Till Wegmüller <******@****.***>
Tim <******@****.***>
Tim Bart <******@****.***>
Tim Bosse <******@****.***>
Tim Dettrick <******@****.***>
Tim Düsterhus <******@****.***>
Tim Hockin <thockin@google.com>
Tim Potter <******@****.***>
Tim Ruffles <******@****.***>
Tim Smith <******@****.***>
Tim Terhorst <******@****.***>
Tim Wagner <******@****.***>

Optimistic locking allows concurrent access to model records for edits and prevents conflicts from overwriting...

  realizations="true" associations="true" dependencies="false" nesting-relationships="true">  
  <class id="1" language="java" name="com.iluwatar.doublechecked.locking.Item" project="double-checked-locking" 
    file="/double-checked-locking/src/main/java/com/iluwatar/doublechecked/locking/Item.java" binary="false" 
    corner="BOTTOM_RIGHT">    
    <position height="124" width="205" x="146" y="504"/>    

const Support = require('../support');
const DataTypes = require('../../../lib/data-types');
const chai = require('chai');
const expect = chai.expect;

describe(Support.getTestDialectTeaser('Model'), () => {
  describe('optimistic locking', () => {
    let Account;
    beforeEach(async function () {
      Account = this.sequelize.define(
        'Account',
        {
          number: {
            type: DataTypes.INTEGER
          }
        },

double-checked-locking.png...

@startuml
package com.iluwatar.doublechecked.locking {
  class App {
    - LOGGER : Logger {static}
    + App()
    + main(args : String[]) {static}
  }
  class Inventory {
    - LOGGER : Logger {static}
    - inventorySize : int
    - items : List<Item>
    - lock : Lock
    + Inventory(inventorySize : int)
    + addItem(item : Item) : boolean
    + getItems() : List<Item>
  }
  class Item {
    + Item()
  }
}

double_checked_locking_1.png...

     * returned by this mock function call
     */
    results: Array<{isThrow: boolean, value: TReturn}>,
  },
  /**
   * Resets all information stored in the mockFn.mock.calls and
   * mockFn.mock.instances arrays. Often this is useful when you want to clean
   * up a mock's usage data between two assertions.
   */
  mockClear(): void,
  /**

layout: pattern
title: Double Checked Locking
folder: double-checked-locking
permalink: /patterns/double-checked-locking/
categories: Idiom
language: en
tags:
 - Performance
---

## Intent
Reduce the overhead of acquiring a lock by first testing the
locking criterion (the "lock hint") without actually acquiring the lock. Only
if the locking criterion check indicates that locking is required does the
actual locking logic proceed.

daysUntilLock: 365
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  activity. Please open a new issue for related bugs and link to relevant
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# exemptLabels:
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