Can you explain the working mechanism of the Sync method in a thread-safe queue implementation?

The sync method in a thread-safe queue is typically used to execute a block of code synchronously, meaning the current thread is paused until the block completes. This ensures that operations on the queue are performed sequentially, preventing race conditions.

In the implementation of a thread-safe queue, sync locks access to the internal data of the queue, executes the passed code, and only after that unlocks, allowing other threads to work with the queue.

An example in Swift using DispatchQueue:

let queue = DispatchQueue(label: "com.example.queue")

queue.sync {
    // Code that should execute sequentially
    // For example, adding an element to the queue
}

Thus, sync provides atomicity of operations and prevents concurrent access from different threads.