rSearch: Ring-Based Semantic Overlay for Efficient Recall-Guaranteed Search in P2P Networks

Providing recall-guaranteed search is critical for P2P networks. While building semantic overlay improves search performance, existing designs suffer from a tradeoff between search time and search quality (i.e. high recall). Moreover, they require to use high control overhead for overlay maintenance. In this paper, we present rSearch to achieve fast search with guaranteed high recall. The rSearch-enabled overlay topology looks like a ring, augmented with semantic chord links. Given a query, rSearch uses multiple query walkers that traverse on the ring independently to find relevant semantic nodes for answers. The ring structure facilitates fast and low-redundancy query forwarding, while the abundant semantic chord links enable large semantic clusters. Bloom Filter is used to encode and compress node semantic summaries, greatly saving control overhead. rSearch further considers churn resilience and network awareness to enhance system performance. Extensive simulations with real-life file sharing trace and network latency trace show that rSearch greatly outperforms GES.