mirror of https://github.com/vladmandic/human
71 lines
2.5 KiB
JavaScript
71 lines
2.5 KiB
JavaScript
const threads = require('worker_threads');
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let debug = false;
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/** @type SharedArrayBuffer */
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let buffer;
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/** @type Float32Array */
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let view;
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let threshold = 0;
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let records = 0;
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const descLength = 1024; // descriptor length in bytes
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function distance(descBuffer, index, options = { order: 2 }) {
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const descriptor = new Float32Array(descBuffer);
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let sum = 0;
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for (let i = 0; i < descriptor.length; i++) {
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const diff = (options.order === 2) ? (descriptor[i] - view[index * descLength + i]) : (Math.abs(descriptor[i] - view[index * descLength + i]));
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sum += (options.order === 2) ? (diff * diff) : (diff ** options.order);
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}
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return sum;
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}
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function match(descBuffer, options = { order: 2 }) {
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let best = Number.MAX_SAFE_INTEGER;
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let index = -1;
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for (let i = 0; i < records; i++) {
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const res = distance(descBuffer, i, { order: options.order });
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if (res < best) {
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best = res;
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index = i;
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}
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if (best < threshold || best === 0) break; // short circuit
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}
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best = (options.order === 2) ? Math.sqrt(best) : best ** (1 / options.order);
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return { index, distance: best, similarity: Math.max(0, 100 - best) / 100.0 };
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}
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threads.parentPort?.on('message', (msg) => {
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if (typeof msg.descriptor !== 'undefined') { // actual work order to find a match
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const t0 = performance.now();
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const result = match(msg.descriptor);
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const t1 = performance.now();
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threads.parentPort?.postMessage({ request: msg.request, time: Math.trunc(t1 - t0), ...result });
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return; // short circuit
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}
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if (msg instanceof SharedArrayBuffer) { // called only once to receive reference to shared array buffer
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buffer = msg;
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view = new Float32Array(buffer); // initialize f64 view into buffer
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if (debug) threads.parentPort?.postMessage(`buffer: ${buffer?.byteLength}`);
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}
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if (typeof msg.records !== 'undefined') { // recived every time when number of records changes
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records = msg.records;
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if (debug) threads.parentPort?.postMessage(`records: ${records}`);
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}
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if (typeof msg.debug !== 'undefined') { // set verbose logging
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debug = msg.debug;
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if (debug) threads.parentPort?.postMessage(`debug: ${debug}`);
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}
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if (typeof msg.threshold !== 'undefined') { // set minimum similarity threshold
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threshold = msg.threshold;
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if (debug) threads.parentPort?.postMessage(`threshold: ${threshold}`);
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}
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if (typeof msg.shutdown !== 'undefined') { // got message to close worker
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if (debug) threads.parentPort?.postMessage('shutting down');
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process.exit(0);
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}
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});
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if (debug) threads.parentPort?.postMessage('started');
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