Experimental JS API based on tracking values #2013
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Signed-off-by: Jakub Gonet <jakub.gonet@swmansion.com>
Signed-off-by: Jakub Gonet <jakub.gonet@swmansion.com>
It's a field in emscripten platform struct. It could be a callback entirely in JS but we use threads. Threads are emulated via webworkers which have their own contexts and variables aren't shared with each other. This means that we would lose uniqueness of the keys. This commit also changes output format from file loaded and ran at <script src=...> to ES6 classes which have greater control over initialization of Wasm. Signed-off-by: Jakub Gonet <jakub.gonet@swmansion.com>
Signed-off-by: Jakub Gonet <jakub.gonet@swmansion.com>
Signed-off-by: Jakub Gonet <jakub.gonet@swmansion.com>
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cc @pguyot |
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This PR upstreams API we're using in Popcorn.
It doesn't have tests or extended docs. I'd gladly take some instructions about testing Wasm. Docs will be added after first round of review – I need to know if approach is sane at all.
Design notes
We needed some API to track values in JS with their lifetime in the VM. This was achieved by using new type of resource –
TrackedValue. Popcorn also wants to customize JS behavior without maintaining custom Emscripten hooks in.cfiles – we extracted them to functions inatomvm.pre.js. You can see our implementation in Popcorn repo.We also need JS to have access to DOM. We hardcoded thread executing JS to be main thread (or in our case, iframe thread).
We were thinking about relaxing that constraint but it'd need
js_tracked_evalto forward script to it's destination JS context (e.g.postMessage()to iframe).js_get_tracked_objectsworks by batchingTrackedObjects and their status (missing, bad type, etc). This allows to reduce communication overhead between JS and Wasm.We also needed to use ES modules instead of current, IIFE format. It makes it easier to load in iframes and to use in modern JS projects.
These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).
SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later