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diff --git a/testing/web-platform/tests/common/dispatcher/README.md b/testing/web-platform/tests/common/dispatcher/README.md new file mode 100644 index 0000000000..cfaafb6e5d --- /dev/null +++ b/testing/web-platform/tests/common/dispatcher/README.md @@ -0,0 +1,228 @@ +# `RemoteContext`: API for script execution in another context + +`RemoteContext` in `/common/dispatcher/dispatcher.js` provides an interface to +execute JavaScript in another global object (page or worker, the "executor"), +based on: + +- [WPT RFC 88: context IDs from uuid searchParams in URL](https://github.com/web-platform-tests/rfcs/pull/88), +- [WPT RFC 89: execute_script](https://github.com/web-platform-tests/rfcs/pull/89) and +- [WPT RFC 91: RemoteContext](https://github.com/web-platform-tests/rfcs/pull/91). + +Tests can send arbitrary javascript to executors to evaluate in its global +object, like: + +``` +// injector.html +const argOnLocalContext = ...; + +async function execute() { + window.open('executor.html?uuid=' + uuid); + const ctx = new RemoteContext(uuid); + await ctx.execute_script( + (arg) => functionOnRemoteContext(arg), + [argOnLocalContext]); +}; +``` + +and on executor: + +``` +// executor.html +function functionOnRemoteContext(arg) { ... } + +const uuid = new URLSearchParams(window.location.search).get('uuid'); +const executor = new Executor(uuid); +``` + +For concrete examples, see +[events.html](../../html/browsers/browsing-the-web/back-forward-cache/events.html) +and +[executor.html](../../html/browsers/browsing-the-web/back-forward-cache/resources/executor.html) +in back-forward cache tests. + +Note that `executor*` files under `/common/dispatcher/` are NOT for +`RemoteContext.execute_script()`. Use `remote-executor.html` instead. + +This is universal and avoids introducing many specific `XXX-helper.html` +resources. +Moreover, tests are easier to read, because the whole logic of the test can be +defined in a single file. + +## `new RemoteContext(uuid)` + +- `uuid` is a UUID string that identifies the remote context and should match + with the `uuid` parameter of the URL of the remote context. +- Callers should create the remote context outside this constructor (e.g. + `window.open('executor.html?uuid=' + uuid)`). + +## `RemoteContext.execute_script(fn, args)` + +- `fn` is a JavaScript function to execute on the remote context, which is + converted to a string using `toString()` and sent to the remote context. +- `args` is null or an array of arguments to pass to the function on the + remote context. Arguments are passed as JSON. +- If the return value of `fn` when executed in the remote context is a promise, + the promise returned by `execute_script` resolves to the resolved value of + that promise. Otherwise the `execute_script` promise resolves to the return + value of `fn`. + +Note that `fn` is evaluated on the remote context (`executor.html` in the +example above), while `args` are evaluated on the caller context +(`injector.html`) and then passed to the remote context. + +## Return value of injected functions and `execute_script()` + +If the return value of the injected function when executed in the remote +context is a promise, the promise returned by `execute_script` resolves to the +resolved value of that promise. Otherwise the `execute_script` promise resolves +to the return value of the function. + +When the return value of an injected script is a Promise, it should be resolved +before any navigation starts on the remote context. For example, it shouldn't +be resolved after navigating out and navigating back to the page again. +It's fine to create a Promise to be resolved after navigations, if it's not the +return value of the injected function. + +## Calling timing of `execute_script()` + +When `RemoteContext.execute_script()` is called when the remote context is not +active (for example before it is created, before navigation to the page, or +during the page is in back-forward cache), the injected script is evaluated +after the remote context becomes active. + +Multiple calls to `RemoteContext.execute_script()` will result in multiple scripts +being executed in remote context and ordering will be maintained. + +## Errors from `execute_script()` + +Errors from `execute_script()` will result in promise rejections, so it is +important to await the result. This can be `await ctx.execute_script(...)` for +every call but if there are multiple scripts to executed, it may be preferable +to wait on them in parallel to avoid incurring full round-trip time for each, +e.g. + +```js +await Promise.all( + ctx1.execute_script(...), + ctx1.execute_script(...), + ctx2.execute_script(...), + ctx2.execute_script(...), + ... +) +``` + +## Evaluation timing of injected functions + +The script injected by `RemoteContext.execute_script()` can be evaluated any +time during the remote context is active. +For example, even before DOMContentLoaded events or even during navigation. +It's the responsibility of test-specific code/helpers to ensure evaluation +timing constraints (which can be also test-specific), if any needed. + +### Ensuring evaluation timing around page load + +For example, to ensure that injected functions (`mainFunction` below) are +evaluated after the first `pageshow` event, we can use pure JavaScript code +like below: + +``` +// executor.html +window.pageShowPromise = new Promise(resolve => + window.addEventListener('pageshow', resolve, {once: true})); + + +// injector.html +const waitForPageShow = async () => { + while (!window.pageShowPromise) { + await new Promise(resolve => setTimeout(resolve, 100)); + } + await window.pageShowPromise; +}; + +await ctx.execute(waitForPageShow); +await ctx.execute(mainFunction); +``` + +### Ensuring evaluation timing around navigation out/unloading + +It can be important to ensure there are no injected functions nor code behind +`RemoteContext` (such as Fetch APIs accessing server-side stash) running after +navigation is initiated, for example in the case of back-forward cache testing. + +To ensure this, + +- Do not call the next `RemoteContext.execute()` for the remote context after + triggering the navigation, until we are sure that the remote context is not + active (e.g. after we confirm that the new page is loaded). +- Call `Executor.suspend(callback)` synchronously within the injected script. + This suspends executor-related code, and calls `callback` when it is ready + to start navigation. + +The code on the injector side would be like: + +``` +// injector.html +await ctx.execute_script(() => { + executor.suspend(() => { + location.href = 'new-url.html'; + }); +}); +``` + +## Future Work: Possible integration with `test_driver` + +Currently `RemoteContext` is implemented by JavaScript and WPT-server-side +stash, and not integrated with `test_driver` nor `testharness`. +There is a proposal of `test_driver`-integrated version (see the RFCs listed +above). + +The API semantics and guidelines in this document are designed to be applicable +to both the current stash-based `RemoteContext` and `test_driver`-based +version, and thus the tests using `RemoteContext` will be migrated with minimum +modifications (mostly in `/common/dispatcher/dispatcher.js` and executors), for +example in a +[draft CL](https://chromium-review.googlesource.com/c/chromium/src/+/3082215/). + + +# `send()`/`receive()` Message passing APIs + +`dispatcher.js` (and its server-side backend `dispatcher.py`) provides a +universal queue-based message passing API. +Each queue is identified by a UUID, and accessed via the following APIs: + +- `send(uuid, message)` pushes a string `message` to the queue `uuid`. +- `receive(uuid)` pops the first item from the queue `uuid`. +- `showRequestHeaders(origin, uuid)` and + `cacheableShowRequestHeaders(origin, uuid)` return URLs, that push request + headers to the queue `uuid` upon fetching. + +It works cross-origin, and even access different browser context groups. + +Messages are queued, this means one doesn't need to wait for the receiver to +listen, before sending the first message +(but still need to wait for the resolution of the promise returned by `send()` +to ensure the order between `send()`s). + +## Executors + +Similar to `RemoteContext.execute_script()`, `send()`/`receive()` can be used +for sending arbitrary javascript to be evaluated in another page or worker. + +- `executor.html` (as a Document), +- `executor-worker.js` (as a Web Worker), and +- `executor-service-worker.js` (as a Service Worker) + +are examples of executors. +Note that these executors are NOT compatible with +`RemoteContext.execute_script()`. + +## Future Work + +`send()`, `receive()` and the executors below are kept for COEP/COOP tests. + +For remote script execution, new tests should use +`RemoteContext.execute_script()` instead. + +For message passing, +[WPT RFC 90](https://github.com/web-platform-tests/rfcs/pull/90) is still under +discussion. diff --git a/testing/web-platform/tests/common/dispatcher/dispatcher.js b/testing/web-platform/tests/common/dispatcher/dispatcher.js new file mode 100644 index 0000000000..a0f9f43e62 --- /dev/null +++ b/testing/web-platform/tests/common/dispatcher/dispatcher.js @@ -0,0 +1,256 @@ +// Define a universal message passing API. It works cross-origin and across +// browsing context groups. +const dispatcher_path = "/common/dispatcher/dispatcher.py"; +const dispatcher_url = new URL(dispatcher_path, location.href).href; + +// Return a promise, limiting the number of concurrent accesses to a shared +// resources to |max_concurrent_access|. +const concurrencyLimiter = (max_concurrency) => { + let pending = 0; + let waiting = []; + return async (task) => { + pending++; + if (pending > max_concurrency) + await new Promise(resolve => waiting.push(resolve)); + let result = await task(); + pending--; + waiting.shift()?.(); + return result; + }; +} + +// Wait for a random amount of time in the range [10ms,100ms]. +const randomDelay = () => { + return new Promise(resolve => setTimeout(resolve, 10 + 90*Math.random())); +} + +// Sending too many requests in parallel causes congestion. Limiting it improves +// throughput. +// +// Note: The following table has been determined on the test: +// ../cache-storage.tentative.https.html +// using Chrome with a 64 core CPU / 64GB ram, in release mode: +// ┌───────────┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬────┐ +// │concurrency│ 1 │ 2 │ 3 │ 4 │ 5 │ 6 │ 10│ 15│ 20│ 30│ 50│ 100│ +// ├───────────┼───┼───┼───┼───┼───┼───┼───┼───┼───┼───┼───┼────┤ +// │time (s) │ 54│ 38│ 31│ 29│ 26│ 24│ 22│ 22│ 22│ 22│ 34│ 36 │ +// └───────────┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴────┘ +const limiter = concurrencyLimiter(6); + +// While requests to different remote contexts can go in parallel, we need to +// ensure that requests to each remote context are done in order. This maps a +// uuid to a queue of requests to send. A queue is processed until it is empty +// and then is deleted from the map. +const sendQueues = new Map(); + +// Sends a single item (with rate-limiting) and calls the associated resolver +// when it is successfully sent. +const sendItem = async function (uuid, resolver, message) { + await limiter(async () => { + // Requests might be dropped. Retry until getting a confirmation it has been + // processed. + while(1) { + try { + let response = await fetch(dispatcher_url + `?uuid=${uuid}`, { + method: 'POST', + body: message + }) + if (await response.text() == "done") { + resolver(); + return; + } + } catch (fetch_error) {} + await randomDelay(); + }; + }); +} + +// While the queue is non-empty, send the next item. This is async and new items +// may be added to the queue while others are being sent. +const processQueue = async function (uuid, queue) { + while (queue.length) { + const [resolver, message] = queue.shift(); + await sendItem(uuid, resolver, message); + } + // The queue is empty, delete it. + sendQueues.delete(uuid); +} + +const send = async function (uuid, message) { + const itemSentPromise = new Promise((resolve) => { + const item = [resolve, message]; + if (sendQueues.has(uuid)) { + // There is already a queue for `uuid`, just add to it and it will be processed. + sendQueues.get(uuid).push(item); + } else { + // There is no queue for `uuid`, create it and start processing. + const queue = [item]; + sendQueues.set(uuid, queue); + processQueue(uuid, queue); + } + }); + // Wait until the item has been successfully sent. + await itemSentPromise; +} + +const receive = async function (uuid) { + while(1) { + let data = "not ready"; + try { + data = await limiter(async () => { + let response = await fetch(dispatcher_url + `?uuid=${uuid}`); + return await response.text(); + }); + } catch (fetch_error) {} + + if (data == "not ready") { + await randomDelay(); + continue; + } + + return data; + } +} + +// Returns an URL. When called, the server sends toward the `uuid` queue the +// request headers. Useful for determining if something was requested with +// Cookies. +const showRequestHeaders = function(origin, uuid) { + return origin + dispatcher_path + `?uuid=${uuid}&show-headers`; +} + +// Same as above, except for the response is cacheable. +const cacheableShowRequestHeaders = function(origin, uuid) { + return origin + dispatcher_path + `?uuid=${uuid}&cacheable&show-headers`; +} + +// This script requires +// - `/common/utils.js` for `token()`. + +// Returns the URL of a document that can be used as a `RemoteContext`. +// +// `uuid` should be a UUID uniquely identifying the given remote context. +// `options` has the following shape: +// +// { +// host: (optional) Sets the returned URL's `host` property. Useful for +// cross-origin executors. +// protocol: (optional) Sets the returned URL's `protocol` property. +// } +function remoteExecutorUrl(uuid, options) { + const url = new URL("/common/dispatcher/remote-executor.html", location); + url.searchParams.set("uuid", uuid); + + if (options?.host) { + url.host = options.host; + } + + if (options?.protocol) { + url.protocol = options.protocol; + } + + return url; +} + +// Represents a remote executor. For more detailed explanation see `README.md`. +class RemoteContext { + // `uuid` is a UUID string that identifies the remote context and should + // match with the `uuid` parameter of the URL of the remote context. + constructor(uuid) { + this.context_id = uuid; + } + + // Evaluates the script `expr` on the executor. + // - If `expr` is evaluated to a Promise that is resolved with a value: + // `execute_script()` returns a Promise resolved with the value. + // - If `expr` is evaluated to a non-Promise value: + // `execute_script()` returns a Promise resolved with the value. + // - If `expr` throws an error or is evaluated to a Promise that is rejected: + // `execute_script()` returns a rejected Promise with the error's + // `message`. + // Note that currently the type of error (e.g. DOMException) is not + // preserved, except for `TypeError`. + // The values should be able to be serialized by JSON.stringify(). + async execute_script(fn, args) { + const receiver = token(); + await this.send({receiver: receiver, fn: fn.toString(), args: args}); + const response = JSON.parse(await receive(receiver)); + if (response.status === 'success') { + return response.value; + } + + // exception + if (response.name === 'TypeError') { + throw new TypeError(response.value); + } + throw new Error(response.value); + } + + async send(msg) { + return await send(this.context_id, JSON.stringify(msg)); + } +}; + +class Executor { + constructor(uuid) { + this.uuid = uuid; + + // If `suspend_callback` is not `null`, the executor should be suspended + // when there are no ongoing tasks. + this.suspend_callback = null; + + this.execute(); + } + + // Wait until there are no ongoing tasks nor fetch requests for polling + // tasks, and then suspend the executor and call `callback()`. + // Navigation from the executor page should be triggered inside `callback()`, + // to avoid conflict with in-flight fetch requests. + suspend(callback) { + this.suspend_callback = callback; + } + + resume() { + } + + async execute() { + while(true) { + if (this.suspend_callback !== null) { + this.suspend_callback(); + this.suspend_callback = null; + // Wait for `resume()` to be called. + await new Promise(resolve => this.resume = resolve); + + // Workaround for https://crbug.com/1244230. + // Without this workaround, the executor is resumed and the fetch + // request to poll the next task is initiated synchronously from + // pageshow event after the page restored from BFCache, and the fetch + // request promise is never resolved (and thus the test results in + // timeout) due to https://crbug.com/1244230. The root cause is not yet + // known, but setTimeout() with 0ms causes the resume triggered on + // another task and seems to resolve the issue. + await new Promise(resolve => setTimeout(resolve, 0)); + + continue; + } + + const task = JSON.parse(await receive(this.uuid)); + + let response; + try { + const value = await eval(task.fn).apply(null, task.args); + response = JSON.stringify({ + status: 'success', + value: value + }); + } catch(e) { + response = JSON.stringify({ + status: 'exception', + name: e.name, + value: e.message + }); + } + await send(task.receiver, response); + } + } +} diff --git a/testing/web-platform/tests/common/dispatcher/dispatcher.py b/testing/web-platform/tests/common/dispatcher/dispatcher.py new file mode 100644 index 0000000000..9fe7a38ac8 --- /dev/null +++ b/testing/web-platform/tests/common/dispatcher/dispatcher.py @@ -0,0 +1,53 @@ +import json +from wptserve.utils import isomorphic_decode + +# A server used to store and retrieve arbitrary data. +# This is used by: ./dispatcher.js +def main(request, response): + # This server is configured so that is accept to receive any requests and + # any cookies the web browser is willing to send. + response.headers.set(b"Access-Control-Allow-Credentials", b"true") + response.headers.set(b'Access-Control-Allow-Methods', b'OPTIONS, GET, POST') + response.headers.set(b'Access-Control-Allow-Headers', b'Content-Type') + response.headers.set(b"Access-Control-Allow-Origin", request.headers.get(b"origin") or '*') + + if b"cacheable" in request.GET: + response.headers.set(b"Cache-Control", b"max-age=31536000") + else: + response.headers.set(b'Cache-Control', b'no-cache, no-store, must-revalidate') + + # CORS preflight + if request.method == u'OPTIONS': + return b'' + + uuid = request.GET[b'uuid'] + stash = request.server.stash; + + # The stash is accessed concurrently by many clients. A lock is used to + # avoid unterleaved read/write from different clients. + with stash.lock: + queue = stash.take(uuid, '/common/dispatcher') or []; + + # Push into the |uuid| queue, the requested headers. + if b"show-headers" in request.GET: + headers = {}; + for key, value in request.headers.items(): + headers[isomorphic_decode(key)] = isomorphic_decode(request.headers[key]) + headers = json.dumps(headers); + queue.append(headers); + ret = b''; + + # Push into the |uuid| queue, the posted data. + elif request.method == u'POST': + queue.append(request.body) + ret = b'done' + + # Pull from the |uuid| queue, the posted data. + else: + if len(queue) == 0: + ret = b'not ready' + else: + ret = queue.pop(0) + + stash.put(uuid, queue, '/common/dispatcher') + return ret; diff --git a/testing/web-platform/tests/common/dispatcher/executor-service-worker.js b/testing/web-platform/tests/common/dispatcher/executor-service-worker.js new file mode 100644 index 0000000000..0b47d66b65 --- /dev/null +++ b/testing/web-platform/tests/common/dispatcher/executor-service-worker.js @@ -0,0 +1,24 @@ +importScripts('./dispatcher.js'); + +const params = new URLSearchParams(location.search); +const uuid = params.get('uuid'); + +// The fetch handler must be registered before parsing the main script response. +// So do it here, for future use. +fetchHandler = () => {} +addEventListener('fetch', e => { + fetchHandler(e); +}); + +// Force ServiceWorker to immediately activate itself. +addEventListener('install', event => { + skipWaiting(); +}); + +let executeOrders = async function() { + while(true) { + let task = await receive(uuid); + eval(`(async () => {${task}})()`); + } +}; +executeOrders(); diff --git a/testing/web-platform/tests/common/dispatcher/executor-worker.js b/testing/web-platform/tests/common/dispatcher/executor-worker.js new file mode 100644 index 0000000000..ea065a6bf1 --- /dev/null +++ b/testing/web-platform/tests/common/dispatcher/executor-worker.js @@ -0,0 +1,12 @@ +importScripts('./dispatcher.js'); + +const params = new URLSearchParams(location.search); +const uuid = params.get('uuid'); + +let executeOrders = async function() { + while(true) { + let task = await receive(uuid); + eval(`(async () => {${task}})()`); + } +}; +executeOrders(); diff --git a/testing/web-platform/tests/common/dispatcher/executor.html b/testing/web-platform/tests/common/dispatcher/executor.html new file mode 100644 index 0000000000..5fe6a95efa --- /dev/null +++ b/testing/web-platform/tests/common/dispatcher/executor.html @@ -0,0 +1,15 @@ +<script src="./dispatcher.js"></script> +<script> + +const params = new URLSearchParams(window.location.search); +const uuid = params.get('uuid'); + +let executeOrders = async function() { + while(true) { + let task = await receive(uuid); + eval(`(async () => {${task}})()`); + } +}; +executeOrders(); + +</script> diff --git a/testing/web-platform/tests/common/dispatcher/remote-executor.html b/testing/web-platform/tests/common/dispatcher/remote-executor.html new file mode 100644 index 0000000000..8b0030390d --- /dev/null +++ b/testing/web-platform/tests/common/dispatcher/remote-executor.html @@ -0,0 +1,12 @@ +<!DOCTYPE html> +<html> +<meta charset="utf-8"> +<body> +</body> +<script src="./dispatcher.js"></script> +<script> + const params = new URLSearchParams(window.location.search); + const uuid = params.get('uuid'); + const executor = new Executor(uuid); // `execute()` is called in constructor. +</script> +</html> |