Coordination

202405012332
Status: #idea
Tags: DC

Coordination

Synchronization

Internal synchronization -> Maintains precision
External synchronization -> Maintains accuracy

Logical Clock

Before executing any new event in a process $P$ -> $C_{i} \leftarrow C_{i} + 1$
During send
- Set timestamp of message $m$ -> $t s (m) \leftarrow C_{i}$ , after the above step
During receive
- After receiving $m_{k}$ from a process $P_{k}$
- Set $C_{i} \leftarrow max {C_{i}, t s (m_{k})}$
- Increment $C_{i} \leftarrow C_{i} + 1$

Attention

Lamport's clock guarantees that guarantees that if $b$ depends on $a$ , then $C (a) < C (b)$ , but not vice versa.

References