My take on the LMAX Disruptor, with a different API. Existing C++ implementations of the LMAX disruptor relied on virtual interfaces and dispatch methods that copied from Java. This implementation attempts to do things in a more C++ way and provide what I hope to be a simpler interface.
There are 3 primary types that users of the API must be familiar with:
- ring_buffer<T,Size> is a circular buffer with Power of 2 Size
- write_cursor tracks a position in the buffer and can follow other read cursors to ensure things don't wrap.
- shared_write_cursor is a write_cursor that may be used from multiple threads other read cursors to ensure things don't wrap.
- read_cursor tracks the read position and can follow / block on other cursors (read or write).
- thread enables posting of functors to be executed by another thread. This class is 30x faster than fc::thread at posting a request between threads and fc::thread already used a lock-free algorithm with 'constant' event posting time.
The concept of the cursors are separated from the data storage. Every cursor should read from one or more sources and write to its own outbut buffer.
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Progressive-backoff blocking. When one cursor needs to wait on another it starts out with a busy wait, followed by a yield, and ultimately falls back to sleeping wait if the queue is stalled.
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Batch writing / Reading with 'iterator like' interface. Producers and consumers always work with a 'range' of valid positions. The ring buffer provides the ability to detect 'wraping' and therefore it should be possible to use this as a data queue for a socket that can read/write many slots all at once. Slots could be single bytes and the result would be a very effecient stream-processing library. This manner of operation is not possible with LMAX's API.
Simple benchmarks indicate that performance of this implementation is better than other known C++ implementations of this pattern.