Distributed Price Synchronization

Overview

A distributed Elixir application that simulates multi-domain price divergence and autonomous price syncronization. Each node runs a price server that randomly updates its price value. When prices between nodes diverge beyond a defined threshold, they are automatically reset to maintain consistency.

System Architecture

graph TD
    %% Define the three nodes in a triangle
    subgraph "Node A"
        direction TB
        A[PriceServer]
        AM[Monitor]
    end

    subgraph "Node B"
        direction TB
        B[PriceServer]
        BM[Monitor]
    end

    subgraph "Node C"
        direction TB
        C[PriceServer]
        CM[Monitor]
    end

    %% Define the central lock
    Lock((Distributed Lock))

    %% Price update loops
    A ==>|"1. Random update\nevery 1s"| A
    B ==>|"1. Random update\nevery 1s"| B
    C ==>|"1. Random update\nevery 1s"| C

    %% Price monitoring between nodes
    AM -->|"2. Check prices\nevery 2s"| B
    AM -->|"2. Check prices\nevery 2s"| C
    BM -->|"2. Check prices\nevery 2s"| A
    BM -->|"2. Check prices\nevery 2s"| C
    CM -->|"2. Check prices\nevery 2s"| A
    CM -->|"2. Check prices\nevery 2s"| B

    %% Lock and reset flow
    AM -.-|"3. If divergence > 2.0"| Lock
    BM -.-|"3. If divergence > 2.0"| Lock
    CM -.-|"3. If divergence > 2.0"| Lock
    Lock ==>|"4. Reset prices\n(5s timeout)"| A & B & C

    %% Styling
    classDef server fill:#e1f5fe,stroke:#01579b
    classDef monitor fill:#f3e5f5,stroke:#4a148c
    classDef lock fill:#fff3e0,stroke:#e65100,stroke-width:2px

    %% Link styling
    linkStyle default stroke:#666,stroke-width:1
    linkStyle 0,1,2 stroke:#01579b,stroke-width:2
    linkStyle 3,4,5,6,7,8 stroke:#4a148c,stroke-width:1
    linkStyle 9,10,11 stroke:#e65100,stroke-width:1,stroke-dasharray:3
    linkStyle 12 stroke:#e65100,stroke-width:2

    class A,B,C server
    class AM,BM,CM monitor
    class Lock lock

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Components

PriceSync.PriceServer

• Maintains a price value that updates every second
• Updates use Gaussian-distributed random values
• Provides functions to get and reset the price
• Initial price: 10.0
• Update interval: 1 second

PriceSync.Monitor

• Monitors price divergence between connected nodes
• Checks prices every 2 seconds
• If price difference exceeds 2.0, affected nodes reset their prices
• Uses a locking mechanism to prevent concurrent resets
• Lock timeout: 5 seconds

PriceSync.Application

• OTP Application that supervises both PriceServer and Monitor
• Automatically starts services when nodes launch
• Uses one-for-one supervision strategy

Environment Setup

To get started, enter the development shell:

nix develop

The test script (test_price_sync.sh) automates the process of running and testing the distributed system. The test script performs the following steps, using your machine's hostname to ensure proper node naming and connectivity. Price synchronization is visible in the logged output.

Run it with:

sh test_price_sync.sh

1. Cleans and compiles the project
2. Ensures hex package manager is up to date
3. Starts 3 nodes in the background (node_a, node_b, node_c)
4. Connects the nodes in a mesh topology
5. Waits for the system to stabilize
6. Queries prices from each node to verify operation
7. Allows time for divergence checks
8. Cleanly terminates all nodes