learn.md Learn ===== TaskParallelLibrary --------------------- IfyouarenewtotheTaskParallelLibrary,pleaseseethisoverviewbySachaBarberon[CodeProject](http://www.codeproject.com/Articles/152765/Task-Parallel-Library-1-of-n) orthereferencedocumentationon[MSDN](http://msdn.microsoft.com/en-us/library/dd537609(v=vs.100).aspx). APIReference ------------- The[ConcurrencyKitAPIReference](http://spicypixel.com/developer/concurrency-kit/api-reference/)isagoodplacetostartifyouwanttoseewhatisinthelibraryandlearnmoreabouthowfibersandcoroutinesaresupported. Tasksvs.UnityCoroutines -------------------------- Unityhas[built-insupport](http://unity3d.com/support/documentation/ScriptReference/index.Coroutines_26_Yield.html)forcoroutinesandsoyoumaybewonderinghowtasksaredifferent.Thissectioncallsoutafewkeydistinctions. ###DeclarationandExecution StartingacoroutineinUnityrequiresonetodefineanexplicitmethodfortheroutineandtheninitiateitwith[MonoBehaviour.StartCoroutine](http://unity3d.com/support/documentation/ScriptReference/MonoBehaviour.StartCoroutine.html). ```{.cs} usingUnityEngine; usingSystem.Collections; publicclassexample:MonoBehaviour{ voidStart(){ print("Starting"+Time.time); StartCoroutine(WaitAndPrint(2.0F)); print("BeforeWaitAndPrintFinishes"+Time.time); } IEnumeratorWaitAndPrint(floatwaitTime){ yieldreturnnewWaitForSeconds(waitTime); print("WaitAndPrint"+Time.time); } } ``` NotehowtheWaitAndPrintmethodrequiresthespecialIEnumeratorreturntype,thesignatureofallcoroutines.Usingtasks,thesameexamplecouldbewrittenasfollows. ```{.cs} usingUnityEngine; usingSystem.Collections; publicclassexample:ConcurrentBehaviour{ voidStart(){ print("Starting"+Time.time); taskFactory.StartNew(WaitAndPrint(2.0F)); print("BeforeWaitAndPrintFinishes"+Time.time); } IEnumeratorWaitAndPrint(floatwaitTime){ yieldreturnnewWaitForSeconds(waitTime); print("WaitAndPrint"+Time.time); } } ``` Asyoucansee,onlyaminimalchangeisrequiredtouseanexistingcoroutineasataskwiththeConcurrencyKit.But,thesearesomeofthebenefitsyougetwhendoingso.BecausetheTaskFactory.StartNewmethodreturnsaTaskyoucan: *Waitfromanyotherthreadforthetasktocompleteusing[Task.Wait](http://msdn.microsoft.com/en-us/library/dd235635.aspx) *Continueexecutionbasedonmultipletasksusing[Task.WaitAny](http://msdn.microsoft.com/en-us/library/dd270672)or[Task.WaitAll](http://msdn.microsoft.com/en-us/library/dd270695) *Checkboththe[completionstatus](http://msdn.microsoft.com/en-us/library/system.threading.tasks.taskstatus.aspx)andthe[result](http://msdn.microsoft.com/en-us/library/dd321405)ofatask Additionally,youcanpassina[CancellationToken](http://msdn.microsoft.com/en-us/library/system.threading.cancellationtoken.aspx)inordertocancelaspecificinstanceofanexecutingtaskoragroupofexecutingtasks.Unityonlysupportsstoppingallinstancesofacoroutineusing[MonoBehaviour.StopCoroutine](http://unity3d.com/support/documentation/ScriptReference/MonoBehaviour.StopCoroutine.html)or[MonoBehaviour.StopAllCoroutines](http://unity3d.com/support/documentation/ScriptReference/MonoBehaviour.StopAllCoroutines.html) whichinsomecircumstancesisn'tfinegrainedenough. ###AnonymousMethods Sometimesitismoreconvenienttowriteaworkflowusinganonymousmethodsinsteadofdeclaringacoroutine,especiallyforsimplepropertychanges.Hereisthesameexamplerewrittentouseananonymousmethodinsteadofanexplicitlydeclaredone. ```{.cs} usingUnityEngine; usingSystem.Collections; publicclassexample:ConcurrentBehaviour{ voidStart(){ print("Starting"+Time.time); taskFactory.StartNew(newYieldForSeconds(2.0F)). ContinueWith(lastTask=>print("WaitAndPrint"+Time.time), taskScheduler); print("BeforeWaitAndPrintFinishes"+Time.time); } } ``` Tasksalsoallowinvocationofstandardmethodsandfunctionsthatdon'thavean**IEnumerator**returntypesuchasthe**print**methodabove. ###Portability Unitycoroutinesallowonetowriteasynchronouscode,butthatcodeisnotportableoutsideoftheUnityframeworkbecauseofthedependencyontheUnitycoroutinescheduler.IfyouarewritingorusingalibrarythatneedstooperateinaUnityenvironmentbutalsoinanexternalenvironmentsuchasfortools,framework,orcross-platformdevelopment,theTaskParallelLibraryisthestandardwaytoexposeasynchronousbehaviorinyourpublicinterface. AdvancedUses ------------- Tasksmakeiteasytorunfunctionsonanotherthreadandtorunlogicinparallel.Herearesomeofthemoreadvancedthingsyoucandowiththem: ***AI:**Performpathorplanningsearchesinparallelandselecteitherthefirsttocompleteorthebestfrommultipleoptionswhenallsearchescomplete ***AI:**Runhigh-levelagentbehaviorsacrossmultiplethreadsandoptionallyatadifferentfrequencythantheUnityrunloopformorecontroloverscalability ***Physics: **Calculatemultipleballistictrajectoriestozeroinonasolution ***Networking:**Streammultipleassetsinparallelfromaremotesite ***Networking:**AsynchronouslycoordinateacomplexsequenceofeventssuchasNATtypediscovery,matchmakingonamasterserver,connectionmanagement,fallbacks,andtimeouthandling OnecaveattoworkingwithmultiplethreadsandUnityisthatmuchlikeworkingwithaUIframework,allaccesstoUnityobjectsmustbemadefromthemainUnitythread.Thismakesitnecessarytoadoptamulti-threadedarchitecturelikeaproducer/consumermodelinordertosafelyrunoperationsinparallelandaccessormarshalgamestateacrossthreads.