Reference documentation for deal.II version Git e7c9a24 2019-02-08 08:26:19 +0100
\(\newcommand{\dealcoloneq}{\mathrel{\vcenter{:}}=}\)
Public Member Functions | Private Attributes | List of all members

#include <deal.II/base/thread_management.h>

Public Member Functions

 Thread (const std::function< RT()> &function)
 
 Thread ()=default
 
 Thread (const Thread< RT > &t)
 
void join () const
 
internal::return_value< RT >::reference_type return_value ()
 
bool valid () const
 
bool operator== (const Thread &t) const
 

Private Attributes

std::shared_ptr< internal::ThreadDescriptor< RT > > thread_descriptor
 

Detailed Description

template<typename RT = void>
class Threads::Thread< RT >

An object that represents a spawned thread. This object can be freely copied around in user space, and all instances will represent the same thread and can require to wait for its termination and access its return value.

Threads can be abandoned, i.e. if you just call Threads::new_thread but don't care about the returned object, or if you assign the return Threads::Thread object to an object that subsequently goes out of scope, then the thread previously created will still continue to do work. You will simply not be able to access its return value any more, and it may also happen that your program terminates before the thread has finished its work.

The default value of the template argument is void, so if the function you are calling on a new thread has no return value, you can omit the template argument.

Author
Wolfgang Bangerth, 2003, 2009

Definition at line 831 of file thread_management.h.

Constructor & Destructor Documentation

template<typename RT = void>
Threads::Thread< RT >::Thread ( const std::function< RT()> &  function)
inline

Construct a thread object with a function object.

Definition at line 837 of file thread_management.h.

template<typename RT = void>
Threads::Thread< RT >::Thread ( )
default

Default constructor. You can't do much with a thread object constructed this way, except for assigning it a thread object that holds data created by the new_thread() functions.

template<typename RT = void>
Threads::Thread< RT >::Thread ( const Thread< RT > &  t)
inline

Copy constructor.

Definition at line 854 of file thread_management.h.

Member Function Documentation

template<typename RT = void>
void Threads::Thread< RT >::join ( ) const
inline

Join the thread represented by this object, i.e. wait for it to finish. If you have used the default constructor of this class and have not assigned a thread object to it, then this function is a no-op.

Definition at line 864 of file thread_management.h.

template<typename RT = void>
internal::return_value<RT>::reference_type Threads::Thread< RT >::return_value ( )
inline

Get the return value of the function of the thread. Since it is only available once the thread finishes, this function internally also calls join(). You can call this function multiple times as long as the object refers to the same task, and expect to get the same return value every time. (With the exception of the case where the returned object has been moved; see below.)

Note
The function returns a non-const reference to the returned object, instead of the returned object. This allows writing code such as
...function returning an int...);
t.return_value() = 42; // overwrite returned value
int i = t.return_value(); // i is now 42
You will rarely have a need to write such code. On the other hand, the function needs to return a writable (non-const) reference to support code such as this:
std::unique_ptr<int> create_int (const std::string &s)
{
...
}
void f()
{
t = Threads::new_thread (&create_int, "42");
std::unique_ptr<int> i = std::move(t.return_value());
...
}
Here, it is necessary to std::move the returned object (namely, the std::unique_ptr object) because std::unique_ptr objects can not be copied. In other words, to get the pointer out of the object returned from the thread, it needs to be moved, and in order to be moved, the current function needs to return a writable (non-const) reference.

Definition at line 914 of file thread_management.h.

template<typename RT = void>
bool Threads::Thread< RT >::valid ( ) const
inline

Return true if this object has had a thread associated with it, either by using the non-default constructor or by assignment.

Definition at line 925 of file thread_management.h.

template<typename RT = void>
bool Threads::Thread< RT >::operator== ( const Thread< RT > &  t) const
inline

Check for equality of thread objects. Since objects of this class store an implicit pointer to an object that exists exactly once for each thread, the check is simply to compare these pointers.

Definition at line 937 of file thread_management.h.

Member Data Documentation

template<typename RT = void>
std::shared_ptr<internal::ThreadDescriptor<RT> > Threads::Thread< RT >::thread_descriptor
private

Shared pointer to the object representing the thread, and abstracting operating system functions to work on it. This also makes sure that the object lives as long as there is at least one subscriber to it.

Definition at line 948 of file thread_management.h.


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