Define happens before with respective to the lamport time stamo
Answers
Distributed algorithms such as resource synchronization often depend on some method of ordering events to function. For example, consider a system with two processes and a disk. The processes send messages to each other, and also send messages to the disk requesting access. The disk grants access in the order the messages were sent. For example process {\displaystyle A} A sends a message to the disk requesting write access, and then sends a read instruction message to process {\displaystyle B} B. Process {\displaystyle B} B receives the message, and as a result sends its own read request message to the disk. If there is a timing delay causing the disk to receive both messages at the same time, it can determine which message happened-before the other: {\displaystyle A} A happens-before {\displaystyle B} B if one can get from {\displaystyle A} A to {\displaystyle B} B by a sequence of moves of two types: moving forward while remaining in the same process, and following a message from its sending to its reception. A logical clock algorithm provides a mechanism to determine facts about the order of such events.