synchronization

Synchronization on immutable objects (in java)

由 感情迁移 提交于 2019-11-28 08:37:40
问题 Code snippet - 1 class RequestObject implements Runnable { private static Integer nRequests = 0; @Override public void run() { synchronized (nRequests) { nRequests++; } } } Code snippet - 2 public class Racer implements Runnable { public static Boolean won = false; @Override public void run() { synchronized (won) { if (!won) won = true; } } } I was having a race condition with the first code snippet. I understood that this was because I was obtaining a lock on an immutable object(of type

Java. Serialization of objects in a multithreaded environment

由 扶醉桌前 提交于 2019-11-28 08:26:07
问题 I have an object whose internal mutable state is being constantly updated by one or more threads. The object is synchronized, and the goal is to periodically save its state (via serialization) from yet another thread: public class Counter implements Serializable { private int dogCount; private int catCount; public synchronized void updateFromDogThread( int count ) { dogCount = count; } public synchronized void updateFromCatThread( int count ) { catCount = count; } } Questions: Is

AtomicBoolean vs Synchronized block, whats the difference

由 南笙酒味 提交于 2019-11-28 08:13:07
问题 I am trying to understand the difference between the two following code blocks AtomicBoolean ab = new AtomicBoolean(false); using the following to get and set state. . ab.get(); ab.set(X); vs. private boolean ab = false; private final Object myboollock = new Ojbect(); public void setAB(boolean state) { synchronized(myboollock) { ab = state; } } public boolean getAB() { synchronized(myboollock) { return ab; } } I need to thread protect a boolean, that is all, and have in the past used the

How Copy SQLite database from Android to a MySQL database - Replicate - Sync [duplicate]

由 断了今生、忘了曾经 提交于 2019-11-28 07:52:48
This question already has an answer here: How to sync SQLite database on Android phone with MySQL database on server? 5 answers I am building an Android app which will take some data and images from user and store them in a local SQLite DB. What i am looking forward to is a way by which i can replicate this DB to a MySQL DB on my server. I looked on the Internet for the answer but there isn't a proper solution to it. Though the most common answers i found were SymmetricDB and Setting up a Webservice. I am still confused which route to take. The SQLite DB may also at need, have to pull updated

C# - how can I get owner's name for a Mutex

由 核能气质少年 提交于 2019-11-28 07:37:03
问题 I have a shared mutex between 2 applications. I want to create an administration console that shows the current owner's name of the mutex. How can I get the application name that currently owns the Mutex? 回答1: I do not believe this is possible at the user mode level. You will have to install a driver or kernel plugin in order to get this information. It's almost the same question as asking "what process opened this file"? 来源： https://stackoverflow.com/questions/541477/c-sharp-how-can-i-get

Is LocalStorage synchronization for Chrome extensions already available?

由 耗尽温柔 提交于 2019-11-28 07:10:58
问题 I found chromium issue titled "Allow extensions/apps to sync their own settings" that has status ' Fixed '. It's from December 2011. So, does it work? If so, how does it work and where are the docs? Last time similar question was asked in 2010 and then the answer was to use bookmarks hack. I think it's time to have an update on this topic. Update : I just found these docs for experimental chrome.storage API. Is this what I'm looking for? Do we have any new alternatives (other than bookmarks)

Explain synchronization of collections when iterators are used?

由 爱⌒轻易说出口 提交于 2019-11-28 06:53:03
I understand that collections like the Hashtable are synchronized, but can someone explain to me how it works, and at what point(s) access is restricted to concurrent calls? For example, let's say I use some iterators like this: Hashtable<Integer,Integer> map = new Hashtable<Integer,Integer>(); void dosomething1(){ for (Iterator<Map.Entry<Integer,Integer>> i = map.entrySet().iterator(); i.hasNext();){ // do something } } void dosomething2(){ for (Iterator<Map.Entry<Integer,Integer>> i = map.entrySet().iterator(); i.hasNext();){ // do something // and remove it i.remove(); } } void putsomething

How to set a variable that represents a time in the future in absolute terms Objective-C

由 你。 提交于 2019-11-28 06:43:42
问题 Motivation: I'm working on an app that makes several (client) phones read audio data from a (server) phone. The idea is that they must all play the song at the exact same time together. Premise: I must figure out a way to make all phones start at a certain time stamp that is absolute (ie it's not relative to the use set clock of either phone etc..).. based on some research I figured the best way to do this is to use CFAbsoluteTimeGetCurrent(); The idea here is that I get the latency it takes

Synchronizing searches and modifications

由 此生再无相见时 提交于 2019-11-28 06:30:58
问题 What's a good way of allowing searches from multiple threads on a list (or other data structure), but preventing searches on the list and edits to the list on different threads from interleaving? I tried using synchronized blocks in the searching and editing methods, but that can cause unnecessary blocking when trying to run searches in multiple threads. EDIT: The ReadWriteLock is exactly what I was looking for! Thanks. 回答1: Usually, yes ReadWriteLock is good enough. But, if you're using Java

Synchronization (of clocks) between two remote computers

由 陌路散爱 提交于 2019-11-28 05:59:56
I'm looking into writing a simple synchronization ability into my app and one of the concerns that has popped up is synchronization of time between two remote computers, each with their own clock (in particular concerning the modification dates of files/objects). I'm sure a lot of research has been done on this topic and don't want to get too theoretical, but I'm wondering if there are any accepted best practices for minimizing temporal discrepancies between remote clocks? For example, a start is to always use universal time (UTC) as that avoids timezone problems, but there is no guarantee
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