strapi-pfapi/src/lib/redis-invalidate.js

a strapi plugin library uses local and redis caches to achieve single digit milliseconds on average api response time.

'use strict';

const logging = require('../app/logging');

module.exports = {
    on_invalidate,
    off_invalidate,
};

async function on_invalidate(redis, on_event, {prefix,  bcast = true, noloop = true}) {

    return await redis.get_client(async (new_client) => {

        const client = await redis.get_client();

        let error;

        for (let i = 0; i < 16; i++) {

            const delay_ms = i ? 1000 : 0;
            await new Promise(resolve => setTimeout(resolve, delay_ms));

            try {

                const id = await redis.get_client_id(new_client);
                const argv = ['tracking', 'on', 'redirect', id, 'prefix', prefix]; 
                if (bcast) argv.push('bcast');
                if (noloop) argv.push('noloop');

                if (await redis.send_command({client, cmd: 'client', argv}) !== 'OK') {
                    error = 'on_invalidate, failed to send_command';
                    break;
                }

                if (await new_client.subscribe('__redis__:invalidate') !== 1) {
                    error = 'on_invalidate, failed to subscribe';
                    break;
                }

                new_client.on('message', async (channel, data) => {
                    const current_id = await redis.get_client_id(new_client);
                    if (current_id !== id) {
                        await off_invalidate_by_id(redis, client, id);
                        return;
                    }
                    const redis_keys = data.split(',');
                    await on_event(redis_keys);
                });

                error = null;

                break;

            } catch(err) {
                error = err;
            }
        }

        if (error) logging.error(error);

    });
}

async function off_invalidate(redis, subscribe_client) {

    const client = await redis.get_client();
    const id = await redis.get_client_id(subscribe_client);
    return off_invalidate_by_id(redis, client, id);

}

async function off_invalidate_by_id(redis, client, id) {

    const argv = ['tracking', 'off', 'redirect', id];
    const result = await redis.send_command({client, cmd: 'client', argv});
    if (result !== 'OK') {
        logging.error('turnoff_invalidate, failed to send_command');
        return false;
    }
    return true;
}