arena

Documentation

Overview

Package arena provides a bump-allocator backed by a single contiguous []byte. The arena hands out []float64 and []byte slices that share that backing buffer; resetting the arena invalidates every slice it ever returned.

Use cases inside Pulse:

• Streaming iterator scratch: each row needs small typed buffers (8-byte field-decode scratch, transient wide-value slots). Bumping into a shared buffer avoids the per-row map/slice make().
• Batch processing: when the row count is known up front, one Grow call up front + AllocF64s per aggregator working buffer collapses N independent makes into one.

Lifetime contract: anything returned from AllocF64s/AllocBytes lives until the next Reset(). After Reset(), every previously-returned slice header is still valid Go memory but its bytes will be overwritten by subsequent allocations. Callers MUST NOT retain slices across Reset.

Concurrency: Arena is not safe for concurrent use. Callers that fan allocations across goroutines must hold one Arena per goroutine.

Index

• type Arena
  • func New(initialBytes int) *Arena
  • func (a *Arena) AllocBytes(n int) []byte
  • func (a *Arena) AllocF64s(n int) []float64
  • func (a *Arena) Cap() int
  • func (a *Arena) Len() int
  • func (a *Arena) Reset()

Types

type Arena

type Arena struct {
	// contains filtered or unexported fields
}

Arena is a bump allocator backed by a single byte buffer.

func New

func New(initialBytes int) *Arena

New creates an Arena with the given initial capacity in bytes. Capacity grows on demand when Alloc requests exceed available space; pre-sizing to the expected high-water mark avoids the grow path.

func (*Arena) AllocBytes

func (a *Arena) AllocBytes(n int) []byte

AllocBytes returns a []byte of length n drawn from the arena. The returned slice is zeroed (Go-init semantics) and aliased to the arena backing buffer.

func (*Arena) AllocF64s

func (a *Arena) AllocF64s(n int) []float64

AllocF64s returns a []float64 of length n drawn from the arena. The underlying memory is 8-byte aligned because Alloc places f64 regions at offsets that are multiples of 8.

func (*Arena) Cap

func (a *Arena) Cap() int

Cap returns the arena's current capacity in bytes.

func (*Arena) Len

func (a *Arena) Len() int

Len returns the number of bytes currently allocated since the last Reset.

func (*Arena) Reset

func (a *Arena) Reset()

Reset returns the offset to zero. All slices previously returned by Alloc* remain valid Go memory but their contents are no longer owned by the caller — subsequent allocations will overwrite them.