Developers’s guide


An end-user software distribution that makes use of HashDist under the hood, e.g., python-hpcmp
The result of a build process, identified by a hash of the inputs to the build
A “prefix” directory structure ready for use through $PATH, containing subdirectories bin, lib, and so on with all/some of the software one wants to use.
Used in the loose sense; a program/library, e.g., NumPy, Python etc.; what is not meant is a specific package format like .spkg, .egg and so on (which is left undefined in the bottom two HashDist layers)

Design principles

  • Many small components with one-way dependencies, accessible through command line and as libraries (initially for Python, but in principle for more languages too).
  • Protocols between components are designed so that one can imagine turning individual components into server applications dealing with high loads.
  • However, implementations of those protocols are currently kept as simple as possible.
  • HashDist is a language-neutral solution; Python is the implementation language chosen but the core tools can (in theory) be rewritten in C or Ruby without the users noticing any difference
  • The components are accessible through a common hit command-line tool. This accesses both power-user low-level features and the higher-level “varnish”, without implying any deep coupling between them (just like git).

Powerusers’ guide, layer by layer

HashDist consists of two (eventually perhaps three) layers. The idea is to provide something useful for as many as possible. If a distribution only uses the the core layer (or even only some of the components within it) it can keep on mostly as before, but get a performance boost from the caching aspect. If the distribution wants to buy into the greater HashDist vision, it can use the profile specification layer. Finally, for end-users, a final user-interface layer is needed to make things friendly. Here HashDist will probably remain silent for some time, but some standards, best practices and utilities may emerge. For now, a user interface ideas section is included below.