folly/docs/FBString.md
folly/FBString.hfbstring is a drop-in replacement for std::string. The main
benefit of fbstring is significantly increased performance on
virtually all important primitives. This is achieved by using a
three-tiered storage strategy and by cooperating with the memory
allocator. In particular, fbstring is designed to detect use of
jemalloc and cooperate with it to achieve significant improvements in
speed and memory usage.
fbstring supports 32- and 64-bit and little- and big-endian
architectures.
Small strings (<= 23 chars) are stored in-situ without memory allocation.
Medium strings (24 - 255 chars) are stored in malloc-allocated memory and copied eagerly.
Large strings (> 255 chars) are stored in malloc-allocated memory and copied lazily.
100% compatible with std::string.
Thread-safe reference counted copy-on-write for "large" strings (> 255 chars).
Uses malloc instead of allocators.
Jemalloc-friendly. fbstring automatically detects if application
uses jemalloc and if so, significantly improves allocation
strategy by using non-standard jemalloc extensions.
find() is implemented using simplified Boyer-Moore
algorithm. Casual tests indicate a 30x speed improvement over
string::find() for successful searches and a 1.5x speed
improvement for failed searches.
Offers conversions to and from std::string.