Posted on Oct 9

The Only Practical Data Structure you'll ever need?

#cpp #tutorial #beginners #webdev

You know that one JavaScript meme? Yeah; this one:

That’s exactly how a queue feels the longer you code, especially when you go low-level.
The craziest part? It’s the simplest data structure ever.

You can simulate one with an array as easily as:

// NOTE: not recommended, O(n) for shift
const queue = []
queue.push() // enqueue 
queue.shift() // dequeue

And here’s why this is wild: if you’re like me and started coding back in the ancient year of 2018, you remember how terrifying algorithms seemed.
I can’t count how many interviews I failed because I had no idea what “find the contiguous subarray (Kadane’s algorithm)” meant.

Fast forward a few years, and now?
A queue is what I throw at everything.

Not just me, literally the whole industry runs on queues.
Node.js? Queue.
MySQL driver? Queue.
RabbitMQ? I’ll stop before this turns into a sermon.

Point is; you’ll use queues. A lot. Even in production.
Yes, you will.

Things I’ve Used a Queue For

1. Buffering Real-Time Data

When working with real-time data, there’s always a producer and a consumer:

producer (usually server) ---> consumer (frontend)

Classic problem? Back pressure.
The producer sends data too fast, the consumer can’t keep up; it lags.
You can’t pause real-time data, so what do you do?

Yep; queue the data on the frontend. Classic move. I’ve used it tons of times.

producer (server) ---> queue ---> consumer (frontend)

2. Synchronizing Threads

Once, I built an immediate mode GUI (imgui) for Node.js.
Quick context; Node.js is single-threaded (one lane). So I had to spawn a separate libuv thread to simulate and render the GUI.

If you’ve worked with ImGui, you know it’s like a game loop. The GUI runs separately; you inject data, it draws each frame:

for (imgui()) {
   inject_state()
   render_gui()
   repeat()
} // not real code, just for illustration

Meaning: state and GUI live in separate worlds.
Some of my state lived in the Node.js thread, while the GUI rendered in the libuv thread.

I couldn’t just stop the running loop to sync them; so when you create an image element, it got buffered in a queue.
On the next tick, the loop pulled it and uploaded it to the GPU, caching it in a sparse set resource manager.

That part looked like this:

{
  std::lock_guard<std::mutex> lock(globalIPCData.textureLoadQueueMutex);
  while (!globalIPCData.textureLoadQueue.empty()) {
    auto &[key, path] = globalIPCData.textureLoadQueue.front();
    gTextures.LoadTexture(key, path);
    globalIPCData.textureLoadQueue.pop();
  }
}

The wild part? It was blazingly fast.

3. BunniMQ Driver - Pure JavaScript Message Broker

Here’s another one.
Think of a driver as a wrapper over a low-level I/O system, like a MySQL driver.

I/O is async by nature. MySQL makes requests over the network; you never know when (or if) you’ll get a response.
Drivers solve that by buffering operations in a queue, making async code feel sync.

That’s why you can write:

const db = mysql.connect(creds)
db.insert(doc)
db.update(id, doc)

Behind the scenes, each operation is queued. When one finishes, the next runs.
Without that queue, your code would look like this mess:

mysql.connect(creds).then(() => {
   db.insert(doc).then(() => {
      db.update(id, doc)
   })
})

See? The queue saves your sanity.

That’s exactly how I built bunniMQ and its driver, a pure JavaScript message broker built entirely on queues.
You can check it out if you’re curious.

And honestly, that’s not even half the times I’ve reached for a queue.
Node.js cluster syncing? Queue.
Breadth-first file system traversal? Queue.
Real-time audio ring buffers? Definitely a queue.

So yeah; if you’re not convinced yet, just remember: Node.js itself is one giant queue for I/O and async.

Queue in C++

The Standard Template Library (STL) makes queues just as simple:

#include <iostream>
#include <queue> // <- here
using namespace std;

int main() {
    // Declare a queue that holds integers
    queue<int> my_queue;

    // enqueue
    my_queue.push(101); // Packet #1 arrives
    my_queue.push(202); // Packet #2 arrives
    my_queue.push(303); // Packet #3 arrives

    cout << "Three packets added to the queue." << endl;

    // peek
    cout << "Next packet to process: " << my_queue.front() << endl; // 101

    // dequeue
    my_queue.pop();
    cout << "Processed the front packet." << endl;

    // now who’s next?
    cout << "Next packet is now: " << my_queue.front() << endl; // 202
}