Problem

In Meta embedded systems, components such as sensor pipelines or device telemetry often use a fixed-size circular buffer to pass data between producers and consumers. Implement the core buffer operations for a bounded circular buffer and return the results of a sequence of commands.

Task

Write a function that simulates a circular buffer of capacity capacity. The buffer stores integers and supports these commands in order:

• "push", value — insert value at the tail if the buffer is not full; otherwise return false for that command.
• "pop" — remove and return the oldest value if the buffer is not empty; otherwise return -1.
• "peek" — return the oldest value without removing it; return -1 if empty.
• "size" — return the current number of elements.

Use a fixed-size array with wraparound indexing. The goal is to model the core logic that a thread-safe C circular buffer would protect with a mutex, while keeping this interview problem focused on correct buffer behavior.

Input / Output

• Input: integer capacity, and a list operations where each item is either ["push", value], ["pop"], ["peek"], or ["size"]
• Output: list of results for each operation in order

Examples

Example 1

• Input: capacity = 3, operations = [["push", 10], ["push", 20], ["peek"], ["pop"], ["size"]]
• Output: [true, true, 10, 10, 1]
• Explanation: 10 is at the front, then removed, leaving one element.

Example 2

• Input: capacity = 2, operations = [["pop"], ["push", 1], ["push", 2], ["push", 3], ["size"], ["pop"], ["pop"], ["pop"]]
• Output: [-1, true, true, false, 2, 1, 2, -1]
• Explanation: The third push fails because the buffer is full, and the final pop fails because it is empty.

Constraints

• 1 <= capacity <= 10^5
• 1 <= len(operations) <= 2 * 10^5
• -10^9 <= value <= 10^9
• All operations must run in O(1) time each