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Class `core.thread.Fiber`

This class provides a cooperative concurrency mechanism integrated with the threading and garbage collection functionality. Calling a fiber may be considered a blocking operation that returns when the fiber yields (via Fiber.yield()). Execution occurs within the context of the calling thread so synchronization is not necessary to guarantee memory visibility so long as the same thread calls the fiber each time. Please note that there is no requirement that a fiber be bound to one specific thread. Rather, fibers may be freely passed between threads so long as they are not currently executing. Like threads, a new fiber thread may be created using either derivation or composition, as in the following example.


						
				class Fiber
				;

Constructors

Name	Description
`this`	Initializes a fiber object which is associated with a static D function.
`this`	Initializes a fiber object which is associated with a dynamic D function.

Properties

Name	Type	Description
`state`[get]	`Fiber.State`	Gets the current state of this fiber.

Methods

Name	Description
`call`	Transfers execution to this fiber object. The calling context will be suspended until the fiber calls Fiber.yield() or until it terminates via an unhandled exception.
`getThis`	Provides a reference to the calling fiber or null if no fiber is currently active.
`reset`	Resets this fiber so that it may be re-used, optionally with a new function/delegate. This routine should only be called for fibers that have terminated, as doing otherwise could result in scope-dependent functionality that is not executed. Stack-based classes, for example, may not be cleaned up properly if a fiber is reset before it has terminated.
`yield`	Forces a context switch to occur away from the calling fiber.
`yieldAndThrow`	Forces a context switch to occur away from the calling fiber and then throws obj in the calling fiber.
`factory`	Create instance of class specified by the fully qualified name classname. The class must either have no constructors or have a default constructor.
`opCmp`	Compare with another Object obj.
`opEquals`	Test whether `this` is equal to `o`. The default implementation only compares by identity (using the `is` operator). Generally, overrides for `opEquals` should attempt to compare objects by their contents.
`toHash`	Compute hash function for Object.
`toString`	Convert Object to a human readable string.

Enums

Name	Description
`Rethrow`	Flag to control rethrow behavior of `call`
`State`	A fiber may occupy one of three states: HOLD, EXEC, and TERM.

Warning

Status registers are not saved by the current implementations. This means floating point exception status bits (overflow, divide by 0), rounding mode and similar stuff is set per-thread, not per Fiber!

Warning

On ARM FPU registers are not saved if druntime was compiled as ARM_SoftFloat. If such a build is used on a ARM_SoftFP system which actually has got a FPU and other libraries are using the FPU registers (other code is compiled as ARM_SoftFP) this can cause problems. Druntime must be compiled as ARM_SoftFP in this case.

Example

int counter;

class DerivedFiber : Fiber
{
    this()
    {
        super( &run );
    }

private :
    void run()
    {
        counter += 2;
    }
}

void fiberFunc()
{
    counter += 4;
    Fiber.yield();
    counter += 8;
}

// create instances of each type
Fiber derived = new DerivedFiber();
Fiber composed = new Fiber( &fiberFunc );

writeln(counter); // 0

derived.call();
writeln(counter); // 2

composed.call();
writeln(counter); // 6

counter += 16;
writeln(counter); // 22

composed.call();
writeln(counter); // 30

// since each fiber has run to completion, each should have state TERM
writeln(derived.state); // Fiber.State.TERM
writeln(composed.state); // Fiber.State.TERM

Authors

Sean Kelly, Walter Bright, Alex Rønne Petersen, Martin Nowak

License

Distributed under the Boost Software License 1.0. (See accompanying file LICENSE)

API Documentation

Class core.thread.Fiber

Constructors

Properties

Methods

Enums

Warning

Warning

Example

Authors

License

Class `core.thread.Fiber`