shingyipcheung / PriorityQueue_lib

Multi-threaded Throttled Preemptive Priority Queue

Thread-Safe Preemptive Priority Queue in C++

A C++ implementation of a custom priority queue designed for multi-threaded environments.

Introduction

This repository presents a custom implementation of a priority queue with specialized behaviors:

• Generic Type (T): The priority queue is type-agnostic.
• Priority-based: Each item comes with a priority, "1" being the highest.
• Throttle Rate: A built-in mechanism to ensure a mix of priorities during deque operations.
• Thread Safety: Designed specifically for multi-threaded environments.

Features

• Fixed Size: The queue has a pre-determined size.
• Producer-Consumer Constraints:
  • If the queue is full, any producer thread trying to add to it is blocked until space becomes available.
  • If the queue is empty, any consumer thread trying to retrieve an item is blocked until an item becomes available.
• Preemptive Modes: Includes mechanisms to prevent lower-priority items from getting stuck indefinitely:
  • Aging: Increases the priority of all items.
  • Next Priority Activation: Temporarily changes the throttle rate.

How to Use

1. Include the PriorityQueue.h header in your project.
2. Create an instance of the priority queue specifying the desired max size, throttle rate, preemptive size, and preemptive mode.
3. Use the push and pop methods to add and retrieve items, respectively.

Sample Usage

#include "PriorityQueue.h"

int main() {
    PriorityQueue<int> pq(100);  // create a priority queue with a max size of 100

    pq.push(5, 1);  // push item with value 5 and priority 1
    int val = pq.pop();  // retrieves the item with the highest priority
}

Debugging

To inspect the current state of the priority queue, you can use the _display() method. This is particularly helpful during development to understand the internal dynamics.

pq._display();