Adding upstream version 2.5.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

search/pool.go

@@ -0,0 +1,91 @@
+//  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
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package search
+
+import (
+	"reflect"
+)
+
+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 {
+		return
+	}
+	// reset DocumentMatch before returning it to available pool
+	d.Reset()
+	p.avail = append(p.avail, d)
+}