Detailed Description

Architecture decision records

Short numbered documents recording the decisions behind Orrery's design, each with its context, the alternatives that were rejected, and what follows from the choice.

An ADR is written when a decision has a credible alternative that a reviewer might reasonably have expected instead. It is never edited after it is merged; a decision that changes is recorded in a new ADR that supersedes the old one.

To add one, copy 0000-template.md, take the next free number, and link it from the table below and from the pull request that introduces it.

Number	Title	Status
0001	Record architecture decisions	Accepted
0002	Pin dependencies to exact commits fetched at configure time	Accepted
0003	Carry build settings on interface targets rather than global flags	Accepted
0004	Store particles as one array per component	Accepted
0005	Allocate particle arrays on cache-line boundaries	Accepted
0006	Select the scalar precision when the project is configured	Accepted
0007	Work in units where the gravitational constant is one	Accepted
0008	Share one softening definition between the solver and the diagnostics	Accepted
0009	Generate the random distributions in the project rather than with the standard library	Accepted
0010	Give initial conditions their own layer	Accepted
0011	Prefer a symplectic second-order integrator to a non-symplectic fourth-order one	Accepted
0012	Give the integrators an abstract acceleration field of their own	Accepted
0013	Carry the acceleration between steps as an interface invariant	Accepted
0014	Give the force solvers an interface of their own above the acceleration field	Accepted
0015	Compute every pair from both ends rather than applying Newton's third law	Accepted
0016	Balance the threads dynamically by stealing ranges	Accepted
0017	Thread the solver through an executor it does not own	Accepted
0018	Compile the vector kernel apart and choose it at run time	Accepted
0019	Report the median with its dispersion, and measure the throttling	Accepted
0020	Keep the arithmetic IEEE and measure what vectorising changed	Accepted
0021	Sort a copy of the configuration rather than the caller's particles	Accepted
0022	Rebuild the tree on every force evaluation	Accepted
0023	Open a cell on the distance to its centre of mass, corrected for where that is	Accepted
0024	Make quadrupole moments an option that is off by default	Accepted
0025	Write the GPU backend in SYCL	Accepted
0026	Put the GPU behind the solver interface, not behind the executor	Accepted
0027	Stage particle data into the solver's own shared allocations	Accepted
0028	Build the tree on the host and walk it on the device	Accepted
0029	Mask the accepted cells rather than descending together	Accepted
0030	Send the node array to the device narrowed rather than transposed	Accepted
0031	Define a configuration format rather than adopting one	Accepted
0032	Store the whole state in a checkpoint, accelerations included	Accepted
0033	Keep the trajectory and the checkpoint apart	Accepted
0034	Draw with OpenGL 3.3 through GLFW	Accepted
0035	Resolve the OpenGL entry points by hand	Accepted
0036	Tone map exported frames on the host	Accepted
0037	Write frames as PPM and leave the encoding to an external tool	Accepted
0038	Sample the galaxy as a scenario rather than as an equilibrium model	Accepted
0039	Bind to Python with pybind11	Accepted
0040	Expose the component arrays rather than arrays of triples	Accepted
0041	Give a running simulation's state a read-only type of its own	Accepted
0042	Package the whole project from the repository root	Accepted
0043	Generate the site with the tool that generates the reference	Accepted
0044	Write the validation report rather than generating it	Accepted
0045	Keep the browser client in this repository	Accepted
0046	Put the renderer's device behind one interface	Accepted
0047	Decode trajectories off the main thread	Accepted
0048	Read the diagnostics the run wrote	Accepted
0049	Put the run and the moment in the address	Accepted