Using a stunt webserver which artificially introduces a 3s delay just
before the last line of the HTML output, I have reproduced a
uwer-reported loading/startup race bug:
Previously the wasm loading was started by the <script> element,
synchronously. If the wasm loading is fast, and finishes before the
HTML loading, the onRuntimeInitialized event may occur before
initPuzzles. But initPuzzles sets up the event handler.
Fix this bug, and introduce a new comment containing an argument for
the correctness of the new approach.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
How embarrassing. When I updated the Emscripten build to use WASM, a
major reason I bothered to do it at all was that I'd heard that WASM
was capable of reallocating its memory arena larger on the fly. Turns
out that it _can_, but only if you specifically set the option in
Emscripten to allow it.
With this option set, I can finish a 25x25 Galaxies, where previously
the game would crash part way through (and not even a very large part)
with errors about memory growth in the Javascript console.
Various cmake variables that I was informally expecting users to set
on the cmake command line (e.g. cmake -DSTRICT=ON, or cmake
-DPUZZLES_GTK_VERSION=2) are now labelled explicitly with the CACHE
tag, and provided with a documentation string indicating what they're
for.
One effect of this is that GUI-like interfaces to your cmake build
directory, such as ccmake or cmake-gui, will show those variables
explicitly to give you a hint that you might want to change them.
Another is that when you do change them, cmake will recognise that it
needs to redo the rest of its configuration. Previously, if you sat in
an existing cmake build directory and did 'cmake -DSTRICT=ON .'
followed by 'cmake -DSTRICT=OFF .', nothing would happen, even though
you obviously meant it to.
I presume this will improve performance. Also, if I've understood
correctly, WASM-based compiled web code is capable of automatically
growing its memory, which the previous asm.js build of the puzzles
could not do, and occasionally caused people to complain that if they
tried to play a _really big_ game in their browser, the JS would
eventually freeze because the emulated memory ran out.
I've been putting off doing this for ages because my previous
Emscripten build setup was so finicky that I didn't like to meddle
with it. But now that the new cmake system in this source tree makes
things generally easier, and particularly since I've just found out
that the up-to-date Emscripten is available as a Docker image (namely
"emscripten/emsdk"), this seemed like a good moment to give it a try.
The source and build changes required for this update weren't too
onerous. I was half expecting a huge API upheaval, and indeed there
was _some_ change, but very little:
- in the JS initPuzzle function, move the call to Module.callMain()
into Module.onRuntimeInitialized instead of doing it at the top
level, because New Emscripten's .js output likes to load the
accompanying .wasm file asynchronously, so you can't call the WASM
main() until it actually exists.
- in the JS-side library code, replace all uses of Emscripten's
Pointer_stringify() function with the new name UTF8ToString(). (The
new version also has an ASCIIToString(), so I guess the reason for
the name change is that now you get to choose which character set
you meant. I need to use UTF-8, so that the × and ÷ signs in Keen
will work.)
- set EXTRA_EXPORTED_RUNTIME_METHODS=[cwrap,callMain] on the emcc
link command line, otherwise they aren't available for my JS setup
code to call.
- (removed -s ASM_JS=1 from the link options, though I'm not actually
sure it made any difference one way or the other in the new WASM
world)
- be prepared for a set of .wasm files to show up as build products
alongside the .js ones.
- stop building with -DCMAKE_BUILD_TYPE=Release! I'm not sure why
that was needed, but if I leave that flag on my cmake command line,
the output .js file fails to embed my emccpre.js, so the initial
call to initPuzzle() fails from the HTML wrapper page, meaning
nothing at all happens.
At least, for the Unix build, so as to support Debian stable and a
couple of prior Ubuntu LTSes.
Not much needed to change in the cmake scripts; the only noticeable
difference was that the 'install' command needs an explicit RUNTIME
DESTINATION.
The puzzle icons are built by compiling and running a preliminary
set of puzzle binaries. We can't do that if the binaries won't run
on the build host.
A distro maintainer reminds me that downstreams often want to rename
my quite generic executable names to avoid clashes in bin directories.
Added a cmake option -DOUTPUT_NAME to make that easy.
It's better to be lax for normal users trying to build the puzzles
from source to actually run them. That way, warning changes in some
particular compiler I haven't seen yet won't break the build.
Instead, I've invented a cmake setting -DSTRICT=ON which turns on all
those flags. So I can build with them myself, to ensure the code is as
portable as possible. And that flag is set in Buildscr, so that my
official builds won't complete until that warning mode is satisfied.
This reinstates the feature of the previous build system, that the C
icon files for the GTK puzzles were included in the source tarball, so
that users building from that instead of from the raw git repo would
not need to run the fiddly piece of build that regenerates them.
Running that fiddly piece of build is much easier in the CMake world
(because it's integrated with the main makefile), but it has a build
dependency on ImageMagick which is easily avoided.
The makefile will still build the icons if it _can_. But in the case
where it can't, it will use pre-built icon source files if they're
available, and only fall back to no-icon.c if it can't even do that.
(So a user checking out from git and building without ImageMagick
present will still be able to build _something_ playable.)
This completely removes the old system of mkfiles.pl + Recipe + .R
files that I used to manage the various per-platform makefiles and
other build scripts in this code base. In its place is a
CMakeLists.txt setup, which is still able to compile for Linux,
Windows, MacOS, NestedVM and Emscripten.
The main reason for doing this is because mkfiles.pl was a horrible
pile of unmaintainable cruft. It was hard to keep up to date (e.g.
didn't reliably support the latest Visual Studio project files); it
was so specific to me that nobody else could maintain it (or was even
interested in trying, and who can blame them?), and it wasn't even
easy to _use_ if you weren't me. And it didn't even produce very good
makefiles.
In fact I've been wanting to hurl mkfiles.pl in the bin for years, but
was blocked by CMake not quite being able to support my clang-cl based
system for cross-compiling for Windows on Linux. But CMake 3.20 was
released this month and fixes the last bug in that area (it had to do
with preprocessing of .rc files), so now I'm unblocked!
CMake is not perfect, but it's better at mkfiles.pl's job than
mkfiles.pl was, and it has the great advantage that lots of other
people already know about it.
Other advantages of the CMake system:
- Easier to build with. At least for the big three platforms, it's
possible to write down a list of build commands that's actually the
same everywhere ("cmake ." followed by "cmake --build ."). There's
endless scope for making your end-user cmake commands more fancy
than that, for various advantages, but very few people _have_ to.
- Less effort required to add a new puzzle. You just add a puzzle()
statement to the top-level CMakeLists.txt, instead of needing to
remember eight separate fiddly things to put in the .R file. (Look
at the reduction in CHECKLST.txt!)
- The 'unfinished' subdirectory is now _built_ unconditionally, even
if the things in it don't go into the 'make install' target. So
they won't bit-rot in future.
- Unix build: unified the old icons makefile with the main build, so
that each puzzle builds without an icon, runs to build its icon,
then relinks with it.
- Windows build: far easier to switch back and forth between debug
and release than with the old makefiles.
- MacOS build: CMake has its own .dmg generator, which is surely
better thought out than my ten-line bodge.
- net reduction in the number of lines of code in the code base. In
fact, that's still true _even_ if you don't count the deletion of
mkfiles.pl itself - that script didn't even have the virtue of
allowing everything else to be done exceptionally concisely.
