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# dispatch_source_type_t

An identifier for the type of system object being monitored by a dispatch source.

```
typedef const struct dispatch_source_type_s * dispatch_source_type_t;
```

## Discussion

Constants of this type represent the class of low-level system object that is being monitored by the dispatch source. Constants of this type are passed as a parameter to [`dispatch_source_create`](/documentation/Dispatch/dispatch_source_create) and determine how the handle argument is interpreted (as a file descriptor, mach port, signal number, process identifier, etc.) and how the mask argument is interpreted.

## Topics

### Dispatch Source Types

[`DISPATCH_SOURCE_TYPE_TIMER`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_TIMER)

A type of dispatch source for monitoring a timer.

[`DISPATCH_SOURCE_TYPE_READ`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_READ)

A type of dispatch source for monitoring read operations on a file descriptor.

[`DISPATCH_SOURCE_TYPE_WRITE`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_WRITE)

A type of dispatch source for monitoring write operations on a file descriptor.

[`DISPATCH_SOURCE_TYPE_VNODE`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_VNODE)

A type of dispatch source for monitoring changes to a file system object.

[`DISPATCH_SOURCE_TYPE_SIGNAL`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_SIGNAL)

A type of dispatch source for monitoring signals.

[`DISPATCH_SOURCE_TYPE_PROC`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_PROC)

A type of dispatch source for monitoring a process.

[`DISPATCH_SOURCE_TYPE_MEMORYPRESSURE`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_MEMORYPRESSURE)

A type of dispatch source for monitoring memory pressure events.

[`DISPATCH_SOURCE_TYPE_MACH_SEND`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_MACH_SEND)

A type of dispatch source for monitoring a mach send port.

[`DISPATCH_SOURCE_TYPE_MACH_RECV`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_MACH_RECV)

A type of dispatch source for monitoring a mach receive port.

[`DISPATCH_SOURCE_TYPE_DATA_ADD`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_DATA_ADD)

A type of dispatch source for monitoring custom events involving the coalescing of data with an AND operator.

[`DISPATCH_SOURCE_TYPE_DATA_OR`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_DATA_OR)

A type of dispatch source for monitoring custom events involving the coalescing of data with an OR operator.


---

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