@logtail/tools

Better Stack JavaScript client: Helper tools

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@logtail/tools

This library provides helper tools used by the JavaScript logger.

Tools

Queue<T>

Generic FIFO queue. Used by makeThrottle to store pipeline functions to be executed as concurrent 'slots' become available. Provides fast retrieval for any primitive or object that needs ordered, first-in, first-out retrieval.

Used to store .log() Promises that are being batched/throttled.

Usage example

import { Queue } from "@logtail/tools";

// Interface representing a person
interface IPerson {
  name: string;
  age: number;
}

// Create a queue to store `IPerson` objects
const q = new Queue<IPerson>();

// Add a couple of records...
q.push({ name: "Jeff", age: 50 });
q.push({ name: "Sally", age: 39 });

// Pull values from the queue...
while (q.length) {
  console.log(q.shift().name); // <-- first Jeff, then Sally...
}

makeThrottle<T>(max: number)

Returns a throttle higher-order function, which wraps an async function, and limits the number of active Promises to max: number

The throttle function has this signature:

throttle(fn: T): (...args: InferArgs<T>[]) => Promise<InferArgs<T>>

Usage example

import Logtail from "@logtail/logger";
import { makeThrottle } from "@logtail/tools";

// Create a new Logtail instance
const logtail = new Logtail("sourceToken");

// Guarantee a pipeline will run a max of 2x at once
const throttle = makeThrottle(2);

// Create a basic pipeline function which resolves after 2 seconds
const pipeline = async (log) =>
  new Promise((resolve) => {
    setTimeout(() => resolve(log), 2000);
  });

// Add a pipeline which has been throttled
logtail.addPipeline(throttle(pipeline));

// Add 10 logs, and store the Promises
const promises = [];
for (let i = 0; i < 10; i++) {
  promises.push(logtail.log({ message: `Hello ${i}` }));
}

void (async () => {
  void (await promises); // <-- will take 10 seconds total!
})();

makeBatch(size: number, flushTimeout: number)

Creates a higher-order batch function aggregates Logtail logs and resolves when either size # of logs have been collected, or when flushTimeout (in ms) has elapsed -- whichever occurs first.

This is used alongside the throttler to provide an array of ILogtailLog to the function set in the .setSync() method, to be synced with Better Stack

Used internally by the @logtail/core Base class to implicitly batch logs:

// Create a throttler, for sync operations
const throttle = makeThrottle(this._options.syncMax);

// Sync after throttling
const throttler = throttle((logs: any) => {
  return this._sync!(logs);
});

// Create a batcher, for aggregating logs by buffer size/interval
const batcher = makeBatch(this._options.batchSize, this._options.batchInterval);

this._batch = batcher((logs: any) => {
  return throttler(logs);
});

LICENSE

ISC