logging_client.go

// Copyright 2023 Google LLC
//
// 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
//
//     https://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.

// Code generated by protoc-gen-go_gapic. DO NOT EDIT.

package logging

import (
	"context"
	"fmt"
	"math"
	"net/url"
	"time"

	loggingpb "cloud.google.com/go/logging/apiv2/loggingpb"
	longrunningpb "cloud.google.com/go/longrunning/autogen/longrunningpb"
	gax "github.com/googleapis/gax-go/v2"
	"google.golang.org/api/iterator"
	"google.golang.org/api/option"
	"google.golang.org/api/option/internaloption"
	gtransport "google.golang.org/api/transport/grpc"
	monitoredrespb "google.golang.org/genproto/googleapis/api/monitoredres"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/protobuf/proto"
)

var newClientHook clientHook

// CallOptions contains the retry settings for each method of Client.
type CallOptions struct {
	DeleteLog                        []gax.CallOption
	WriteLogEntries                  []gax.CallOption
	ListLogEntries                   []gax.CallOption
	ListMonitoredResourceDescriptors []gax.CallOption
	ListLogs                         []gax.CallOption
	TailLogEntries                   []gax.CallOption
	CancelOperation                  []gax.CallOption
	GetOperation                     []gax.CallOption
	ListOperations                   []gax.CallOption
}

func defaultGRPCClientOptions() []option.ClientOption {
	return []option.ClientOption{
		internaloption.WithDefaultEndpoint("logging.googleapis.com:443"),
		internaloption.WithDefaultMTLSEndpoint("logging.mtls.googleapis.com:443"),
		internaloption.WithDefaultAudience("https://logging.googleapis.com/"),
		internaloption.WithDefaultScopes(DefaultAuthScopes()...),
		internaloption.EnableJwtWithScope(),
		option.WithGRPCDialOption(grpc.WithDefaultCallOptions(
			grpc.MaxCallRecvMsgSize(math.MaxInt32))),
	}
}

func defaultCallOptions() *CallOptions {
	return &CallOptions{
		DeleteLog: []gax.CallOption{
			gax.WithTimeout(60000 * time.Millisecond),
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Internal,
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		WriteLogEntries: []gax.CallOption{
			gax.WithTimeout(60000 * time.Millisecond),
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Internal,
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListLogEntries: []gax.CallOption{
			gax.WithTimeout(60000 * time.Millisecond),
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Internal,
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListMonitoredResourceDescriptors: []gax.CallOption{
			gax.WithTimeout(60000 * time.Millisecond),
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Internal,
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListLogs: []gax.CallOption{
			gax.WithTimeout(60000 * time.Millisecond),
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Internal,
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		TailLogEntries: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.DeadlineExceeded,
					codes.Internal,
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		CancelOperation: []gax.CallOption{},
		GetOperation:    []gax.CallOption{},
		ListOperations:  []gax.CallOption{},
	}
}

// internalClient is an interface that defines the methods available from Cloud Logging API.
type internalClient interface {
	Close() error
	setGoogleClientInfo(...string)
	Connection() *grpc.ClientConn
	DeleteLog(context.Context, *loggingpb.DeleteLogRequest, ...gax.CallOption) error
	WriteLogEntries(context.Context, *loggingpb.WriteLogEntriesRequest, ...gax.CallOption) (*loggingpb.WriteLogEntriesResponse, error)
	ListLogEntries(context.Context, *loggingpb.ListLogEntriesRequest, ...gax.CallOption) *LogEntryIterator
	ListMonitoredResourceDescriptors(context.Context, *loggingpb.ListMonitoredResourceDescriptorsRequest, ...gax.CallOption) *MonitoredResourceDescriptorIterator
	ListLogs(context.Context, *loggingpb.ListLogsRequest, ...gax.CallOption) *StringIterator
	TailLogEntries(context.Context, ...gax.CallOption) (loggingpb.LoggingServiceV2_TailLogEntriesClient, error)
	CancelOperation(context.Context, *longrunningpb.CancelOperationRequest, ...gax.CallOption) error
	GetOperation(context.Context, *longrunningpb.GetOperationRequest, ...gax.CallOption) (*longrunningpb.Operation, error)
	ListOperations(context.Context, *longrunningpb.ListOperationsRequest, ...gax.CallOption) *OperationIterator
}

// Client is a client for interacting with Cloud Logging API.
// Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
//
// Service for ingesting and querying logs.
type Client struct {
	// The internal transport-dependent client.
	internalClient internalClient

	// The call options for this service.
	CallOptions *CallOptions
}

// Wrapper methods routed to the internal client.

// Close closes the connection to the API service. The user should invoke this when
// the client is no longer required.
func (c *Client) Close() error {
	return c.internalClient.Close()
}

// setGoogleClientInfo sets the name and version of the application in
// the `x-goog-api-client` header passed on each request. Intended for
// use by Google-written clients.
func (c *Client) setGoogleClientInfo(keyval ...string) {
	c.internalClient.setGoogleClientInfo(keyval...)
}

// Connection returns a connection to the API service.
//
// Deprecated: Connections are now pooled so this method does not always
// return the same resource.
func (c *Client) Connection() *grpc.ClientConn {
	return c.internalClient.Connection()
}

// DeleteLog deletes all the log entries in a log for the _Default Log Bucket. The log
// reappears if it receives new entries. Log entries written shortly before
// the delete operation might not be deleted. Entries received after the
// delete operation with a timestamp before the operation will be deleted.
func (c *Client) DeleteLog(ctx context.Context, req *loggingpb.DeleteLogRequest, opts ...gax.CallOption) error {
	return c.internalClient.DeleteLog(ctx, req, opts...)
}

// WriteLogEntries writes log entries to Logging. This API method is the
// only way to send log entries to Logging. This method
// is used, directly or indirectly, by the Logging agent
// (fluentd) and all logging libraries configured to use Logging.
// A single request may contain log entries for a maximum of 1000
// different resources (projects, organizations, billing accounts or
// folders)
func (c *Client) WriteLogEntries(ctx context.Context, req *loggingpb.WriteLogEntriesRequest, opts ...gax.CallOption) (*loggingpb.WriteLogEntriesResponse, error) {
	return c.internalClient.WriteLogEntries(ctx, req, opts...)
}

// ListLogEntries lists log entries.  Use this method to retrieve log entries that originated
// from a project/folder/organization/billing account.  For ways to export log
// entries, see Exporting
// Logs (at https://cloud.google.com/logging/docs/export).
func (c *Client) ListLogEntries(ctx context.Context, req *loggingpb.ListLogEntriesRequest, opts ...gax.CallOption) *LogEntryIterator {
	return c.internalClient.ListLogEntries(ctx, req, opts...)
}

// ListMonitoredResourceDescriptors lists the descriptors for monitored resource types used by Logging.
func (c *Client) ListMonitoredResourceDescriptors(ctx context.Context, req *loggingpb.ListMonitoredResourceDescriptorsRequest, opts ...gax.CallOption) *MonitoredResourceDescriptorIterator {
	return c.internalClient.ListMonitoredResourceDescriptors(ctx, req, opts...)
}

// ListLogs lists the logs in projects, organizations, folders, or billing accounts.
// Only logs that have entries are listed.
func (c *Client) ListLogs(ctx context.Context, req *loggingpb.ListLogsRequest, opts ...gax.CallOption) *StringIterator {
	return c.internalClient.ListLogs(ctx, req, opts...)
}

// TailLogEntries streaming read of log entries as they are ingested. Until the stream is
// terminated, it will continue reading logs.
func (c *Client) TailLogEntries(ctx context.Context, opts ...gax.CallOption) (loggingpb.LoggingServiceV2_TailLogEntriesClient, error) {
	return c.internalClient.TailLogEntries(ctx, opts...)
}

// CancelOperation is a utility method from google.longrunning.Operations.
func (c *Client) CancelOperation(ctx context.Context, req *longrunningpb.CancelOperationRequest, opts ...gax.CallOption) error {
	return c.internalClient.CancelOperation(ctx, req, opts...)
}

// GetOperation is a utility method from google.longrunning.Operations.
func (c *Client) GetOperation(ctx context.Context, req *longrunningpb.GetOperationRequest, opts ...gax.CallOption) (*longrunningpb.Operation, error) {
	return c.internalClient.GetOperation(ctx, req, opts...)
}

// ListOperations is a utility method from google.longrunning.Operations.
func (c *Client) ListOperations(ctx context.Context, req *longrunningpb.ListOperationsRequest, opts ...gax.CallOption) *OperationIterator {
	return c.internalClient.ListOperations(ctx, req, opts...)
}

// gRPCClient is a client for interacting with Cloud Logging API over gRPC transport.
//
// Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
type gRPCClient struct {
	// Connection pool of gRPC connections to the service.
	connPool gtransport.ConnPool

	// Points back to the CallOptions field of the containing Client
	CallOptions **CallOptions

	// The gRPC API client.
	client loggingpb.LoggingServiceV2Client

	operationsClient longrunningpb.OperationsClient

	// The x-goog-* metadata to be sent with each request.
	xGoogHeaders []string
}

// NewClient creates a new logging service v2 client based on gRPC.
// The returned client must be Closed when it is done being used to clean up its underlying connections.
//
// Service for ingesting and querying logs.
func NewClient(ctx context.Context, opts ...option.ClientOption) (*Client, error) {
	clientOpts := defaultGRPCClientOptions()
	if newClientHook != nil {
		hookOpts, err := newClientHook(ctx, clientHookParams{})
		if err != nil {
			return nil, err
		}
		clientOpts = append(clientOpts, hookOpts...)
	}

	connPool, err := gtransport.DialPool(ctx, append(clientOpts, opts...)...)
	if err != nil {
		return nil, err
	}
	client := Client{CallOptions: defaultCallOptions()}

	c := &gRPCClient{
		connPool:         connPool,
		client:           loggingpb.NewLoggingServiceV2Client(connPool),
		CallOptions:      &client.CallOptions,
		operationsClient: longrunningpb.NewOperationsClient(connPool),
	}
	c.setGoogleClientInfo()

	client.internalClient = c

	return &client, nil
}

// Connection returns a connection to the API service.
//
// Deprecated: Connections are now pooled so this method does not always
// return the same resource.
func (c *gRPCClient) Connection() *grpc.ClientConn {
	return c.connPool.Conn()
}

// setGoogleClientInfo sets the name and version of the application in
// the `x-goog-api-client` header passed on each request. Intended for
// use by Google-written clients.
func (c *gRPCClient) setGoogleClientInfo(keyval ...string) {
	kv := append([]string{"gl-go", gax.GoVersion}, keyval...)
	kv = append(kv, "gapic", getVersionClient(), "gax", gax.Version, "grpc", grpc.Version)
	c.xGoogHeaders = []string{"x-goog-api-client", gax.XGoogHeader(kv...)}
}

// Close closes the connection to the API service. The user should invoke this when
// the client is no longer required.
func (c *gRPCClient) Close() error {
	return c.connPool.Close()
}

func (c *gRPCClient) DeleteLog(ctx context.Context, req *loggingpb.DeleteLogRequest, opts ...gax.CallOption) error {
	hds := []string{"x-goog-request-params", fmt.Sprintf("%s=%v", "log_name", url.QueryEscape(req.GetLogName()))}

	hds = append(c.xGoogHeaders, hds...)
	ctx = gax.InsertMetadataIntoOutgoingContext(ctx, hds...)
	opts = append((*c.CallOptions).DeleteLog[0:len((*c.CallOptions).DeleteLog):len((*c.CallOptions).DeleteLog)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		_, err = c.client.DeleteLog(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	return err
}

func (c *gRPCClient) WriteLogEntries(ctx context.Context, req *loggingpb.WriteLogEntriesRequest, opts ...gax.CallOption) (*loggingpb.WriteLogEntriesResponse, error) {
	ctx = gax.InsertMetadataIntoOutgoingContext(ctx, c.xGoogHeaders...)
	opts = append((*c.CallOptions).WriteLogEntries[0:len((*c.CallOptions).WriteLogEntries):len((*c.CallOptions).WriteLogEntries)], opts...)
	var resp *loggingpb.WriteLogEntriesResponse
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.WriteLogEntries(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *gRPCClient) ListLogEntries(ctx context.Context, req *loggingpb.ListLogEntriesRequest, opts ...gax.CallOption) *LogEntryIterator {
	ctx = gax.InsertMetadataIntoOutgoingContext(ctx, c.xGoogHeaders...)
	opts = append((*c.CallOptions).ListLogEntries[0:len((*c.CallOptions).ListLogEntries):len((*c.CallOptions).ListLogEntries)], opts...)
	it := &LogEntryIterator{}
	req = proto.Clone(req).(*loggingpb.ListLogEntriesRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*loggingpb.LogEntry, string, error) {
		resp := &loggingpb.ListLogEntriesResponse{}
		if pageToken != "" {
			req.PageToken = pageToken
		}
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else if pageSize != 0 {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.client.ListLogEntries(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetEntries(), resp.GetNextPageToken(), nil
	}
	fetch := func(pageSize int, pageToken string) (string, error) {
		items, nextPageToken, err := it.InternalFetch(pageSize, pageToken)
		if err != nil {
			return "", err
		}
		it.items = append(it.items, items...)
		return nextPageToken, nil
	}

	it.pageInfo, it.nextFunc = iterator.NewPageInfo(fetch, it.bufLen, it.takeBuf)
	it.pageInfo.MaxSize = int(req.GetPageSize())
	it.pageInfo.Token = req.GetPageToken()

	return it
}

func (c *gRPCClient) ListMonitoredResourceDescriptors(ctx context.Context, req *loggingpb.ListMonitoredResourceDescriptorsRequest, opts ...gax.CallOption) *MonitoredResourceDescriptorIterator {
	ctx = gax.InsertMetadataIntoOutgoingContext(ctx, c.xGoogHeaders...)
	opts = append((*c.CallOptions).ListMonitoredResourceDescriptors[0:len((*c.CallOptions).ListMonitoredResourceDescriptors):len((*c.CallOptions).ListMonitoredResourceDescriptors)], opts...)
	it := &MonitoredResourceDescriptorIterator{}
	req = proto.Clone(req).(*loggingpb.ListMonitoredResourceDescriptorsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*monitoredrespb.MonitoredResourceDescriptor, string, error) {
		resp := &loggingpb.ListMonitoredResourceDescriptorsResponse{}
		if pageToken != "" {
			req.PageToken = pageToken
		}
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else if pageSize != 0 {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.client.ListMonitoredResourceDescriptors(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetResourceDescriptors(), resp.GetNextPageToken(), nil
	}
	fetch := func(pageSize int, pageToken string) (string, error) {
		items, nextPageToken, err := it.InternalFetch(pageSize, pageToken)
		if err != nil {
			return "", err
		}
		it.items = append(it.items, items...)
		return nextPageToken, nil
	}

	it.pageInfo, it.nextFunc = iterator.NewPageInfo(fetch, it.bufLen, it.takeBuf)
	it.pageInfo.MaxSize = int(req.GetPageSize())
	it.pageInfo.Token = req.GetPageToken()

	return it
}

func (c *gRPCClient) ListLogs(ctx context.Context, req *loggingpb.ListLogsRequest, opts ...gax.CallOption) *StringIterator {
	hds := []string{"x-goog-request-params", fmt.Sprintf("%s=%v", "parent", url.QueryEscape(req.GetParent()))}

	hds = append(c.xGoogHeaders, hds...)
	ctx = gax.InsertMetadataIntoOutgoingContext(ctx, hds...)
	opts = append((*c.CallOptions).ListLogs[0:len((*c.CallOptions).ListLogs):len((*c.CallOptions).ListLogs)], opts...)
	it := &StringIterator{}
	req = proto.Clone(req).(*loggingpb.ListLogsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]string, string, error) {
		resp := &loggingpb.ListLogsResponse{}
		if pageToken != "" {
			req.PageToken = pageToken
		}
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else if pageSize != 0 {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.client.ListLogs(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetLogNames(), resp.GetNextPageToken(), nil
	}
	fetch := func(pageSize int, pageToken string) (string, error) {
		items, nextPageToken, err := it.InternalFetch(pageSize, pageToken)
		if err != nil {
			return "", err
		}
		it.items = append(it.items, items...)
		return nextPageToken, nil
	}

	it.pageInfo, it.nextFunc = iterator.NewPageInfo(fetch, it.bufLen, it.takeBuf)
	it.pageInfo.MaxSize = int(req.GetPageSize())
	it.pageInfo.Token = req.GetPageToken()

	return it
}

func (c *gRPCClient) TailLogEntries(ctx context.Context, opts ...gax.CallOption) (loggingpb.LoggingServiceV2_TailLogEntriesClient, error) {
	ctx = gax.InsertMetadataIntoOutgoingContext(ctx, c.xGoogHeaders...)
	var resp loggingpb.LoggingServiceV2_TailLogEntriesClient
	opts = append((*c.CallOptions).TailLogEntries[0:len((*c.CallOptions).TailLogEntries):len((*c.CallOptions).TailLogEntries)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.client.TailLogEntries(ctx, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *gRPCClient) CancelOperation(ctx context.Context, req *longrunningpb.CancelOperationRequest, opts ...gax.CallOption) error {
	hds := []string{"x-goog-request-params", fmt.Sprintf("%s=%v", "name", url.QueryEscape(req.GetName()))}

	hds = append(c.xGoogHeaders, hds...)
	ctx = gax.InsertMetadataIntoOutgoingContext(ctx, hds...)
	opts = append((*c.CallOptions).CancelOperation[0:len((*c.CallOptions).CancelOperation):len((*c.CallOptions).CancelOperation)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		_, err = c.operationsClient.CancelOperation(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	return err
}

func (c *gRPCClient) GetOperation(ctx context.Context, req *longrunningpb.GetOperationRequest, opts ...gax.CallOption) (*longrunningpb.Operation, error) {
	hds := []string{"x-goog-request-params", fmt.Sprintf("%s=%v", "name", url.QueryEscape(req.GetName()))}

	hds = append(c.xGoogHeaders, hds...)
	ctx = gax.InsertMetadataIntoOutgoingContext(ctx, hds...)
	opts = append((*c.CallOptions).GetOperation[0:len((*c.CallOptions).GetOperation):len((*c.CallOptions).GetOperation)], opts...)
	var resp *longrunningpb.Operation
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.operationsClient.GetOperation(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *gRPCClient) ListOperations(ctx context.Context, req *longrunningpb.ListOperationsRequest, opts ...gax.CallOption) *OperationIterator {
	hds := []string{"x-goog-request-params", fmt.Sprintf("%s=%v", "name", url.QueryEscape(req.GetName()))}

	hds = append(c.xGoogHeaders, hds...)
	ctx = gax.InsertMetadataIntoOutgoingContext(ctx, hds...)
	opts = append((*c.CallOptions).ListOperations[0:len((*c.CallOptions).ListOperations):len((*c.CallOptions).ListOperations)], opts...)
	it := &OperationIterator{}
	req = proto.Clone(req).(*longrunningpb.ListOperationsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*longrunningpb.Operation, string, error) {
		resp := &longrunningpb.ListOperationsResponse{}
		if pageToken != "" {
			req.PageToken = pageToken
		}
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else if pageSize != 0 {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.operationsClient.ListOperations(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetOperations(), resp.GetNextPageToken(), nil
	}
	fetch := func(pageSize int, pageToken string) (string, error) {
		items, nextPageToken, err := it.InternalFetch(pageSize, pageToken)
		if err != nil {
			return "", err
		}
		it.items = append(it.items, items...)
		return nextPageToken, nil
	}

	it.pageInfo, it.nextFunc = iterator.NewPageInfo(fetch, it.bufLen, it.takeBuf)
	it.pageInfo.MaxSize = int(req.GetPageSize())
	it.pageInfo.Token = req.GetPageToken()

	return it
}

// LogEntryIterator manages a stream of *loggingpb.LogEntry.
type LogEntryIterator struct {
	items    []*loggingpb.LogEntry
	pageInfo *iterator.PageInfo
	nextFunc func() error

	// Response is the raw response for the current page.
	// It must be cast to the RPC response type.
	// Calling Next() or InternalFetch() updates this value.
	Response interface{}

	// InternalFetch is for use by the Google Cloud Libraries only.
	// It is not part of the stable interface of this package.
	//
	// InternalFetch returns results from a single call to the underlying RPC.
	// The number of results is no greater than pageSize.
	// If there are no more results, nextPageToken is empty and err is nil.
	InternalFetch func(pageSize int, pageToken string) (results []*loggingpb.LogEntry, nextPageToken string, err error)
}

// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
func (it *LogEntryIterator) PageInfo() *iterator.PageInfo {
	return it.pageInfo
}

// Next returns the next result. Its second return value is iterator.Done if there are no more
// results. Once Next returns Done, all subsequent calls will return Done.
func (it *LogEntryIterator) Next() (*loggingpb.LogEntry, error) {
	var item *loggingpb.LogEntry
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

func (it *LogEntryIterator) bufLen() int {
	return len(it.items)
}

func (it *LogEntryIterator) takeBuf() interface{} {
	b := it.items
	it.items = nil
	return b
}

// MonitoredResourceDescriptorIterator manages a stream of *monitoredrespb.MonitoredResourceDescriptor.
type MonitoredResourceDescriptorIterator struct {
	items    []*monitoredrespb.MonitoredResourceDescriptor
	pageInfo *iterator.PageInfo
	nextFunc func() error

	// Response is the raw response for the current page.
	// It must be cast to the RPC response type.
	// Calling Next() or InternalFetch() updates this value.
	Response interface{}

	// InternalFetch is for use by the Google Cloud Libraries only.
	// It is not part of the stable interface of this package.
	//
	// InternalFetch returns results from a single call to the underlying RPC.
	// The number of results is no greater than pageSize.
	// If there are no more results, nextPageToken is empty and err is nil.
	InternalFetch func(pageSize int, pageToken string) (results []*monitoredrespb.MonitoredResourceDescriptor, nextPageToken string, err error)
}

// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
func (it *MonitoredResourceDescriptorIterator) PageInfo() *iterator.PageInfo {
	return it.pageInfo
}

// Next returns the next result. Its second return value is iterator.Done if there are no more
// results. Once Next returns Done, all subsequent calls will return Done.
func (it *MonitoredResourceDescriptorIterator) Next() (*monitoredrespb.MonitoredResourceDescriptor, error) {
	var item *monitoredrespb.MonitoredResourceDescriptor
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

func (it *MonitoredResourceDescriptorIterator) bufLen() int {
	return len(it.items)
}

func (it *MonitoredResourceDescriptorIterator) takeBuf() interface{} {
	b := it.items
	it.items = nil
	return b
}

// OperationIterator manages a stream of *longrunningpb.Operation.
type OperationIterator struct {
	items    []*longrunningpb.Operation
	pageInfo *iterator.PageInfo
	nextFunc func() error

	// Response is the raw response for the current page.
	// It must be cast to the RPC response type.
	// Calling Next() or InternalFetch() updates this value.
	Response interface{}

	// InternalFetch is for use by the Google Cloud Libraries only.
	// It is not part of the stable interface of this package.
	//
	// InternalFetch returns results from a single call to the underlying RPC.
	// The number of results is no greater than pageSize.
	// If there are no more results, nextPageToken is empty and err is nil.
	InternalFetch func(pageSize int, pageToken string) (results []*longrunningpb.Operation, nextPageToken string, err error)
}

// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
func (it *OperationIterator) PageInfo() *iterator.PageInfo {
	return it.pageInfo
}

// Next returns the next result. Its second return value is iterator.Done if there are no more
// results. Once Next returns Done, all subsequent calls will return Done.
func (it *OperationIterator) Next() (*longrunningpb.Operation, error) {
	var item *longrunningpb.Operation
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

func (it *OperationIterator) bufLen() int {
	return len(it.items)
}

func (it *OperationIterator) takeBuf() interface{} {
	b := it.items
	it.items = nil
	return b
}

// StringIterator manages a stream of string.
type StringIterator struct {
	items    []string
	pageInfo *iterator.PageInfo
	nextFunc func() error

	// Response is the raw response for the current page.
	// It must be cast to the RPC response type.
	// Calling Next() or InternalFetch() updates this value.
	Response interface{}

	// InternalFetch is for use by the Google Cloud Libraries only.
	// It is not part of the stable interface of this package.
	//
	// InternalFetch returns results from a single call to the underlying RPC.
	// The number of results is no greater than pageSize.
	// If there are no more results, nextPageToken is empty and err is nil.
	InternalFetch func(pageSize int, pageToken string) (results []string, nextPageToken string, err error)
}

// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
func (it *StringIterator) PageInfo() *iterator.PageInfo {
	return it.pageInfo
}

// Next returns the next result. Its second return value is iterator.Done if there are no more
// results. Once Next returns Done, all subsequent calls will return Done.
func (it *StringIterator) Next() (string, error) {
	var item string
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

func (it *StringIterator) bufLen() int {
	return len(it.items)
}

func (it *StringIterator) takeBuf() interface{} {
	b := it.items
	it.items = nil
	return b
}