This commit adds a significant portion of the existing MicroPython asyncio
module to the webassembly port, using parts of the existing asyncio code
and some custom JavaScript parts.
The key difference to the standard asyncio is that this version uses the
JavaScript runtime to do the actual scheduling and waiting on events, eg
Promise fulfillment, timeouts, fetching URLs.
This implementation does not include asyncio.run(). Instead one just uses
asyncio.create_task(..) to start tasks and then returns to the JavaScript.
Then JavaScript will run the tasks.
The implementation here tries to reuse as much existing asyncio code as
possible, and gets all the semantics correct for things like cancellation
and asyncio.wait_for. An alternative approach would reimplement Task,
Event, etc using JavaScript Promise's. That approach is very difficult to
get right when trying to implement cancellation (because it's not possible
to cancel a JavaScript Promise).
Signed-off-by: Damien George <damien@micropython.org>
With this commit, `interpreter.runPythonAsync(code)` can now be used to run
Python code that uses `await` at the top level. That will yield up to
JavaScript and produce a thenable, which the JavaScript runtime can then
resume. Also implemented is the ability for Python code to await on
JavaScript promises/thenables. For example, outer JavaScript code can
await on `runPythonAsync(code)` which then runs Python code that does
`await js.fetch(url)`. The entire chain of calls will be suspended until
the fetch completes.
Signed-off-by: Damien George <damien@micropython.org>
This commit improves the webassembly port by adding:
- Proxying of Python objects to JavaScript with a PyProxy type that lives
on the JavaScript side. PyProxy implements JavaScript Proxy traps such
as has, get, set and ownKeys, to make Python objects have functionality
on the JavaScript side.
- Proxying of JavaScript objects to Python with a JsProxy type that lives
on the Python side. JsProxy passes through calls, attributes,
subscription and iteration from Python to JavaScript.
- A top-level API on the JavaScript side to construct a MicroPython
interpreter instance via `loadMicroPython()`. That function returns an
object that can be used to execute Python code, access the Python globals
dict, access the Emscripten filesystem, and other things. This API is
based on the API provided by Pyodide (https://pyodide.org/). As part of
this, the top-level file is changed from `micropython.js` to
`micropython.mjs`.
- A Python `js` module which can be used to access all JavaScript-side
symbols, for example the DOM when run within a browser.
- A Python `jsffi` module with various helper functions like
`create_proxy()` and `to_js()`.
- A dedenting lexer which automatically dedents Python source code if every
non-empty line in that source starts with a common whitespace prefix.
This is very helpful when Python source code is indented within a string
within HTML or JavaScript for formatting reasons.
Signed-off-by: Damien George <damien@micropython.org>
This commit cleans up and generalises the Makefile, adds support for
variants (following the unix port) and adds the "standard" variant as the
default variant.
Signed-off-by: Damien George <damien@micropython.org>
It's no longer supported by Emscripten (at least at 3.1.55). And it's not
needed when the output is WASM, which it is by default.
Signed-off-by: Damien George <damien@micropython.org>
Emscripten strongly advises the use of optimisation when compiling with
ASYNCIFY enabled. Testing the difference betwen O3 and Os for various
configurations gives:
flags firmware.wasm micropython.js perf
-O3 -s ASYNCIFY 1342003 212845 0 (baseline)
-O3 -s ASYNCIFY -s WASM=0 - 7064750 -30%
-O3 367131 196569 +140%
-O3 -s WASM=0 - 2818260 +30%
-Os -s ASYNCIFY 1135450 213064 +40%
-Os -s ASYNCIFY -s WASM=0 - 6239768 -30%
-Os 295028 196569 +180%
-Os -s WASM=0 - 2271358 +30%
The first row is prior to this commit. The second and third columns show
firmware size (add them to get the total size). The fourth column shows
the approximate change in performance compared to the baseline. The
performance was measured using run-perfbench.py and the error was large, up
to 20%, although general trends in the change in performance could still be
seen.
In summary, using using Os instead of O3 makes it a little bit faster in
all cases, and smaller output (wasm/js) in all cases.
Signed-off-by: Damien George <damien@micropython.org>
Damien George