A hybrid token-based distributed mutual exclusion algorithm using wraparound two-dimensional array logical topology

In token-based distributed mutual exclusion algorithms a unique object (token) is used to grant the right to enter the critical section. For the movement of the token within the computer network, two possible methods can be considered: perpetual mobility of the token and token-asking method. This paper presents a distributed token-based algorithm scheduling mutually exclusive access to a critical resource by the processes in a distributed network. This network is composed of N nodes that communicate by message exchanges. The proposed hybrid algorithm imposes a logical structure in the form of wraparound two-dimensional array on the network. It applies the concept of perpetual mobility of the token in columns and token-asking in rows of the array. The major purpose of the algorithm is to increase the scalability property and decrease overhead due to additional communication in a system with at least one unresponded critical section request at any given time. In this status, typically, the number of message exchanges is between √ N and 2 √ N under light demand and reduces to √ N message exchanges under heavy demand. Therefore, it outperforms lots of well known algorithms in terms of number of messages exchanged. The algorithm satisfies safety and liveness properties.