@versatiles/google-cloud/dist/lib/versatiles/cache.js

A server for VersaTiles in Google Cloud Run

import { Versatiles } from './versatiles.js';
const containerCache = new Map();
export async function getVersatiles(file, url) {
    const metadata = await file.getMetadata();
    let container = containerCache.get(file.name);
    if (container != null) {
        if (container.etag !== metadata.etag)
            container = undefined;
    }
    if (container == null) {
        const reader = buildReader(file);
        container = await Versatiles.fromReader(reader, url, metadata.etag);
        containerCache.set(file.name, container);
    }
    return container;
}
function buildReader(file) {
    return async (position, length) => {
        // Read data from the file stream
        return new Promise((resolve, reject) => {
            const buffers = Array();
            file.createReadStream({ start: position, end: position + length - 1 })
                .on('data', (chunk) => buffers.push(chunk))
                .on('end', () => {
                resolve(Buffer.concat(buffers));
            })
                .on('error', (err) => {
                reject(`error accessing bucket stream - ${String(err)}`);
            });
        });
    };
}