synchronization

Laravel, sync() – how to sync an array and also pass additional pivot fields?

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In order to sync multiple models along with custom pivot data, you need this: $user->roles()->sync([ 1 => [‘expires’ => true], 2 => [‘expires’ => false], … ]); Ie. sync([ related_id => [‘pivot_field’ => value], … ]); edit Answering the comment: $speakers = (array) Input::get(‘speakers’); // related ids $pivotData = array_fill(0, count($speakers), [‘is_speaker’ => true]); $syncData … Read more

Java Synchronized Block for .class

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The snippet synchronized(X.class) uses the class instance as a monitor. As there is only one class instance (the object representing the class metadata at runtime) one thread can be in this block. With synchronized(this) the block is guarded by the instance. For every instance only one thread may enter the block. synchronized(X.class) is used to … Read more

fs.writeFile in a promise, asynchronous-synchronous stuff

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As of 2019… …the correct answer is to use async/await with the native fs promises module included in node. Upgrade to Node.js 10 or 11 (already supported by major cloud providers) and do this: const fs = require(‘fs’).promises; // This must run inside a function marked `async`: const file = await fs.readFile(‘filename.txt’, ‘utf8’); await fs.writeFile(‘filename.txt’, … Read more

How to synchronize a static variable among threads running different instances of a class in Java?

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There are several ways to synchronize access to a static variable. Use a synchronized static method. This synchronizes on the class object. public class Test { private static int count = 0; public static synchronized void incrementCount() { count++; } } Explicitly synchronize on the class object. public class Test { private static int count … Read more

Java Singleton and Synchronization

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Yes, it is necessary. There are several methods you can use to achieve thread safety with lazy initialization: Draconian synchronization: private static YourObject instance; public static synchronized YourObject getInstance() { if (instance == null) { instance = new YourObject(); } return instance; } This solution requires that every thread be synchronized when in reality only … Read more

How to wait until a predicate condition becomes true in JavaScript?

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Javascript is single threaded, hence the page blocking behaviour. You can use the deferred/promise approach suggested by others. The most basic way would be to use window.setTimeout. E.g. function checkFlag() { if(flag === false) { window.setTimeout(checkFlag, 100); /* this checks the flag every 100 milliseconds*/ } else { /* do something*/ } } checkFlag(); Here … Read more

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