pool.go

// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// THE SOFTWARE.

package postings

import (
	xpool "github.com/m3db/m3/src/x/pool"
)

const (
	defaultPoolSize = 8
)

type pool struct {
	pool xpool.ObjectPool
}

// PoolAllocateFn returns a new MutableList.
type PoolAllocateFn func() MutableList

// NewPool returns a new Pool.
func NewPool(
	opts xpool.ObjectPoolOptions,
	allocator PoolAllocateFn,
) Pool {
	if opts == nil {
		// Use a small pool by default, postings lists can become
		// very large and can be dangerous to pool in any significant
		// quantity (have observed individual postings lists of size 4mb
		// frequently even when reset).
		opts = xpool.NewObjectPoolOptions().SetSize(defaultPoolSize)
	}

	p := &pool{
		pool: xpool.NewObjectPool(opts),
	}
	p.pool.Init(func() interface{} {
		return allocator()
	})
	return p
}

func (p *pool) Get() MutableList {
	return p.pool.Get().(MutableList)
}

func (p *pool) Put(pl MutableList) {
	pl.Reset()
	p.pool.Put(pl)
}