sabcom/build/index.js

A TypeScript/Node.js library for inter-thread communication using SharedArrayBuffer with atomic operations for raw buffer data transfer

export const SEMAPHORE = 0;
export var Semaphore = /*#__PURE__*/ function(Semaphore) {
    Semaphore[Semaphore["READY"] = 0] = "READY";
    Semaphore[Semaphore["HANDSHAKE"] = 1] = "HANDSHAKE";
    Semaphore[Semaphore["PAYLOAD"] = 2] = "PAYLOAD";
    return Semaphore;
}({});
export var Handshake = /*#__PURE__*/ function(Handshake) {
    Handshake[Handshake["TOTAL_SIZE"] = 1] = "TOTAL_SIZE";
    Handshake[Handshake["TOTAL_CHUNKS"] = 2] = "TOTAL_CHUNKS";
    return Handshake;
}({});
export var Header = /*#__PURE__*/ function(Header) {
    Header[Header["CHUNK_INDEX"] = 1] = "CHUNK_INDEX";
    Header[Header["CHUNK_OFFSET"] = 2] = "CHUNK_OFFSET";
    Header[Header["CHUNK_SIZE"] = 3] = "CHUNK_SIZE";
    return Header;
}({});
export const HEADER_VALUES = 1 + Math.max(Object.values(Handshake).length, Object.values(Header).length) / 2;
export const HEADER_SIZE = Uint32Array.BYTES_PER_ELEMENT * HEADER_VALUES;
export function* writeGenerator(data, buffer, { timeout = 5000 } = {}) {
    const chunkSize = buffer.byteLength - HEADER_SIZE;
    const totalSize = data.length;
    const totalChunks = Math.ceil(totalSize / chunkSize);
    const header = new Int32Array(buffer);
    header[1] = totalSize;
    header[2] = totalChunks;
    Atomics.store(header, SEMAPHORE, 1);
    Atomics.notify(header, SEMAPHORE);
    try {
        const handshakeResult = yield {
            target: header,
            index: SEMAPHORE,
            value: 1,
            timeout
        };
        if (handshakeResult === 'timed-out') {
            throw new Error('Reader handshake timeout');
        }
        const payload = new Uint8Array(buffer, HEADER_SIZE);
        for(let i = 0; i < totalChunks; i++){
            const start = i * chunkSize;
            const end = Math.min(start + chunkSize, totalSize);
            const size = end - start;
            payload.set(data.subarray(start, end), 0);
            header[1] = i;
            header[2] = start;
            header[3] = size;
            Atomics.store(header, SEMAPHORE, 2);
            Atomics.notify(header, SEMAPHORE);
            const chunkResult = yield {
                target: header,
                index: SEMAPHORE,
                value: 2,
                timeout
            };
            if (chunkResult === 'timed-out') {
                throw new Error(`Reader timeout on chunk ${i}/${totalChunks - 1}`);
            }
        }
    } finally{
        Atomics.store(header, SEMAPHORE, 0);
    }
}
export function* readGenerator(buffer, { timeout = 5000 } = {}) {
    const header = new Int32Array(buffer);
    const handshakeResult = yield {
        target: header,
        index: SEMAPHORE,
        value: 0,
        timeout
    };
    if (handshakeResult === 'timed-out') {
        throw new Error('Handshake timeout');
    }
    if (header[SEMAPHORE] !== 1) {
        throw new Error('Invalid handshake state');
    }
    const totalSize = header[1];
    const totalChunks = header[2];
    const data = new Uint8Array(totalSize);
    Atomics.store(header, SEMAPHORE, 0);
    Atomics.notify(header, SEMAPHORE);
    const payload = new Uint8Array(buffer, HEADER_SIZE);
    for(let i = 0; i < totalChunks; i++){
        const chunkResult = yield {
            target: header,
            index: SEMAPHORE,
            value: 0,
            timeout
        };
        if (chunkResult === 'timed-out') {
            throw new Error(`Writer timeout waiting for chunk ${i}`);
        }
        if (header[SEMAPHORE] !== 2) {
            throw new Error(`Expected payload header, received ${Semaphore[header[SEMAPHORE]]}`);
        }
        const chunkIndex = header[1];
        if (i !== chunkIndex) {
            throw new Error(`Reader integrity failure for chunk ${chunkIndex} expected ${i}`);
        }
        const offset = header[2];
        const size = header[3];
        data.set(payload.subarray(0, size), offset);
        Atomics.store(header, SEMAPHORE, 0);
        Atomics.notify(header, SEMAPHORE);
    }
    return data;
}
export const writeSync = (data, buffer, options)=>{
    const gen = writeGenerator(data, buffer, options);
    let result = gen.next();
    while(!result.done){
        const waitResult = Atomics.wait(result.value.target, result.value.index, result.value.value, result.value.timeout);
        result = gen.next(waitResult);
    }
};
export const write = async (data, buffer, options)=>{
    const gen = writeGenerator(data, buffer, options);
    let result = gen.next();
    while(!result.done){
        const request = result.value;
        const waitResult = await Atomics.waitAsync(request.target, request.index, request.value, request.timeout).value;
        result = gen.next(waitResult);
    }
};
export const readSync = (buffer, options)=>{
    const gen = readGenerator(buffer, options);
    let result = gen.next();
    while(!result.done){
        const waitResult = Atomics.wait(result.value.target, result.value.index, result.value.value, result.value.timeout);
        result = gen.next(waitResult);
    }
    return result.value;
};
export const read = async (buffer, options)=>{
    const gen = readGenerator(buffer, options);
    let result = gen.next();
    while(!result.done){
        const request = result.value;
        const waitResult = await Atomics.waitAsync(request.target, request.index, request.value, request.timeout).value;
        result = gen.next(waitResult);
    }
    return result.value;
};

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