Intern

Fast, immutable string interning for C.

What is this?

• A way of assigning a unique integer ID to each unique string, without collisions
• Two-way lookup: ID => string, string => ID
• Each string is stored only once in memory
• Optional inlining of unsigned integer strings
• Very low fragmentation via a custom block allocator
• Minimal overhead per string: currently ~40 bytes, which could be lower at the cost of additional fragmentation
• Fast: intern many millions of strings per second
• String repository optimization based on frequency analysis (improve locality)
• Support for snapshots (restore to a previous state)

Installation

$ cmake -G 'Unix Makefiles' -Wno-dev [OPTIONS]
$ make install

Options are:

• -DBUILD_STATIC=1: Build a static library (libintern.a) rather than a shared library (libintern.so or libintern.dylib)
• -DMMAP_PAGES=1: Allocate pages with mmap(2) rather than malloc(3)
• -DPAGE_SIZE=4096: Set the page size
• -DINLINE_UNSIGNED=1: Inline unsigned integers between 0 and INT_MAX
• -DCMAKE_BUILD_TYPE=Release: Do a release build / enable optimization

Usage

Build your project with -lintern and include <intern/strings.h>.

See strings.h and optimize.h for more details.

Extra

Bindings for Go

License

MIT