#cell #threads #mistakes #tearing #torn

no-std tearor

Easily turn data races into data corruption!

1 unstable release

0.1.0 Jun 11, 2020

#31 in #threads

CC0 license

212 lines


tearor provides the TearCell, a (barely) thread-safe lock-free cell type providing tearing access to any type which is Pod.

Tearing access refers to when multiple smaller, separate read or write operations are used to perform a larger unit of work. For example, if you wrote to a &mut u32 by performing 4 writes, one to each byte, or vice-versa.

TearCell uses the same idea, but with atomics. If your T is too large to fit inside an atomic, then TearCell will split it over a few operations.

Needless to say, this means calls to TearCell::load, TearCell::store, (etc) are not atomic (nor do they provide any guarantees about ordering), however every individual operation the TearCell performs is atomic (with the weakest ordering we can get our hands on), which is enough to avoid data races.

It's essentially a tool for turning data races into data corruption. If the lack of synchronization would cause a data race (e.g. with UnsafeCell), then TearCell is very likely to corrupt your data.

However, if this does not matter to you for one reason or another (examples: your synchronization is performed externally, you want to perform an optimistic read, all threads are writing the same value, or you miss the fun you had debugging data corruption issues in C++), then TearCell might be what you want.


Public domain, as explained here