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Thread-Safe Function Design
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Thread-Safe Function Design

HardPython

Problem

Write a function to handle X while maintaining thread safety. Interpret X as applying a batch of add and get operations to a shared counter dictionary, with the entire batch executed atomically and results returned in order. The function must use synchronization so concurrent calls cannot observe partial batches; input is state = {"value": int} and operations = [{"type": "add", "amount": int} | {"type": "get"}], and examples are [{"type": "add", "amount": 3}, {"type": "get"}] returning [3, 3]; support 0 to 1,000 operations and arbitrary Python integers.

Constraints

  • state contains an integer field named "value"
  • Each operation has type "add" or "get"
  • An add operation contains an integer field named "amount"
  • 0 <= len(operations) <= 1,000
  • The same state dictionary may be passed to handle_x concurrently from multiple threads
  • The complete batch must be linearizable

Function Signature

def handle_x(state, operations):
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