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Thread-Safe High-Frequency Data Buffer

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Problem

Autonomous Solutions receives high-frequency sensor readings that must be buffered briefly before downstream processing. Design the deterministic behavior of a bounded FIFO buffer: every put adds the newest reading, and when the buffer is full, it discards the oldest reading. In a production C++ implementation, all state-changing operations must be protected by one mutex so concurrent producers and consumers cannot observe inconsistent state.

Implement process_sensor_buffer, which models the buffer operations in order.

Formal Specification

  • Input capacity is a positive integer.
  • Input operations is a list of two-element lists.
  • ['put', value] inserts value. If the buffer is full, remove its oldest value first. This operation produces no output.
  • ['get'] removes and returns the oldest value, or returns None when empty.
  • ['peek'] returns the oldest value without removing it, or None when empty.
  • ['size'] returns the current number of buffered values.
  • Return a list containing the result of every get, peek, and size operation in order.

A C++ production solution should use a fixed-size circular array, a mutex, and condition variables if blocking behavior is added. This task uses drop-oldest semantics so the operation log has deterministic results.

Constraints

  • 1 <= capacity <= 10^5
  • 1 <= len(operations) <= 10^6
  • Each operation is either ['put', value], ['get'], ['peek'], or ['size']
  • Sensor values are integers
  • Operations are processed in the listed order

Function Signature

def process_sensor_buffer(capacity, operations):
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