synchronization

问题 Okay now i am working on Angular 6 webApp and it is offline first. I am able to setup a fully functional service worker which can retrieve and store requests and response and what not. But, at one point , while registering a sync event, i needed refresh tokens which are stored in the local storage of my webApp. The problem is that service workers are not allowed to access local storage directly, means i don't have any access to the tokens residing in the local storage.How can i make use of

问题 While this question is about the MemoryCache class, I can imagine the same need with a Dictionary or ConcurrentDictionary.GetOrAdd where the valueFactory -lambda is also a lengthy operation. In essence I want to synchronize/lock threads on a per-item base. I know MemoryCache is thread safe, but still, checking if an item exists and add the item when it doesn't exist, still needs to be synchronized. Consider this sample code: public class MyCache { private static readonly MemoryCache cache =

问题 This question already has answers here : Does lock() guarantee acquired in order requested? (5 answers) Closed 6 years ago . I require a section of the code to be run by only one thread at time (single resource lock). the lock(object) statement in C# allows this. It doesn't however, preserve the order of requests to the lock. For example, consider the 100 threadstarts below where numbered threads try to lock on padlock in order: for (int i = 0; i < 100; i++) { (new Thread(delegate(object

问题 there was already a question whether threads can simultaneously safely read/iterate LinkeList. It seems the answer is yes as far as no-one structurally changes it (add/delete) from the linked list. Although one answer was warning about "unflushed cache" and advicing to know "java memory model". So I'm asking to elaborate those "evil" caches. I'm a newbie and so far I still naively believe that following code is ok (at least from my tests) public static class workerThread implements Runnable {

问题 I have a bug where my app wont pull icloud inforamtion on the first launch but it does on the subsequent tries. here is my code to load a file from icloud. void DLC::loadFromiCloud(std::string fileName){ NSURL *mUbiqUrl = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil]; if (mUbiqUrl) { std::string fullPath = getLibraryPath_iOS() + fileName; NSString* restorePath = [NSString stringWithUTF8String:(fullPath.c_str())]; NSError *error = nil; NSURL *fileToDownload = [mUbiqUrl

问题 Say, I have the following code: IPrincipal capturedPrincipal = Thread.CurrentPrincipal; myseq.AsParallel().Select(x => { Thread.CurrenctPrincipal = capturedPrincipal; /*call code protected with CAS*/ }); to be sure Thread.CurrenctPrincipal will be propagated to every thread where Select 's delegate will be executed on. I've realized that if I had proper SynchronizationContext set up this would happen automatically. So does PLINQ use SynchronizationContext when queuing work items on ThreadPool

问题 i am trying to concatenate 3 mp4 files into 1. This is the ffmpeg command im making: shell_exec('ffmpeg -f concat -i '.$random.'.txt -c:v libx264 -preset ultrafast -crf 30 -c:a copy '.$uploadfolder.$random.'.mp4 2>&1'); The 1st and 3rd files are entry and end graphic scenes, which have the above information: pinicial.mp4 ffprobe version N-76417-gee20354 Copyright (c) 2007-2015 the FFmpeg developers built with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5) configuration: --prefix=/home/dmarcos89

问题 This question is based on Synchronizing on an Integer value. The solution there seems excellent only there is small problem it does not address the concern how to delete values from ConcurrentHashMap . So to address that I did below program import java.util.concurrent.ConcurrentHashMap; public class Example { private final ConcurrentHashMap<Integer, Integer> concurrentHashMap = new ConcurrentHashMap<Integer, Integer>(); public void doSomething(int i) { synchronized (getLockForId(i)) {

问题 I have an application that works with timeout (let's say -> ring in 3 days ). My problem occurs if a user change the device local time while being offline because I am comparing two NSDate (the final date and today) to check that timeout. So I am trying to get notified when a user made a significant time change (several hours or days) in order to update my timers depending on the difference between before and after the update . I found the UIApplicationSignificantTimeChangeNotification ,

问题 If a synchronized block of code contains an unsynchronized collection. Is the collection considered thread safe? If not, can you provide any practical scenarios where two threads could unsafely access the collection within the synced code? Thanks. 回答1: Only if ALL the code that access the collection is synchronized and they use the same "object" to synchronize it. For example, the code below would not be synchronized because they are synced to different objects. public class Foo { private