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  • How do I make my ArrayList Thread-Safe? Another approach to problem in Java?

    - by thechiman
    I have an ArrayList that I want to use to hold RaceCar objects that extend the Thread class as soon as they are finished executing. A class, called Race, handles this ArrayList using a callback method that the RaceCar object calls when it is finished executing. The callback method, addFinisher(RaceCar finisher), adds the RaceCar object to the ArrayList. This is supposed to give the order in which the Threads finish executing. I know that ArrayList isn't synchronized and thus isn't thread-safe. I tried using the Collections.synchronizedCollection(c Collection) method by passing in a new ArrayList and assigning the returned Collection to an ArrayList. However, this gives me a compiler error: Race.java:41: incompatible types found : java.util.Collection required: java.util.ArrayList finishingOrder = Collections.synchronizedCollection(new ArrayList(numberOfRaceCars)); Here is the relevant code: public class Race implements RaceListener { private Thread[] racers; private ArrayList finishingOrder; //Make an ArrayList to hold RaceCar objects to determine winners finishingOrder = Collections.synchronizedCollection(new ArrayList(numberOfRaceCars)); //Fill array with RaceCar objects for(int i=0; i<numberOfRaceCars; i++) { racers[i] = new RaceCar(laps, inputs[i]); //Add this as a RaceListener to each RaceCar ((RaceCar) racers[i]).addRaceListener(this); } //Implement the one method in the RaceListener interface public void addFinisher(RaceCar finisher) { finishingOrder.add(finisher); } What I need to know is, am I using a correct approach and if not, what should I use to make my code thread-safe? Thanks for the help!

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  • Java threads not working correctly with linkedlist

    - by user69514
    Hi I am working on the sleeping barber problem. with the addition of having priority customer when they arrive they go in the front of the line and they are the next ones to get a haircut. I'm using a linkedlist and if I see a priority customer I put him in the beginning of the list, if the customer is not priority he goes to the end of the list. then I call the wantHaircut method getting the first element of the list. my problem is that the customer are being processed in the order they arrive, and the priority customer have to wait. here is the code where it all happens. any ideas what I am doing wrong? thanks public void arrivedBarbershop(Customer c){ if(waiting < numChairs && c.isPriority()){ System.out.println("Customer " + c.getID() + ": is a priority customer - SITTING -"); mutex.up(); customer_list.addFirst(c); } else if(waiting >= numChairs && c.isPriority()){ System.out.println("Customer " + c.getID() + ": is a priority customer - STANDING -"); mutex.up(); customer_list.addFirst(c); } else if(waiting < numChairs && !c.isPriority()){ waiting++; System.out.println("Customer " + c.getID() + ": arrived, sitting in the waiting room"); customer_list.addLast(c); customers.up(); // increment waiting customers } else if(waiting >= numChairs && !c.isPriority()) { System.out.println("Customer " + c.getID() + ": went to another barber because waiting room was full - " + waiting + " waiting"); mutex.up(); } if(!customer_list.isEmpty()){ this.wantHairCut(customer_list.removeFirst()); } } public void wantHairCut(Customer c) { mutex.up(); barber.down(); // waits for being allowed in barber chair System.out.println("Customer " + c.getID() + ": getting haircut"); try { /** haircut takes between 1 and 2 seconds **/ Thread.sleep(Barbershop.randomInt(1, 2) * 1000); } catch (InterruptedException e) { } System.out.println("Barber: finished cutting customer " + c.getID() + "'s hair"); c.gotHaircut = true; cutting.up(); // signals cutting has finished /** customer must pay now **/ this.wantToCashout(c); }

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  • how many processors can I get in a block on cuda GPU?

    - by Vickey
    hi all, I have two questions to ask 1) If I create only one block of threads in cuda and execute the my parallel program on it then is it possible that more than one processors would be given to single block so that my program get some benefit of multiprocessor platform ? 2) can I synchronize the threads of different blocks ? if yes please give some hints. Thanks in advance since I know I'll get replies as always I get.

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  • Why there is no scoped locks for multiple mutexes in C++0x or Boost.Thread?

    - by Vicente Botet Escriba
    C++0x thread library or Boost.thread define non-member variadic template function that lock all lock avoiding dead lock. template <class L1, class L2, class... L3> void lock(L1&, L2&, L3&...); While this function avoid help to deadlock, the standard do not includes the associated scoped lock to write exception safe code. { std::lock(l1,l2); // do some thing // unlock li l2 exception safe } That means that we need to use other mechanism as try-catch block to make exception safe code or define our own scoped lock on multiple mutexes ourselves or even do that { std::lock(l1,l2); std::unique_lock lk1(l1, std::adopted); std::unique_lock lk2(l2, std::adopted); // do some thing // unlock li l2 on destruction of lk1 lk2 } Why the standard doesn't includes a scoped lock on multiple mutexes of the same type, as for example { std::array_unique_lock<std::mutex> lk(l1,l2); // do some thing // unlock l1 l2 on destruction of lk } or tuples of mutexes { std::tuple_unique_lock<std::mutex, std::recursive_mutex> lk(l1,l2); // do some thing // unlock l1 l2 on destruction of lk } Is there something wrong on the design?

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  • How would you implement this "WorkerChain" functionality in .NET?

    - by Dan Tao
    Sorry for the vague question title -- not sure how to encapsulate what I'm asking below succinctly. (If someone with editing privileges can think of a more descriptive title, feel free to change it.) The behavior I need is this. I am envisioning a worker class that accepts a single delegate task in its constructor (for simplicity, I would make it immutable -- no more tasks can be added after instantiation). I'll call this task T. The class should have a simple method, something like GetToWork, that will exhibit this behavior: If the worker is not currently running T, then it will start doing so right now. If the worker is currently running T, then once it is finished, it will start T again immediately. GetToWork can be called any number of times while the worker is running T; the simple rule is that, during any execution of T, if GetToWork was called at least once, T will run again upon completion (and then if GetToWork is called while T is running that time, it will repeat itself again, etc.). Now, this is pretty straightforward with a boolean switch. But this class needs to be thread-safe, by which I mean, steps 1 and 2 above need to comprise atomic operations (at least I think they do). There is an added layer of complexity. I have need of a "worker chain" class that will consist of many of these workers linked together. As soon as the first worker completes, it essentially calls GetToWork on the worker after it; meanwhile, if its own GetToWork has been called, it restarts itself as well. Logically calling GetToWork on the chain is essentially the same as calling GetToWork on the first worker in the chain (I would fully intend that the chain's workers not be publicly accessible). One way to imagine how this hypothetical "worker chain" would behave is by comparing it to a team in a relay race. Suppose there are four runners, W1 through W4, and let the chain be called C. If I call C.StartWork(), what should happen is this: If W1 is at his starting point (i.e., doing nothing), he will start running towards W2. If W1 is already running towards W2 (i.e., executing his task), then once he reaches W2, he will signal to W2 to get started, immediately return to his starting point and, since StartWork has been called, start running towards W2 again. When W1 reaches W2's starting point, he'll immediately return to his own starting point. If W2 is just sitting around, he'll start running immediately towards W3. If W2 is already off running towards W3, then W2 will simply go again once he's reached W3 and returned to his starting point. The above is probably a little convoluted and written out poorly. But hopefully you get the basic idea. Obviously, these workers will be running on their own threads. Also, I guess it's possible this functionality already exists somewhere? If that's the case, definitely let me know!

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  • How do people handle foreign keys on clients when synchronizing to master db

    - by excsm
    Hi, I'm writing an application with offline support. i.e. browser/mobile clients sync commands to the master db every so often. I'm using uuid's on both client and server-side. When synching up to the server, the servre will return a map of local uuids (luid) to server uuids (suid). Upon receiving this map, clients updated their records suid attributes with the appropriate values. However, say a client record, e.g. a todo, has an attribute 'list_id' which holds the foreign key to the todos' list record. I use luids in foreign_keys on clients. However, when that attribute is sent over to the server, it would dirty the server db with luids rather than the suid the server is using. My current solution, is for the master server to keep a record of the mappings of luids to suids (per client id) and for each foreign key in a command, look up the suid for that particular client and use the suid instead. I'm wondering wether others have come across thus problem and if so how they have solved it? Is there a more efficient, simpler way? I took a look at this question "Synchronizing one or more databases with a master database - Foreign keys (5)" and someone seemed to suggest my current solution as one option, composite keys using suids and autoincrementing sequences and another option using -ve ids for client ids and then updating all negative ids with the suids. Both of these other options seem like a lot more work. Thanks, Saimon

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  • database synchronisation

    - by chetan
    hello friends, I have two databases at two different places, both databases are same with table name as well as fields. now I want to synchronise both database. Is there any java code or we can achieve that directly from mysql or sql ? How ?

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  • How to unit test synchronized code

    - by gillJ
    Hi, I am new to Java and junit. I have the following peice of code that I want to test. Would appreciate if you could send your ideas about what's the best way to go about testing it. Basically, the following code is about electing a leader form a Cluster. The leader holds a lock on the shared cache and services of the leader get resumed and disposed if it somehow looses the lock on the cache. How can i make sure that a leader/thread still holds the lock on the cache and that another thread cannot get its services resumed while the first is in execution? public interface ContinuousService { public void resume(); public void pause(); } public abstract class ClusterServiceManager { private volatile boolean leader = false; private volatile boolean electable = true; private List<ContinuousService> services; protected synchronized void onElected() { if (!leader) { for (ContinuousService service : services) { service.resume(); } leader = true; } } protected synchronized void onDeposed() { if (leader) { for (ContinuousService service : services) { service.pause(); } leader = false; } } public void setServices(List<ContinuousService> services) { this.services = services; } @ManagedAttribute public boolean isElectable() { return electable; } @ManagedAttribute public boolean isLeader() { return leader; } public class TangosolLeaderElector extends ClusterServiceManager implements Runnable { private static final Logger log = LoggerFactory.getLogger(TangosolLeaderElector.class); private String election; private long electionWaitTime= 5000L; private NamedCache cache; public void start() { log.info("Starting LeaderElector ({})",election); Thread t = new Thread(this, "LeaderElector ("+election+")"); t.setDaemon(true); t.start(); } public void run() { // Give the connection a chance to start itself up try { Thread.sleep(1000); } catch (InterruptedException e) {} boolean wasElectable = !isElectable(); while (true) { if (isElectable()) { if (!wasElectable) { log.info("Leadership requested on election: {}",election); wasElectable = isElectable(); } boolean elected = false; try { // Try and get the lock on the LeaderElectorCache for the current election if (!cache.lock(election, electionWaitTime)) { // We didn't get the lock. cycle round again. // This code to ensure we check the electable flag every now & then continue; } elected = true; log.info("Leadership taken on election: {}",election); onElected(); // Wait here until the services fail in some way. while (true) { try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} if (!cache.lock(election, 0)) { log.warn("Cache lock no longer held for election: {}", election); break; } else if (!isElectable()) { log.warn("Node is no longer electable for election: {}", election); break; } // We're fine - loop round and go back to sleep. } } catch (Exception e) { if (log.isErrorEnabled()) { log.error("Leadership election " + election + " failed (try bfmq logs for details)", e); } } finally { if (elected) { cache.unlock(election); log.info("Leadership resigned on election: {}",election); onDeposed(); } // On deposition, do not try and get re-elected for at least the standard wait time. try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} } } else { // Not electable - wait a bit and check again. if (wasElectable) { log.info("Leadership NOT requested on election ({}) - node not electable",election); wasElectable = isElectable(); } try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} } } } public void setElection(String election) { this.election = election; } @ManagedAttribute public String getElection() { return election; } public void setNamedCache(NamedCache nc) { this.cache = nc; }

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  • Efficient implementation of threads in the given scenario

    - by shadeMe
    I've got a winforms application that is set up in the following manner: 2 buttons, a textbox, a collection K, function X and another function, Y. Function X parses a large database and enumerates some of its data in the global collection. Button 1 calls function X. Function Y walks through the above collection and prints out the data in the textbox. Button 2 calls function Y. I'd like to call function X through a worker thread in such a way that: The form remains responsive to user input. This comes intrinsically from the use of a separate thread. There is never more than a single instance of function X running at any point in time. K can be accessed by both functions at all times. What would be the most efficient implementation of the above environment ?

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  • Git repos over multiple machines - backups and keeping in sync

    - by a-or-b
    I'm new to git so please feel free to RTFM me... I have multiple development sites (none of which can communicate via a network with each other) and am working on a few projects (with a few people) at any one time. What I would ideally have is at each site a centralized repository that can be pulled from but development would occur in our own (personal) repos. Then I would like to be able to sync across the centralized repos (via USB key for example). I want a centralized repo at each location as (1) I'm new to git and do break my (personal) local repo by playing around and (2) some projects get put on hold so I want to be able to free up disk space by deleting them. This is the "backup" part of my question. I was also hoping to be able to use 'git clone --bare' for my centralized repos (and the USB key repos to?) as we don't need the full checkout, just the git benefits. However I can't seem to get a bare repo to work as repo I can push from. I've used 'git remote' to set up an remote origin (similar to http://toolmantim.com/thoughts/setting_up_a_new_remote_git_repository) but I can't get 'git push' to work - it seems I need a checked-out repo. . Does anyone else use this sort of repo/development structure or is there something fundamental about git usage that I'm missing? . A solution that I thought about that might not work - If I had a 'git clone --bare' at each site and then use a git repo on my removable media which has remotes set up for each site then I could ('pull') sync my USB key with each repo. But then can I update the site repo from my USB key? Could I push from USB?

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  • Microsoft Sync Framework - How to reprovision a table (or entire scope) after schema changes?

    - by Rabbi
    I have already setup syncing with Microsoft Sync Framework, and now I need to add fields to a table. How do I re-provision the databases? The setup is exceedingly simple: Two SQL Express 2008 servers The scope includes the entire database Using Microsoft Sync Framework 2.0 Synchronizing by direct access. Using the standard new SqlSyncProvider Do I make the structural changes at both ends? Or do I only change one server and let Sync Framework somehow propagate the change? Do I need to delete the _tracking tables and/or the stored procedures? How about the triggers? Has anyone been using the Sync Framework? Please help.

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  • How can I fix this touch event / draw loop "deadlock"?

    - by Josh
    Just want to start out by saying this seems like a great site, hope you guys can help! I'm trying to use the structure laid out in LunarLander to create a simple game in which the user can drag some bitmaps around on the screen (the actual game is more complex, but that's not important). I ripped out the irrelevant parts of LanderLander, and set up my own bitmap drawing, something like BoardThread (an inner class of BoardView): run() { while(mRun) { canvas = lockSurfaceHolder... syncronized(mSurfaceHolder) { /* drawStuff using member position fields in BoardView */ } unlockSurfaceHolder } } My drawStuff simply walks through some arrays and throws bitmaps onto the canvas. All that works fine. Then I wanted to start handling touch events so that when the user presses a bitmap, it is selected, when the user unpresses a bitmap, it is deselected, and if a bitmap is selected during a touch move event, the bitmap is dragged. I did this stuff by listening for touch events in the BoardView's parent, BoardActivity, and passing them down into the BoardView. Something like In BoardView handleTouchEvent(MotionEvent e) { synchronized(mSurfaceHolder) { /* Modify shared member fields in BoardView so BoardThread can render the bitmaps */ } } This ALSO works fine. I can drag my tiles around the screen no problem. However, every once in a while, when the app first starts up and I trigger my first touch event, the handleTouchEvent stops executing at the synchronized line (as viewed in DDMS). The drawing loop is active during this time (I can tell because a timer changes onscreen), and it usually takes several seconds or more before a bunch of touch events come through the pipeline and everything is fine again. This doesn't seem like deadlock to me, since the draw loop is constantly going in and out of its syncronized block. Shouldn't this allow the event handling thread to grab a lock on mSurfaceHolder? What's going on here? Anyone have suggestions for improving how I've structured this? Some other info. This "hang" only ever occurs on first touch event after activity start. This includes on orientation change after restoreState has been called. Also, I can remove EVERYTHING within the syncronized block in the event handler, and it will still get hung up at the syncronized call. Thanks!

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  • Are C++ Reads and Writes of an int atomic

    - by theschmitzer
    I have two threads, one updating an int and one reading it. This value is a statistic where the order of the read and write is irrelevant. My question is, do I need to synchronize access to this multi-byte value anyway? Or, put another way, can part of the write be complete and get interrupted, and then the read happen. For example, think of value = ox0000FFFF increment value to 0x00010000 Is there a time where the value looks like 0x0001FFFF that I should be worried about? Certainly the larger the type, the more possible something like this is I've always synchronized these types of accesses, but was curious what the community thought.

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  • Cloud sync between iPad/iPhone app

    - by Macatomy
    I have a Core Data app that will end up being an iPhone/iPad universal application. I would like to implement cloud syncing so that an iPhone and an iPad both running the app could share data. I'm planning to use the recently released Dropbox API. Does anyone have any thoughts on the best way to go about doing this? The Dropbox API allows for apps to store files on the cloud. What I was thinking was to original store the database (sqlite) for the app on the cloud and then download that database, but I then realized that using that method would make it painfully difficult to merge changes (rather than replacing the whole database). Any thoughts are appreciated. Thanks.

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  • Why is JSON outputting out of order?

    - by dcp3450
    I'm am trying to get a list of weather information for 8 locations. I'm using a weather API that accepts longitude and latitude and spits back json output with the weather info for that location. I feed the coords in order 0-7 but when json processes the data it comes back in a seemingly random order. I assume it's because some process faster than others and json is outputing what it gets back as it gets it. The output is correct, only the order is wrong. var loc = null; var body = ""; var campuses = new Array(8); campuses[0] = "34.47242,-84.42489,1"; campuses[1] = "33.81488,-84.62048,2"; campuses[2] = "34.27502,-84.46976,3"; campuses[3] = "33.92987,-84.55065,4"; campuses[4] = "34.03433,-84.46723,5"; campuses[5] = "34.08362,-84.67115,6"; campuses[6] = "33.91124,-84.82634,7"; campuses[7] = "34.10409,-84.51804,8"; function getWeather(campusArray) { body += '<p class="topTitle">Campus Weather</p>'; var cSplit = new Array(); cSplit = campusArray.split(','); var loc = "http://www.worldweatheronline.com/feed/weather.ashx?q="+cSplit[0]+","+cSplit[1]+"&format=json&num_of_days=2&key=0a05fff921162948110401&callback=?"; $('#content').html('asdf'); $.getJSON(loc,function(js) { var data = js.data; var humidity = data.current_condition[0].humidity; var tempF = data.current_condition[0].temp_F; var iconDESC = data.current_condition[0].weatherDesc[0].value; var iconURL = data.current_condition[0].weatherIconUrl[0].value; var windDir = data.current_condition[0].winddir16Point; var windSpeed = data.current_condition[0].windspeedMiles; var tempMaxF = data.weather[0].tempMaxF; var tempMinF = data.weather[0].tempMinF; body += '<p class="title">'+cSplit[2]+'</p>'+ '<span class="body">'+tempF+ ' '+windSpeed+ '<img src="'+iconURL+'" /></span>'; $('#content').html(body); }); } getWeather(campuses[0]); getWeather(campuses[1]); getWeather(campuses[2]); getWeather(campuses[3]); getWeather(campuses[4]); getWeather(campuses[5]); getWeather(campuses[6]); getWeather(campuses[7]); I have also tried it as $.ajax var loc = null; var body = ""; var campuses = new Array(8); campuses[0] = "34.47242,-84.42489,1"; campuses[1] = "33.81488,-84.62048,2"; campuses[2] = "34.27502,-84.46976,3"; campuses[3] = "33.92987,-84.55065,4"; campuses[4] = "34.03433,-84.46723,5"; campuses[5] = "34.08362,-84.67115,6"; campuses[6] = "33.91124,-84.82634,7"; campuses[7] = "34.10409,-84.51804,8"; function getWeather(campusArray) { body += '<p class="topTitle">Campus Weather</p>'; var cSplit = new Array(); cSplit = campusArray.split(','); var loc = "http://www.worldweatheronline.com/feed/weather.ashx?q="+cSplit[0]+","+cSplit[1]+"&format=json&num_of_days=2&key=0a05fff921162948110401&callback=?"; $.ajax({ url: loc, async: true, dataType: "json", success: function(js) { var data = js.data; var humidity = data.current_condition[0].humidity; var tempF = data.current_condition[0].temp_F; var iconDESC = data.current_condition[0].weatherDesc[0].value; var iconURL = data.current_condition[0].weatherIconUrl[0].value; var windDir = data.current_condition[0].winddir16Point; var windSpeed = data.current_condition[0].windspeedMiles; var tempMaxF = data.weather[0].tempMaxF; var tempMinF = data.weather[0].tempMinF; body += '<p class="title">'+cSplit[2]+'</p>'+ '<span class="body">'+tempF+ ' '+windSpeed+ '<img src="'+iconURL+'" /></span>'; $('#content').html(body); } }); } getWeather(campuses[0]); getWeather(campuses[1]); getWeather(campuses[2]); getWeather(campuses[3]); getWeather(campuses[4]); getWeather(campuses[5]); getWeather(campuses[6]); getWeather(campuses[7]); EDIT: example of json output: { "data": { "current_condition": [ {"cloudcover": "100", "humidity": "93", "observation_time": "04:04 PM", "precipMM": "0.0", "pressure": "1009", "temp_C": "2", "temp_F": "36", "visibility": "8", "weatherCode": "116", "weatherDesc": [ {"value": "Mist" } ], "weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0006_mist.png" } ], "winddir16Point": "WNW", "winddirDegree": "290", "windspeedKmph": "7", "windspeedMiles": "4" } ], "request": [ {"query": "Lat 34.47 and Lon -84.42", "type": "LatLon" } ], "weather": [ {"date": "2011-01-06", "precipMM": "9.3", "tempMaxC": "7", "tempMaxF": "45", "tempMinC": "2", "tempMinF": "35", "weatherCode": "113", "weatherDesc": [ {"value": "Sunny" } ], "weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0001_sunny.png" } ], "winddir16Point": "WNW", "winddirDegree": "293", "winddirection": "WNW", "windspeedKmph": "20", "windspeedMiles": "13" }, {"date": "2011-01-07", "precipMM": "0.0", "tempMaxC": "6", "tempMaxF": "44", "tempMinC": "0", "tempMinF": "31", "weatherCode": "116", "weatherDesc": [ {"value": "Partly Cloudy" } ], "weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0002_sunny_intervals.png" } ], "winddir16Point": "WNW", "winddirDegree": "286", "winddirection": "WNW", "windspeedKmph": "25", "windspeedMiles": "16" } ] }}

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  • Writing a synchronized thread-safety wrapper for NavigableMap

    - by polygenelubricants
    java.util.Collections currently provide the following utility methods for creating synchronized wrapper for various collection interfaces: synchronizedCollection(Collection<T> c) synchronizedList(List<T> list) synchronizedMap(Map<K,V> m) synchronizedSet(Set<T> s) synchronizedSortedMap(SortedMap<K,V> m) synchronizedSortedSet(SortedSet<T> s) Analogously, it also has 6 unmodifiedXXX overloads. The glaring omission here are the utility methods for NavigableMap<K,V>. It's true that it extends SortedMap, but so does SortedSet extends Set, and Set extends Collection, and Collections have dedicated utility methods for SortedSet and Set. Presumably NavigableMap is a useful abstraction, or else it wouldn't have been there in the first place, and yet there are no utility methods for it. So the questions are: Is there a specific reason why Collections doesn't provide utility methods for NavigableMap? How would you write your own synchronized wrapper for NavigableMap? Glancing at the source code for OpenJDK version of Collections.java seems to suggest that this is just a "mechanical" process Is it true that in general you can add synchronized thread-safetiness feature like this? If it's such a mechanical process, can it be automated? (Eclipse plug-in, etc) Is this code repetition necessary, or could it have been avoided by a different OOP design pattern?

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  • Syncing Data to Remote Services, Best Practices for Caching?

    - by viatropos
    I want to be able to publish events to Eventbrite, Eventful, and Google Calendar for my Google Apps. Each service has slightly different properties for events... I will be syncing many other things too, such as users with Google Contacts and MailChimp, Documents with Google Docs and some other services, etc... So I'm wondering, what is the recommended way of retrieving the data for the end user so that it's reasonably maintainable and optimized? Here are the things I'm thinking that I'm having trouble with: My App keeps a central database of all the models (Event, Document, User, Form, etc.), and whenever Admin creates an object (e.g. create through Eventbrite or through our Admin panel), we sync them and store a copy in our local database. When User goes to the site /events, App retrieves the events from the database. Read Events from a target feed, such as the Eventbrite or Eventful feed, and scrap the local database. Basically, I'm wondering, if we're storing all of the data on a remote service, do we really need to have a local database copy of the data? When would we need to have a local database, when wouldn't we?

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  • Storing data locally and synchronizing it with data base on linux server

    - by Miraaj
    Hi all, I have developed a mac application, which is continuously interacting with database on linux server. As data is increasing it has become costlier affair in terms of time to fetch data from server. So I am planning to store required data locally, say on mysqlite and find some mechanism through which I can synchronize it with database on linux server. Can anyone suggest me some way to accomplish it? Thanks, Miraaj

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  • Develop a custom file sync provider over file transfer WCF service

    - by user336622
    Hi All I'm trying to develop a custom sync provider to sync files over the internet using WCF service. We already have a file transfer service and it's working in production but I need to implement a custom sync provider on top of it. I've checked the solution in Braynt Likes blog here but this doesn't fulfill my needs. Any advices, guidance, or sample code to help is really appreciated?

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  • Open source framework à la Microsoft Sync Framework suggestions?

    - by drskol
    We are implementing a warehouse management system atop an open source stack (Java, web services & friends). In this system, we want to integrate many mobile devices which should also be capable of adequate online/offline functionality, e.g. preparing database inserts while a mobile device is temporarily unconnected, and performing them on the backend database when reconnected. For a .NET stack, Microsoft Sync Framework would be a perfect solution, e.g. to do database replication and hoarding. Can anyone suggest an open source alternative to the MS Sync Framework and possibly describe his experiences with it? Thanks in advance for any answers.

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  • Callers block until getFoo() has a value ready?

    - by Sean Owen
    I have a Java Thread which exposes a property which other threads want to access: class MyThread extends Thread { private Foo foo; ... Foo getFoo() { return foo; } ... public void run() { ... foo = makeTheFoo(); ... } } The problem is that it takes some short time from the time this runs until foo is available. Callers may call getFoo() before this and get a null. I'd rather they simply block, wait, and get the value once initialization has occurred. (foo is never changed afterwards.) It will be a matter of milliseconds until it's ready, so I'm comfortable with this approach. Now, I can make this happen with wait() and notifyAll() and there's a 95% chance I'll do it right. But I'm wondering how you all would do it; is there a primitive in java.util.concurrent that would do this, that I've missed? Or, how would you structure it? Yes, make foo volatile. Yes, synchronize on an internal lock Object and put the check in a while loop until it's not null. Am I missing anything?

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  • .NET platform independant sync framework

    - by Quandary
    Question: I need to synchronize a few ActionScript files from my computer to a network share (backup). I saw a quick fix would be using Microsoft Sync Framework for this, and write a windows service. My problem is I also use Linux, and before I start with MS vendor lockin, is there any sync framework/library/whatever I could use that works accross platform? Or does the MS sync framework work on Linux, too? It is my understanding that it is a wrapper around some com objects, thus it wouldn't work. All I need is synchronizing files. So never mind the database part, although it would be nice to have it, too.

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