tardis-machine/dist/http/replaynormalized.js

Locally runnable server with built-in data caching, providing both tick-level historical and consolidated real-time cryptocurrency market data via HTTP and WebSocket APIs

import { once } from 'node:events';
import { combine, compute, replayNormalized } from 'tardis-dev';
import { debug } from "../debug.js";
import { constructDataTypeFilter, getComputables, getNormalizers } from "../helpers.js";
export const replayNormalizedHttp = async (req, res) => {
    try {
        const startTimestamp = new Date().getTime();
        const requestUrl = new URL(req.url, 'http://localhost');
        const optionsString = requestUrl.searchParams.get('options') ?? undefined;
        const replayNormalizedOptions = JSON.parse(optionsString);
        debug('GET /replay-normalized request started, options: %o', replayNormalizedOptions);
        const streamedMessagesCount = await writeMessagesToResponse(res, replayNormalizedOptions);
        const endTimestamp = new Date().getTime();
        debug('GET /replay-normalized request finished, options: %o, time: %d seconds, total messages count: %d', replayNormalizedOptions, (endTimestamp - startTimestamp) / 1000, streamedMessagesCount);
    }
    catch (e) {
        const errorInfo = {
            responseText: e.responseText,
            message: e.message,
            url: e.url
        };
        debug('GET /replay-normalized request error: %o', e);
        console.error('GET /replay-normalized request error:', e);
        if (!res.finished) {
            res.statusCode = e.status || 500;
            res.end(JSON.stringify(errorInfo));
        }
    }
};
async function writeMessagesToResponse(res, options) {
    const BATCH_SIZE = 32;
    res.setHeader('Content-Type', 'application/x-json-stream');
    let buffers = [];
    let totalMessagesCount = 0;
    const replayNormalizedOptions = Array.isArray(options) ? options : [options];
    const messagesIterables = replayNormalizedOptions.map((option) => {
        // let's map from provided options to options and normalizers that needs to be added for dataTypes provided in options
        const messages = replayNormalized(option, ...getNormalizers(option.dataTypes));
        // separately check if any computables are needed for given dataTypes
        const computables = getComputables(option.dataTypes);
        if (computables.length > 0) {
            return compute(messages, ...computables);
        }
        return messages;
    });
    const filterByDataType = constructDataTypeFilter(replayNormalizedOptions);
    const messages = messagesIterables.length === 1 ? messagesIterables[0] : combine(...messagesIterables);
    for await (const message of messages) {
        // filter out messages not explicitly requested via options.dataTypes
        // eg.: return only book_snapshots when someone asked only for those
        // as by default also book_changes are returned as well
        if (filterByDataType(message) === false) {
            continue;
        }
        totalMessagesCount++;
        buffers.push(JSON.stringify(message));
        if (buffers.length === BATCH_SIZE) {
            const ok = res.write(`${buffers.join('\n')}\n`);
            buffers = [];
            if (!ok) {
                await once(res, 'drain');
            }
        }
    }
    if (buffers.length > 0) {
        res.write(`${buffers.join('\n')}\n`);
        buffers = [];
    }
    res.end('');
    return totalMessagesCount;
}
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