Search bar for issues/pulls (#530)

vendor/github.com/blevesearch/bleve/registry/cache.go

@@ -0,0 +1,87 @@
+//  Copyright (c) 2016 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 registry
+
+import (
+	"fmt"
+	"sync"
+)
+
+var ErrAlreadyDefined = fmt.Errorf("item already defined")
+
+type CacheBuild func(name string, config map[string]interface{}, cache *Cache) (interface{}, error)
+
+type ConcurrentCache struct {
+	mutex sync.RWMutex
+	data  map[string]interface{}
+}
+
+func NewConcurrentCache() *ConcurrentCache {
+	return &ConcurrentCache{
+		data: make(map[string]interface{}),
+	}
+}
+
+func (c *ConcurrentCache) ItemNamed(name string, cache *Cache, build CacheBuild) (interface{}, error) {
+	c.mutex.RLock()
+	item, cached := c.data[name]
+	if cached {
+		c.mutex.RUnlock()
+		return item, nil
+	}
+	// give up read lock
+	c.mutex.RUnlock()
+	// try to build it
+	newItem, err := build(name, nil, cache)
+	if err != nil {
+		return nil, err
+	}
+	// acquire write lock
+	c.mutex.Lock()
+	defer c.mutex.Unlock()
+	// check again because it could have been created while trading locks
+	item, cached = c.data[name]
+	if cached {
+		return item, nil
+	}
+	c.data[name] = newItem
+	return newItem, nil
+}
+
+func (c *ConcurrentCache) DefineItem(name string, typ string, config map[string]interface{}, cache *Cache, build CacheBuild) (interface{}, error) {
+	c.mutex.RLock()
+	_, cached := c.data[name]
+	if cached {
+		c.mutex.RUnlock()
+		return nil, ErrAlreadyDefined
+	}
+	// give up read lock so others lookups can proceed
+	c.mutex.RUnlock()
+	// really not there, try to build it
+	newItem, err := build(typ, config, cache)
+	if err != nil {
+		return nil, err
+	}
+	// now we've built it, acquire lock
+	c.mutex.Lock()
+	defer c.mutex.Unlock()
+	// check again because it could have been created while trading locks
+	_, cached = c.data[name]
+	if cached {
+		return nil, ErrAlreadyDefined
+	}
+	c.data[name] = newItem
+	return newItem, nil
+}