Add Point In Time API (#1480)

This commit adds the Point in Time API as described here:
https://www.elastic.co/guide/en/elasticsearch/reference/7.x/point-in-time-api.html

Close #1433

client.go

@@ -1636,6 +1636,16 @@ func (c *Client) ClearScroll(scrollIds ...string) *ClearScrollService {
 	return NewClearScrollService(c).ScrollId(scrollIds...)
 }
 
+// OpenPointInTime opens a new Point in Time.
+func (c *Client) OpenPointInTime(indices ...string) *OpenPointInTimeService {
+	return NewOpenPointInTimeService(c).Index(indices...)
+}
+
+// ClosePointInTime closes an existing Point in Time.
+func (c *Client) ClosePointInTime(id string) *ClosePointInTimeService {
+	return NewClosePointInTimeService(c).ID(id)
+}
+
 // -- Indices APIs --
 
 // CreateIndex returns a service to create a new index.

pit.go

@@ -0,0 +1,36 @@
+// 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
+
+// PointInTime is a lightweight view into the state of the data that existed
+// when initiated. It can be created with OpenPointInTime API and be used
+// when searching, e.g. in Search API or with SearchSource.
+type PointInTime struct {
+	// Id that uniquely identifies the point in time, as created with the
+	// OpenPointInTime API.
+	Id string `json:"id,omitempty"`
+	// KeepAlive is the time for which this specific PointInTime will be
+	// kept alive by Elasticsearch.
+	KeepAlive string `json:"keep_alive,omitempty"`
+}
+
+// NewPointInTime creates a new PointInTime.
+func NewPointInTime(id, keepAlive string) *PointInTime {
+	return &PointInTime{
+		Id:        id,
+		KeepAlive: keepAlive,
+	}
+}
+
+// Source generates the JSON serializable fragment for the PointInTime.
+func (pit *PointInTime) Source() (interface{}, error) {
+	if pit == nil {
+		return nil, nil
+	}
+	return map[string]interface{}{
+		"id":         pit.Id,
+		"keep_alive": pit.KeepAlive,
+	}, nil
+}

pit_close.go

@@ -0,0 +1,176 @@
+// 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 (
+	"context"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+// ClosePointInTimeService removes a point in time.
+//
+// See https://www.elastic.co/guide/en/elasticsearch/reference/7.x/point-in-time-api.html
+// for details.
+type ClosePointInTimeService struct {
+	client *Client
+
+	pretty     *bool       // pretty format the returned JSON response
+	human      *bool       // return human readable values for statistics
+	errorTrace *bool       // include the stack trace of returned errors
+	filterPath []string    // list of filters used to reduce the response
+	headers    http.Header // custom request-level HTTP headers
+
+	id         string
+	bodyJson   interface{}
+	bodyString string
+}
+
+// NewClosePointInTimeService creates a new ClosePointInTimeService.
+func NewClosePointInTimeService(client *Client) *ClosePointInTimeService {
+	return &ClosePointInTimeService{
+		client: client,
+	}
+}
+
+// Pretty tells Elasticsearch whether to return a formatted JSON response.
+func (s *ClosePointInTimeService) Pretty(pretty bool) *ClosePointInTimeService {
+	s.pretty = &pretty
+	return s
+}
+
+// Human specifies whether human readable values should be returned in
+// the JSON response, e.g. "7.5mb".
+func (s *ClosePointInTimeService) Human(human bool) *ClosePointInTimeService {
+	s.human = &human
+	return s
+}
+
+// ErrorTrace specifies whether to include the stack trace of returned errors.
+func (s *ClosePointInTimeService) ErrorTrace(errorTrace bool) *ClosePointInTimeService {
+	s.errorTrace = &errorTrace
+	return s
+}
+
+// FilterPath specifies a list of filters used to reduce the response.
+func (s *ClosePointInTimeService) FilterPath(filterPath ...string) *ClosePointInTimeService {
+	s.filterPath = filterPath
+	return s
+}
+
+// Header adds a header to the request.
+func (s *ClosePointInTimeService) Header(name string, value string) *ClosePointInTimeService {
+	if s.headers == nil {
+		s.headers = http.Header{}
+	}
+	s.headers.Add(name, value)
+	return s
+}
+
+// Headers specifies the headers of the request.
+func (s *ClosePointInTimeService) Headers(headers http.Header) *ClosePointInTimeService {
+	s.headers = headers
+	return s
+}
+
+// ID to close.
+func (s *ClosePointInTimeService) ID(id string) *ClosePointInTimeService {
+	s.id = id
+	return s
+}
+
+// BodyJson is the document as a serializable JSON interface.
+func (s *ClosePointInTimeService) BodyJson(body interface{}) *ClosePointInTimeService {
+	s.bodyJson = body
+	return s
+}
+
+// BodyString is the document encoded as a string.
+func (s *ClosePointInTimeService) BodyString(body string) *ClosePointInTimeService {
+	s.bodyString = body
+	return s
+}
+
+// buildURL builds the URL for the operation.
+func (s *ClosePointInTimeService) buildURL() (string, string, url.Values, error) {
+	var (
+		method = "DELETE"
+		path   = "/_pit"
+	)
+
+	// Add query string parameters
+	params := url.Values{}
+	if v := s.pretty; v != nil {
+		params.Set("pretty", fmt.Sprint(*v))
+	}
+	if v := s.human; v != nil {
+		params.Set("human", fmt.Sprint(*v))
+	}
+	if v := s.errorTrace; v != nil {
+		params.Set("error_trace", fmt.Sprint(*v))
+	}
+	if len(s.filterPath) > 0 {
+		params.Set("filter_path", strings.Join(s.filterPath, ","))
+	}
+	return method, path, params, nil
+}
+
+// Validate checks if the operation is valid.
+func (s *ClosePointInTimeService) Validate() error {
+	return nil
+}
+
+// Do executes the operation.
+func (s *ClosePointInTimeService) Do(ctx context.Context) (*ClosePointInTimeResponse, error) {
+	// Check pre-conditions
+	if err := s.Validate(); err != nil {
+		return nil, err
+	}
+
+	// Get URL for request
+	method, path, params, err := s.buildURL()
+	if err != nil {
+		return nil, err
+	}
+
+	// Setup HTTP request body
+	var body interface{}
+	if s.id != "" {
+		body = map[string]interface{}{
+			"id": s.id,
+		}
+	} else if s.bodyJson != nil {
+		body = s.bodyJson
+	} else {
+		body = s.bodyString
+	}
+
+	// Get HTTP response
+	res, err := s.client.PerformRequest(ctx, PerformRequestOptions{
+		Method:  method,
+		Path:    path,
+		Params:  params,
+		Body:    body,
+		Headers: s.headers,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	// Return operation response
+	ret := new(ClosePointInTimeResponse)
+	if err := s.client.decoder.Decode(res.Body, ret); err != nil {
+		return nil, err
+	}
+	return ret, nil
+}
+
+// ClosePointInTimeResponse is the result of closing a point in time.
+type ClosePointInTimeResponse struct {
+	Succeeded bool `json:"succeeded,omitempty"`
+	NumFreed  int  `json:"num_freed,omitempty"`
+}