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RWTRunnableIOUFunction< Return > Class Template Reference

Handle class for functor-based runnable objects. More...

#include <rw/thread/RWTRunnableIOUFunction.h>

Inheritance diagram for RWTRunnableIOUFunction< Return >:
RWRunnable RWRunnableHandle RWHandleBase

Public Member Functions

 RWTRunnableIOUFunction (const RWTRunnableIOUFunction< Return > &second)
 
 RWTRunnableIOUFunction (void)
 
 ~RWTRunnableIOUFunction (void)
 
RWTFunctor< Return()> getFunctor () const
 
RWTIOUResult< Return > operator() () const
 
RWTRunnableIOUFunction< Return > & operator= (const RWTRunnableIOUFunction< Return > &second)
 
RWTIOUResult< Return > result () const
 
void setFunctor (const RWTFunctor< Return()> &functor)
 
void setIOUEscrow (const RWTIOUEscrow< Return > &escrow)
 
- Public Member Functions inherited from RWRunnable
 RWRunnable ()
 
 RWRunnable (const RWRunnable &second)
 
 RWRunnable (RWStaticCtor)
 
 ~RWRunnable ()
 
RWRunnable getNestedRunnable () const
 
RWRunnableSelf getRWRunnableSelf () const
 
RWWaitStatus join (unsigned long milliseconds)
 
void join (void)
 
RWRunnableoperator= (const RWRunnable &second)
 
void raise () const
 
void releaseInterrupt ()
 
RWWaitStatus requestCancellation ()
 
RWWaitStatus requestCancellation (unsigned long milliseconds)
 
RWWaitStatus requestInterrupt ()
 
RWWaitStatus requestInterrupt (unsigned long milliseconds)
 
RWCompletionState start ()
 
RWExecutionState wait (unsigned long stateMask)
 
RWWaitStatus wait (unsigned long stateMask, RWExecutionState *state, unsigned long milliseconds)
 
- Public Member Functions inherited from RWRunnableHandle
void addCallback (const RWTFunctor< void(const RWRunnable &, RWExecutionState)> &functor, unsigned long stateMask, RWCallbackScope scope=RW_CALL_REPEATEDLY)
 
RWCompletionState getCompletionState () const
 
RWExecutionState getExecutionState () const
 
bool isInterruptRequested () const
 
bool isSelf () const
 
bool isSelf (const RWThreadId &id) const
 
void removeCallback (const RWTFunctor< void(const RWRunnable &, RWExecutionState)> &functor)
 
RWThreadId threadId () const
 
- Public Member Functions inherited from RWHandleBase
bool isValid (void) const
 
bool operator!= (const RWHandleBase &second) const
 
bool operator== (const RWHandleBase &second) const
 

Static Public Member Functions

static RWTRunnableIOUFunction< Return > make ()
 
static RWTRunnableIOUFunction< Return > make (const RWTFunctor< Return()> &functor)
 
static RWTRunnableIOUFunction< Return > make (const RWTIOUEscrow< Return > &escrow, const RWTFunctor< Return()> &functor)
 

Additional Inherited Members

- Protected Member Functions inherited from RWRunnable
 RWRunnable (const RWRunnableSelf &second)
 
- Protected Member Functions inherited from RWRunnableHandle
 RWRunnableHandle ()
 
 RWRunnableHandle (const RWRunnableHandle &second)
 
 RWRunnableHandle (RWRunnableImp *runnableImpP)
 
 RWRunnableHandle (RWStaticCtor)
 
 ~RWRunnableHandle ()
 
RWRunnableHandleoperator= (const RWRunnableHandle &second)
 
- Protected Member Functions inherited from RWHandleBase
 RWHandleBase (const RWHandleBase &second)
 
 RWHandleBase (RWBodyBase *body)
 
 RWHandleBase (RWStaticCtor)
 
 RWHandleBase (void)
 
 ~RWHandleBase (void)
 
RWBodyBasebody (void) const
 
RWHandleBaseoperator= (const RWHandleBase &second)
 

Detailed Description

template<class Return>
class RWTRunnableIOUFunction< Return >

The RWTRunnableIOUFunction class is a handle class for functor-based runnable objects.

A runnable object provides the basic mechanisms used to create, control, and monitor the threads of execution within your application. Runnables are used to define the task or activity to be performed by a thread.

Each runnable object is reference-counted. A runnable body instance keeps a count of the number of handles that currently reference it. A runnable object is deleted when the last handle that references the body is deleted.

A functor-based runnable accepts a functor object for execution. A functor is an object used to encapsulate a function call. Each functor keeps a pointer to the function and copies of the argument values that are to be passed to the function. Invoking a functor produces a call to the function, and in this case, a return value.

A functor-based runnable simply redefines the basic run() member to invoke a functor instance stored within the runnable. With this capability, you do not have to resort to sub-classing or other intrusive techniques to customize the execution behavior of a runnable. The functor-base runnables allow you to dynamically specify the functions you want to execute when a runnable is started.

RWTRunnableIOUFunction is used to access a synchronous runnable. A synchronous runnable executes the specified functor in the same thread that calls start(). The result of the functor is returned in the form of an IOU. An IOU may be obtained as soon as the runnable is created. To get the actual result from the IOU you must redeem it. If the result has not yet been calculated, the calling thread blocks until it has.

Although RWTRunnableIOUFunction is an RWRunnable, it does not store exceptions generated by its target function in the same way that other runnables do. Instead of setting the runnable state to RW_THR_EXCEPTION and storing the exception in the runnable, it intercepts the exception and sets it as an exception on the RWTIOUResult to be returned.

Since RWTRunnableIOUFunction does not store an RW_THR_EXCEPTION, a callback designed to detect it will not be triggered if the runnable function throws an exception. This differs from the usual runnable behavior. Another side effect is that, even if the runnable terminates because of an exception, calling raise() on the runnable does not generate the exception. Instead the IOUResult returned by the function throws the exception when it is redeemed.

Example
#include <rw/thread/RWRunnableServer.h>
#include <rw/thread/RWTRunnableIOUFunction.h>
#include <rw/functor/rwBind.h>
#include <iostream>
#include <math.h>
int greatestPrime(int limit) {
// The sieve of Eratosthenes:
int i, m;
char* sieve = new char[limit + 1];
if (sieve == 0) {
return -1; // not enough memory
}
for (i = 0; i <= limit; ++i) {
sieve[i] = 1;
}
for (i = 2; i <= sqrt((double)limit); ++i) {
if (sieve[i] != 0) {
for (m = i + i; m <= limit; m += i) {
sieve[m] = 0;
}
}
}
// Return the greatest prime less than or equal to limit:
for (i = limit; i >= 2; --i) {
if (sieve[i] != 0) {
return i;
}
}
return 0;
}
int main() {
RWTRunnableIOUFunction<int>::make(rwBind(greatestPrime, 6000000));
RWTIOUResult<int> answer = eratosthenes.result(); // get an IOU
server.start(); // Start the server
server.enqueue(eratosthenes); //calculate prime in server thread
// While the thread is busy calculating, print this
// suspenseful message to keep the user entertained:
std::cout << "The greatest prime less than six million is... "
<< std::flush;
// Block until the answer has been calculated and
// then print it:
std::cout << answer.redeem() << std::endl;
server.stop();
server.join();
return 0;
}
Represents a runnable server for executing runnable objects.
Definition RWRunnableServer.h:137
static RWRunnableServer make()
void enqueue(const RWRunnable &runnable)
RWCompletionState start()
void join(void)
A readable IOU handle.
Definition RWTIOUResult.h:122
Redeemable redeem(void) const
Definition RWTIOUResult.h:312
Handle class for functor-based runnable objects.
Definition RWTRunnableIOUFunction.h:146
RWTIOUResult< Return > result() const
static RWTRunnableIOUFunction< Return > make()
unspecified_type rwBind(C &&c, As &&... args)
Binds a callable and arguments into a callable object.

OUTPUT:

The greatest prime less than six million is... 5999993
See also
RWTFunctor, RWRunnable, RWRunnableHandle

Constructor & Destructor Documentation

◆ RWTRunnableIOUFunction() [1/2]

template<class Return >
RWTRunnableIOUFunction< Return >::RWTRunnableIOUFunction ( void )
inline

Constructs an empty RWTRunnableIOUFunction handle instance.

◆ RWTRunnableIOUFunction() [2/2]

template<class Return >
RWTRunnableIOUFunction< Return >::RWTRunnableIOUFunction ( const RWTRunnableIOUFunction< Return > & second)
inline

Binds a new handle to the runnable instance, if any, pointed to by the handle second.

◆ ~RWTRunnableIOUFunction()

template<class Return >
RWTRunnableIOUFunction< Return >::~RWTRunnableIOUFunction ( void )
inline

Destructor.

Member Function Documentation

◆ getFunctor()

template<class Return >
RWTFunctor< Return()> RWTRunnableIOUFunction< Return >::getFunctor ( ) const

Gets the current functor instance, if any, associated with the runnable.

◆ make() [1/3]

template<class Return >
static RWTRunnableIOUFunction< Return > RWTRunnableIOUFunction< Return >::make ( )
static

Constructs and returns an RWTRunnableIOUFunction object with an undefined functor. The setFunctor() member must be used to define a functor prior to starting.

◆ make() [2/3]

template<class Return >
static RWTRunnableIOUFunction< Return > RWTRunnableIOUFunction< Return >::make ( const RWTFunctor< Return()> & functor)
static

Constructs and returns an RWTRunnableIOUFunction that executes the specified functor when started.

◆ make() [3/3]

template<class Return >
static RWTRunnableIOUFunction< Return > RWTRunnableIOUFunction< Return >::make ( const RWTIOUEscrow< Return > & escrow,
const RWTFunctor< Return()> & functor )
static

Constructs and returns an RWTRunnableIOUFunction that executes the specified functor when started, and places the functor result in escrow.

◆ operator()()

template<class Return >
RWTIOUResult< Return > RWTRunnableIOUFunction< Return >::operator() ( ) const

Returns the IOU that will receive the result of the function.

◆ operator=()

template<class Return >
RWTRunnableIOUFunction< Return > & RWTRunnableIOUFunction< Return >::operator= ( const RWTRunnableIOUFunction< Return > & second)
inline

Binds this to the runnable instance, if any, pointed to by the handle second.

◆ result()

template<class Return >
RWTIOUResult< Return > RWTRunnableIOUFunction< Return >::result ( ) const

Returns the IOU that will receive the result of the function.

◆ setFunctor()

template<class Return >
void RWTRunnableIOUFunction< Return >::setFunctor ( const RWTFunctor< Return()> & functor)

Sets the functor to be executed by this runnable.

◆ setIOUEscrow()

template<class Return >
void RWTRunnableIOUFunction< Return >::setIOUEscrow ( const RWTIOUEscrow< Return > & escrow)

Specifies an IOU escrow that is to receive the result of the function. The new IOU is used until the next time start() is called. Each time an RWTRunnableIOUFunction object is restarted, it checks its current IOU escrow handle to see if it is valid, and if so, checks to see whether the escrow has already been used to capture a result or exception, or has been aborted. If the escrow object is found to be in any of these "redeemable" states, then a new escrow instance is automatically created to capture the next result.

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