector from center of sphere to point of collision should become zero. How do i do that? I am a bit mathematically challenged but i think it has something to do with dot product of vectors. Or maybe i am wrong :) I have the initial velocity vector and 'radiusvector' say :- 1)velocity <-1.03054, -1.56563, 1.33341e-016 2) radius vector <2.04406, 2.19587, 1.0514 Pseudo code for the problem is: foreach( particle particle in particlesCollections) { //sphere.x, sphere.y sphere.z give the center of the sphere dist = particle.pos-vector(sphere.x,sphere.y,sphere.z); //detect if a collision has taken place. if (dist.mag < sphere.radius) { rVector=dist/dist.mag*sphere.radius; particle.pos=vector(sphere.x,sphere.y,sphere.z) + rVector; //particle.Velocity gives the velocity vector of the particle at the time of collision //i need to modify particle.Velocity so that the component of velocity that runs along // with the rvector becomes zero as i have a non elsatic collision. The remaining //velocity that the particle will have is the one which runs along with tangent to the //rVector. The sphere remains stationary. //example values: particle.Velocity == <-1.03054, -1.56563, .006> //and rVector = <2.04406, 2.19587, 1.0514> } } Thanks

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