There were a few areas in Source where a function was assumed to be executed synchronously when a function was resolved. Native Promises however, by spec, will resolve at the end of a frame. There were also some strange handling of promise rejection in imagery providers that I cleaned up a bit in order to make them testable.
- In LabelCollection and EntityCluster, order of execution adjustment where made.
- Added TextureAtlas.addImageSync to support the order of execution fix in LabelCollection
- ArcGisMapServerImageryProvider.readyPromise will not reject if there is a failure unless the request cannot be retried.
- SingleTileImageryProvider.readyPromise will not reject if there is a failure unless the request cannot be retried.
The majority of the changes lie in the Specs, where unresolved promises weren’t being awaited before finishing executions, and where resolved promises are assumed to be synchronous all over the place and needed a good amount of fixes. Another issue which came up was calling Promise.reject in the body of a spec can cause node to halt execution when running via the command line.
Locked to version 6.7.0 since that is the version we are already using and
updating it requires additinal work because of the use of util.lazyResolve
in the GoogleEarthEnterpriceMetadata root parser code.
Rather than submit libraries to Source/ThirdParty, which always end up
being modified for our build system and quickly go out of date, this
change starts to use libraries via npm instead. Currently Autolinker,
earcut, when, tween.js, rbush, kdbush, quickselect, and topojson are
ported.
The main hurdle that prevented us from doing this sooner was the fact that
Cesium has a long history of not requiring a build step after every code
change and has a goal of writing valid JS code, unlike many libraries today
that mandate a bundler to turn invalid JS code into valid code.
Rather than mandate a bundler during development, this initial step adds a
"buildThirdyParty" function to the current "build" step. This function runs
third party libraries (defined in the ThirdParty/npm/ folder) through
RollUp and creates an equivalent file in `Source/ThirdPartyNpm`.
The change to end users will be non-existent, especially since the combined
Cesium.js will still re-export any third party modules as part of the
private API just like it used to.
This doesn't prevent code duplication for users using some of the same
third party libraries as Cesium. This is just an improvement as to how
depend on third party libraries internally.
I think Cesium's days of being "bundler free" are probably limited long
term, performance is the main hurdle and newer tools like esbuild may make
that no longer a problem. But that's outside the scope of this initial
goal.
See https://github.com/AnalyticalGraphicsInc/cesium/pull/8224 for details.
eslint
There are a handful of new .eslintrc.json files, mostly to identify the files that are still AMD modules (Sandcastle/Workers). These are needed because you can't change the parser type with a comment directive (since the parser is the thing reading the file). We can finally detect unusued modules! So those have all been cleaned up as well.
requirejs -> rollup & clean-css
requirejs, almond, and karma-requirejs have all been removed. We now use rollup for building and minifying (via uglify) JS code and clean-css for css. These changes are fairly straight-forward and just involve calling rollup instead of requirejs in the build process.
Overall build time is significantly faster. CI is ~11 minutes compared to ~17 in master. Running makeZipFile on my machine takes 69 seconds compared to 112 seconds in master. There's probably plenty of room for additional optimization here too.
We wrote an published a small npm module, rollup-plugin-strip-pragma, for stripping the requirejs pragmas we use out of the release builds. This is maintained in the Tools/rollup-plugin-strip-pragma directory.
As for what we produce. The built version of Cesium is now a UMD module. So it should work anywhere that hasn't made the jump to ES6 yet. For users that were already using the "legacy" combined/minified approach, nothing changes.
One awesome thing about roll-up is that it compiles all of the workers at once and automatically detects shared codes and generates separate bundles under the hood. This means the size of our worker modules shrink dramatically and Cesium itself will load them much faster. The total minified/gzipped size of all workers in master is 2.6 MB compared to 225 KB in this branch! This should be most noticeable on demos like Geometry & Appearances which load lots of workers for the various geometry typs.
roll-up is also used to build Cesium Viewer, which is now an ES6 app.
We use clean-css via gulp and it is also a straightforward change from requirejs that requires no special mention.
Workers
While the spec allows for ES6 Web Workers, no browser actually supports them yet. That means we needed a way to get our workers into non-ES6 form. Thankfully, roll-up can generate AMD modules, which means we now have a build step to compile our Worker source code back into AMD and use the existing TaskProcessor to load and execute them. This build step is part of the standard build task and is called createWorkers. During development, these "built" workers are un-optimized so you can still debug them and read the code.
Since there is a build step, that means if you are changing code that affects a worker, you need to re-run build, or you can use the build-watch task to do it automatically.
The ES6 versions of Worker code has moved into Source/WorkersES6 and we build the workers into their "old home" of Source/Workers. cesiumWorkerBootstrapper and transferTypedArrayTest which were already non-AMD ES5 scripts remain living in the Workers directory.
Surprisingly little was changed about TaskProcessor or the worker system in general, especially considering that I thought this would be one of the major hurdles.
ThirdParty
A lot of our ThirdParty either already had a hand-written wrapper for AMD (which I updated to ES6) or had UMD which created problems when importing the same code in both Node and the browser. I basically had to update the wrapper of every third-party library to fix these problems. In some cases I updated the library version itself (Autolinker, topojson). Nothing to be too concerned about, but future clean-up would be using npm versions of these libraries and auto-generating the wrappers as needed so we don't hand-edit things.
Sandcastle
Sandcastle is eternal and manages to live another day in it's ancient requirejs/dojo 1.x form. Sandcastle now automatically uses the ES6 version of Cesium if it is available and fallsback to the ES5 unminified version if it is now. The built version of Sandcastle always uses CesiumUnminified, just like master. This means Sandcastle still works in IE11 if you run the combine step first (or use the relase zip)
Removed Cesium usage from Sandcastle proper, since it wasn't really needed
Generate a VERSION propertyin the gallery index since Cesium is no longer being included.
Remove requirejs from Sandcastle bucket
Update bucket to use the built version of Cesium if it is available by fallbackto the ES6 version during development.
Standalone.html was also updated
There's a bit of room for further clean-up here, but I think this gets us into master. I did not rename bucket-requirejs.html because I'm pretty sure it would break previously shared demos. We can put in some backwards compatible code later on if we want. (But I'd rather just see a full Sandcastle rewrite).
Specs
Specs are now all ES6, except for TestWorkers, which remain standard JS worker modules. This means you can no longer run the unbuilt unit tests in IE11. No changes for Chrome and Firefox.
Since the specs use ES6 modules and built Cesium is an ES5 UMD, I added a build-specs build step which generates a combined ES5 version of the specs which rely on Cesium as a global variable. We then inject these files into jasmine instead of the standard specs and everything works exactly as it did before. SpecRunner.html has been updated to inject the correct version of the script depending on the build/release query parameters.
The Specs must always use Cesium by importing Source/Cesium.js, this is so we can replace it with the built Cesium as describe above.
There's a bunch of room for clean-up here, such as unifying our two copies of jasmine into a single helper file, but I didn't want to start doing that clean-up as part of this already overly big PR. The important thing is that we can still test the built version and still test on IE/Edge as needed.
I also found and fixed two bugs that were causing failing unit tests, one in BingMapsImageryProviderSpec.js (which was overwriting createImage andnot setting it back) and ShadowVolumeAppearance.js (which had a module level caching bug). I think these may have been the cause of random CI failures in master as well, but only time will tell.
For coverage, we had to switch to karma-coverage-istanbul-instrumenter for native ES6 support, but that's it.
Finally, I updated appveryor to build Cesium and run the built tests under IE. We still don't fail the build for IE, but we should probably fix that if we want to keep it going.
NodeJS
When NODE_ENV is production, we now require in the minified CesiumJS directly, which works great because it's now a UMD module. Otherwise, we use the excellant esmpackage to load individual modules, it was a fairly straightforward swap from our old requirejs usage. We could probably drop esm too if we don't care about debugging or if we provie source maps at some point.
Jasmine doesn't like it when an async spec (one that takes a done parameter) actually ends up being synchronous and calls `done()` before the spec returns. It mostly works, but ends up creating a deep call stack that risks causing a stach overflow.
This change makes jasmine detect when done() is called before the spec returns and treat the spec as it would a normal synchronous spec. This should improve performance a bit too because all Cesium specs are async from the perspective of Jasmine, but only some of them actually are.
Gabby Getz
Sean Lilley
Eli Bogomolny
ebogo1
Matthew Amato
Peter Gagliardi
Scott Hunter
Frederic Junod
Kevin Ring
Dan Bagnell
Scott Hunter