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Implementing Notification Chain in TCP/IP Stack 🛠️

Introduction 🌟

  • Discusses the implementation of a generic notification chain in the files
  • The aim is to create a data structure for notification chains in the TCP/IP stack.

Data Structures 📦

Notification Chain 🚨

  • A linked list of function pointers coupled with keys.
  • Contains two members:
    • Name: For user information only, doesn't add functionality.
    • Head: Points to the start of the linked list of callbacks.

Notification Chain Element 📚

  • A single node in the Notification Chain.
  • Has four members:
    • Key: Memory allocated to store the key, bounded by Max_Notify_Key_Size.
    • Key Size: Actual size of the stored key.
    • Boolean Flag: Indicates whether a key is specified.
    • Function Pointer: Points to the subscriber's callback function.

Constants 📝

  • Max_Notify_Key_Size set to 64 bytes in this example.

Callback Function Prototype 📞

  • Should be generic to suit all types of data and subscribers.
  • Accepts a void* type argument and another argument indicating its size in bytes.

Interview Questions and Answers ❓👩‍💼

Q1: What is a Notification Chain?

A1:

A Notification Chain is a linked list that holds function pointers and associated keys.

Q2: What does a Notification Chain Element represent?

A2:

  • A Notification Chain Element is a single node in the Notification Chain linked list.
  • It holds a key, the size of the key, a boolean flag indicating if a key is specified, and a function pointer for callbacks.

Q3: What is Max_Notify_Key_Size and what's its significance?

A3:

Max_Notify_Key_Size is a constant value that represents the maximum size (in bytes) that can be allocated for storing keys in a Notification Chain Element. It's set to 64 bytes in this example.

Q4: How is the callback function in the Notification Chain Element designed to be generic?

A4:

The callback function is designed to accept arguments of void* type and another argument specifying its size in bytes. This ensures that it can handle all types of data.

Q5: How do you specify if a subscriber is a wildcard subscriber in the Notification Chain Element?

A5:

A boolean flag in the Notification Chain Element is used to indicate if a subscriber has specified a key or not. If not, the subscriber is considered a wildcard subscriber.

Q7: Why does the Notification Chain have a 'Name' field, and what is its use?

A7:

The 'Name' field in the Notification Chain is optional and is solely for the user's information. It doesn't contribute to the chain's functionality.

Q8: What operations would you need to perform on a Notification Chain?

A8:

The operations to perform would include adding new Notification Chain Elements, removing elements, and triggering the callback functions of matching elements.