98 lines
3.3 KiB
Markdown
98 lines
3.3 KiB
Markdown
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# Generic jobs
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While Burst supports generics, it has limited support for generic jobs or function pointers. If you notice that a job runs at full speed in the Editor but not in a built Player, the problem might be related to generic jobs.
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The following example defines a generic job:
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```c#
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// Direct generic job
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[BurstCompile]
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struct MyGenericJob<TData> : IJob where TData : struct {
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public void Execute() { ... }
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}
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```
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You can also nest generic jobs:
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```c#
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// Nested generic job
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public class MyGenericSystem<TData> where TData : struct {
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[BurstCompile]
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struct MyGenericJob : IJob {
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public void Execute() { ... }
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}
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public void Run()
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{
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var myJob = new MyGenericJob(); // implicitly MyGenericSystem<TData>.MyGenericJob
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myJob.Schedule();
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}
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}
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```
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Jobs that are Burst-compiled look like this:
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```c#
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// Direct Generic Job
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var myJob = new MyGenericJob<int>();
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myJob.Schedule();
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// Nested Generic Job
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var myJobSystem = new MyGenericSystem<float>();
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myJobSystem.Run();
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```
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In both cases, in a Player build, the Burst compiler detects that it has to compile `MyGenericJob<int>` and `MyGenericJob<float>`. This is because the generic jobs (or the type surrounding it for the nested job) are used with fully resolved generic arguments (`int` and `float`).
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However, if these jobs are used indirectly through a generic parameter, the Burst compiler can't detect the jobs it has to compile at Player build time:
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```c#
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public static void GenericJobSchedule<TData>() where TData: struct {
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// Generic argument: Generic Parameter TData
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// This Job won't be detected by the Burst Compiler at standalone-player build time.
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var job = new MyGenericJob<TData>();
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job.Schedule();
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}
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// The implicit MyGenericJob<int> will run at Editor time in full Burst speed
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// but won't be detected at standalone-player build time.
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GenericJobSchedule<int>();
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```
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The same restriction applies if you declare the job in the context of a generic parameter that comes from a type:
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```c#
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// Generic Parameter TData
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public class SuperJobSystem<TData>
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{
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// Generic argument: Generic Parameter TData
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// This Job won't be detected by the Burst Compiler at standalone-player build time.
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public MyGenericJob<TData> MyJob;
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}
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```
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If you want to use generic jobs, you must use them directly with fully resolved generic arguments (for example, `int`, `MyOtherStruct`). You can't use them with a generic parameter indirection (for example, `MyGenericJob<TContext>`).
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>[!IMPORTANT]
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>Burst doesn't support scheduling generic Jobs through generic methods.
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## Function pointers
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Function pointers are restricted because you can't use a generic delegate through a function pointer with Burst:
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```c#
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public delegate void MyGenericDelegate<T>(ref TData data) where TData: struct;
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var myGenericDelegate = new MyGenericDelegate<int>(MyIntDelegateImpl);
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// Will fail to compile this function pointer.
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var myGenericFunctionPointer = BurstCompiler.CompileFunctionPointer<MyGenericDelegate<int>>(myGenericDelegate);
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```
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This limitation is because of a limitation of the .NET runtime to interop with such delegates.
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For more information, refer to [Function pointers](csharp-function-pointers.md).
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## Additional resources
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* [Burst compilation in Play mode](compilation-synchronous.md)
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* [Job system](xref:um-job-system)
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