v0.1.0 — O(1) Offset Allocator for Go

What's New

First release of galloc — O(1) offset allocator for GPU memory sub-allocation. Pure Go port of Sebastian Aaltonen's OffsetAllocator (C++, MIT, 1,051 stars). First Go implementation of this algorithm.

Features

• O(1) allocate and free — two-level bitfield bin lookup via math/bits.TrailingZeros32
• 256 size classes — SmallFloat encoding (3-bit mantissa + 5-bit exponent), max 12.5% overhead
• Automatic coalescing — adjacent free regions merge on free via doubly-linked neighbor list
• Zero heap allocations on hot path — all node storage pre-allocated in New()
• Thread-safe wrapper — SyncAllocator with sync.Mutex
• Pure Go — no unsafe, no CGO, no assembly, stdlib only

Performance

Benchmark	ns/op	allocs/op
Allocate	~44	0
Free	~40	0
AllocFree	~39	0

Use Cases

• GPU buffer sub-allocation (VkBuffer, ID3D12Resource heaps)
• Ring buffer management (staging belts)
• Any contiguous-range sub-allocation needing O(1) performance

Credits

Based on OffsetAllocator by Sebastian Aaltonen. Also informed by offset-allocator (Rust port by Patrick Walton, used in Bevy).

Part of the GoGPU ecosystem.