The interview process was very smooth.

The recruiter called to set up the phone interview. The interviewer called on time, and the interview went for about an hour.

The onsite interview was scheduled for the following week. I had three rounds of interviews after which I was let go.

• First round: Coding
• Next two rounds: Data structures and algorithms, high-level design, and low-level design.

Implement a connection pool that clients can use to obtain an active connection, use it, and return it to the pool when done. If a connection is invalidated, the implementation should handle it. For the prototype, assume a connection library.