cancellation_token Class
The cancellation_token class represents the ability to determine whether some operation has been requested to cancel. A given token can be associated with a task_group, structured_task_group, or task to provide implicit cancellation. It can also be polled for cancellation or have a callback registered for if and when the associated cancellation_token_source is canceled.
Syntax
class cancellation_token;
Members
Public Constructors
| Name | Description |
|---|---|
| cancellation_token::cancellation_token Constructor | |
| cancellation_token::~cancellation_token Destructor |
Public Methods
| Name | Description |
|---|---|
| cancellation_token::deregister_callback Method | Removes a callback previously registered via the register method based on the cancellation_token_registration object returned at the time of registration. |
| cancellation_token::is_cancelable Method | Returns an indication of whether this token can be canceled or not. |
| cancellation_token::is_canceled Method | Returns true if the token has been canceled. |
| cancellation_token::none Method | Returns a cancellation token which can never be subject to cancellation. |
| cancellation_token::register_callback Method | Registers a callback function with the token. If and when the token is canceled, the callback will be made. Note that if the token is already canceled at the point where this method is called, the callback will be made immediately and synchronously. |
Public Operators
| Name | Description |
|---|---|
| cancellation_token::operator!= Operator | |
| cancellation_token::operator= Operator | |
| cancellation_token::operator== Operator |
Inheritance Hierarchy
cancellation_token
Requirements
Header: pplcancellation_token.h
Namespace: concurrency
cancellation_token::~cancellation_token Destructor
~cancellation_token();
cancellation_token::cancellation_token Constructor
cancellation_token(const cancellation_token& _Src);
cancellation_token(cancellation_token&& _Src);
Parameters
_Src
cancellation_token::deregister_callback Method
Removes a callback previously registered via the register method based on the cancellation_token_registration object returned at the time of registration.
void deregister_callback(const cancellation_token_registration& _Registration) const;
Parameters
_Registration
The cancellation_token_registration object corresponding to the callback to be deregistered. This token must have been previously returned from a call to the register method.
cancellation_token::is_cancelable Method
Returns an indication of whether this token can be canceled or not.
bool is_cancelable() const;
Return Value
An indication of whether this token can be canceled or not.
cancellation_token::is_canceled Method
Returns true if the token has been canceled.
bool is_canceled() const;
Return Value
The value true if the token has been canceled; otherwise, the value false.
cancellation_token::none Method
Returns a cancellation token which can never be subject to cancellation.
static cancellation_token none();
Return Value
A cancellation token that cannot be canceled.
cancellation_token::operator!= Operator
bool operator!= (const cancellation_token& _Src) const;
Parameters
_Src
Return Value
cancellation_token::operator= Operator
cancellation_token& operator= (const cancellation_token& _Src);
cancellation_token& operator= (cancellation_token&& _Src);
Parameters
_Src
Return Value
cancellation_token::operator== Operator
bool operator== (const cancellation_token& _Src) const;
Parameters
_Src
Return Value
cancellation_token::register_callback Method
Registers a callback function with the token. If and when the token is canceled, the callback will be made. Note that if the token is already canceled at the point where this method is called, the callback will be made immediately and synchronously.
template<typename _Function>
::Concurrency::cancellation_token_registration register_callback(const _Function& _Func) const;
Parameters
_Function
The type of the function object that will be called back when this cancellation_token is canceled.
_Func
The function object that will be called back when this cancellation_token is canceled.
Return Value
A cancellation_token_registration object which can be utilized in the deregister method to deregister a previously registered callback and prevent it from being made. The method will throw an invalid_operation exception if it is called on a cancellation_token object that was created using the cancellation_token::none method.