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/exists.go

@@ -0,0 +1,175 @@
+// Copyright 2012-2015 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/http"
+	"net/url"
+
+	"gopkg.in/olivere/elastic.v3/uritemplates"
+)
+
+// ExistsService checks for the existence of a document using HEAD.
+//
+// See https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-get.html
+// for details.
+type ExistsService struct {
+	client     *Client
+	pretty     bool
+	id         string
+	index      string
+	typ        string
+	preference string
+	realtime   *bool
+	refresh    *bool
+	routing    string
+	parent     string
+}
+
+// NewExistsService creates a new ExistsService.
+func NewExistsService(client *Client) *ExistsService {
+	return &ExistsService{
+		client: client,
+	}
+}
+
+// Id is the document ID.
+func (s *ExistsService) Id(id string) *ExistsService {
+	s.id = id
+	return s
+}
+
+// Index is the name of the index.
+func (s *ExistsService) Index(index string) *ExistsService {
+	s.index = index
+	return s
+}
+
+// Type is the type of the document (use `_all` to fetch the first document
+// matching the ID across all types).
+func (s *ExistsService) Type(typ string) *ExistsService {
+	s.typ = typ
+	return s
+}
+
+// Preference specifies the node or shard the operation should be performed on (default: random).
+func (s *ExistsService) Preference(preference string) *ExistsService {
+	s.preference = preference
+	return s
+}
+
+// Realtime specifies whether to perform the operation in realtime or search mode.
+func (s *ExistsService) Realtime(realtime bool) *ExistsService {
+	s.realtime = &realtime
+	return s
+}
+
+// Refresh the shard containing the document before performing the operation.
+func (s *ExistsService) Refresh(refresh bool) *ExistsService {
+	s.refresh = &refresh
+	return s
+}
+
+// Routing is a specific routing value.
+func (s *ExistsService) Routing(routing string) *ExistsService {
+	s.routing = routing
+	return s
+}
+
+// Parent is the ID of the parent document.
+func (s *ExistsService) Parent(parent string) *ExistsService {
+	s.parent = parent
+	return s
+}
+
+// Pretty indicates that the JSON response be indented and human readable.
+func (s *ExistsService) Pretty(pretty bool) *ExistsService {
+	s.pretty = pretty
+	return s
+}
+
+// buildURL builds the URL for the operation.
+func (s *ExistsService) buildURL() (string, url.Values, error) {
+	// Build URL
+	path, err := uritemplates.Expand("/{index}/{type}/{id}", map[string]string{
+		"id":    s.id,
+		"index": s.index,
+		"type":  s.typ,
+	})
+	if err != nil {
+		return "", url.Values{}, err
+	}
+
+	// Add query string parameters
+	params := url.Values{}
+	if s.pretty {
+		params.Set("pretty", "1")
+	}
+	if s.realtime != nil {
+		params.Set("realtime", fmt.Sprintf("%v", *s.realtime))
+	}
+	if s.refresh != nil {
+		params.Set("refresh", fmt.Sprintf("%v", *s.refresh))
+	}
+	if s.routing != "" {
+		params.Set("routing", s.routing)
+	}
+	if s.parent != "" {
+		params.Set("parent", s.parent)
+	}
+	if s.preference != "" {
+		params.Set("preference", s.preference)
+	}
+	return path, params, nil
+}
+
+// Validate checks if the operation is valid.
+func (s *ExistsService) Validate() error {
+	var invalid []string
+	if s.id == "" {
+		invalid = append(invalid, "Id")
+	}
+	if s.index == "" {
+		invalid = append(invalid, "Index")
+	}
+	if s.typ == "" {
+		invalid = append(invalid, "Type")
+	}
+	if len(invalid) > 0 {
+		return fmt.Errorf("missing required fields: %v", invalid)
+	}
+	return nil
+}
+
+// Do executes the operation.
+func (s *ExistsService) Do() (bool, error) {
+	// Check pre-conditions
+	if err := s.Validate(); err != nil {
+		return false, err
+	}
+
+	// Get URL for request
+	path, params, err := s.buildURL()
+	if err != nil {
+		return false, err
+	}
+
+	// Get HTTP response
+	res, err := s.client.PerformRequest("HEAD", path, params, nil, 404)
+	if err != nil {
+		return false, err
+	}
+
+	// Return operation response
+	switch res.StatusCode {
+	case http.StatusOK:
+		return true, nil
+	case http.StatusNotFound:
+		return false, nil
+	default:
+		return false, fmt.Errorf("elastic: got HTTP code %d when it should have been either 200 or 404", res.StatusCode)
+	}
+}