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// Copyright (c) 2014 Couchbase, Inc.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package search
import (
var reflectStaticSizeDocumentMatchPool int
func init() {
var dmp DocumentMatchPool
reflectStaticSizeDocumentMatchPool = int(reflect.TypeOf(dmp).Size())
// DocumentMatchPoolTooSmall is a callback function that can be executed
// when the DocumentMatchPool does not have sufficient capacity
// By default we just perform just-in-time allocation, but you could log
// a message, or panic, etc.
type DocumentMatchPoolTooSmall func(p *DocumentMatchPool) *DocumentMatch
// DocumentMatchPool manages use/re-use of DocumentMatch instances
// it pre-allocates space from a single large block with the expected
// number of instances. It is not thread-safe as currently all
// aspects of search take place in a single goroutine.
type DocumentMatchPool struct {
avail DocumentMatchCollection
TooSmall DocumentMatchPoolTooSmall
func defaultDocumentMatchPoolTooSmall(p *DocumentMatchPool) *DocumentMatch {
return &DocumentMatch{}
// NewDocumentMatchPool will build a DocumentMatchPool with memory
// pre-allocated to accommodate the requested number of DocumentMatch
// instances
func NewDocumentMatchPool(size, sortsize int) *DocumentMatchPool {
avail := make(DocumentMatchCollection, size)
// pre-allocate the expected number of instances
startBlock := make([]DocumentMatch, size)
startSorts := make([]string, size*sortsize)
// make these initial instances available
i, j := 0, 0
for i < size {
avail[i] = &startBlock[i]
avail[i].Sort = startSorts[j:j]
i += 1
j += sortsize
return &DocumentMatchPool{
avail: avail,
TooSmall: defaultDocumentMatchPoolTooSmall,
// Get returns an available DocumentMatch from the pool
// if the pool was not allocated with sufficient size, an allocation will
// occur to satisfy this request. As a side-effect this will grow the size
// of the pool.
func (p *DocumentMatchPool) Get() *DocumentMatch {
var rv *DocumentMatch
if len(p.avail) > 0 {
rv, p.avail = p.avail[len(p.avail)-1], p.avail[:len(p.avail)-1]
} else {
rv = p.TooSmall(p)
return rv
// Put returns a DocumentMatch to the pool
func (p *DocumentMatchPool) Put(d *DocumentMatch) {
if d == nil {
// reset DocumentMatch before returning it to available pool
p.avail = append(p.avail, d)
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