When to use the rust version of the library
The limits of the javascript library become obvious when developing interactive applications that process large datasets.
For example the examples/globe applications operate on a 50m resolution map of the earth. On a desktop machine this is beyond the javascript version.
Current Status
Not all projections have been implemented and there are number of known bugs that I am activley working on. The majority of the library has been ported along with the associated tests. The aim is to eventaully release a "1.0" version.
but at the moment is this alpha grade software.
Before the "1.0" release breaking changes trigger the minor version to increment.
A summary of the change can be found in CHANGELOG.md
Here is a summary of things to-do before the crate is published.
The recenter state-based API refacor is almost complete.
Once fitsizeresampling() is reinstated the code-coverage metric will jump 10% back to the previous value of approx 82%
The API is not stabalised. If perfomance issues arise then the API will change. Additionaly I plan a final review to remove anything uneeded before making changes become complicated.
The clipping algorithm in clip/rejoin/mod.rs needs to be refactored.
see The intersection Problem.
Test coverage in that area is high so the algortihms is working but the data structures make extensive use of vectors ( heap objects ) containng references to other heap objects Vec<Options<Rc<RefCell<_Intersection_>>>> which is not performant.
Running the examples
See the details.
Requirements:
To view the application either create a devleopment build, or construct a static-web site as follows
Start And Run A Development Build
console
git clone https://github.com/martinfrances107/rust_d3_geo.git
cd rust_d3_geo/examples/ring/
npm install
npm run start
The last command "npm run start" will automatically open your default browser at http:://localhost::8080
Building A Static Site
Much better performance can be acheived by bulding a static web site and viewing that directly.
console
git clone https://github.com/martinfrances107/rust_d3_geo.git
cd rust_d3_geo/examples/ring
npm install
npm run build
npm run serve
This creates a static HTML site in the dist/ directory.
To view the site you cannot just point you browser at a location of the form file:://home/user/alice/dist/index.html
By security reasons, browsers prevent HTML pages with WASM files from being viewed this way. You must host the site first.
Benchmarking
See the details.
In this project, we have two benchmarks, based on the ring and graticule examples ( see above. )
Also rustd3geo_voronoi
uses this library, and that project contains a benchmark which contains an exact port of a benchmark in d3-geo-voronoi.
Based on that benchmark rust is 31% faster, or permits a 37% increase in throughput.
Flamegraph
See the details.
profile_target is binary that outputs a HTML page containing a SVG image showing the globe with graticule markings.
A flamegraph can be created with the following
bash
cd profile_target
sudo CARGO_PROFILE_RELEASE_DEBUG=true cargo flamegraph
The complexity of rendering 240 countries/polygons provides a good view in memory allocation issues.
Future Multi thread support
See the details.
On my todo list.
rayon is rust's crate for multithread support.
I have made extensive use of iterators when porting the code and rayon support the easy conversion of single threaded iterators to multithread iterators.
The Hashmaps - appear slow.
Maybe I can get performace improvements by replacing them with B-tree collections?
Architecture discussion
There is an aspect of the design that needs review. It related to the best way to implement a doubly-linked list which has cross links between nodes. A full discusion can be found here
Coding Standard
- Idomatic RUST, as defined by cargo clippy where possible.
No booleans as arguments to functions/methods, use two state enums instead.
See "Reflect" as an example.
rust
pub trait ReflectSet {
/// f64 or f32.
type T;
/// Set the projection builder to invert the x-coordinate.
fn reflect_x_set(&mut self, reflect: REFLECT) -> &mut Self;
/// Set the projection builder to invert the y-coordinate.
fn reflect_y_set(&mut self, reflect: REFLECT) -> &mut Self;
}
This allow for a clearer statement of intent :-
```rust
builder.reflectyset(REFLECT::Flipped);
```
"Type-Driven API Design" is the
preferred way of constructing state machines.
In the example below, when assembling a stream pipeline, connect() can only be called
when the state is "Unconnected". The output type's STATE is "Connected\
rust
impl StreamTransformRadians<Unconnected> {
#[inline]
/// Connect this node to the next element in the pipeline.
pub const fn connect<EP, SINK, T>(self, sink: SINK) -> StreamTransformRadians<Connected<SINK>>
where
SINK: Clone,
{
StreamTransformRadians(Connected { sink })
}
}
The "Stream" trait is only implemented when the STATE is "Connected\
Unimplemented sections of the library
See the details.
Support for a custom projection is not yet supported.
For an example of this see the test labelled "projection.fitExtent(…) custom projection"
I am trying to get a program of mine to run faster, but I want this to eventually be a true library port. So feel free to add suggestions to my todo list.
A complete list of all ported projections can be found in invert-test.rs. Out of the 15 distinct projections listed only 7 have been ported so far.
Other To-do's
See the details.
Document API changes such as
- src/projection/clipanglereset()
- src/projection/clipextentclear()
Finally
todo.md contains a more detailed list
