array_view Class

2015-04-28

Represents an N-dimensional view over the data held in another container.

template <
   typename _Value_type,
   int _Rank = 1
>
class array_view : public _Array_view_base<_Rank, sizeof(_Value_type)/sizeof(int)>;

template <
   typename _Value_type,
   int _Rank
>
class array_view<const _Value_type, _Rank> : public _Array_view_base<_Rank, sizeof(_Value_type)/sizeof(int)>;

Parameters

_Value_type
The data type of the elements in the array_view object.
_Rank
The rank of the array_view object.

Members

Public Constructors

Name	Description
array_view::array_view Constructor	Initializes a new instance of the array_view class. There is no default constructor for array<T,N>. All constructors are restricted to run on the CPU only and cannot be executed on a Direct3D target.
array_view::~array_view Destructor	Destroys the array_view object.

Public Methods

Name	Description
array_view::copy_to Method	Copies the contents of the array_view object to the specified destination by calling copy(*this, dest).
array_view::data Method	Returns a pointer to the raw data of the array_view.
array_view::discard_data Method	Discards the current data underlying this view.
array_view::get_extent Method	Returns the extent object of the array_view object.
array_view::get_ref Method	Returns a reference to the indexed element.
array_view::get_source_accelerator_view Method	Returns the accelerator_view where the data source of the array_view is located.
array_view::refresh Method	Notifies the array_view object that its bound memory has been modified outside the array_view interface. A call to this method renders all cached information stale.
array_view::reinterpret_as Method	Returns a one-dimensional array that contains all the elements in the array_view object.
array_view::section Method	Returns a subsection of the array_view object that's at the specified origin and, optionally, that has the specified extent.
array_view::synchronize Method	Synchronizes any modifications made to the array_view object back to its source data.
array_view::synchronize_async Method	Asynchronously synchronizes any modifications made to the array_view object back to its source data.
array_view::synchronize_to Method	Synchronizes any modifications made to the array_view object to the specified accelerator_view.
array_view::synchronize_to_async Method	Asynchronously synchronizes any modifications made to the array_view object to the specified accelerator_view.
array_view::view_as Method	Produces an array_view object of a different rank using this array_view object’s data.

Public Operators

Name	Description
array_view::operator() Operator	Returns the value of the element that is specified by the parameter or parameters.
array_view::operator[] Operator	Returns the element that is specified by the parameters.
array_view::operator= Operator	Copies the contents of the specified array_view object into this one.

Public Constants

Name	Description
array_view::rank Constant	Stores the rank of the array_view object.

Data Members

Name	Description
array_view::extent Data Member	Gets the extent object that defines the shape of the array_view object.
array_view::source_accelerator_view Data Member	Gets the accelerator_view where the data source of the array_view is located
array_view::value_type Data Member	The value type of the array_view and the bound array.

Remarks

The array_view class represents a view into the data that is contained in an array object or a subsection of an array object.

You can access the array_view object where the source data is located (locally) or on a different accelerator or a coherence ___domain (remotely). When you access the object remotely, views are copied and cached as necessary. Except for the effects of automatic caching, array_view objects have a performance profile similar to that of array objects. There is a small performance penalty when you access the data through views.

There are three remote usage scenarios:

A view to a system memory pointer is passed by means of a parallel_for_each call to an accelerator and accessed on the accelerator.
A view to an array located on an accelerator is passed by means of a parallel_for_each call to another accelerator and is accessed there.
A view to an array located on an accelerator is accessed on the CPU.

In any one of these scenarios, the referenced views are copied by the runtime to the remote ___location and, if modified by the calls to the array_view object, are copied back to the local ___location. The runtime might optimize the process of copying changes back, might copy only changed elements, or might copy unchanged portions also. Overlapping array_view objects on one data source are not guaranteed to maintain referential integrity in a remote ___location.

You must synchronize any multithreaded access to the same data source.

The runtime makes the following guarantees regarding the caching of data in array_view objects:

All well-synchronized accesses to an array object and an array_view object on it in program order obey a serial happens-before relationship.
All well-synchronized accesses to overlapping array_view objects on the same accelerator on a single array object are aliased through the array object. They induce a total occurs-before relationship which obeys program order. There is no caching. If the array_view objects are executing on different accelerators, the order of access is undefined, creating a race condition.

When you create an array_view object using a pointer in system memory, you must change the view array_view object only through the array_view pointer. Alternatively, you must call refresh() on one of the array_view objects that are attached to the system pointer, if the underlying native memory is changed directly, instead of through the array_view object.

Either action notifies the array_view object that the underlying native memory is changed and that any copies that are located on an accelerator are outdated. If you follow these guidelines, the pointer-based views are identical to those provided to views of data-parallel arrays.

Inheritance Hierarchy

_Array_view_shape

_Array_view_base

array_view

Requirements

Header: amp.h

Namespace: Concurrency

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