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add preload function
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It makes sense to start loading the runner scripts as soon as the exam
starts, instead of waiting for the student to run code.

`Numbas.extensions.programming.preload(language, packages)` starts
loading the given language, and the optional list of packages.
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@christianp
christianp committed Nov 23, 2023
1 parent ebf9748 commit 50ae81d
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17 changes: 16 additions & 1 deletion README.md
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Expand Up @@ -33,6 +33,21 @@ pre_submit:
]
```

## Pre-loading a language

If the scripts for a language have not already been loaded when you try to run some code, then they are loaded automatically.
However, this can take a long time, depending on the speed of the student's internet connection.

You can pre-load a language with the function `Numbas.extensions.programming.preload(language, packages)`. The list of packages to load is optional.

For example, if your question will use R with the packages `ggplot2` and `dplyr`, put this line in your question's JavaScript preamble:

```
Numbas.extensions.programming.preload('webr', ['ggplot2', 'dply']);
```

The necessary files will start loading as soon as part of the exam loading process, so will usually be ready to use by the time the student submits some code.

## The code editor input method

The extension provides the [Ace editor](https://ace.c9.io/) as an input method for custom part types.
Expand All @@ -46,7 +61,7 @@ It has three options:

### `run_code(language,codes)`

* `language` is a string containing the name of the code runner to use.
* `language` is a string containing the name of the code runner to use. The available code runners are `"pyodide"`, for Python, and `"webr"`, for R.
* `codes` is a list of strings of code.

Run some blocks of code and return the results in a `promise`.
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111 changes: 83 additions & 28 deletions programming.js
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Expand Up @@ -293,6 +293,13 @@ Numbas.addExtension('programming', ['display', 'util', 'jme'], function(programm
this.clear_buffers();
}

/** Preload the files necessary to run code in this language, and optionally install a list of packages.
*
* @param {Array.<string>} [packages] - Names of packages to install.
*/
async preload(packages) {
}

/** Clear the STDOUT and STDERR buffers.
*/
clear_buffers() {
Expand Down Expand Up @@ -444,41 +451,73 @@ Numbas.addExtension('programming', ['display', 'util', 'jme'], function(programm
class PyodideRunner extends CodeRunner {
constructor() {
super();
var worker = this.worker = new Worker(Numbas.getStandaloneFileURL('programming', 'pyodide_worker.js'));
}

/* // Needs a cross-origin isolated context, which I can't work out how to achieve.
this.interruptBuffer = new Uint8Array(new SharedArrayBuffer(1));
worker.postMessage({
command: "setInterruptBuffer",
interruptBuffer: this.interruptBuffer
});
*/

worker.onmessage = (event) => {
const job_id = event.data.job_id;
const job = this.get_job(job_id);
if(event.data.error) {
if(event.data.error_name == 'ConversionError') {
job.resolve({
result: null,
job_id,
stdout: event.data.stdout,
stderr: event.data.stderr
});
load_pyodide(packages) {
if(!this.pyodidePromise) {
this.pyodidePromise = new Promise((resolve, reject) => {
var worker = this.worker = new Worker(Numbas.getStandaloneFileURL('programming', 'pyodide_worker.js'));

/* // Needs a cross-origin isolated context, which I can't work out how to achieve.
this.interruptBuffer = new Uint8Array(new SharedArrayBuffer(1));
worker.postMessage({
command: "setInterruptBuffer",
interruptBuffer: this.interruptBuffer
});
*/
worker.postMessage({
command: 'init',
options: {
packages: packages || []
}
});

worker.onmessage = (event) => {
const job_id = event.data.job_id;
const job = this.get_job(job_id);
if(event.data.error) {
if(event.data.error_name == 'ConversionError') {
job.resolve({
result: null,
job_id,
stdout: event.data.stdout,
stderr: event.data.stderr
});
}
job.reject(event.data);
} else {
job.resolve(event.data);
}
}
job.reject(event.data);
} else {
job.resolve(event.data);

resolve(worker);
});
} else {
if(packages) {
this.pyodidePromise.then(worker => {
worker.postMessage({
command: 'loadPackages',
packages: packages
});
});
}
}
return this.pyodidePromise;
}

async preload(packages) {
const worker = await this.load_pyodide(packages);
}

run_code(code, session) {
const job = this.new_job();
this.worker.postMessage({
command: 'runPython',
job_id: job.id,
namespace_id: session.namespace_id,
code: code
this.load_pyodide().then(worker => {
worker.postMessage({
command: 'runPython',
job_id: job.id,
namespace_id: session.namespace_id,
code: code
});
});
return job;
}
Expand Down Expand Up @@ -538,6 +577,17 @@ Numbas.addExtension('programming', ['display', 'util', 'jme'], function(programm
return this.webRPromise;
}

/** Preload the files necessary to run code in this language, and optionally install a list of packages.
*
* @param {Array.<string>} [packages] - Names of packages to install.
*/
async preload(packages) {
const webR = await this.load_webR();
if(packages !== undefined) {
await webR.installPackages(packages);
}
}

async r_to_js(obj) {
switch(await obj.type()) {
case "list":
Expand Down Expand Up @@ -697,6 +747,11 @@ Numbas.addExtension('programming', ['display', 'util', 'jme'], function(programm
}
}

/** Preload the given language, and load the given list of packages.
*/
var preload = programming.preload = function(language, packages) {
language_runners[language].preload(packages);
};

//////////////////////////// SERIALIZE JME TO OTHER LANGUAGES

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46 changes: 32 additions & 14 deletions standalone_scripts/pyodide_worker.js
View file
@@ -1,23 +1,31 @@
importScripts("https://cdn.jsdelivr.net/pyodide/v0.21.0/full/pyodide.js");
const pyodide_version = 'v0.24.1';
const pyodide_indexURL = `https://cdn.jsdelivr.net/pyodide/${pyodide_version}/full/`;
importScripts(pyodide_indexURL + 'pyodide.js');

self.stdout = [];
self.stderr = [];

self.pyodidePromise;
self.pyodidePromise = null;

async function init() {
if(self.pyodidePromise) {
return self.pyodidePromise;
}
self.pyodidePromise = new Promise(async (resolve,reject) => {
self.pyodide = await loadPyodide({
indexURL: "https://cdn.jsdelivr.net/pyodide/v0.21.0/full/",
async function init(options, preamble) {
if(!self.pyodidePromise) {
preamble = preamble || "import os; os.environ['MPLBACKEND'] = 'AGG'";

const default_options = {
indexURL: pyodide_indexURL,
stdout: s => self.stdout.push(s),
stderr: s => self.stderr.push(s)
};
const final_options = Object.assign(default_options, options);

self.pyodidePromise = new Promise((resolve,reject) => {
loadPyodide(final_options).then(pyodide => {
self.pyodide = pyodide;
self.pyodide.runPython(preamble);
resolve(self.pyodide);
});
});
self.pyodide.runPython("import os; os.environ['MPLBACKEND'] = 'AGG'");
resolve(self.pyodide);
});
}
return self.pyodidePromise;
}

Expand All @@ -32,15 +40,25 @@ self.get_namespace = async function(id) {
}

self.onmessage = async (event) => {
await init();

const {command} = event.data;

switch(command) {
case 'init':
await init(event.data.options);
break;

case 'loadPackages':
await init();
self.pyodide.loadPackage(event.data.packages);
break;

case 'setInterruptBuffer':
await init();
self.pyodide.setInterruptBuffer(event.data.interruptBuffer);
break;

case 'runPython':
await init();
const { job_id, code, namespace_id } = event.data;

self.stdout = [];
Expand Down

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