scholarly journals Formal verification of a concurrent bounded queue in a weak memory model

2021 ◽  
Vol 5 (ICFP) ◽  
pp. 1-29
Author(s):  
Glen Mével ◽  
Jacques-Henri Jourdan
Keyword(s):  
Formal Verification ◽  
Data Structures ◽  
Experimental Verification ◽  
Separation Logic ◽  
Memory Model ◽  
Formal Reasoning ◽  
Concurrent Data Structures ◽  
Concurrent Separation Logic

We use Cosmo, a modern concurrent separation logic, to formally specify and verify an implementation of a multiple-producer multiple-consumer concurrent queue in the setting of the Multicore OCaml weak memory model. We view this result as a demonstration and experimental verification of the manner in which Cosmo allows modular and formal reasoning about advanced concurrent data structures. In particular, we show how the joint use of logically atomic triples and of Cosmo's views makes it possible to describe precisely in the specification the interaction between the queue library and the weak memory model.

scholarly journals Verifying concurrent multicopy search structures

2021 ◽  
Vol 5 (OOPSLA) ◽  
pp. 1-32
Author(s):  
Nisarg Patel ◽  
Siddharth Krishna ◽  
Dennis Shasha ◽  
Thomas Wies
Keyword(s):  
Data Structures ◽  
General Framework ◽  
Directed Acyclic Graphs ◽  
Separation Logic ◽  
A Value ◽  
Acyclic Graphs ◽  
Multiple Copies ◽  
File Structures ◽  
Search Structure ◽  
Concurrent Separation Logic

Multicopy search structures such as log-structured merge (LSM) trees are optimized for high insert/update/delete (collectively known as upsert) performance. In such data structures, an upsert on key k , which adds ( k , v ) where v can be a value or a tombstone, is added to the root node even if k is already present in other nodes. Thus there may be multiple copies of k in the search structure. A search on k aims to return the value associated with the most recent upsert. We present a general framework for verifying linearizability of concurrent multicopy search structures that abstracts from the underlying representation of the data structure in memory, enabling proof-reuse across diverse implementations. Based on our framework, we propose template algorithms for (a) LSM structures forming arbitrary directed acyclic graphs and (b) differential file structures, and formally verify these templates in the concurrent separation logic Iris. We also instantiate the LSM template to obtain the first verified concurrent in-memory LSM tree implementation.

scholarly journals Cosmo: a concurrent separation logic for multicore OCaml

2020 ◽  
Vol 4 (ICFP) ◽  
pp. 1-29
Author(s):  
Glen Mével ◽  
Jacques-Henri Jourdan ◽  
François Pottier
Keyword(s):  
Separation Logic ◽  
Concurrent Separation Logic

scholarly journals TaDA Live: Compositional Reasoning for Termination of Fine-grained Concurrent Programs

2021 ◽  
Vol 43 (4) ◽  
pp. 1-134
Author(s):  
Emanuele D’Osualdo ◽  
Julian Sutherland ◽  
Azadeh Farzan ◽  
Philippa Gardner
Keyword(s):  
Case Studies ◽  
Separation Logic ◽  
Proof System ◽  
Concurrent Programs ◽  
Semantic Model ◽  
Compositional Reasoning ◽  
Fine Grained ◽  
Fundamental Innovation ◽  
Concurrent Separation Logic

We present TaDA Live, a concurrent separation logic for reasoning compositionally about the termination of blocking fine-grained concurrent programs. The crucial challenge is how to deal with abstract atomic blocking : that is, abstract atomic operations that have blocking behaviour arising from busy-waiting patterns as found in, for example, fine-grained spin locks. Our fundamental innovation is with the design of abstract specifications that capture this blocking behaviour as liveness assumptions on the environment. We design a logic that can reason about the termination of clients that use such operations without breaking their abstraction boundaries, and the correctness of the implementations of the operations with respect to their abstract specifications. We introduce a novel semantic model using layered subjective obligations to express liveness invariants and a proof system that is sound with respect to the model. The subtlety of our specifications and reasoning is illustrated using several case studies.

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