A Hybrid Distributed Mutual Exclusion Algorithm for Cluster-Based Systems

Algorithm 2

Raysuz’s algorithm for ordinary node.

Step  1. Upon 𝑂_𝑗=𝑂_{𝑖𝑑𝑙𝑒} or 𝑂_𝑗=𝑂_{ℎ𝑎𝑣𝑒𝑅𝑒𝑞𝑢𝑒𝑠𝑡} and receives request from 𝑃_𝑖

 1.1 if  𝑃_𝑖∩𝐶_𝑗=∅ then

  1.1.1 enqueue 𝑃_𝑖 to RaymQ

  1.1.2  if !Asked

   1.1.2.1 send own request to Dir

   1.1.2.2 set Asked True

  1.1.3 end if

 1.2 else

  1.2.1 increase corresponding request array element by 1

 1.3 end if

Step  2. Upon 𝑂_𝑗=𝑂_{𝑖𝑑𝑙𝑒} or 𝑂_𝑗=𝑂_{ℎ𝑎𝑣𝑒𝑅𝑒𝑞𝑢𝑒𝑠𝑡} and receives ExToken

 2.1 set Asked False

 2.2 dequeue RaymQ and set Dir with dequeued node

 2.3 send ExToken to Dir

 2.4 if  RaymQ.length ≥ 1 then

  2.4.1 send ExReq to Dir

  2.4.2 set Asked True

 2.5 end if

Step  3. Upon 𝑂_𝑗=𝑂_{𝑖𝑑𝑙𝑒} and receives Pulse

 3.1 increase corresponding request array element by 1 and broadcast request

 3.2  𝑂_𝑗=𝑂_{ℎ𝑎𝑣𝑒𝑅𝑒𝑞𝑢𝑒𝑠𝑡}

Step  4. Upon 𝑂_𝑗=𝑂_{ℎ𝑎𝑣𝑒𝑅𝑒𝑞𝑢𝑒𝑠𝑡} receives InToken for 𝑂_𝑗 and SuzQ.length = 0

 4.1 enter CS

 4.2 update SuzQ

 4.3 send InToken to head of SuzQ

 4.4 set Dir as head

Step  5. Upon 𝑂_𝑗=𝑂_{ℎ𝑎𝑣𝑒𝑅𝑒𝑞𝑢𝑒𝑠𝑡} receives InToken for 𝑂_𝑗 and SuzQ.length > 0

 5.1 enter CS

 5.2 update SuzQ

 5.3  𝑂_𝑗=𝑂_{ℎ𝑎𝑣𝑒𝑇𝑜𝑘𝑒𝑛}

Step  6. Upon 𝑂_𝑗=𝑂_{ℎ𝑎𝑣𝑒𝑇𝑜𝑘𝑒𝑛} receives request from 𝑃_𝑖

 6.1  if  𝑃_𝑖∩𝐶_𝑗=∅ then

  6.1.1 enqueue 𝑃_𝑖 to RaymQ

  6.1.2  if !Asked

   6.1.2.1 send own request to Dir

   6.1.2.2 set Asked True

  6.1.3 end if

 6.2 else

  6.2.1 increase corresponding request array element by 1

  6.2.2 update SuzQ

  6.2.3 send InToken to 𝑃_𝑖

  6.2.4  𝑂_𝑗=𝑂_{𝑖𝑑𝑙𝑒}

 6.3 end if

Step  7. Upon 𝑂_𝑗=𝑂_{ℎ𝑎𝑣𝑒𝑇𝑜𝑘𝑒𝑛} and receives Pulse

 7.1 enter CS