81 lines
1.9 KiB
JavaScript
81 lines
1.9 KiB
JavaScript
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/**
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* This example demonstrates how to run math.js in a child process with limited
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* execution time.
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*
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* Prerequisites:
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*
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* npm install express workerpool
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*
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* Start the server:
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*
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* node ./server.js
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*
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* Make a request to the server:
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*
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* GET http://localhost:8080/mathjs?expr=sqrt(16)
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*
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* Note that the query parameter `expr` should be properly url encoded.
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*/
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const path = require('path')
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let express
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let workerpool
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try {
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express = require('express')
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workerpool = require('workerpool')
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} catch (err) {
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console.log('Error: To run this example, install express and workerpool first via:\n\n' +
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' npm install express workerpool\n')
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process.exit()
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}
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const app = express()
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const pool = workerpool.pool(path.join(__dirname, '/math_worker.js'))
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const TIMEOUT = 10000 // milliseconds
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/**
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* GET /mathjs?expr=...
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*/
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app.get('/mathjs', function (req, res) {
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const expr = req.query.expr
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if (expr === undefined) {
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return res.status(400).send('Error: Required query parameter "expr" missing in url.')
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}
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pool.exec('evaluate', [expr])
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.timeout(TIMEOUT)
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.then(function (result) {
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res.send(result)
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})
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.catch(function (err) {
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res.status(400).send(formatError(err))
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})
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})
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/**
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* Format error messages as string
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* @param {Error} err
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* @return {String} message
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*/
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function formatError (err) {
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if (err instanceof workerpool.Promise.TimeoutError) {
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return 'TimeoutError: Evaluation exceeded maximum duration of ' + TIMEOUT / 1000 + ' seconds'
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} else {
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return err.toString()
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}
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}
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// handle uncaught exceptions so the application cannot crash
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process.on('uncaughtException', function (err) {
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console.log('Caught exception: ' + err)
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console.trace()
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})
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// start the server
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const PORT = process.env.PORT || 8080
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app.listen(PORT, function () {
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console.log('Listening at http://localhost:' + PORT)
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console.log('Example request:\n GET http://localhost:' + PORT + '/mathjs?expr=sqrt(16)')
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})
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