MADNESS  0.10.1
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madness::Future< T > Class Template Reference

A future is a possibly yet unevaluated value. More...

#include <future.h>

Classes

class  dddd
 

Public Types

typedef RemoteReference< FutureImpl< T > > remote_refT
 

Public Member Functions

 Future ()
 Makes an unassigned future. More...
 
 Future (const archive::BufferInputArchive &input_arch)
 Makes an assigned future from an input archive. More...
 
 Future (const Future< T > &other)
 Shallow copy constructor. More...
 
 Future (const remote_refT &remote_ref)
 Makes a future wrapping a remote reference. More...
 
 Future (const T &t)
 Makes an assigned future. More...
 
 ~Future ()
 Destructor. More...
 
Tget (bool dowork=true) &
 Gets the value, waiting if necessary. More...
 
T get (bool dowork=true) &&
 Gets the value, waiting if necessary. More...
 
const Tget (bool dowork=true) const &
 Gets the value, waiting if necessary. More...
 
bool is_default_initialized () const
 Check if the future is default initialized. More...
 
bool is_local () const
 Checks the future remoteness trait. More...
 
bool is_remote () const
 Checks the future remoteness trait. More...
 
 operator const T & () const &
 Same as get() const&. More...
 
 operator T () &&
 An rvalue analog of get(). More...
 
 operator T& () &
 Same as get()&. More...
 
Future< T > & operator= (const Future< T > &other)
 Shallow assignment operator. More...
 
bool probe () const
 Check whether this future has been assigned. More...
 
void register_callback (CallbackInterface *callback)
 Registers an object to be called when future is assigned. More...
 
remote_refT remote_ref (World &world) const
 Returns a structure used to pass references to another process. More...
 
void set (const archive::BufferInputArchive &input_arch)
 Assigns the value. More...
 
void set (const Future< T > &other)
 A.set(B), where A and B are futures ensures A has/will have the same value as B. More...
 
void set (const T &value)
 Assigns the value. More...
 
void set (T &&value)
 Assigns the value. More...
 

Static Public Member Functions

static const Future< Tdefault_initializer ()
 See "Gotchas" on Futures about why this exists and how to use it. More...
 

Private Member Functions

 Future (const dddd &blah)
 

Private Attributes

char buffer [sizeof(T)]
 Buffer to hold a single T object. More...
 
std::shared_ptr< FutureImpl< T > > f
 Pointer to the implementation object. More...
 
T *const value
 Pointer to buffer when it holds a T object. More...
 

Friends

std::ostream & operator (std::ostream &out, const Future< T > &f)
 

Detailed Description

template<typename T>
class madness::Future< T >

A future is a possibly yet unevaluated value.

Uses delegation to FutureImpl to provide desired copy/assignment semantics, as well as safe reference counting for remote futures.

Since we are using futures a lot to store local values coming from containers and inside task wrappers for messages, we included in this class a value. If a future is assigned before a copy/remote-reference is taken, the shared pointer is never made. The point of this is to eliminate the two mallocs that must be peformed for every new shared_ptr.

Template Parameters
TThe type of future.
Todo:
Can this detailed description be made clearer?

Member Typedef Documentation

◆ remote_refT

template<typename T >
typedef RemoteReference< FutureImpl<T> > madness::Future< T >::remote_refT
Todo:
Brief description needed.

Constructor & Destructor Documentation

◆ Future() [1/6]

template<typename T >
madness::Future< T >::Future ( const dddd blah)
inlineexplicitprivate
Todo:
Constructor for ...
Todo:
Description needed.
Parameters
[in]blahDescription needed.

◆ Future() [2/6]

template<typename T >
madness::Future< T >::Future ( )
inline

Makes an unassigned future.

◆ Future() [3/6]

template<typename T >
madness::Future< T >::Future ( const T t)
inlineexplicit

Makes an assigned future.

Todo:
Description needed.
Parameters
[in]tDescription needed.

◆ Future() [4/6]

template<typename T >
madness::Future< T >::Future ( const remote_refT remote_ref)
inlineexplicit

Makes a future wrapping a remote reference.

Parameters
[in]remote_refThe remote reference.

◆ Future() [5/6]

template<typename T >
madness::Future< T >::Future ( const archive::BufferInputArchive input_arch)
inlineexplicit

Makes an assigned future from an input archive.

Parameters
[in]input_archThe input archive.

◆ Future() [6/6]

template<typename T >
madness::Future< T >::Future ( const Future< T > &  other)
inline

Shallow copy constructor.

Parameters
[in]otherThe future to copy.

References madness::Future< T >::f, and madness::Future< T >::is_default_initialized().

◆ ~Future()

template<typename T >
madness::Future< T >::~Future ( )
inline

Destructor.

References madness::Future< T >::value.

Member Function Documentation

◆ default_initializer()

template<typename T >
static const Future<T> madness::Future< T >::default_initializer ( )
inlinestatic

See "Gotchas" on Futures about why this exists and how to use it.

Todo:
Informative description needed.

Referenced by madness::future_vector_factory(), and madness::WorldGopInterface::reduce_internal().

◆ get() [1/3]

template<typename T >
T& madness::Future< T >::get ( bool  dowork = true) &
inline

◆ get() [2/3]

template<typename T >
T madness::Future< T >::get ( bool  dowork = true) &&
inline

Gets the value, waiting if necessary.

Parameters
doworkIf true (default) and the future is not ready this thread will execute other tasks while waiting
Warning
PaRSEC backend does not support dowork=true from a callstack containing a running MADNESS task already, hence must use dowork=false when need to call from within a task
Returns
the contained value
Precondition
this->is_local()

References madness::Future< T >::f, madness::Future< T >::is_local(), MADNESS_CHECK, and madness::Future< T >::value.

◆ get() [3/3]

template<typename T >
const T& madness::Future< T >::get ( bool  dowork = true) const &
inline

Gets the value, waiting if necessary.

Parameters
doworkIf true (default) and the future is not ready this thread will execute other tasks while waiting
Warning
PaRSEC backend does not support dowork=true from a callstack containing a running MADNESS task already, hence must use dowork=false when need to call from within a task
Returns
reference to the contained value
Precondition
this->is_local()

References madness::Future< T >::f, madness::Future< T >::is_local(), MADNESS_CHECK, and madness::Future< T >::value.

◆ is_default_initialized()

template<typename T >
bool madness::Future< T >::is_default_initialized ( ) const
inline

Check if the future is default initialized.

Returns
True if this future was constructed with default_initializer(); false otherwise.

References madness::Future< T >::f, and madness::Future< T >::value.

Referenced by madness::Future< T >::Future().

◆ is_local()

template<typename T >
bool madness::Future< T >::is_local ( ) const
inline

Checks the future remoteness trait.

Returns
true if the future refers to an already available or to-be-locally-produced result

References madness::Future< T >::f, and madness::Future< T >::value.

Referenced by madness::Future< T >::get(), and madness::Future< T >::is_remote().

◆ is_remote()

template<typename T >
bool madness::Future< T >::is_remote ( ) const
inline

Checks the future remoteness trait.

Returns
true if the future refers to another future on a another rank, i.e. it will be set when the referred-to future is set

References madness::Future< T >::is_local().

◆ operator const T &()

template<typename T >
madness::Future< T >::operator const T & ( ) const &
inline

Same as get() const&.

Returns
A const lvalue reference to the value.

◆ operator T()

template<typename T >
madness::Future< T >::operator T ( ) &&
inline

An rvalue analog of get().

Returns
An rvalue reference to the value.

◆ operator T&()

template<typename T >
madness::Future< T >::operator T& ( ) &
inline

Same as get()&.

Returns
An lvalue reference to the value.

◆ operator=()

template<typename T >
Future<T>& madness::Future< T >::operator= ( const Future< T > &  other)
inline

Shallow assignment operator.

Parameters
[in]otherThe future to copy.
Returns
This.

References madness::Future< T >::f, MADNESS_ASSERT, madness::Future< T >::probe(), madness::Future< T >::set(), and madness::Future< T >::value.

◆ probe()

template<typename T >
bool madness::Future< T >::probe ( ) const
inline

◆ register_callback()

template<typename T >
void madness::Future< T >::register_callback ( CallbackInterface callback)
inline

Registers an object to be called when future is assigned.

Callbacks are invoked in the order registered. If the future is already assigned, the callback is immediately invoked.

Parameters
[in]callbackThe callback to be invoked.

References madness::Future< T >::f, MADNESS_ASSERT, madness::CallbackInterface::notify(), and madness::Future< T >::probe().

Referenced by madness::TaskFn< fnT, arg1T, arg2T, arg3T, arg4T, arg5T, arg6T, arg7T, arg8T, arg9T >::check_dependency().

◆ remote_ref()

template<typename T >
remote_refT madness::Future< T >::remote_ref ( World world) const
inline

Returns a structure used to pass references to another process.

This is used for passing pointers/references to another process. To make remote references completely safe, the RemoteReference increments the internal reference count of the Future. The counter is decremented by either assigning to the remote Future or its destructor if it is never assigned. The remote Future is only useful for setting the future. It will not be notified if the value is set elsewhere.

If this is already a reference to a remote future, the actual remote reference is returned; that is, not a a reference to the local future. Therefore, the local future will not be notified when the result is set (i.e., the communication is short circuited).

Parameters
[in,out]worldThe communication world.
Todo:
Verify the return comment.
Returns
The remote reference.

References madness::Future< T >::f, MADNESS_ASSERT, and madness::Future< T >::probe().

Referenced by madness::Function< T, NDIM >::eval(), madness::Function< T, NDIM >::evaldepthpt(), madness::Function< T, NDIM >::evalR(), madness::WorldContainerImpl< keyT, valueT, hashfunT >::find(), madness::FunctionImpl< T, NDIM >::find_me(), madness::DerivativeBase< T, NDIM >::find_neighbor(), madness::FunctionImpl< T, NDIM >::project_out2(), and madness::WorldObject< Derived >::send_am().

◆ set() [1/4]

template<typename T >
void madness::Future< T >::set ( const archive::BufferInputArchive input_arch)
inline

Assigns the value.

The value can only be set once.

Todo:
Description needed.
Parameters
[in]input_archDescription needed.

References madness::Future< T >::f, and MADNESS_CHECK.

◆ set() [2/4]

template<typename T >
void madness::Future< T >::set ( const Future< T > &  other)
inline

A.set(B), where A and B are futures ensures A has/will have the same value as B.

An exception is thrown if A is already assigned since a Future is a single assignment variable. We don't yet track multiple assignments from unassigned futures.

If B is already assigned, this is the same as A.set(B.get()), which sets A to the value of B.

If B has not yet been assigned, the behavior is to ensure that, when B is assigned, both A and B will be assigned and have the same value (though they may/may not refer to the same underlying copy of the data and indeed may even be in different processes).

Todo:
Verification needed in the param statement.
Parameters
[in]otherThe future B described above. *this is A.

References madness::Future< T >::f, fred(), madness::Future< T >::get(), MADNESS_ASSERT, and madness::Future< T >::probe().

Referenced by madness::FunctionImpl< T, NDIM >::eval(), madness::FunctionImpl< T, NDIM >::evaldepthpt(), madness::FunctionImpl< T, NDIM >::evalR(), madness::detail::DistCache< keyT >::get_cache_value(), main(), madness::Future< T >::operator=(), madness::detail::ForEachRootTask< rangeT, opT >::run(), madness::detail::run_function(), madness::FunctionImpl< T, NDIM >::sock_it_to_me(), madness::FunctionImpl< T, NDIM >::sock_it_to_me_too(), test5(), and test9().

◆ set() [3/4]

template<typename T >
void madness::Future< T >::set ( const T value)
inline

Assigns the value.

The value can only be set once.

Parameters
[in]valueThe value to be assigned.

References madness::Future< T >::f, MADNESS_CHECK, and madness::Future< T >::value.

◆ set() [4/4]

template<typename T >
void madness::Future< T >::set ( T &&  value)
inline

Assigns the value.

The value can only be set once.

Parameters
[in]valueThe value to be assigned.

References madness::Future< T >::f, MADNESS_CHECK, and madness::Future< T >::value.

Friends And Related Function Documentation

◆ operator

template<typename T >
std::ostream& operator ( std::ostream &  out,
const Future< T > &  f 
)
friend

Member Data Documentation

◆ buffer

template<typename T >
char madness::Future< T >::buffer[sizeof(T)]
private

Buffer to hold a single T object.

◆ f

template<typename T >
std::shared_ptr< FutureImpl<T> > madness::Future< T >::f
private

◆ value

template<typename T >
T* const madness::Future< T >::value
private

The documentation for this class was generated from the following file: