shaw92g / laiyang

Lai-Yang Distributed Global Snapshot Recording Algorithm implemented in Java

Requirements

• You should have Java Runtime Environment (1.8 and above) installed on your system
• It can be run on Windows, Linux or iOS

How to run the code?

• Verify that java is installed an working on your terminal by executing java -version
• To run the jar executejava -jar laiyang/out/artifacts/laiyang_jar/laiyang.jar
• This executable has been tested to be working in iOS and Windows.

Assumptions:

• Distributed processes are simulated using threads
• Channels re simulated using priority queues with different priority condition for FIFO and non FIFO modes.
  • For FIFO, priority order = system timestamp value (in milli sec) (in ascending order)
  • For non FIFO, priority order = system timestamp value (in milli sec) % 10
  • Since priority queues in Java are not thread safe, access to these queues are synchronized inside the channel class.
• Every message has three parts {creationTimestamp, amount, color}
• Every process sends min 3 and max 5 messages to other prcesses randomly,
• Each message transfers an amount of Rs 20 from sender to the receiver process
• All distributed processes if inactive (no events occur in them) for 5sec terminate automatically.

Inputs

• Input 1: Number of processes in the distributed system (n) (recommended value 3)
• Input 2: processId that initiates the algorithm (i). 0 <= i <= n-1
• Input 3: Channel mode (FIFO = 0, NON-FIFO = 1)

Output

• Logs
  • Every process logs its events on the terminal like
    • process start event
    • send event
    • receive event
    • color change event
    • local snapshot recording event
    • process stop event
  • Each log line has its processId and color as prefix. e.g. [P2](RED):
• Recorded Global Snapshot
  • The recorded global snapshot is presented at the end after all the processes, except the initiator process has terminated.
  • The initiator process presents a summary of the account balance of each process and the list of messages that were in transit when the global snapshot was taken.
  • Snapshot summary looks like:

  [P2](RED): Lai-Yang Global snapshot computation started
  [P2](RED): Global Snapshot:
  
  P0 = 60
  
  P1 = 120
  
  P2 = 60
  
  P0 to P1 --> [Message{1618482921854, 20, WHITE}]
  
  P0 to P2 --> [Message{1618482921220, 20, WHITE}]
  
  P1 to P2 --> [Message{1618482920342, 20, WHITE}]
  
  Global snapshot is consistent. Expeceted: 300, Actual: 300
  
  [P2](RED): Global snapshot computation ended