Windows 8 Store Apps Learning (48) multi-line threads other auxiliary classes

Multi-line Threads other Auxiliary classes: SpinWait, Spinlock, Volatile, SynchronizationContext, Coredispatcher, ThreadLocal, ThreadStaticAttribute

Introduced

Re-imagine other auxiliary classes for multiple threading operations in Windows 8 Store Apps

SpinWait-Spin Wait

Spinlock-Spin Lock

Volatile-must be in memory

SynchronizationContext-Synchronizes data on a specified thread

Coredispatcher-Scheduler, for thread synchronization

ThreadLocal-for saving each thread's own data

ThreadStaticAttribute-The static variable specified is unique to each thread

Example

1. Demonstrate the use of spinwait

Thread/other/spinwaitdemo.xaml.cs

/ *
 * SpinWait-Spin wait, a low-level synchronization type. It will not give up any CPU time, but let the CPU wait in a loop
 *
 * Applicable scenarios: multi-core cpu, the expected waiting time is very short (a few microseconds)
 * This example is only used to describe the usage of SpinWait, and does not represent the applicable scenario
 * /
    
using System;
using System.Threading;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;
    
namespace XamlDemo.Thread.Other
{
    public sealed partial class SpinWaitDemo: Page
    {
        public SpinWaitDemo ()
        {
            this.InitializeComponent ();
        }
    
        protected override void OnNavigatedTo (NavigationEventArgs e)
        {
            lblMsg.Text = DateTime.Now.ToString ("mm: ss.fff");
    
            SpinWait.SpinUntil (
                () => // End the wait when the following conditions are met
                {
                    return false;
                }
                // If the specified condition has not been met after this timeout period has elapsed, the wait is forcibly ended
                , 1000);
    
            lblMsg.Text + = Environment.NewLine;
            lblMsg.Text + = DateTime.Now.ToString ("mm: ss.fff");
    
            SpinWait.SpinUntil (
                () => // End the wait when the following conditions are met
                {
                    return DateTime.Now.Second% 2 == 0;
                });
    
            lblMsg.Text + = Environment.NewLine;
            lblMsg.Text + = DateTime.Now.ToString ("mm: ss.fff");
        }
    }
}

2. Demonstrate the use of spinlock

Thread/other/spinlockdemo.xaml.cs

/ *
 * SpinLock-Spin lock, a low-level mutex. It will not give up any CPU time, but let the CPU wait indefinitely until the lock becomes available
 *
 * Applicable scenarios: multi-core cpu, the expected waiting time is very short (a few microseconds)
 * This example is only used to describe the usage of SpinLock, and does not represent the applicable scenario
 * /
    
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;
    
namespace XamlDemo.Thread.Other
{
    public sealed partial class SpinLockDemo: Page
    {
        private static int _count;
    
        public SpinLockDemo ()
        {
            this.InitializeComponent ();
        }
    
        protected async override void OnNavigatedTo (NavigationEventArgs e)
        {
            SpinLock spinLock = new SpinLock ();
    
            List <Task> tasks = new List <Task> ();
    
            // A total of 100 tasks are executed in parallel, and each task accumulates the same static variable 100000 times to simulate the scenario of concurrently accessing static variables
            for (int i = 0; i <100; i ++)
            {
                Task task = Task.Run (
                    () =>
                    {
                        bool lockTaken = false;
    
                        try
                        {
                            // IsHeld-whether the lock is currently occupied by any thread
                            // IsHeldByCurrentThread-whether the lock is occupied by the current thread
                            // To get the IsHeldByCurrentThread property, IsThreadOwnerTrackingEnabled must be true, which can be specified in the constructor, the default is true
    
                            // Enter the lock, lockTaken-whether the lock has been acquired
                            spinLock.Enter (ref lockTaken);
    
                            for (int j = 0; j <100000; j ++)
                            {
                                _count ++;
                            }
                        }
                        finally
                        {
                            // release the lock
                            if (lockTaken)
                                spinLock.Exit ();
                        }
                    });
    
                tasks.Add (task);
            }
    
            // wait for all tasks to complete
            await Task.WhenAll (tasks);
    
            lblMsg.Text = "count:" + _count.ToString ();
        }
    }
}