librcimmixcons

This is an implementation of the RCImmixCons garbage collector written in the Rust Programming Language. For details please refer to:

• S. M. S. Blackburn and K. K. S. McKinley. Immix: a mark-region garbage collector with space efficiency, fast collection, and mutator performance. ACM SIGPLAN Notices, 43(6):22, May 2008.
• R. Shahriyar, S. M. Blackburn, and D. Frampton. Down for the count? Getting reference counting back in the ring. ACM SIGPLAN Notices, 47(11):73, Jan. 2013.
• R. Shahriyar, S. M. Blackburn, and K. S. McKinley. Fast conservative garbage collection. In Proceedings of the 2014 ACM International Conference on Object Oriented Programming Systems Languages & Applications - OOPSLA ’14, pages 121-139, New York, New York, USA, Oct. 2014. ACM Press.
• R. Shahriyar, S. M. Blackburn, X. Yang, and K. S. McKinley. Taking off the gloves with reference counting Immix. ACM SIGPLAN Notices, 48(10):93-110, Nov. 2013.

Status

This is not usable an the moment. Major TODOs are:

• TESTING
• Optimize GCHeader fields and use limited reference count bits
• Implement multi-threading (only single-thread applications are supported right now)
• Improve performance

What somewhat works (please refer to the integration tests in tests/):

• The C FFI and Valgrind integration
• Simple allocation and and overflow allocation
• Deferred coalesced reference counting collection
• Immix backup tracing (cycle) collection
• Opportunistic proactive and reactive defragmentation
• A simple free-list large-object-space with RC and MS collection
• Explicit adding of global (static) roots by the mutator program

And some features that would be nice:

• Pinning of objects by the mutator program
• Explicit setting kind of collection by the mutator program
• BlockInfo.{line_counter, object_map} as embedded data structures

Building

You'll need Rust (please use the nightly version) and cargo installed. To build a development version use:

cargo build

To build without the debugging output and with some optimization please use:

cargo build --release

The compiled shared-object file will be in target/ or target/release

Using

To include project in your C code include the header file src/rcimmixcons.h and link against the shared-object file.

Large Object Space

The large object space (LOS) is currently implemented quite inefficiently. To disable it build using the feature no_large_object_space.

cargo build --features "no_large_object_space"
cargo build --release --features "no_large_object_space"

Valgrind

The tool Memcheck from Valgrind is supported using the macros VALGRIND_MALLOCLIKE_BLOCK und VALGRIND_FREELIKE_BLOCK internally. Please build using the feature valgrind. This is not enabled by default as it introduces some overhead to determine freed objects after collection due to how Immix works.

cargo build --features "valgrind"
cargo build --release --features "valgrind"