Design multi-tab browser history and trade-offs
Company: Chime
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Technical Screen
Extend the single-tab history to support multiple tabs.
APIs to support (design the interface):
- int openTab(string homepage): Create a new tab and return its identifier.
- void closeTab(int tabId): Close the tab and free its history.
- void switchTab(int tabId): Make tabId the active tab.
- void visit(string url), string back(int steps), string forward(int steps): Apply to the active tab.
- Optional: bool haveVisited(string url): Define per-tab and/or global semantics.
Requirements and discussion:
- Choose data structures to manage tabs and their histories (e.g., map from tabId to per-tab history, list/array to track tab order). Compare trade-offs (map vs list), memory footprint, and operation complexity.
- Consider thread-safety if multiple tabs can act concurrently; outline locking or immutability strategies.
- Discuss history capping/eviction policies and their effect on haveVisited semantics.
- Specify complexity targets for each operation and justify your design decisions.
Overview: This question evaluates a candidate's competence in system design, data-structure selection, API specification, concurrency control, and eviction/semantic strategies for a multi-tab browser-history manager, testing skills in reasoning about per-tab state, operation complexity, and memory trade-offs.