pool

Tiny memory reuse helpers for Go.

generic

Without use of subpackages, pool allows to reuse any struct distinguishable by size in generic way:

package main

import "github.com/gobwas/pool"

func main() {
	x, n := pool.Get(100) // Returns object with size 128 or nil.
	if x == nil {
		// Create x somehow with knowledge that n is 128.
	}
	defer pool.Put(x, n)
	
	// Work with x.
}

Pool allows you to pass specific options for constructing custom pool:

package main

import "github.com/gobwas/pool"

func main() {
	p := pool.Custom(
        pool.WithLogSizeMapping(),      // Will ceil size n passed to Get(n) to nearest power of two.
        pool.WithLogSizeRange(64, 512), // Will reuse objects in logarithmic range [64, 512].
        pool.WithSize(65536),           // Will reuse object with size 65536.
    )
	x, n := p.Get(1000)  // Returns nil and 1000 because mapped size 1000 => 1024 is not reusing by the pool.
    defer pool.Put(x, n) // Will not reuse x.
	
	// Work with x.
}

Note that there are few non-generic pooling implementations inside subpackages.

pbytes

Subpackage pbytes is intended for []byte reuse.

package main

import "github.com/gobwas/pool/pbytes"

func main() {
	bts := pbytes.GetCap(100) // Returns make([]byte, 0, 128).
	defer pbytes.Put(bts)

	// Work with bts.
}

You can also create your own range for pooling:

package main

import "github.com/gobwas/pool/pbytes"

func main() {
	// Reuse only slices whose capacity is 128, 256, 512 or 1024.
	pool := pbytes.New(128, 1024) 

	bts := pool.GetCap(100) // Returns make([]byte, 0, 128).
	defer pool.Put(bts)

	// Work with bts.
}

pbufio

Subpackage pbufio is intended for *bufio.{Reader, Writer} reuse.

package main

import "github.com/gobwas/pool/pbufio"

func main() {
	bw := pbufio.GetWriter(os.Stdout, 100) // Returns bufio.NewWriterSize(128).
	defer pbufio.PutWriter(bw)

	// Work with bw.
}

Like with pbytes, you can also create pool with custom reuse bounds.