Time and order

Total and partial order A total order is a binary relation that defines an order for every element in some set. a partial order is a weaker variant of total order

Order Duration Interpretation

Vector clocks (time for causal order)

A Lamport clock

• Whenever a process does work, increment the counter
• Whenever a process sends a message, include the counter
• When a message is received, set the counter to max(local_counter, received_counter) + 1

A vector clock

• Whenever a process does work, increment the logical clock value of the node in the vector
• Whenever a process sends a message, include the full vector of logical clocks
• When a message is received:
  • update each element in the vector to be max(local, received)
  • increment the logical clock value representing the current node in the vector