Plan B for UUIDs: double AES-128

Per Vognsen sent me a link to Maziarz et al’s Hashing Modulo Alpha-Equivalence because its Lemma 6.6 claims to solve a thorny problem we have both encountered several times. Essentially, the lemma says that computing the natural recursive combination of hash values over \(2^b\) bits for two distinct trees (ADT instances) \(a\) and \(b\) yields a...

Sometimes you just want to abuse Linux perf to make it do a thing it’s not designed for, and a proper C program would represent an excessive amount of work. Here are two tricks I find helpful when jotting down hacky analysis scripts. Programmatically interacting with addr2line -i Perf can resolve symbols itself, but addr2line is a lot more...

Originally posted on the Backtrace I/O tech blog. All long-lived programs are either implemented in dynamic languages,1 or eventually Greenspun themselves into subverting static programming languages to create a dynamic system (e.g., Unix process trees). The latter approach isn’t a bad idea, but it’s easy to introduce more flexibility than...

Originally posted on the Backtrace I/O tech blog. Slitter is Backtrace’s deliberately middle-of-the-road thread-caching slab allocator, with explicit allocation class tags (rather than derived from the object’s size class). It’s mostly written in Rust, and we use it in our C backend server. Slitter’s design is about as standard as it gets: we...