How to make Firefox builds 17% faster

13 hours ago

Buildcache's Lua plugin system allows caching of non-compiler programs, demonstrated by caching Firefox's WebIDL binding code generation.
A small Makefile change passes a command wrapper to the webidl action, enabling buildcache to intercept and cache the Python codegen step.
A custom Lua wrapper for WebIDL specifies inputs (.webidl files, Python scripts) and outputs (generated C++ files) for buildcache to hash and cache.
Benchmarks show buildcache with the WebIDL wrapper reduces warm build times to 1m12s, a significant speedup over other caching tools.
Setup involves configuring buildcache with the Lua wrapper via config file or environment variable, and adjusting cache size for large entries.
The Lua plugin system can extend caching to other deterministic build steps in Firefox, improving the edit-compile-test cycle.

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