Unity主线程和子线程跳转调用（1）

　　Unity除了一些基本的数据类型，几乎所有的API都不能在非unity线程中调用，如果项目中有一段很耗时操作，unity可能会出现“假死”。如果这段操作是和unity无关的，我们可以把这个耗时的操作放到子线程中去运行，防止unity假死提高性能，如下面这个伪代码

Function
{
    //这个函数会进行大量文件读写操作
    LoadLocalFile();

    //这个函数是unity函数
    UnityFunction();
}

　　必须保证LoadLocalFile() 不“假死”。怎么做呢？只要把Function放到多线程中，UnityFunction()回到主线程即可

　　网上的做法一般都是借鉴Loom，摘录一个脚本

  1 using UnityEngine;
  2 using System.Collections;
  3 using System.Collections.Generic;
  4 using System;
  5 using System.Threading;
  6 using System.Linq;
  7 
  8     public class Loom :MonoBehaviour
  9     {
 10         public static int maxThreads = 8;
 11         static int numThreads;
 12 
 13         private static Loom _current;
 14         //private int _count;
 15         public static Loom Current
 16         {
 17             get
 18             {
 19                 Initialize();
 20                 return _current;
 21             }
 22         }
 23 
 24         void Awake()
 25         {
 26             _current = this;
 27             initialized = true;
 28         }
 29 
 30         static bool initialized;
 31 
 32         public static void Initialize()
 33         {
 34             if (!initialized)
 35             {
 36 
 37                 if (!Application.isPlaying)
 38                     return;
 39                 initialized = true;
 40                 var g = new GameObject("Loom");
 41                 _current = g.AddComponent<Loom>();
 42 #if !ARTIST_BUILD
 43                 UnityEngine.Object.DontDestroyOnLoad(g);
 44 #endif
 45             }
 46 
 47         }
 48         public struct NoDelayedQueueItem
 49         {
 50             public Action<object> action;
 51             public object param;
 52         }
 53 
 54         private List<NoDelayedQueueItem> _actions = new List<NoDelayedQueueItem>();
 55         public struct DelayedQueueItem
 56         {
 57             public float time;
 58             public Action<object> action;
 59             public object param;
 60         }
 61         private List<DelayedQueueItem> _delayed = new List<DelayedQueueItem>();
 62 
 63         List<DelayedQueueItem> _currentDelayed = new List<DelayedQueueItem>();
 64 
 65         public static void QueueOnMainThread(Action<object> taction, object tparam)
 66         {
 67             QueueOnMainThread(taction, tparam, 0f);
 68         }
 69         public static void QueueOnMainThread(Action<object> taction, object tparam, float time)
 70         {
 71             if (time != 0)
 72             {
 73                 lock (Current._delayed)
 74                 {
 75                     Current._delayed.Add(new DelayedQueueItem { time = Time.time + time, action = taction, param = tparam });
 76                 }
 77             }
 78             else
 79             {
 80                 lock (Current._actions)
 81                 {
 82                     Current._actions.Add(new NoDelayedQueueItem { action = taction, param = tparam });
 83                 }
 84             }
 85         }
 86 
 87         public static Thread RunAsync(Action a)
 88         {
 89             Initialize();
 90             while (numThreads >= maxThreads)
 91             {
 92                 Thread.Sleep(100);
 93             }
 94             Interlocked.Increment(ref numThreads);
 95             ThreadPool.QueueUserWorkItem(RunAction, a);
 96             return null;
 97         }
 98 
 99         private static void RunAction(object action)
100         {
101             try
102             {
103                 ((Action)action)();
104             }
105             catch
106             {
107             }
108             finally
109             {
110                 Interlocked.Decrement(ref numThreads);
111             }
112 
113         }
114 
115 
116         void OnDisable()
117         {
118             if (_current == this)
119             {
120 
121                 _current = null;
122             }
123         }
124 
125 
126 
127         // Use this for initialization
128         void Start()
129         {
130 
131         }
132 
133         List<NoDelayedQueueItem> _currentActions = new List<NoDelayedQueueItem>();
134 
135         // Update is called once per frame
136         void Update()
137         {
138             if (_actions.Count > 0)
139             {
140                 lock (_actions)
141                 {
142                     _currentActions.Clear();
143                     _currentActions.AddRange(_actions);
144                     _actions.Clear();
145                 }
146                 for (int i = 0; i < _currentActions.Count; i++)
147                 {
148                     _currentActions[i].action(_currentActions[i].param);
149                 }
150             }
151 
152             if (_delayed.Count > 0)
153             {
154                 lock (_delayed)
155                 {
156                     _currentDelayed.Clear();
157                     _currentDelayed.AddRange(_delayed.Where(d => d.time <= Time.time));
158                     for (int i = 0; i < _currentDelayed.Count; i++)
159                     {
160                         _delayed.Remove(_currentDelayed[i]);
161                     }
162                 }
163 
164                 for (int i = 0; i < _currentDelayed.Count; i++)
165                 {
166                     _currentDelayed[i].action(_currentDelayed[i].param);
167                 }
168             }
169         }
170     }

使用方式

Function
{
//异步在多线程下运行
Loom.RunAsync(() =>
    {
        //这个函数会进行大量文件读写操作
        LoadLocalFile();

        //回到unity线程继续运行
        Loom.QueueOnMainThread(()=>
        {    
            //这个函数是unity函数
            UnityFunction();
        }
    }
}

这个Loom类的大概思路就是把整个代码块放多线程中，并把需要在主线程运行的代码按委托的方式封装起来保存的list里，Updata函数是unity函数，他会自动每帧执行一次。所以他可以判断list是否有任务并执行任务，从而实现了回到主线程