Lock-Free Buffer Memory Data Structure for Multi-Producer Consumer Systems
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Solution Overview
Problem
In multi-producer multi-consumer systems, especially in high-safety domains like semi-autonomous driving, existing buffer memories are limited by their fixed capacity and prone to deadlocks when processes terminate abnormally, requiring a thread-safe and dynamically adaptable solution to manage data transfer efficiently.
Innovation Solution
A lock-free buffer memory data structure with multiple queues (first, second, and third queues) that manage unique identifiers for slots, allowing capacity adaptation during operation without dynamic memory usage, using integer values to represent identifiers and cycles, and supporting lock-free, atomic operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If locks are used to ensure thread safety in buffer memory, then thread safety is improved, but the risk of deadlock increases when processes terminate abnormally
Solution Approach 1:
The patent extracts the locking mechanism entirely from the buffer memory access operations. Instead of using locks to protect shared data structures, the invention uses lock-free data structures with atomic operations (compare-and-swap) to ensure thread safety, thereby eliminating the deadlock risk associated with abnormal process termination while holding locks.
Solution Approach 2:
The patent replaces the mechanical locking system with an atomic operation-based synchronization mechanism. The compare-and-swap atomic instruction provides memory ordering and mutual exclusion without requiring traditional locks, substituting a lock-based mechanical system with an atomic operation-based system that is inherently more resilient to abnormal termination.
2Reliability
If buffer memory capacity is fixed at compilation time, then safety is improved by avoiding dynamic memory usage, but adaptability to changing runtime requirements deteriorates
Solution Approach 1:
The patent implements dynamic capacity adjustment through a control queue that manages the allocation and deallocation of buffer slots at runtime. The buffer memory capacity can be dynamically increased or decreased by adding or removing slots based on runtime requirements, while maintaining safety through the lock-free atomic operations that protect all capacity modification operations.
Solution Approach 2:
The patent creates a universal buffer memory structure that can adapt to different capacity requirements through the control queue mechanism. The same buffer memory structure serves multiple functions: it maintains fixed-capacity safety guarantees while simultaneously providing dynamic adaptability through controlled slot allocation and deallocation, making it universally applicable to various runtime scenarios.
3Adaptability or versatility
If multiple queues are used to manage slot identifiers, then capacity adaptation is improved, but device complexity increases
Solution Approach 1:
The patent segments the buffer memory management into distinct functional queues: a control queue for managing slot identifier allocation and deallocation, and the main buffer queue for data storage. This segmentation allows independent management of capacity adaptation (through the control queue) and data storage (through the buffer queue), reducing overall complexity by separating concerns while maintaining adaptability.
Data Source
AI summary
A data structure for a buffer memory for a multi-producer multi-consumer system. The data structure includes at least one slot for storing data, a first queue, a second queue, a third queue. Each slot of the buffer memory is assigned a unique identifier. At all times, each of the identifiers being assigned either to the first queue or to the second queue or to the third queue.