神马都是浮云，unity中自己写Coroutine协程源代码

孙广东 2014.7.19

无意之间看到了，Unity维基上的一篇文章， 是关于自己写协程的介绍。

认为非常好，这样能更好的了解到协程的执行机制等特性。还是不错的。

原文链接地址例如以下：

http://wiki.unity3d.com/index.php?title=CoroutineScheduler

项目地址: http://download.csdn.net/detail/u010019717/8912069

详细的内容例如以下：
一个简单的协同调度程序。

这个协同调度程序同意全然控制一套协同程序的执行机制。 阅读代码也将帮助您了解 协同怎样在幕后工作。了解协同程序怎样构建.Net 发电机的基础上构建，将同意您将协同支持加入到非Unity的项目。

协同能够yield等待 直到下次更新"yield;", 直到给定的数量的更新已通过 "yield anInt;", 直到给定的秒已通过 "yield aFloat;", 或者直到还有一个协程已完毕"yield scheduler.StartCoroutine(Coroutine());".StartCoroutine(Coroutine());"。

多个 调度 程序实例支持，而且能够非常实用。协同执行能够执行在一个全然不同的 调度程序实例下 (等待)。

不使用Unity的 YieldInstruction 类。由于我门不能訪问这个类所需的调度的内部数据。 语义学Semantics 是和Unity的调度程序略有不同。 比如，在 Unity 中假设你開始协同 它将对其第一次的 yield 马上执行，然而 在自己写的调度程序中，它将不会执行，直到下一次调用 UpdateAllCoroutines。 此功能同意在不论什么时候的不论什么代码開始启动一个协程。

同一时候确保启动协同程序仅仅能执行在特定的时间。

在同样的update协同程序执行之间不应该依赖 更新order。

为更深入地了解和学会很多其它关于 协同程序 怎样实现。

使用：

using UnityEngine;
using System.Collections;

/// <summary>
/// CoroutineSchedulerTest.cs
///
/// Port of the Javascript version from
/// http://www.unifycommunity.com/wiki/index.php?title=CoroutineScheduler ///
/// Linked list node type used by coroutine scheduler to track scheduling of coroutines.
///
/// BMBF Researchproject http://playfm.htw-berlin.de /// PlayFM - Serious Games für den IT-gestützten Wissenstransfer im Facility Management
///	Gefördert durch das bmb+f - Programm Forschung an Fachhochschulen profUntFH
///
///	<author>Frank.Otto@htw-berlin.de</author>
///
/// </summary>

public class testAPI : MonoBehaviour {
CoroutineScheduler scheduler;
CoroutineScheduler m_scheduler2;
string requestURL = "http://www.my-server.com/cgi-bin/screenshot.pl";

void Start () {
scheduler = new CoroutineScheduler ();
scheduler.StartCoroutine (MyCoroutine ());

m_scheduler2 = new CoroutineScheduler();
m_scheduler2.StartCoroutine(test());
}

IEnumerator MyCoroutine ()
{
Debug.Log ("MyCoroutine: Begin");
yield return 0;
// wait for next update
Debug.Log ("MyCoroutine: next update;" + Time.time);
yield return 2;
// wait for 2 updates, same as yield; yield;
Debug.Log ("MyCoroutine: After yield 2;" + Time.time);
yield return 3.5f;
// wait for 3.5 seconds
Debug.Log ("MyCoroutine: After 3.5 seconds;" + Time.time);
// you can also yield for a coroutine running on a completely different scheduler instance
yield return scheduler.StartCoroutine (WaitForMe ());
Debug.Log ("MyCoroutine: After WaitForMe() finished;" + Time.time);
}

IEnumerator WaitForMe ()
{
yield return 7.8f;
// wait for 7.8 seconds before finishing
}

// Update is called once per
void Update ()
{

scheduler.UpdateAllCoroutines (Time.frameCount, Time.time);
}

IEnumerator test()
{
// ...set up request

var www = new UnityEngine.WWW(requestURL);
yield return new UnityWWWYieldWrapper(www);

// ...loading complete do some stuff
}
}

CoroutineScheduler.cs

using System.Collections;
using UnityEngine;

/// <summary>
/// CoroutineScheduler.cs
///
/// Port of the Javascript version from
/// http://www.unifycommunity.com/wiki/index.php? 
title=CoroutineScheduler
///
/// Linked list node type used by coroutine scheduler to track scheduling of coroutines.
///
///
/// BMBF Researchproject http://playfm.htw-berlin.de /// PlayFM - Serious Games für den IT-gestützten Wissenstransfer im Facility Management
///	Gefördert durch das bmb+f - Programm Forschung an Fachhochschulen profUntFH
///
///	<author>Frank.Otto@htw-berlin.de</author>
///
///
/// A simple coroutine scheduler. Coroutines can yield until the next update
/// "yield;", until a given number of updates "yield anInt", until a given
/// amount of seconds "yield aFloat;", or until another coroutine has finished
/// "yield scheduler.StartCoroutine(Coroutine())".
///
/// Multiple scheduler instances are supported and can be very useful. A
/// coroutine running under one scheduler can yield (wait) for a coroutine
/// running under a completely different scheduler instance.
///
/// Unity's YieldInstruction classes are not used because I cannot
/// access their internal data needed for scheduling. Semantics are slightly
/// different from Unity's scheduler. For example, in Unity if you start a
/// coroutine it will run up to its first yield immediately, while in this
/// scheduler it will not run until the next time UpdateAllCoroutines is called.
/// This feature allows any code to start coroutines at any time, while
/// making sure the started coroutines only run at specific times.
///
/// You should not depend on update order between coroutines running on the same
/// update. For example, StartCoroutine(A), StartCoroutine(B), StartCoroutine(C)
/// where A, B, C => while(true) { print(A|B|C); yield; }, do not expect "ABC" or
/// "CBA" or any other specific ordering.
/// </summary>
public class CoroutineScheduler : MonoBehaviour
{

CoroutineNode first = null;
int currentFrame;
float currentTime;

/**
* Starts a coroutine, the coroutine does not run immediately but on the
* next call to UpdateAllCoroutines. The execution of a coroutine can
* be paused at any point using the yield statement. The yield return value
* specifies when the coroutine is resumed.
*/

public CoroutineNode StartCoroutine (IEnumerator fiber)
{
// if function does not have a yield, fiber will be null and we no-op
if (fiber == null) {
return null;
}
// create coroutine node and run until we reach first yield
CoroutineNode coroutine = new CoroutineNode (fiber);
AddCoroutine (coroutine);
return coroutine;
}

/**
* Stops all coroutines running on this behaviour. Use of this method is
* discouraged, think of a natural way for your coroutines to finish
* on their own instead of being forcefully stopped before they finish.
* If you need finer control over stopping coroutines you can use multiple
* schedulers.
*/
public void StopAllCoroutines ()
{
first = null;
}

/**
* Returns true if this scheduler has any coroutines. You can use this to
* check if all coroutines have finished or been stopped.
*/
public bool HasCoroutines ()
{
return first != null;
}

/**
* Runs all active coroutines until their next yield. Caller must provide
* the current frame and time. This allows for schedulers to run under
* frame and time regimes other than the Unity's main game loop.
*/
public void UpdateAllCoroutines(int frame, float time)
{
currentFrame = frame;
currentTime = time;
CoroutineNode coroutine = this.first;
while (coroutine != null)
{
// store listNext before coroutine finishes and is removed from the list
CoroutineNode listNext = coroutine.listNext;

if (coroutine.waitForFrame > 0 && frame >= coroutine.waitForFrame)
{
coroutine.waitForFrame = -1;
UpdateCoroutine(coroutine);
}
else if (coroutine.waitForTime > 0.0f && time >= coroutine.waitForTime)
{
coroutine.waitForTime = -1.0f;
UpdateCoroutine(coroutine);
}
else if (coroutine.waitForCoroutine != null && coroutine.waitForCoroutine.finished)
{
coroutine.waitForCoroutine = null;
UpdateCoroutine(coroutine);
}
else if (coroutine.waitForUnityObject != null && coroutine.waitForUnityObject.finished)//lonewolfwilliams
{
coroutine.waitForUnityObject = null;
UpdateCoroutine(coroutine);
}
else if (coroutine.waitForFrame == -1 && coroutine.waitForTime == -1.0f
&& coroutine.waitForCoroutine == null && coroutine.waitForUnityObject == null)
{
// initial update
UpdateCoroutine(coroutine);
}
coroutine = listNext;
}
}

/**
* Executes coroutine until next yield. If coroutine has finished, flags
* it as finished and removes it from scheduler list.
*/
private void UpdateCoroutine(CoroutineNode coroutine)
{
IEnumerator fiber = coroutine.fiber;
if (coroutine.fiber.MoveNext())
{
System.Object yieldCommand = fiber.Current == null ? (System.Object)1 : fiber.Current;

if (yieldCommand.GetType() == typeof(int))
{
coroutine.waitForFrame = (int)yieldCommand;
coroutine.waitForFrame += (int)currentFrame;
}
else if (yieldCommand.GetType() == typeof(float))
{
coroutine.waitForTime = (float)yieldCommand;
coroutine.waitForTime += (float)currentTime;
}
else if (yieldCommand.GetType() == typeof(CoroutineNode))
{
coroutine.waitForCoroutine = (CoroutineNode)yieldCommand;
}
else if (yieldCommand is IYieldWrapper) //lonewolfwilliams
{
coroutine.waitForUnityObject = yieldCommand as IYieldWrapper;
}
else
{
throw new System.ArgumentException("CoroutineScheduler: Unexpected coroutine yield type: " + yieldCommand.GetType());

//this is an alternative if you don't have access to the function passed to the couroutineScheduler - maybe it's
//precompiled in a dll for example - remember you will have to add a case every time you add a wrapper :/
/*
var commandType = yieldCommand.GetType();
if(commandType == typeof(UnityEngine.WWW))
{
coroutine.waitForUnityObject =
new UnityWWWWrapper(yieldCommand as UnityEngine.WWW);
}
else if(commandType == typeof(UnityEngine.AsyncOperation))
{
coroutine.waitForUnityObject =
new UnityASyncOpWrapper(yieldCommand as UnityEngine.AsyncOperation);
}
else if(commandType == typeof(UnityEngine.AssetBundleRequest))
{
coroutine.waitForUnityObject =
new UnityAssetBundleRequestWrapper(yieldCommand as UnityEngine.AssetBundleRequest);
}
else
{
throw new System.ArgumentException("CoroutineScheduler: Unexpected coroutine yield type: " + yieldCommand.GetType());
}
*/
}
}
else
{
// coroutine finished
coroutine.finished = true;
RemoveCoroutine(coroutine);
}
}

private void AddCoroutine (CoroutineNode coroutine)
{

if (this.first != null) {
coroutine.listNext = this.first;
first.listPrevious = coroutine;
}
first = coroutine;
}

private void RemoveCoroutine (CoroutineNode coroutine)
{
if (this.first == coroutine) {
// remove first
this.first = coroutine.listNext;
} else {
// not head of list
if (coroutine.listNext != null) {
// remove between
coroutine.listPrevious.listNext = coroutine.listNext;
coroutine.listNext.listPrevious = coroutine.listPrevious;
} else if (coroutine.listPrevious != null) {
// and listNext is null
coroutine.listPrevious.listNext = null;
// remove last
}
}
coroutine.listPrevious = null;
coroutine.listNext = null;
}

}//class

CoroutineNode.cs

using System.Collections;
using UnityEngine;

/// <summary>
/// CoroutineNode.cs
///
/// Port of the Javascript version from
/// http://www.unifycommunity.com/wiki/index.php?title=CoroutineScheduler ///
/// Linked list node type used by coroutine scheduler to track scheduling of coroutines.
///
/// BMBF Researchproject http://playfm.htw-berlin.de /// PlayFM - Serious Games für den IT-gestützten Wissenstransfer im Facility Management
///	Gefördert durch das bmb+f - Programm Forschung an Fachhochschulen profUntFH
///
///	<author>Frank.Otto@htw-berlin.de</author>
///
/// </summary>

public class CoroutineNode
{
public CoroutineNode listPrevious = null;
public CoroutineNode listNext = null;
public IEnumerator fiber;
public bool finished = false;
public int waitForFrame = -1;
public float waitForTime = -1.0f;
public CoroutineNode waitForCoroutine;
public IYieldWrapper waitForUnityObject; //lonewolfwilliams

public CoroutineNode(IEnumerator _fiber)
{
this.fiber = _fiber;
}
}

IYieldWrapper.cs

/*
* gareth williams
* http://www.lonewolfwilliams.com */

public interface IYieldWrapper
{
bool finished { get; }
}

Example Wrappers

Below are some examples of wrappers I have used, in fact they have almost identical signatures so a more generic implementation could probably be written ^_^

UnityASyncOpWrapper

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

/*
*   Gareth Williams
*   http://www.lonewolfwilliams.com */

class UnityASyncOpWrapper : IYieldWrapper
{
private UnityEngine.AsyncOperation m_UnityObject;
public bool finished
{
get
{
return m_UnityObject.isDone;
}
}

public UnityASyncOpWrapper(UnityEngine.AsyncOperation wraps)
{
m_UnityObject = wraps;
}
}

UnityWWWYieldWrapper

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

/*
* Gareth Williams
* http://www.lonewolfwilliams.com */

public class UnityWWWYieldWrapper : IYieldWrapper
{
private UnityEngine.WWW m_UnityObject;
public bool finished
{
get
{
return m_UnityObject.isDone;
}
}

public UnityWWWYieldWrapper(UnityEngine.WWW wraps)
{
m_UnityObject = wraps;
}
}