latch & barrier

[samchon]

Latch and Barrier are thread supporting classes who can block critical sections with downward counter. They're strong candidates who may come into the C++20 revision. Thus, it would better to implement them into the experimental namespace.

• http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0666r2.pdf

Latch

The Latch class locks a critical section until its downward counter to be zero.

namespace std.experimental
{
    export class Latch
    {
        public constructor(size: number);

        public is_ready(): boolean;
        public arrive(n: number = 1): Promise<void>;
        public arrive_and_wait(): Promise<void>;

        public wait(): Promise<void>;
        public wait_for(ms: number): Promise<boolean>;
        public wait_until(at: Date): Promise<boolean>;
    }
}

Barrier

The Barrier class can re-use the downward counter..

namespace std.experimental
{
    export class Barrier extends FlexBarrier
    {
        public constructor(size: number);
    }

    export class FlexBarrier
    {
        public constructor(size: number);
        public constructor(size: number, completion: () => number);

        public arrive_and_wait(): Promise<void>;
        public arrive_and_drop(): Promise<void>;

        public try_arrive(): Promise<boolean>;
        public wait(): Promise<void>;
        public wait_for(ms: number): Promise<boolean>;
        public wait_until(at: Date): Promise<boolean>;
    }
}

[samchon]

Class	Source File
Latch	https://github.com/samchon/tstl/blob/v2.1/src/experimental/thread/Latch.ts
Barrier	https://github.com/samchon/tstl/blob/v2.1/src/experimental/thread/Barrier.ts
FlexBarrier	https://github.com/samchon/tstl/blob/v2.1/src/experimental/thread/FlexBarrier.ts

I've implemented and published those latch & barrier features with the @next tag. I think Latch is implemented exactly, however, I can't sure that Barrier and FlexBarrier are exact. I don't know the exact specs and definitions of those features. Can anyone help me?

[samchon]

latch and barriers are now regular features in the C++20. They must be escaped from the experimental features.

[samchon]

https://github.com/cplusplus/draft/blob/master/papers/n4830.pdf

Definition of latch and barriers are fixed like below:

Latch

namespace std
{
    export class Latch
    {
        public constructor(size: number);

        public count_down(): Promise<void>;
        public arrive_and_wait(): Promise<void>;

        public try_wait(): Promise<boolean>;
        public wait(): Promise<void>;
        public wait_for(ms: number): Promise<boolean>;
        public wait_until(at: Date): Promise<boolean>;
    }
}

Barrier

namespace std
{
    export class Barrier extends FlexBarrier
    {
        public constructor(size: number);
    }

    export class FlexBarrier
    {
        public constructor(size: number);
        public constructor(size: number, completion: () => number);

        public arrive(n: number = 1): Promise<void>;
        public arrive_and_wait(): Promise<void>;
        public arrive_and_drop(): Promise<void>;
        public wait(): Promise<void>;
    }
}