locking

We are using Xamarin to write C# code with SQLite for android and ios. However about how to use sqlite, I seem to have a conceptual misunderstanding: What are the best practices for SQLite on Android? According to the stackoverflow answer it says - one helper and one db connection. Use lock around it to make sure only one thread is accessing sqlite db at any time. My question is - if that is the case - what is the use for async? I tried to use async with synchronized code - and the code gave me compile errors rightfully to avoid deadlocks. Why can't I use the 'await' operator within the body

This problem crops up every now and then at work. Our build machine can have it's files accessed via a normal windows file share. If someone browses a folder remotely on the machine, and leaves the window open overnight, then the build fails (as it has done now). The explorer window left opened points at one of the sub folders in the source tree. The build deletes the source, and does a clean checkout before building. The delete is failing. Right now, I'd like to get the build to work. I'm logged in from home, and I'd rather not reboot the build machine. I'm unable to get hold of the person

I'm wondering if there are any downsides to locking over a collection such as a List<T> , HashSet<T> , or a Dictionary<TKey, TValue> rather than a simple object . Note: in the following examples, that is the only place where the locks occur, it's not being locked from multiple places, but the static method may be called from multiple threads. Also, the _dict is never accessed outside of the GetSomething method. My current code looks like this: private static readonly Dictionary<string, string> _dict = new Dictionary<string, string>(); public static string GetSomething(string key) { string

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I have multiple processes that can potentially insert duplicate rows into the database. These inserts do not happen very frequently (a few times every hour) so it is not performance critical. I've tried an exist check before doing the insert, like so: #Assume we're inserting a camera object, that's a valid SQLAlchemy ORM object that inherits from declarative_base... try : stmt = exists (). where ( Camera . id == camera_id ) exists_result = session . query ( Camera ). with_lockmode ( "update" ). filter ( stmt ). first () if exists

In Java, do ReentrantLock.lock() and ReetrantLock.unlock() use the same locking mechanism as synchronized() ? My guess is "No," but I'm hoping to be wrong. Example: Imagine that Thread 1 and Thread 2 both have access to: ReentrantLock lock = new ReentrantLock(); Thread 1 runs: synchronized (lock) { // blah } Thread 2 runs: lock.lock(); try { // blah } finally { lock.unlock(); } Assume Thread 1 reaches its part first, then Thread 2 before Thread 1 is finished: will Thread 2 wait for Thread 1 to leave the synchronized() block, or will it go ahead and run? No, Thread 2 can lock() even when Thread