@libp2p/webrtc-peer/dist/src/channel.js

Simple one-to-one WebRTC data channels

import errCode from 'err-code';
import defer from 'p-defer';
const MAX_BUFFERED_AMOUNT = 64 * 1024;
const CHANNEL_CLOSING_TIMEOUT = 5 * 1000;
export class WebRTCDataChannel {
    constructor(channel, opts) {
        this.label = channel.label;
        this.open = defer();
        this.channel = channel;
        this.channel.binaryType = 'arraybuffer';
        this.log = opts.log;
        if (typeof this.channel.bufferedAmountLowThreshold === 'number') {
            this.channel.bufferedAmountLowThreshold = MAX_BUFFERED_AMOUNT;
        }
        channel.addEventListener('message', event => {
            opts.onMessage(event);
        });
        channel.addEventListener('bufferedamountlow', () => {
            this.log('stop backpressure: bufferedAmount %d', this.channel.bufferedAmount);
            this.open.resolve();
        });
        channel.addEventListener('open', () => {
            this.open.resolve();
            opts.onOpen();
        });
        channel.addEventListener('close', () => {
            opts.onClose();
        });
        channel.addEventListener('error', event => {
            // @ts-expect-error ChannelErrorEvent is just an Event in the types?
            if (event.error?.message === 'Transport channel closed') {
                return this.close();
            }
            // @ts-expect-error ChannelErrorEvent is just an Event in the types?
            opts.log.error('channel encounter an error in state "%s" message: "%s" detail: "%s', channel.readyState, event.error?.message, event.error?.errorDetail); // eslint-disable-line @typescript-eslint/restrict-template-expressions
            // @ts-expect-error ChannelErrorEvent is just an Event in the types?
            const err = event.error instanceof Error
                // @ts-expect-error ChannelErrorEvent is just an Event in the types?
                ? event.error
                // @ts-expect-error ChannelErrorEvent is just an Event in the types?
                : new Error(`datachannel error: ${event.error?.message} ${event.error?.errorDetail}`); // eslint-disable-line @typescript-eslint/restrict-template-expressions
            opts.onError(errCode(err, 'ERR_DATA_CHANNEL'));
        });
        // HACK: Chrome will sometimes get stuck in readyState "closing", let's check for this condition
        // https://bugs.chromium.org/p/chromium/issues/detail?id=882743
        let isClosing = false;
        this.closingInterval = setInterval(() => {
            if (channel.readyState === 'closing') {
                if (isClosing) {
                    opts.onClose(); // closing timed out: equivalent to onclose firing
                }
                isClosing = true;
            }
            else {
                isClosing = false;
            }
        }, CHANNEL_CLOSING_TIMEOUT);
    }
    async send(data) {
        await this.open.promise;
        this.channel.send(data);
        if (this.channel.bufferedAmount > MAX_BUFFERED_AMOUNT) {
            this.log('start backpressure: bufferedAmount %d', this.channel.bufferedAmount);
            this.open = defer();
        }
    }
    close() {
        clearInterval(this.closingInterval);
        this.channel.close();
    }
    get bufferedAmount() {
        return this.channel.bufferedAmount;
    }
}
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