Add bit fields API with atomic wrapper #2549
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Summary: Inspired by work in RocksDB for HyperClockCache and parallel compression revamp, this change includes * BitFields.h - An API for declaring encapsulated bit field types with guaranteed layout, variant layout capability, and multi-field update capability * BitFieldsAtomic.h - Provides an extension of AtomicStruct for bit fields types, adding capability for non-CAS atomic updates to multiple fields (when possible). Together these lower the barriers to entry and maintenance hurdles associated with bit-packing atomic data in data structures and algorithms. Bit-packing data into atomics not only increases the scope of problems that can be solved with lock-free or low-locking usage of atomics, it can greatly simplify the algorithmic complexity. Packing more data fields into a single atomic means fewer overheads and hazards associated with interleaved updates to separate fields. In other words, with lean design and sufficient foresight, bit-packed atomic solutions can often be simpler *and* more efficient than solutions involving more atomics or synchronization primitives. Also see follow-up diff D88903968 that refactors existing structure LifoSem to use this new API. Differential Revision: D88903954
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Summary: Inspired by work in RocksDB for HyperClockCache and parallel compression revamp, this change includes * BitFields.h - An API for declaring encapsulated bit field types with guaranteed layout, variant layout capability, and multi-field update capability * BitFieldsAtomic.h - Provides an extension of AtomicStruct for bit fields types, adding capability for non-CAS atomic updates to multiple fields (when possible). Together these lower the barriers to entry and maintenance hurdles associated with bit-packing atomic data in data structures and algorithms. Bit-packing data into atomics not only increases the scope of problems that can be solved with lock-free or low-locking usage of atomics, it can greatly simplify the algorithmic complexity. Packing more data fields into a single atomic means fewer overheads and hazards associated with interleaved updates to separate fields. In other words, with lean design and sufficient foresight, bit-packed atomic solutions can often be simpler *and* more efficient than solutions involving more atomics or synchronization primitives. Also see follow-up diff D88903968 that refactors existing structure LifoSem to use this new API. Differential Revision: D88903954
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Summary:
Inspired by work in RocksDB for HyperClockCache and parallel compression revamp, this change includes
Together these lower the barriers to entry and maintenance hurdles associated with bit-packing atomic data in data structures and algorithms. Bit-packing data into atomics not only increases the scope of problems that can be solved with lock-free or low-locking usage of atomics, it can greatly simplify the algorithmic complexity. Packing more data fields into a single atomic means fewer overheads and hazards associated with interleaved updates to separate fields. In other words, with lean design and sufficient foresight, bit-packed atomic solutions can often be simpler and more efficient than solutions involving more atomics or synchronization primitives.
Also see follow-up diff D88903968 that refactors existing structure LifoSem to use this new API.
Differential Revision: D88903954