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  • which sql query is more efficient: select count(*) or select ... where key>value?

    - by davka
    I need to periodically update a local cache with new additions to some DB table. The table rows contain an auto-increment sequential number (SN) field. The cache keeps this number too, so basically I just need to fetch all rows with SN larger than the highest I already have. SELECT * FROM table where SN > <max_cached_SN> However, the majority of the attempts will bring no data (I just need to make sure that I have an absolutely up-to-date local copy). So I wander if this will be more efficient: count = SELECT count(*) from table; if (count > <cache_size>) // fetch new rows as above I suppose that selecting by an indexed numeric field is quite efficient, so I wander whether using count has benefit. On the other hand, this test/update will be done quite frequently and by many clients, so there is a motivation to optimize it.

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  • mysql ORDER BY date_time field not sorting as expected

    - by undefined
    I have a field in my database that stores the datetime that an item was added to the database. If I want to sort the items in reverse chronological order I would expect that doing ORDER by date_added DESC would do the trick. But this seems not to work. I also tried ORDER by UNIX_TIMESTAMP(date_added) but this still did not sort the results as I would expect. I also have an auto-increment field that I can use to sort items so I will use this, but I am curious as to why ORDER by datetime was not behaving as expected. any ideas?

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  • STL ostream_iterator writes to screen even though I overwrote it?

    - by adam_0
    In my code, I have the following: ostream_iterator<double> doubleWriter(cout, " ~ "); // ... *doubleWriter = 1.1; doubleWriter++; *doubleWriter = 2.2; *doubleWriter = 3.3; // shouldn't 2.2 be overwritten? doubleWriter++; *doubleWriter = 44.2; cout << endl << endl; I expected it to output this: 1.1 ~ 3.3 ~ 44.2 ~ Instead, the output was this: 1.1 ~ 2.2 ~ 3.3 ~ 44.2 ~ Why does this happen? It would seem to me that I overwrite 2.2 and stick 3.3 in its spot, since I didn't increment. Is incrementation an optional step?

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  • error defining foreign key PhpMyAdmin

    - by Ngounou lassale
    I am new to PhpMyAdmin. I will like to create a foreign key for my tables. In fact i have create tableI with this structures(A as int(11) autoincrement, B as varchar) TableII ( A_2 as int(11) auto increment, B_2 as varchar, A as int(11). I have declared A as an index in tableII, now when i go to relationship view to precise A as a foreign key i always have this error Erreur lors de la création de la clé étrangère sur ID_Ville (vérifiez le type des colonnes) Erreur ALTER TABLE tb_quartier ADD FOREIGN KEY ( ID_Ville ) REFERENCES ingenieris2.tb_ville ( ID_Ville ) ON DELETE RESTRICT ; Please Help thanks!

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  • Adding form inputs in javascript (jquery)

    - by matthewsteiner
    I understand that you do something like: $('form').append('<input type="text" name="color-1" value="Hello" />'); But I have two questions about it. First off, I don't want it added to the end of the form, but after the last input in the "color" section. Secondly, where "name=color-1", I need the one to increment if they want to add more than one input, you know? So that I can process it on the server. Any ideas?

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  • Python finding index in a array

    - by NIH
    I am trying to see if a company from a list of companies is in a line in a file. If it is I utilize the index of that company to increment a variable in another array. The following is my python code. I keep getting the following error: AttributeError: 'set' object has no attribute 'index'. I cannot figure out what is going wrong and think the error is the line that is surrounded by **. companies={'white house black market', 'macy','nordstrom','filene','walmart'} positives=[0 for x in xrange(len(companies))] negatives=[0 for x in xrange(len(companies))] for line in f: for company in companies: if company in line.lower(): words=tokenize.word_tokenize(line) bag=bag_of_words(words) classif=classifier.classify(bag) if classif=='pos': **indice =companies.index(company)** positives[indice]+=1 elif classif=='neg': **indice =companies.index(company)** negatives[indice]+=1

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  • Android ArrayList Calendar add and get is different

    - by Raku ShinShou
    I put increment date of the calendar and add into arraylist, but when i loop them out, the date is all same. Calendar a = Calendar.getInstance(); ArrayList<Calendar> b = new ArrayList<Calendar>(); for (int i=0; i<3; i++) { a.add(Calendar.DATE, i>0 ? 1 : 0); b.add(a); } for (int i=0; i<b.size(); i++){ Log.d("xxx", "test=" + b.get(i)); } suppose i wan 10/11/2012, 11/11/2012, 12/11/2012 but it come out like 12/11/2012, 12/11/2012, 12/11/2012 Anyone know how to solve this?

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  • C# Deserializing to a dictionary<string, Object>

    - by lovecraft
    I'm writing a C#/VB application to connect to a database and do stuff with the data. I was given this code to take a serialized byte array and deserialized it, which is then written to a Dictionary The line of code is: Dictionary<string, Object> DictionaryEmployee = (Dictionary<string, Object> Deserializer(byteArrayEmp)); The errors I'm getting are exceedingly unhelpful. "Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement" if I mouse over Object and "Using the generic type 'System.Collections.Generic.Dictionary' requires 2 type arguments if I mouse over Dictionary.

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  • ANTS CLR and Memory Profiler In Depth Review (Part 1 of 2 &ndash; CLR Profiler)

    - by ToStringTheory
    One of the things that people might not know about me, is my obsession to make my code as efficient as possible.  Many people might not realize how much of a task or undertaking that this might be, but it is surely a task as monumental as climbing Mount Everest, except this time it is a challenge for the mind…  In trying to make code efficient, there are many different factors that play a part – size of project or solution, tiers, language used, experience and training of the programmer, technologies used, maintainability of the code – the list can go on for quite some time. I spend quite a bit of time when developing trying to determine what is the best way to implement a feature to accomplish the efficiency that I look to achieve.  One program that I have recently come to learn about – Red Gate ANTS Performance (CLR) and Memory profiler gives me tools to accomplish that job more efficiently as well.  In this review, I am going to cover some of the features of the ANTS profiler set by compiling some hideous example code to test against. Notice As a member of the Geeks With Blogs Influencers program, one of the perks is the ability to review products, in exchange for a free license to the program.  I have not let this affect my opinions of the product in any way, and Red Gate nor Geeks With Blogs has tried to influence my opinion regarding this product in any way. Introduction The ANTS Profiler pack provided by Red Gate was something that I had not heard of before receiving an email regarding an offer to review it for a license.  Since I look to make my code efficient, it was a no brainer for me to try it out!  One thing that I have to say took me by surprise is that upon downloading the program and installing it you fill out a form for your usual contact information.  Sure enough within 2 hours, I received an email from a sales representative at Red Gate asking if she could help me to achieve the most out of my trial time so it wouldn’t go to waste.  After replying to her and explaining that I was looking to review its feature set, she put me in contact with someone that setup a demo session to give me a quick rundown of its features via an online meeting.  After having dealt with a massive ordeal with one of my utility companies and their complete lack of customer service, Red Gates friendly and helpful representatives were a breath of fresh air, and something I was thankful for. ANTS CLR Profiler The ANTS CLR profiler is the thing I want to focus on the most in this post, so I am going to dive right in now. Install was simple and took no time at all.  It installed both the profiler for the CLR and Memory, but also visual studio extensions to facilitate the usage of the profilers (click any images for full size images): The Visual Studio menu options (under ANTS menu) Starting the CLR Performance Profiler from the start menu yields this window If you follow the instructions after launching the program from the start menu (Click File > New Profiling Session to start a new project), you are given a dialog with plenty of options for profiling: The New Session dialog.  Lots of options.  One thing I noticed is that the buttons in the lower right were half-covered by the panel of the application.  If I had to guess, I would imagine that this is caused by my DPI settings being set to 125%.  This is a problem I have seen in other applications as well that don’t scale well to different dpi scales. The profiler options give you the ability to profile: .NET Executable ASP.NET web application (hosted in IIS) ASP.NET web application (hosted in IIS express) ASP.NET web application (hosted in Cassini Web Development Server) SharePoint web application (hosted in IIS) Silverlight 4+ application Windows Service COM+ server XBAP (local XAML browser application) Attach to an already running .NET 4 process Choosing each option provides a varying set of other variables/options that one can set including options such as application arguments, operating path, record I/O performance performance counters to record (43 counters in all!), etc…  All in all, they give you the ability to profile many different .Net project types, and make it simple to do so.  In most cases of my using this application, I would be using the built in Visual Studio extensions, as they automatically start a new profiling project in ANTS with the options setup, and start your program, however RedGate has made it easy enough to profile outside of Visual Studio as well. On the flip side of this, as someone who lives most of their work life in Visual Studio, one thing I do wish is that instead of opening an entirely separate application/gui to perform profiling after launching, that instead they would provide a Visual Studio panel with the information, and integrate more of the profiling project information into Visual Studio.  So, now that we have an idea of what options that the profiler gives us, its time to test its abilities and features. Horrendous Example Code – Prime Number Generator One of my interests besides development, is Physics and Math – what I went to college for.  I have especially always been interested in prime numbers, as they are something of a mystery…  So, I decided that I would go ahead and to test the abilities of the profiler, I would write a small program, website, and library to generate prime numbers in the quantity that you ask for.  I am going to start off with some terrible code, and show how I would see the profiler being used as a development tool. First off, the IPrimes interface (all code is downloadable at the end of the post): interface IPrimes { IEnumerable<int> GetPrimes(int retrieve); } Simple enough, right?  Anything that implements the interface will (hopefully) provide an IEnumerable of int, with the quantity specified in the parameter argument.  Next, I am going to implement this interface in the most basic way: public class DumbPrimes : IPrimes { public IEnumerable<int> GetPrimes(int retrieve) { //store a list of primes already found var _foundPrimes = new List<int>() { 2, 3 }; //if i ask for 1 or two primes, return what asked for if (retrieve <= _foundPrimes.Count()) return _foundPrimes.Take(retrieve); //the next number to look at int _analyzing = 4; //since I already determined I don't have enough //execute at least once, and until quantity is sufficed do { //assume prime until otherwise determined bool isPrime = true; //start dividing at 2 //divide until number is reached, or determined not prime for (int i = 2; i < _analyzing && isPrime; i++) { //if (i) goes into _analyzing without a remainder, //_analyzing is NOT prime if (_analyzing % i == 0) isPrime = false; } //if it is prime, add to found list if (isPrime) _foundPrimes.Add(_analyzing); //increment number to analyze next _analyzing++; } while (_foundPrimes.Count() < retrieve); return _foundPrimes; } } This is the simplest way to get primes in my opinion.  Checking each number by the straight definition of a prime – is it divisible by anything besides 1 and itself. I have included this code in a base class library for my solution, as I am going to use it to demonstrate a couple of features of ANTS.  This class library is consumed by a simple non-MVVM WPF application, and a simple MVC4 website.  I will not post the WPF code here inline, as it is simply an ObservableCollection<int>, a label, two textbox’s, and a button. Starting a new Profiling Session So, in Visual Studio, I have just completed my first stint developing the GUI and DumbPrimes IPrimes class, so now I want to check my codes efficiency by profiling it.  All I have to do is build the solution (surprised initiating a profiling session doesn’t do this, but I suppose I can understand it), and then click the ANTS menu, followed by Profile Performance.  I am then greeted by the profiler starting up and already monitoring my program live: You are provided with a realtime graph at the top, and a pane at the bottom giving you information on how to proceed.  I am going to start by asking my program to show me the first 15000 primes: After the program finally began responding again (I did all the work on the main UI thread – how bad!), I stopped the profiler, which did kill the process of my program too.  One important thing to note, is that the profiler by default wants to give you a lot of detail about the operation – line hit counts, time per line, percent time per line, etc…  The important thing to remember is that this itself takes a lot of time.  When running my program without the profiler attached, it can generate the 15000 primes in 5.18 seconds, compared to 74.5 seconds – almost a 1500 percent increase.  While this may seem like a lot, remember that there is a trade off.  It may be WAY more inefficient, however, I am able to drill down and make improvements to specific problem areas, and then decrease execution time all around. Analyzing the Profiling Session After clicking ‘Stop Profiling’, the process running my application stopped, and the entire execution time was automatically selected by ANTS, and the results shown below: Now there are a number of interesting things going on here, I am going to cover each in a section of its own: Real Time Performance Counter Bar (top of screen) At the top of the screen, is the real time performance bar.  As your application is running, this will constantly update with the currently selected performance counters status.  A couple of cool things to note are the fact that you can drag a selection around specific time periods to drill down the detail views in the lower 2 panels to information pertaining to only that period. After selecting a time period, you can bookmark a section and name it, so that it is easy to find later, or after reloaded at a later time.  You can also zoom in, out, or fit the graph to the space provided – useful for drilling down. It may be hard to see, but at the top of the processor time graph below the time ticks, but above the red usage graph, there is a green bar. This bar shows at what times a method that is selected in the ‘Call tree’ panel is called. Very cool to be able to click on a method and see at what times it made an impact. As I said before, ANTS provides 43 different performance counters you can hook into.  Click the arrow next to the Performance tab at the top will allow you to change between different counters if you have them selected: Method Call Tree, ADO.Net Database Calls, File IO – Detail Panel Red Gate really hit the mark here I think. When you select a section of the run with the graph, the call tree populates to fill a hierarchical tree of method calls, with information regarding each of the methods.   By default, methods are hidden where the source is not provided (framework type code), however, Red Gate has integrated Reflector into ANTS, so even if you don’t have source for something, you can select a method and get the source if you want.  Methods are also hidden where the impact is seen as insignificant – methods that are only executed for 1% of the time of the overall calling methods time; in other words, working on making them better is not where your efforts should be focused. – Smart! Source Panel – Detail Panel The source panel is where you can see line level information on your code, showing the code for the currently selected method from the Method Call Tree.  If the code is not available, Reflector takes care of it and shows the code anyways! As you can notice, there does seem to be a problem with how ANTS determines what line is the actual line that a call is completed on.  I have suspicions that this may be due to some of the inline code optimizations that the CLR applies upon compilation of the assembly.  In a method with comments, the problem is much more severe: As you can see here, apparently the most offending code in my base library was a comment – *gasp*!  Removing the comments does help quite a bit, however I hope that Red Gate works on their counter algorithm soon to improve the logic on positioning for statistics: I did a small test just to demonstrate the lines are correct without comments. For me, it isn’t a deal breaker, as I can usually determine the correct placements by looking at the application code in the region and determining what makes sense, but it is something that would probably build up some irritation with time. Feature – Suggest Method for Optimization A neat feature to really help those in need of a pointer, is the menu option under tools to automatically suggest methods to optimize/improve: Nice feature – clicking it filters the call tree and stars methods that it thinks are good candidates for optimization.  I do wish that they would have made it more visible for those of use who aren’t great on sight: Process Integration I do think that this could have a place in my process.  After experimenting with the profiler, I do think it would be a great benefit to do some development, testing, and then after all the bugs are worked out, use the profiler to check on things to make sure nothing seems like it is hogging more than its fair share.  For example, with this program, I would have developed it, ran it, tested it – it works, but slowly. After looking at the profiler, and seeing the massive amount of time spent in 1 method, I might go ahead and try to re-implement IPrimes (I actually would probably rewrite the offending code, but so that I can distribute both sets of code easily, I’m just going to make another implementation of IPrimes).  Using two pieces of knowledge about prime numbers can make this method MUCH more efficient – prime numbers fall into two buckets 6k+/-1 , and a number is prime if it is not divisible by any other primes before it: public class SmartPrimes : IPrimes { public IEnumerable<int> GetPrimes(int retrieve) { //store a list of primes already found var _foundPrimes = new List<int>() { 2, 3 }; //if i ask for 1 or two primes, return what asked for if (retrieve <= _foundPrimes.Count()) return _foundPrimes.Take(retrieve); //the next number to look at int _k = 1; //since I already determined I don't have enough //execute at least once, and until quantity is sufficed do { //assume prime until otherwise determined bool isPrime = true; int potentialPrime; //analyze 6k-1 //assign the value to potential potentialPrime = 6 * _k - 1; //if there are any primes that divise this, it is NOT a prime number //using PLINQ for quick boost isPrime = !_foundPrimes.AsParallel() .Any(prime => potentialPrime % prime == 0); //if it is prime, add to found list if (isPrime) _foundPrimes.Add(potentialPrime); if (_foundPrimes.Count() == retrieve) break; //analyze 6k+1 //assign the value to potential potentialPrime = 6 * _k + 1; //if there are any primes that divise this, it is NOT a prime number //using PLINQ for quick boost isPrime = !_foundPrimes.AsParallel() .Any(prime => potentialPrime % prime == 0); //if it is prime, add to found list if (isPrime) _foundPrimes.Add(potentialPrime); //increment k to analyze next _k++; } while (_foundPrimes.Count() < retrieve); return _foundPrimes; } } Now there are definitely more things I can do to help make this more efficient, but for the scope of this example, I think this is fine (but still hideous)! Profiling this now yields a happy surprise 27 seconds to generate the 15000 primes with the profiler attached, and only 1.43 seconds without.  One important thing I wanted to call out though was the performance graph now: Notice anything odd?  The %Processor time is above 100%.  This is because there is now more than 1 core in the operation.  A better label for the chart in my mind would have been %Core time, but to each their own. Another odd thing I noticed was that the profiler seemed to be spot on this time in my DumbPrimes class with line details in source, even with comments..  Odd. Profiling Web Applications The last thing that I wanted to cover, that means a lot to me as a web developer, is the great amount of work that Red Gate put into the profiler when profiling web applications.  In my solution, I have a simple MVC4 application setup with 1 page, a single input form, that will output prime values as my WPF app did.  Launching the profiler from Visual Studio as before, nothing is really different in the profiler window, however I did receive a UAC prompt for a Red Gate helper app to integrate with the web server without notification. After requesting 500, 1000, 2000, and 5000 primes, and looking at the profiler session, things are slightly different from before: As you can see, there are 4 spikes of activity in the processor time graph, but there is also something new in the call tree: That’s right – ANTS will actually group method calls by get/post operations, so it is easier to find out what action/page is giving the largest problems…  Pretty cool in my mind! Overview Overall, I think that Red Gate ANTS CLR Profiler has a lot to offer, however I think it also has a long ways to go.  3 Biggest Pros: Ability to easily drill down from time graph, to method calls, to source code Wide variety of counters to choose from when profiling your application Excellent integration/grouping of methods being called from web applications by request – BRILLIANT! 3 Biggest Cons: Issue regarding line details in source view Nit pick – Processor time vs. Core time Nit pick – Lack of full integration with Visual Studio Ratings Ease of Use (7/10) – I marked down here because of the problems with the line level details and the extra work that that entails, and the lack of better integration with Visual Studio. Effectiveness (10/10) – I believe that the profiler does EXACTLY what it purports to do.  Especially with its large variety of performance counters, a definite plus! Features (9/10) – Besides the real time performance monitoring, and the drill downs that I’ve shown here, ANTS also has great integration with ADO.Net, with the ability to show database queries run by your application in the profiler.  This, with the line level details, the web request grouping, reflector integration, and various options to customize your profiling session I think create a great set of features! Customer Service (10/10) – My entire experience with Red Gate personnel has been nothing but good.  their people are friendly, helpful, and happy! UI / UX (8/10) – The interface is very easy to get around, and all of the options are easy to find.  With a little bit of poking around, you’ll be optimizing Hello World in no time flat! Overall (8/10) – Overall, I am happy with the Performance Profiler and its features, as well as with the service I received when working with the Red Gate personnel.  I WOULD recommend you trying the application and seeing if it would fit into your process, BUT, remember there are still some kinks in it to hopefully be worked out. My next post will definitely be shorter (hopefully), but thank you for reading up to here, or skipping ahead!  Please, if you do try the product, drop me a message and let me know what you think!  I would love to hear any opinions you may have on the product. Code Feel free to download the code I used above – download via DropBox

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  • 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

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  • How To Approach 360 Degree Snake

    - by Austin Brunkhorst
    I've recently gotten into XNA and must say I love it. As sort of a hello world game I decided to create the classic game "Snake". The 90 degree version was very simple and easy to implement. But as I try to make a version of it that allows 360 degree rotation using left and right arrows, I've come into sort of a problem. What i'm doing now stems from the 90 degree version: Iterating through each snake body part beginning at the tail, and ending right before the head. This works great when moving every 100 milliseconds. The problem with this is that it makes for a choppy style of gameplay as technically the game progresses at only 6 fps rather than it's potential 60. I would like to move the snake every game loop. But unfortunately because the snake moves at the rate of it's head's size it goes way too fast. This would mean that the head would need to move at a much smaller increment such as (2, 2) in it's direction rather than what I have now (32, 32). Because I've been working on this game off and on for a couple of weeks while managing school I think that I've been thinking too hard on how to accomplish this. It's probably a simple solution, i'm just not catching it. Here's some pseudo code for what I've tried based off of what makes sense to me. I can't really think of another way to do it. for(int i = SnakeLength - 1; i > 0; i--){ current = SnakePart[i], next = SnakePart[i - 1]; current.x = next.x - (current.width * cos(next.angle)); current.y = next.y - (current.height * sin(next.angle)); current.angle = next.angle; } SnakeHead.x += cos(SnakeAngle) * SnakeSpeed; SnakeHead.y += sin(SnakeAngle) * SnakeSpeed; This produces something like this: Code in Action. As you can see each part always stays behind the head and doesn't make a "Trail" effect. A perfect example of what i'm going for can be found here: Data Worm. Not the viewport rotation but the trailing effect of the triangles. Thanks for any help!

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  • Automated build platform for .NET portfolio - best choice?

    - by jkohlhepp
    I am involved with maintaining a fairly large portfolio of .NET applications. Also in the portfolio are legacy applications built on top of other platforms - native C++, ECLIPS Forms, etc. I have a complex build framework on top of NAnt right now that manages the builds for all of these applications. The build framework uses NAnt to do a number of different things: Pull code out of Subversion, as well as create tags in Subversion Build the code, using MSBuild for .NET or other compilers for other platforms Peek inside AssemblyInfo files to increment version numbers Do deletes of certain files that shouldn't be included in builds / releases Releases code to deployment folders Zips code up for backup purposes Deploy Windows services; start and stop them Etc. Most of those things can be done with just NAnt by itself, but we did build a couple of extension tasks for NAnt to do some things that were specific to our environment. Also, most of those processes above are genericized and reused across a lot of our different application build scripts, so that we don't repeat logic. So it is not simple NAnt code, and not simple build scripts. There are dozens of NAnt files that come together to execute a build. Lately I've been dissatisfied with NAnt for a couple reasons: (1) it's syntax is just awful - programming languages on top of XML are really horrific to maintain, (2) the project seems to have died on the vine; there haven't been a ton of updates lately and it seems like no one is really at the helm. Trying to get it working with .NET 4 has cause some pain points due to this lack of activity. So, with all of that background out of the way, here's my question. Given some of the things that I want to accomplish based on that list above, and given that I am primarily in a .NET shop, but I also need to build non-.NET projects, is there an alternative to NAnt that I should consider switching to? Things on my radar include Powershell (with or without psake), MSBuild by itself, and rake. These all have pros and cons. For example, is MSBuild powerful enough? I remember using it years ago and it didn't seem to have as much power as NAnt. Do I really want to have my team learn Ruby just to do builds using rake? Is psake really mature enough of a project to pin my portfolio to? Is Powershell "too close to the metal" and I'll end up having to write my own build library akin to psake to use it on its own? Are there other tools that I should consider? If you were involved with maintaining a .NET portfolio of significant complexity, what build tool would you be looking at? What does your team currently use?

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  • OpenGL - have object follow mouse

    - by kevin james
    I want to have an object follow around my mouse on the screen in OpenGL. (I am also using GLEW, GLFW, and GLM). The best idea I've come up with is: Get the coordinates within the window with glfwGetCursorPos. The window was created with window = glfwCreateWindow( 1024, 768, "Test", NULL, NULL); and the code to get coordinates is double xpos, ypos; glfwGetCursorPos(window, &xpos, &ypos); Next, I use GLM unproject, to get the coordinates in "object space" glm::vec4 viewport = glm::vec4(0.0f, 0.0f, 1024.0f, 768.0f); glm::vec3 pos = glm::vec3(xpos, ypos, 0.0f); glm::vec3 un = glm::unProject(pos, View*Model, Projection, viewport); There are two potential problems I can already see. The viewport is fine, as the initial x,y, coordinates of the lower left are indeed 0,0, and it's indeed a 1024*768 window. However, the position vector I create doesn't seem right. The Z coordinate should probably not be zero. However, glfwGetCursorPos returns 2D coordinates, and I don't know how to go from there to the 3D window coordinates, especially since I am not sure what the 3rd dimension of the window coordinates even means (since computer screens are 2D). Then, I am not sure if I am using unproject correctly. Assume the View, Model, Projection matrices are all OK. If I passed in the correct position vector in Window coordinates, does the unproject call give me the coordinates in Object coordinates? I think it does, but the documentation is not clear. Finally, to each vertex of the object I want to follow the mouse around, I just increment the x coordinate by un[0], the y coordinate by -un[1], and the z coordinate by un[2]. However, since my position vector that is being unprojected is likely wrong, this is not giving good results; the object does move as my mouse moves, but it is offset quite a bit (i.e. moving the mouse a lot doesn't move the object that much, and the z coordinate is very large). I actually found that the z coordinate un[2] is always the same value no matter where my mouse is, probably because the position vector I pass into unproject always has a value of 0.0 for z. Edit: The (incorrectly) unprojected x-values range from about -0.552 to 0.552, and the y-values from about -0.411 to 0.411.

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  • SQL SERVER – A Puzzle Part 3 – Fun with SEQUENCE in SQL Server 2012 – Guess the Next Value

    - by pinaldave
    Before continuing this blog post – please read the two part of the SEQUENCE Puzzle here A Puzzle – Fun with SEQUENCE in SQL Server 2012 – Guess the Next Value and A Puzzle Part 2 – Fun with SEQUENCE in SQL Server 2012 – Guess the Next Value Where we played a simple guessing game about predicting next value. The answers the of puzzle is shared on the blog posts as a comment. Now here is the next puzzle based on yesterday’s puzzle. I recently shared the puzzle of the blog post on local user group and it was appreciated by attendees. First execute the script which I have written here. Today’s script is bit different than yesterday’s script as well it will require you to do some service related activities. I suggest you try this on your personal computer’s test environment when no one is working on it. Do not attempt this on production server as it will for sure get you in trouble. The purpose to learn how sequence behave during the unexpected shutdowns and services restarts. Now guess what will be the next value as requested in the query. USE AdventureWorks2012 GO -- Create sequence CREATE SEQUENCE dbo.SequenceID AS BIGINT START WITH 1 INCREMENT BY 1 MINVALUE 1 MAXVALUE 500 CYCLE CACHE 100; GO -- Following will return 1 SELECT next value FOR dbo.SequenceID; ------------------------------------- -- simulate server crash by restarting service -- do not attempt this on production or any server in use ------------------------------------ -- Following will return ??? SELECT next value FOR dbo.SequenceID; -- Clean up DROP SEQUENCE dbo.SequenceID; GO Once the server is restarted what will be the next value for SequenceID. We can learn interesting trivia’s about this new feature of SQL Server using this puzzle. Hint: Pay special attention to the difference between new number and earlier number. Can you see the same number in the definition of the CREATE SEQUENCE? Bonus Question: How to avoid the behavior demonstrated in above mentioned query. Does it have any effect of performance? I suggest you try to attempt to answer this question without running this code in SQL Server 2012. You can restart SQL Server using command prompt as well. I will follow up of the answer in comments below. Recently my friend Vinod Kumar wrote excellent blog post on SQL Server 2012: Using SEQUENCE, you can head over there for learning sequence in details. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Android, how important is deltaTime?

    - by iQue
    Im making a game that is getting pretty big and sometimes my thread has to skip a frame, so far I'm not using deltaTime for setting the speed of my different objects in the game because it's still not a big enough game for it to matter imo. But its getting bigger then I planned, so my question is, how important is delta Time? If I should use delta time there is a problem, since speedX and speedY are integers(they have to be for eclipse to let you make a rectangle of them), I cant add delta time very functionally as far as I understand, but might be wrong? Ive tried adding deltaTime to the code below, and sometimes my enemies just not move after spawn, they just stand there and run in the same place Will add an some code for how I set / use speed: public void update(int dx, int dy) { double theta = 180.0 / Math.PI * Math.atan2(-(y - controls.pointerPosition.y), controls.pointerPosition.x - x); x +=dx * Math.cos(Math.toRadians(theta)); y +=dy * Math.sin(Math.toRadians(theta)); currentFrame = ++currentFrame % BMP_COLUMNS; } public void draw(Canvas canvas) { int srcX = currentFrame * width; int srcY = 1 * height; Rect src = new Rect(srcX, srcY, srcX + width, srcY + height); Rect dst = new Rect(x, y, x + width, y + height); canvas.drawBitmap(bitmap, src, dst, null); } So if someone with some experience with this has any thoughts, please share. Thank you! Changed code: public void update(int dx, int dy, float delta) { double theta = 180.0 / Math.PI * Math.atan2(-(y - controls.pointerPosition.y), controls.pointerPosition.x - x); double speedX = delta * dx * Math.cos(Math.toRadians(theta)); double speedY = delta * dy * Math.sin(Math.toRadians(theta)); x += speedX; y += speedY; currentFrame = ++currentFrame % BMP_COLUMNS; } public void draw(Canvas canvas) { int srcX = currentFrame * width; int srcY = 1 * height; Rect src = new Rect(srcX, srcY, srcX + width, srcY + height); Rect dst = new Rect(x, y, x + width, y + height); canvas.drawBitmap(bitmap, src, dst, null); } with this code my enemies move like before, except they wont move to the right (wont increment x), all other directions work.

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  • Using INotifyPropertyChanged in background threads

    - by digitaldias
    Following up on a previous blog post where I exemplify databinding to objects, a reader was having some trouble with getting the UI to update. Here’s the rough UI: The idea is, when pressing Start, a background worker process starts ticking at the specified interval, then proceeds to increment the databound Elapsed value. The problem is that event propagation is limeted to current thread, meaning, you fire an event in one thread, then other threads of the same application will not catch it. The Code behind So, somewhere in my ViewModel, I have a corresponding bethod Start that initiates a background worker, for example: public void Start( ) { BackgroundWorker backgroundWorker = new BackgroundWorker( ); backgroundWorker.DoWork += IncrementTimerValue; backgroundWorker.RunWorkerAsync( ); } protected void IncrementTimerValue( object sender, DoWorkEventArgs e ) { do { if( this.ElapsedMs == 100 ) this.ElapsedMs = 0; else this.ElapsedMs++; }while( true ); } Assuming that there is a property: public int ElapsedMs { get { return _elapsedMs; } set { if( _elapsedMs == value ) return; _elapsedMs = value; NotifyThatPropertyChanged( "ElapsedMs" ); } } The above code will not work. If you step into this code in debug, you will find that INotifyPropertyChanged is called, but it does so in a different thread, and thus the UI never catches it, and does not update. One solution Knowing that the background thread updates the ElapsedMs member gives me a chance to activate BackgroundWorker class’ progress reporting mechanism to simply alert the main thread that something has happened, and that it is probably a good idea to refresh the ElapsedMs binding. public void Start( ) { BackgroundWorker backgroundWorker = new BackgroundWorker( ); backgroundWorker.DoWork += IncrementTimerValue; // Listen for progress report events backgroundWorker.WorkerReportsProgress = true; // Tell the UI that ElapsedMs needs to update backgroundWorker.RunWorkerCompleted += ( sender, e ) => { NotifyThatPropertyChanged( "ElapsedMs" ) }; backgroundWorker.RunWorkerAsync( ); } protected void IncrementTimerValue( object sender, DoWorkEventArgs e ) { do { if( this.ElapsedMs == 100 ) this.ElapsedMs = 0; else this.ElapsedMs++; // report any progress ( sender as BackgroundWorker ).ReportProgress( 0 ); }while( true ); } What happens above now is that I’ve used the BackgroundWorker cross thread mechanism to alert me of when it is ok for the UI to update it’s ElapsedMs field. Because the property itself is being updated in a different thread, I’m removing the NotifyThatPropertyChanged call from it’s Set method, and moving that responsability to the anonymous method that I created in the Start method. This is one way of solving the issue of having a background thread update your UI. I would be happy to hear of other cross-threading mechanisms for working in a MCP/MVC/MVVM pattern.

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  • Several New Hints

    - by Ondrej Brejla
    Hi all! Today we would like to introduce you some of our new experimental hints for NetBeans 7.2. They are called: Unused Use Statement and Immutable Variables. Unused Use Statement This hint is quite simple. It highlights (underlines) your use statements, which are not used. Typical use case is after some refactoring, when you forgot to remove some obsolete use statements. This hint warns you on them and allows you to remove them easily. Just click on the hint bulb in the gutter and select Remove Unused Use Statement. And of course, it works in multiple use statements combined too. Immutable Variables The next one is the hint which checks too many assignments into a variable. And why? That's simple. Mostly you should use just one assignment into one variable. But sometimes you are lazy and you do something like: But it's quite wrong, because what you really do is: And that's exactly the case, when our new hint warns you, that Too many assignments (2) into variable $foo occured. Nothing more. Yes, we know that there are some cases, where could be more assignments and no warning should occur, e.g.: Because maybe one likes longer increment syntax more than the short one. So we tried to handle these cases to don't bother you if it's not a need. Note: We are almost sure that this hint doesn't cover all your use cases, because there are a lot of them. So if you find something strange, write it into our bugzilla so we can handle it better for you. Thanks for your patience! And the last thing is, that you can set the number of allowed assignments in Tools -> Options -> Editor -> Hints -> PHP: Immutable Variables. Note: This hint works just for a common variables, not for fields. We have an enhancement request for that and it should be implemented in next version of NetBeans (probably 7.3). And that's all for today and as usual, please test it and if you find something strange, don't hesitate to file a new issue (product php, component Editor). Thanks.

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  • Bukkit inventory saving: crashing somewhere

    - by HcgRandon
    I'm working on a command for a bukkit plugin that lets you transfer worlds. In the section about saving the player's inventory, I'm getting a runtime error. My question is: Why is the error happening, and how can I prevent it? The plugin code public void savePlayerInv(Player p, World w){ File playerInvConfigFile = new File(plugin.getDataFolder() + File.separator + "players" + File.separator + p.getName(), "inventory.yml"); FileConfiguration pInv = YamlConfiguration.loadConfiguration(playerInvConfigFile); PlayerInventory inv = p.getInventory(); int i = 0; for (ItemStack stack : inv.getContents()) { //increment integer i++; String startInventory = w.getName() + ".inv." + Integer.toString(i); //save inv pInv.set(startInventory + ".amount", stack.getAmount()); pInv.set(startInventory + ".durability", Short.toString(stack.getDurability())); pInv.set(startInventory + ".type", stack.getTypeId()); //pInv.set(startInventory + ".enchantment", stack.getEnchantments()); //TODO add enchant saveing } i = 0; for (ItemStack armor : inv.getArmorContents()){ i++; String startArmor = w.getName() + ".armor." + Integer.toString(i); //save armor pInv.set(startArmor + ".amount", armor.getAmount()); pInv.set(startArmor + ".durability", armor.getDurability()); pInv.set(startArmor + ".type", armor.getTypeId()); //pInv.set(startArmor + ".enchantment", armor.getEnchantments()); } //save exp if (p.getExp() != 0) { pInv.set(w.getName() + ".exp", p.getExp()); } } The offending line The stack trace complains about line 130, which is this line. pInv.set(startInventory + ".amount", stack.getAmount()); The stack trace 2012-03-21 13:23:25 [SEVERE] null org.bukkit.command.CommandException: Unhandled exception executing command 'wtp' in plugin Needs v1.0 at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42) at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:166) at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:461) at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:818) at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:778) at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:761) at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:33) at net.minecraft.server.NetworkManager.b(NetworkManager.java:229) at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:112) at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78) at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:554) at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:452) at net.minecraft.server.ThreadServerApplication.run(SourceFile:490) Caused by: java.lang.NullPointerException at com.devoverflow.improved.needs.commands.CommandWorldtp.savePlayerInv(CommandWorldtp.java:130) at com.devoverflow.improved.needs.commands.CommandWorldtp.onCommand(CommandWorldtp.java:60) at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40) ... 12 more

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  • Bukkit saving inventory

    - by HcgRandon
    Alright i will make this quick... I am working on a command in my plugin to allow you to transfer worlds and i am trying to save inventory but i am getting a problem here is the code: public void savePlayerInv(Player p, World w){ File playerInvConfigFile = new File(plugin.getDataFolder() + File.separator + "players" + File.separator + p.getName(), "inventory.yml"); FileConfiguration pInv = YamlConfiguration.loadConfiguration(playerInvConfigFile); PlayerInventory inv = p.getInventory(); int i = 0; for (ItemStack stack : inv.getContents()) { //increment integer i++; String startInventory = w.getName() + ".inv." + Integer.toString(i); //save inv pInv.set(startInventory + ".amount", stack.getAmount()); pInv.set(startInventory + ".durability", Short.toString(stack.getDurability())); pInv.set(startInventory + ".type", stack.getTypeId()); //pInv.set(startInventory + ".enchantment", stack.getEnchantments()); //TODO add enchant saveing } i = 0; for (ItemStack armor : inv.getArmorContents()){ i++; String startArmor = w.getName() + ".armor." + Integer.toString(i); //save armor pInv.set(startArmor + ".amount", armor.getAmount()); pInv.set(startArmor + ".durability", armor.getDurability()); pInv.set(startArmor + ".type", armor.getTypeId()); //pInv.set(startArmor + ".enchantment", armor.getEnchantments()); } //save exp if (p.getExp() != 0) { pInv.set(w.getName() + ".exp", p.getExp()); } } Now here is the stack trace i recive it is commplaing about line 130 which is this line pInv.set(startInventory + ".amount", stack.getAmount()); okay now trace 2012-03-21 13:23:25 [SEVERE] null org.bukkit.command.CommandException: Unhandled exception executing command 'wtp' in plugin Needs v1.0 at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42) at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:166) at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:461) at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:818) at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:778) at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:761) at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:33) at net.minecraft.server.NetworkManager.b(NetworkManager.java:229) at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:112) at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78) at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:554) at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:452) at net.minecraft.server.ThreadServerApplication.run(SourceFile:490) Caused by: java.lang.NullPointerException at com.devoverflow.improved.needs.commands.CommandWorldtp.savePlayerInv(CommandWorldtp.java:130) at com.devoverflow.improved.needs.commands.CommandWorldtp.onCommand(CommandWorldtp.java:60) at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40) ... 12 more

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  • Strategy for avoiding duplicate object ids for data shared across devices using iCloud

    - by rmaddy
    I have a data intensive iOS app that is not using CoreData nor does it support iCloud synching (yet). All of my objects are created with unique keys. I use a simple long long initialized with the current time. Then as I need a new key I increment the value by 1. This has all worked well for a few years with the app running isolated on a single device. Now I want to add support for automatic data sync across devices using iCloud. As my app is written, there is the possibility that two objects created on two different devices could end up with the same key. I need to avoid this possibility. I'm looking for ideas for solving this issue. I have a few requirements that the solution must meet: 1) The key needs to remain a single integral data type. Converting all existing keys to a compound key or to a string or other type would affect the entire code base and likely result in more bugs than it's worth. 2) The solution can't depend on an Internet connection. A user must be able to run the app and add data even with no Internet connection. The data should still resolve properly later when the data syncs through iCloud once a connection is available. I'll accept one exception to this rule. If no other option is available, I may be open to requiring an Internet connection the first time the app's data is initialized. One idea I have been toying around with in my head is logically splitting the integer key into two parts. The high 4 or 5 bits could be used as some sort of device id while the rest represents the actual key. The fuzzy part is figuring out how to come up with non-conflicting device ids that fit in a few bits. This should be viable since I don't need to deal will millions of devices. I just need to deal with the few devices that would be shared by a given iCloud account. I'm open to suggestions. Thanks.

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  • Accessing Controls Within A Gridview

    - by Bunch
    Sometimes you need to access a control within a GridView, but it isn’t quite as straight forward as just using FindControl to grab the control like you can in a FormView. Since the GridView builds multiple rows the key is to specify the row. In this example there is a GridView with a control for a player’s errors. If the errors is greater than 9 the GridView should display the control (lblErrors) in red so it stands out. Here is the GridView: <asp:GridView ID="gvFielding" runat="server" DataSourceID="sqlFielding" DataKeyNames="PlayerID" AutoGenerateColumns="false" >     <Columns>         <asp:BoundField DataField="PlayerName" HeaderText="Player Name" />         <asp:BoundField DataField="PlayerNumber" HeaderText="Player Number" />         <asp:TemplateField HeaderText="Errors">             <ItemTemplate>                 <asp:Label ID="lblErrors" runat="server" Text='<%# EVAL("Errors") %>'  />             </ItemTemplate>         </asp:TemplateField>     </Columns> </asp:GridView> In the code behind you can add the code to change the label’s ForeColor property to red based on the amount of errors. In this case 10 or more errors triggers the color change. Protected Sub gvFielding_DataBound(ByVal sender As Object, ByVal e As System.EventArgs) Handles gvFielding.DataBound     Dim errorLabel As Label     Dim errors As Integer     Dim i As Integer = 0     For Each row As GridViewRow In gvFielding.Rows         errorLabel = gvFielding.Rows(i).FindControl("lblErrors")         If Not errorLabel.Text = Nothing Then             Integer.TryParse(errorLabel.Text, errors)             If errors > 9 Then                 errorLabel.ForeColor = Drawing.Color.Red             End If         End If         i += 1     Next End Sub The main points in the DataBound sub is use a For Each statement to loop through the rows and to increment the variable i so you loop through every row. That way you check each one and if the value is greater than 9 the label changes to red. The If Not errorLabel.Text = Nothing line is there as a check in case no data comes back at all for Errors. Technorati Tags: GridView,ASP.Net,VB.Net

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  • Multi-threaded JOGL Problem

    - by moeabdol
    I'm writing a simple OpenGL application in Java that implements the Monte Carlo method for estimating the value of PI. The method is pretty easy. Simply, you draw a circle inside a unit square and then plot random points over the scene. Now, for each point that is inside the circle you increment the counter for in points. After determining for all the random points wither they are inside the circle or not you divide the number of in points over the total number of points you have plotted all multiplied by 4 to get an estimation of PI. It goes something like this PI = (inPoints / totalPoints) * 4. This is because mathematically the ratio of a circle's area to a square's area is PI/4, so when we multiply it by 4 we get PI. My problem doesn't lie in the algorithm itself; however, I'm having problems trying to plot the points as they are being generated instead of just plotting everything at once when the program finishes executing. I want to give the application a sense of real-time display where the user would see the points as they are being plotted. I'm a beginner at OpenGL and I'm pretty sure there is a multi-threading feature built into it. Non the less, I tried to manually create my own thread. Each worker thread plots one point at a time. Following is the psudo-code: /* this part of the code exists in display() method in MyCanvas.java which extends GLCanvas and implements GLEventListener */ // main loop for(int i = 0; i < number_of_points; i++){ RandomGenerator random = new RandomGenerator(); float x = random.nextFloat(); float y = random.nextFloat(); Thread pointThread = new Thread(new PointThread(x, y)); } gl.glFlush(); /* this part of the code exists in run() method in PointThread.java which implements Runnable */ void run(){ try{ gl.glPushMatrix(); gl.glBegin(GL2.GL_POINTS); if(pointIsIn) gl.glColor3f(1.0f, 0.0f, 0.0f); // red point else gl.glColor3f(0.0f, 0.0f, 1.0f); // blue point gl.glVertex3f(x, y, 0.0f); // coordinates gl.glEnd(); gl.glPopMatrix(); }catch(Exception e){ } } I'm not sure if my approach to solving this issue is correct. I hope you guys can help me out. Thanks.

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  • C# .Net 3.5 Asynchronous Socket Server Performance Problem

    - by iBrAaAa
    I'm developing an Asynchronous Game Server using .Net Socket Asynchronous Model( BeginAccept/EndAccept...etc.) The problem I'm facing is described like that: When I have only one client connected, the server response time is very fast but once a second client connects, the server response time increases too much. I've measured the time from a client sends a message to the server until it gets the reply in both cases. I found that the average time in case of one client is about 17ms and in case of 2 clients about 280ms!!! What I really see is that: When 2 clients are connected and only one of them is moving(i.e. requesting service from the server) it is equivalently equal to the case when only one client is connected(i.e. fast response). However, when the 2 clients move at the same time(i.e. requests service from the server at the same time) their motion becomes very slow (as if the server replies each one of them in order i.e. not simultaneously). Basically, what I am doing is that: When a client requests a permission for motion from the server and the server grants him the request, the server then broadcasts the new position of the client to all the players. So if two clients are moving in the same time, the server is eventually trying to broadcast to both clients the new position of each of them at the same time. EX: Client1 asks to go to position (2,2) Client2 asks to go to position (5,5) Server sends to each of Client1 & Client2 the same two messages: message1: "Client1 at (2,2)" message2: "Client2 at (5,5)" I believe that the problem comes from the fact that Socket class is thread safe according MSDN documentation http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.aspx. (NOT SURE THAT IT IS THE PROBLEM) Below is the code for the server: /// /// This class is responsible for handling packet receiving and sending /// public class NetworkManager { /// /// An integer to hold the server port number to be used for the connections. Its default value is 5000. /// private readonly int port = 5000; /// /// hashtable contain all the clients connected to the server. /// key: player Id /// value: socket /// private readonly Hashtable connectedClients = new Hashtable(); /// /// An event to hold the thread to wait for a new client /// private readonly ManualResetEvent resetEvent = new ManualResetEvent(false); /// /// keeps track of the number of the connected clients /// private int clientCount; /// /// The socket of the server at which the clients connect /// private readonly Socket mainSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); /// /// The socket exception that informs that a client is disconnected /// private const int ClientDisconnectedErrorCode = 10054; /// /// The only instance of this class. /// private static readonly NetworkManager networkManagerInstance = new NetworkManager(); /// /// A delegate for the new client connected event. /// /// the sender object /// the event args public delegate void NewClientConnected(Object sender, SystemEventArgs e); /// /// A delegate for the position update message reception. /// /// the sender object /// the event args public delegate void PositionUpdateMessageRecieved(Object sender, PositionUpdateEventArgs e); /// /// The event which fires when a client sends a position message /// public PositionUpdateMessageRecieved PositionUpdateMessageEvent { get; set; } /// /// keeps track of the number of the connected clients /// public int ClientCount { get { return clientCount; } } /// /// A getter for this class instance. /// /// only instance. public static NetworkManager NetworkManagerInstance { get { return networkManagerInstance; } } private NetworkManager() {} /// Starts the game server and holds this thread alive /// public void StartServer() { //Bind the mainSocket to the server IP address and port mainSocket.Bind(new IPEndPoint(IPAddress.Any, port)); //The server starts to listen on the binded socket with max connection queue //1024 mainSocket.Listen(1024); //Start accepting clients asynchronously mainSocket.BeginAccept(OnClientConnected, null); //Wait until there is a client wants to connect resetEvent.WaitOne(); } /// /// Receives connections of new clients and fire the NewClientConnected event /// private void OnClientConnected(IAsyncResult asyncResult) { Interlocked.Increment(ref clientCount); ClientInfo newClient = new ClientInfo { WorkerSocket = mainSocket.EndAccept(asyncResult), PlayerId = clientCount }; //Add the new client to the hashtable and increment the number of clients connectedClients.Add(newClient.PlayerId, newClient); //fire the new client event informing that a new client is connected to the server if (NewClientEvent != null) { NewClientEvent(this, System.EventArgs.Empty); } newClient.WorkerSocket.BeginReceive(newClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), newClient); //Start accepting clients asynchronously again mainSocket.BeginAccept(OnClientConnected, null); } /// Waits for the upcoming messages from different clients and fires the proper event according to the packet type. /// /// private void WaitForData(IAsyncResult asyncResult) { ClientInfo sendingClient = null; try { //Take the client information from the asynchronous result resulting from the BeginReceive sendingClient = asyncResult.AsyncState as ClientInfo; // If client is disconnected, then throw a socket exception // with the correct error code. if (!IsConnected(sendingClient.WorkerSocket)) { throw new SocketException(ClientDisconnectedErrorCode); } //End the pending receive request sendingClient.WorkerSocket.EndReceive(asyncResult); //Fire the appropriate event FireMessageTypeEvent(sendingClient.ConvertBytesToPacket() as BasePacket); // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } catch (SocketException e) { if (e.ErrorCode == ClientDisconnectedErrorCode) { // Close the socket. if (sendingClient.WorkerSocket != null) { sendingClient.WorkerSocket.Close(); sendingClient.WorkerSocket = null; } // Remove it from the hash table. connectedClients.Remove(sendingClient.PlayerId); if (ClientDisconnectedEvent != null) { ClientDisconnectedEvent(this, new ClientDisconnectedEventArgs(sendingClient.PlayerId)); } } } catch (Exception e) { // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } } /// /// Broadcasts the input message to all the connected clients /// /// public void BroadcastMessage(BasePacket message) { byte[] bytes = message.ConvertToBytes(); foreach (ClientInfo client in connectedClients.Values) { client.WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, client); } } /// /// Sends the input message to the client specified by his ID. /// /// /// The message to be sent. /// The id of the client to receive the message. public void SendToClient(BasePacket message, int id) { byte[] bytes = message.ConvertToBytes(); (connectedClients[id] as ClientInfo).WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, connectedClients[id]); } private void SendAsync(IAsyncResult asyncResult) { ClientInfo currentClient = (ClientInfo)asyncResult.AsyncState; currentClient.WorkerSocket.EndSend(asyncResult); } /// Fires the event depending on the type of received packet /// /// The received packet. void FireMessageTypeEvent(BasePacket packet) { switch (packet.MessageType) { case MessageType.PositionUpdateMessage: if (PositionUpdateMessageEvent != null) { PositionUpdateMessageEvent(this, new PositionUpdateEventArgs(packet as PositionUpdatePacket)); } break; } } } The events fired are handled in a different class, here are the event handling code for the PositionUpdateMessage (Other handlers are irrelevant): private readonly Hashtable onlinePlayers = new Hashtable(); /// /// Constructor that creates a new instance of the GameController class. /// private GameController() { //Start the server server = new Thread(networkManager.StartServer); server.Start(); //Create an event handler for the NewClientEvent of networkManager networkManager.PositionUpdateMessageEvent += OnPositionUpdateMessageReceived; } /// /// this event handler is called when a client asks for movement. /// private void OnPositionUpdateMessageReceived(object sender, PositionUpdateEventArgs e) { Point currentLocation = ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position; Point locationRequested = e.PositionUpdatePacket.Position; ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position = locationRequested; // Broadcast the new position networkManager.BroadcastMessage(new PositionUpdatePacket { Position = locationRequested, PlayerId = e.PositionUpdatePacket.PlayerId }); }

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  • Android Remote Service Keeps Restarting

    - by user244190
    Ok so I've built an app that uses a remote service to do some real time GPS tracking. I am using the below code to start and bind to the service. The remote service uses aidl, sets up a notification icon, runs the GPS and locationListener. In onLocationChanged, a handler sends data back to the caller via the callback. Pretty much straight out of the examples and resources online. I want to allow the service to continue running even if the app closes. When the app is restarted, I want the app to again bind to the service (using the existing service if running) and again receive data from the tracker. I currently have the app mode set to singleTask and cannot use singleinstance due to another issue. My problem is that quit often even after the app and service are shut down either from the app itself, or from AdvancedTaskKiller, or a Forceclose, the service will restart and initialize the GPS. touching on the notification will open the app. I again stop the tracking which removes the notification and turns off the GPS Close the app, and again after a few seconds the service restarts. The only way to stop it is to power off the phone. What can I do to stop this from happening. Does it have to do with the mode of operation? START_NOT_STICKY or START_REDELIVER_INTENT? Or do I need to use stopSelf()? My understanding is that if the service is not running when I use bindService() that the service will be created...so do I really need to use start/stopService also? I thought I would need to use it if I want the service to run even after the app is closed. That is why i do not unbind/stop the service in onDestroy(). Is this correct? I've not seen any other info an this, so I,m not sure where to look. Please Help! Thanks Patrick //Remote Service Startup try{ startService(); }catch (Exception e) { Toast.makeText(ctx, e.getMessage().toString(), Toast.LENGTH_SHORT).show(); } } try{ bindService(); }catch (Exception e) { Toast.makeText(ctx, e.getMessage().toString(), Toast.LENGTH_SHORT).show(); } //Remote service shutdown try { unbindService(); }catch(Exception e) { Toast.makeText(ctx, e.getMessage().toString(), Toast.LENGTH_SHORT).show(); } try{ stopService(); }catch(Exception e) { Toast.makeText(ctx, e.getMessage().toString(), Toast.LENGTH_SHORT).show(); } private void startService() { if( myAdapter.trackServiceStarted() ) { if(SETTING_DEBUG_MODE) Toast.makeText(this, "Service already started", Toast.LENGTH_SHORT).show(); started = true; if(!myAdapter.trackDataExists()) insertTrackData(); updateServiceStatus(); } else { startService( new Intent ( "com.codebase.TRACKING_SERVICE" ) ); Log.d( "startService()", "startService()" ); started = true; updateServiceStatus(); } } private void stopService() { stopService( new Intent ( "com.codebase.TRACKING_SERVICE" ) ); Log.d( "stopService()", "stopService()" ); started = false; updateServiceStatus(); } private void bindService() { bindService(new Intent(ITrackingService.class.getName()), mConnection, Context.BIND_AUTO_CREATE); bindService(new Intent(ITrackingSecondary.class.getName()), mTrackingSecondaryConnection, Context.BIND_AUTO_CREATE); started = true; } private void unbindService() { try { mTrackingService.unregisterCallback(mCallback); } catch (RemoteException e) { // There is nothing special we need to do if the service // has crashed. e.getMessage(); } try { unbindService(mTrackingSecondaryConnection); unbindService(mConnection); } catch (Exception e) { // There is nothing special we need to do if the service // has crashed. e.getMessage(); } started = false; } private ServiceConnection mConnection = new ServiceConnection() { public void onServiceConnected(ComponentName className, IBinder service) { // This is called when the connection with the service has been // established, giving us the service object we can use to // interact with the service. We are communicating with our // service through an IDL interface, so get a client-side // representation of that from the raw service object. mTrackingService = ITrackingService.Stub.asInterface(service); // We want to monitor the service for as long as we are // connected to it. try { mTrackingService.registerCallback(mCallback); } catch (RemoteException e) { // In this case the service has crashed before we could even // do anything with it; we can count on soon being // disconnected (and then reconnected if it can be restarted) // so there is no need to do anything here. } } public void onServiceDisconnected(ComponentName className) { // This is called when the connection with the service has been // unexpectedly disconnected -- that is, its process crashed. mTrackingService = null; } }; private ServiceConnection mTrackingSecondaryConnection = new ServiceConnection() { public void onServiceConnected(ComponentName className, IBinder service) { // Connecting to a secondary interface is the same as any // other interface. mTrackingSecondaryService = ITrackingSecondary.Stub.asInterface(service); try{ mTrackingSecondaryService.setTimePrecision(SETTING_TIME_PRECISION); mTrackingSecondaryService.setDistancePrecision(SETTING_DISTANCE_PRECISION); } catch (RemoteException e) { // In this case the service has crashed before we could even // do anything with it; we can count on soon being // disconnected (and then reconnected if it can be restarted) // so there is no need to do anything here. } } public void onServiceDisconnected(ComponentName className) { mTrackingSecondaryService = null; } }; //TrackService onDestry() public void onDestroy() { try{ if(lm != null) { lm.removeUpdates(this); } if(mNotificationManager != null) { mNotificationManager.cancel(R.string.local_service_started); } Toast.makeText(this, "Service stopped", Toast.LENGTH_SHORT).show(); }catch (Exception e){ Toast.makeText(this, e.getMessage(), Toast.LENGTH_SHORT).show(); } // Unregister all callbacks. mCallbacks.kill(); // Remove the next pending message to increment the counter, stopping // the increment loop. mHandler.removeMessages(REPORT_MSG); super.onDestroy(); } ServiceConnectionLeaked: I'm seeing a lot of these: 04-21 09:25:23.347: ERROR/ActivityThread(3246): Activity com.codebase.GPSTest has leaked ServiceConnection com.codebase.GPSTest$6@4482d428 that was originally bound here 04-21 09:25:23.347: ERROR/ActivityThread(3246): android.app.ServiceConnectionLeaked: Activity com.codebase.GPSTest has leaked ServiceConnection com.codebase.GPSTest$6@4482d428 that was originally bound here 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread$PackageInfo$ServiceDispatcher.<init>(ActivityThread.java:977) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread$PackageInfo.getServiceDispatcher(ActivityThread.java:872) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ApplicationContext.bindService(ApplicationContext.java:796) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.content.ContextWrapper.bindService(ContextWrapper.java:337) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at com.codebase.GPSTest.bindService(GPSTest.java:2206) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at com.codebase.GPSTest.onStartStopClick(GPSTest.java:1589) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at com.codebase.GPSTest.onResume(GPSTest.java:1210) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1149) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.Activity.performResume(Activity.java:3763) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2937) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2965) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2516) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3625) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.access$2300(ActivityThread.java:119) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1867) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.os.Handler.dispatchMessage(Handler.java:99) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.os.Looper.loop(Looper.java:123) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.main(ActivityThread.java:4363) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at java.lang.reflect.Method.invokeNative(Native Method) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at java.lang.reflect.Method.invoke(Method.java:521) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at dalvik.system.NativeStart.main(Native Method) And These: Is this ok, or do I need to make sure i deactivate/close 04-21 09:58:55.487: INFO/dalvikvm(3440): Uncaught exception thrown by finalizer (will be discarded): 04-21 09:58:55.487: INFO/dalvikvm(3440): Ljava/lang/IllegalStateException;: Finalizing cursor android.database.sqlite.SQLiteCursor@447ef258 on gps_data that has not been deactivated or closed 04-21 09:58:55.487: INFO/dalvikvm(3440): at android.database.sqlite.SQLiteCursor.finalize(SQLiteCursor.java:596) 04-21 09:58:55.487: INFO/dalvikvm(3440): at dalvik.system.NativeStart.run(Native Method)

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  • Flash IO error while uploading photo with low uploading internet speed

    - by Beck
    Actionscript: System.security.allowDomain("http://" + _root.tdomain + "/"); import flash.net.FileReferenceList; import flash.net.FileReference; import flash.external.ExternalInterface; import flash.external.*; /* Main variables */ var session_photos = _root.ph; var how_much_you_can_upload = 0; var selected_photos; // container for selected photos var inside_photo_num = 0; // for photo in_array selection var created_elements = _root.ph; var for_js_num = _root.ph; /* Functions & settings for javascript<->flash conversation */ var methodName:String = "addtoflash"; var instance:Object = null; var method:Function = addnewphotonumber; var wasSuccessful:Boolean = ExternalInterface.addCallback(methodName, instance, method); function addnewphotonumber() { session_photos--; created_elements--; for_js_num--; } /* Javascript hide and show flash button functions */ function block(){getURL("Javascript: blocking();");} function unblock(){getURL("Javascript:unblocking();");} /* Creating HTML platform function */ var result = false; /* Uploading */ function uploadthis(photos:Array) { if(!photos[inside_photo_num].upload("http://" + _root.tdomain + "/upload.php?PHPSESSID=" + _root.phpsessionid)) { getURL("Javascript:error_uploading();"); } } /* Flash button(applet) options and bindings */ var fileTypes:Array = new Array(); var imageTypes:Object = new Object(); imageTypes.description = "Images (*.jpg)"; imageTypes.extension = "*.jpg;"; fileTypes.push(imageTypes); var fileListener:Object = new Object(); var btnListener:Object = new Object(); btnListener.click = function(eventObj:Object) { var fileRef:FileReferenceList = new FileReferenceList(); fileRef.addListener(fileListener); fileRef.browse(fileTypes); } uploadButton.addEventListener("click", btnListener); /* Listeners */ fileListener.onSelect = function(fileRefList:FileReferenceList):Void { // reseting values inside_photo_num = 0; var list:Array = fileRefList.fileList; var item:FileReference; // PHP photo counter how_much_you_can_upload = 3 - session_photos; if(list.length > how_much_you_can_upload) { getURL("Javascript:howmuch=" + how_much_you_can_upload + ";list_length=" + list.length + ";limit_reached();"); return; } // if session variable isn't yet refreshed, we check inner counter if(created_elements >= 3) { getURL("Javascript:limit_reached();"); return; } selected_photos = list; for(var i:Number = 0; i < list.length; i++) { how_much_you_can_upload--; item = list[i]; trace("name: " + item.name); trace(item.addListener(this)); if((item.size / 1024) > 5000) {getURL("Javascript:size_limit_reached();");return;} } result = false; setTimeout(block,500); /* Increment number for new HTML container and pass it to javascript, after javascript returns true and we start uploading */ for_js_num++; if(ExternalInterface.call("create_platform",for_js_num)) { uploadthis(selected_photos); } } fileListener.onProgress = function(file:FileReference, bytesLoaded:Number, bytesTotal:Number):Void { getURL("Javascript:files_process(" + bytesLoaded + "," + bytesTotal + "," + for_js_num + ");"); } fileListener.onComplete = function(file:FileReference, bytesLoaded:Number, bytesTotal:Number):Void { inside_photo_num++; var sendvar_lv:LoadVars = new LoadVars(); var loadvar_lv:LoadVars = new LoadVars(); loadvar_lv.onLoad = function(success:Boolean){ if(loadvar_lv.failed == 1) { getURL("Javascript:type_failed();"); return; } getURL("Javascript:filelinks='" + loadvar_lv.json + "';fullname='" + loadvar_lv.fullname + "';completed(" + for_js_num + ");"); created_elements++; if((inside_photo_num + 1) > selected_photos.length) {setTimeout(unblock,1000);return;} // don't create empty containers anymore if(created_elements >= 3) {return;} result = false; /* Increment number for new HTML container and pass it to javascript, after javascript returns true and we start uploading */ for_js_num++; if(ExternalInterface.call("create_platform",for_js_num)) { uploadthis(selected_photos); } } sendvar_lv.getnum = true; sendvar_lv.PHPSESSID = _root.phpsessionid; sendvar_lv.sendAndLoad("http://" + _root.tdomain + "/upload.php",loadvar_lv,"POST"); } fileListener.onCancel = function(file:FileReference):Void { } fileListener.onOpen = function(file:FileReference):Void { } fileListener.onHTTPError = function(file:FileReference, httpError:Number):Void { getURL("Javascript:http_error(" + httpError + ");"); } fileListener.onSecurityError = function(file:FileReference, errorString:String):Void { getURL("Javascript:security_error(" + errorString + ");"); } fileListener.onIOError = function(file:FileReference):Void { getURL("Javascript:io_error();"); selected_photos[inside_photo_num].cancel(); uploadthis(selected_photos); } <PARAM name="allowScriptAccess" value="always"> <PARAM name="swliveconnect" value="true"> <PARAM name="movie" value="http://www.localh.com/fileref.swf?ph=0&phpsessionid=8mirsjsd75v6vk583vkus50qbb2djsp6&tdomain=www.localh.com"> <PARAM name="wmode" value="opaque"> <PARAM name="quality" value="high"> <PARAM name="bgcolor" value="#ffffff"> <EMBED swliveconnect="true" wmode="opaque" src="http://www.localh.com/fileref.swf?ph=0&phpsessionid=8mirsjsd75v6vk583vkus50qbb2djsp6&tdomain=www.localh.com" quality="high" bgcolor="#ffffff" width="100" height="22" name="fileref" align="middle" allowScriptAccess="always" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer"></EMBED> My uploading speed is 40kb/sec Getting flash error while uploading photos bigger than 500kb and getting no error while uploading photos less than 100-500kb~. My friend has 8mbit uploading speed and has no errors even while uploading 3.2mb photos and more. How to fix this problem? I have tried to re-upload on IO error trigger, but it stops at the same place. Any solution regarding this error? By the way, i was watching process via debugging proxy and figured out, that responce headers doesn't come at all on this IO error. And sometimes shows socket error. If need, i will post serverside php script as well. But it stops at if(isset($_FILES['Filedata'])) { so it won't help :) as all processing comes after this check.

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