Design and implement an efficient in-memory trading system similar to a stock exchange, where registered users can place, execute and cancel trades. The system should demonstrate synchronization and concurrency in a multi-threaded environment.

Your system should be able to perform the following items:

Functional Requirements:

Your system should support the following functionalities:

• A registered user can place, modify, and cancel his orders.

• A user should be able to query the status of his order

• [IMPORTANT] - The system should be able to execute trades based on matching buy and sell orders. A trade is executed when the buy and sell price of two different orders match/are equal. If multiple eligible orders can be matched with the same price, match the oldest orders first.

• [IMPORTANT] - Concurrent order placement, modification, cancellation, and execution should be handled appropriately.

• The system should maintain an order book per symbol, which holds all the current unexecuted orders.
  Your system should store at least the following mentioned details.

• User details

  • User ID
  • User Name
  • Phone Number
  • Email Id

• Orders

  • Order ID
  • User ID
  • OrderType (Buy/Sell)
  • Stock Symbol (eg: RELIANCE, WIPRO etc.)
  • Quantity
  • Price
  • Order Accepted Timestamp
  • Status (ACCEPTED, REJECTED, CANCELED)

• Trades

  • Trade ID
  • Trade Type (Buy/Sell)
  • Buyer Order Id
  • Seller Order Id
  • Stock Symbol
  • Quantity
  • Price
  • Trade Timestamp
    Additional functionality, but not compulsory [implement if time permits]:

• Implement trade expiry. A trade should be automatically canceled if that trade is not executed within a specific time.
  Expectation:

• Your code should be executable (at worst partial running would work) & should be clean.

• Your code should be adequately refactored, and exceptions should be gracefully handled.

• Your code should store all the attributes explained under the "Stores" section.

• Your code should cover all the functionality in the "Supports" section.

• If you get extra time, you can code for "Additional functionality, but not compulsory." This will get you extra credit.
  Guidelines:

• You don't have to build the user registration part. Consider some dummy users registered and use those in the entire system.

• You should use the in-memory data structure of your preferred language to store the data but have the right abstractions so that other persistent stores can be plugged in.