api: Implement bucket notification. (#2271)

* Implement basic S3 notifications through queues

Supports multiple queues and three basic queue types:

1. NilQueue -- messages don't get sent anywhere
2. LogQueue -- messages get logged
3. AmqpQueue -- messages are sent to an AMQP queue

* api: Implement bucket notification.

Supports two different queue types

- AMQP
- ElasticSearch.

* Add support for redis

vendor/gopkg.in/olivere/elastic.v3/clear_scroll.go

@@ -0,0 +1,101 @@
+// Copyright 2012-present Oliver Eilhard. All rights reserved.
+// Use of this source code is governed by a MIT-license.
+// See http://olivere.mit-license.org/license.txt for details.
+
+package elastic
+
+import (
+	"fmt"
+	"net/url"
+	"strings"
+)
+
+// ClearScrollService clears one or more scroll contexts by their ids.
+//
+// See https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-scroll.html#_clear_scroll_api
+// for details.
+type ClearScrollService struct {
+	client   *Client
+	pretty   bool
+	scrollId []string
+}
+
+// NewClearScrollService creates a new ClearScrollService.
+func NewClearScrollService(client *Client) *ClearScrollService {
+	return &ClearScrollService{
+		client:   client,
+		scrollId: make([]string, 0),
+	}
+}
+
+// ScrollId is a list of scroll IDs to clear.
+// Use _all to clear all search contexts.
+func (s *ClearScrollService) ScrollId(scrollIds ...string) *ClearScrollService {
+	s.scrollId = append(s.scrollId, scrollIds...)
+	return s
+}
+
+// Pretty indicates that the JSON response be indented and human readable.
+func (s *ClearScrollService) Pretty(pretty bool) *ClearScrollService {
+	s.pretty = pretty
+	return s
+}
+
+// buildURL builds the URL for the operation.
+func (s *ClearScrollService) buildURL() (string, url.Values, error) {
+	// Build URL
+	path := "/_search/scroll/"
+
+	// Add query string parameters
+	params := url.Values{}
+	if s.pretty {
+		params.Set("pretty", "1")
+	}
+	return path, params, nil
+}
+
+// Validate checks if the operation is valid.
+func (s *ClearScrollService) Validate() error {
+	var invalid []string
+	if len(s.scrollId) == 0 {
+		invalid = append(invalid, "ScrollId")
+	}
+	if len(invalid) > 0 {
+		return fmt.Errorf("missing required fields: %v", invalid)
+	}
+	return nil
+}
+
+// Do executes the operation.
+func (s *ClearScrollService) Do() (*ClearScrollResponse, error) {
+	// Check pre-conditions
+	if err := s.Validate(); err != nil {
+		return nil, err
+	}
+
+	// Get URL for request
+	path, params, err := s.buildURL()
+	if err != nil {
+		return nil, err
+	}
+
+	// Setup HTTP request body
+	body := strings.Join(s.scrollId, ",")
+
+	// Get HTTP response
+	res, err := s.client.PerformRequest("DELETE", path, params, body)
+	if err != nil {
+		return nil, err
+	}
+
+	// Return operation response
+	ret := new(ClearScrollResponse)
+	if err := s.client.decoder.Decode(res.Body, ret); err != nil {
+		return nil, err
+	}
+	return ret, nil
+}
+
+// ClearScrollResponse is the response of ClearScrollService.Do.
+type ClearScrollResponse struct {
+}