Implement Bump Allocator for Short-Lived Allocations

Arena Pointer Bumps

Bump (arena) allocators hand out memory by advancing an offset into a preallocated block. Freeing individual objects is unsupported; reset the whole arena in one instruction. Compilers, parsers, and per-request HTTP handlers use bump pointers because allocation is a pointer add.

API Shape

Request n bytes aligned to alignof(max_align_t). If the arena has space, bump offset and return the previous pointer. Otherwise grow or abort.

cCopy
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• Reset per frame, per request, or per compilation unit
• Cannot free one object early; plan lifetimes accordingly
• Combine with a parent pool for rare overflow allocations
• Extremely cache-friendly: allocations are contiguous

Working Through the Exercise

Keep the relevant documentation open while you implement. When your output disagrees with the reference, trace one failing case by hand before changing random lines.

• Trace first: walk one failing input step by step
• Read the manual: skim the official doc for the mechanism named in this task
• Compare baselines: save measurements from the prior step so speedups are honest

Why for this exercise

You will implement a bump allocator and use it for thousands of short-lived objects. This exercise asks you to show allocation speed versus malloc and document the reset strategy.