publisher_client.go

// Copyright 2021 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 pubsub

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

	"github.com/golang/protobuf/proto"
	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"
	iampb "google.golang.org/genproto/googleapis/iam/v1"
	pubsubpb "google.golang.org/genproto/googleapis/pubsub/v1"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/metadata"
)

var newPublisherClientHook clientHook

// PublisherCallOptions contains the retry settings for each method of PublisherClient.
type PublisherCallOptions struct {
	CreateTopic            []gax.CallOption
	UpdateTopic            []gax.CallOption
	Publish                []gax.CallOption
	GetTopic               []gax.CallOption
	ListTopics             []gax.CallOption
	ListTopicSubscriptions []gax.CallOption
	ListTopicSnapshots     []gax.CallOption
	DeleteTopic            []gax.CallOption
	DetachSubscription     []gax.CallOption
	GetIamPolicy           []gax.CallOption
	SetIamPolicy           []gax.CallOption
	TestIamPermissions     []gax.CallOption
}

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

func defaultPublisherCallOptions() *PublisherCallOptions {
	return &PublisherCallOptions{
		CreateTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		UpdateTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		Publish: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Aborted,
					codes.Canceled,
					codes.Internal,
					codes.ResourceExhausted,
					codes.Unknown,
					codes.Unavailable,
					codes.DeadlineExceeded,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		GetTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unknown,
					codes.Aborted,
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListTopics: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unknown,
					codes.Aborted,
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListTopicSubscriptions: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unknown,
					codes.Aborted,
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		ListTopicSnapshots: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unknown,
					codes.Aborted,
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		DeleteTopic: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		DetachSubscription: []gax.CallOption{
			gax.WithRetry(func() gax.Retryer {
				return gax.OnCodes([]codes.Code{
					codes.Unavailable,
				}, gax.Backoff{
					Initial:    100 * time.Millisecond,
					Max:        60000 * time.Millisecond,
					Multiplier: 1.30,
				})
			}),
		},
		GetIamPolicy:       []gax.CallOption{},
		SetIamPolicy:       []gax.CallOption{},
		TestIamPermissions: []gax.CallOption{},
	}
}

// internalPublisherClient is an interface that defines the methods availaible from Cloud Pub/Sub API.
type internalPublisherClient interface {
	Close() error
	setGoogleClientInfo(...string)
	Connection() *grpc.ClientConn
	CreateTopic(context.Context, *pubsubpb.Topic, ...gax.CallOption) (*pubsubpb.Topic, error)
	UpdateTopic(context.Context, *pubsubpb.UpdateTopicRequest, ...gax.CallOption) (*pubsubpb.Topic, error)
	Publish(context.Context, *pubsubpb.PublishRequest, ...gax.CallOption) (*pubsubpb.PublishResponse, error)
	GetTopic(context.Context, *pubsubpb.GetTopicRequest, ...gax.CallOption) (*pubsubpb.Topic, error)
	ListTopics(context.Context, *pubsubpb.ListTopicsRequest, ...gax.CallOption) *TopicIterator
	ListTopicSubscriptions(context.Context, *pubsubpb.ListTopicSubscriptionsRequest, ...gax.CallOption) *StringIterator
	ListTopicSnapshots(context.Context, *pubsubpb.ListTopicSnapshotsRequest, ...gax.CallOption) *StringIterator
	DeleteTopic(context.Context, *pubsubpb.DeleteTopicRequest, ...gax.CallOption) error
	DetachSubscription(context.Context, *pubsubpb.DetachSubscriptionRequest, ...gax.CallOption) (*pubsubpb.DetachSubscriptionResponse, error)
	GetIamPolicy(context.Context, *iampb.GetIamPolicyRequest, ...gax.CallOption) (*iampb.Policy, error)
	SetIamPolicy(context.Context, *iampb.SetIamPolicyRequest, ...gax.CallOption) (*iampb.Policy, error)
	TestIamPermissions(context.Context, *iampb.TestIamPermissionsRequest, ...gax.CallOption) (*iampb.TestIamPermissionsResponse, error)
}

// PublisherClient is a client for interacting with Cloud Pub/Sub API.
// Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
//
// The service that an application uses to manipulate topics, and to send
// messages to a topic.
type PublisherClient struct {
	// The internal transport-dependent client.
	internalClient internalPublisherClient

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

// 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 *PublisherClient) 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 *PublisherClient) setGoogleClientInfo(keyval ...string) {
	c.internalClient.setGoogleClientInfo(keyval...)
}

// Connection returns a connection to the API service.
//
// Deprecated.
func (c *PublisherClient) Connection() *grpc.ClientConn {
	return c.internalClient.Connection()
}

// CreateTopic creates the given topic with the given name. See the [resource name rules]
// (https://cloud.google.com/pubsub/docs/admin#resource_names (at https://cloud.google.com/pubsub/docs/admin#resource_names)).
func (c *PublisherClient) CreateTopic(ctx context.Context, req *pubsubpb.Topic, opts ...gax.CallOption) (*pubsubpb.Topic, error) {
	return c.internalClient.CreateTopic(ctx, req, opts...)
}

// UpdateTopic updates an existing topic. Note that certain properties of a
// topic are not modifiable.
func (c *PublisherClient) UpdateTopic(ctx context.Context, req *pubsubpb.UpdateTopicRequest, opts ...gax.CallOption) (*pubsubpb.Topic, error) {
	return c.internalClient.UpdateTopic(ctx, req, opts...)
}

// Publish adds one or more messages to the topic. Returns NOT_FOUND if the topic
// does not exist.
func (c *PublisherClient) Publish(ctx context.Context, req *pubsubpb.PublishRequest, opts ...gax.CallOption) (*pubsubpb.PublishResponse, error) {
	return c.internalClient.Publish(ctx, req, opts...)
}

// GetTopic gets the configuration of a topic.
func (c *PublisherClient) GetTopic(ctx context.Context, req *pubsubpb.GetTopicRequest, opts ...gax.CallOption) (*pubsubpb.Topic, error) {
	return c.internalClient.GetTopic(ctx, req, opts...)
}

// ListTopics lists matching topics.
func (c *PublisherClient) ListTopics(ctx context.Context, req *pubsubpb.ListTopicsRequest, opts ...gax.CallOption) *TopicIterator {
	return c.internalClient.ListTopics(ctx, req, opts...)
}

// ListTopicSubscriptions lists the names of the attached subscriptions on this topic.
func (c *PublisherClient) ListTopicSubscriptions(ctx context.Context, req *pubsubpb.ListTopicSubscriptionsRequest, opts ...gax.CallOption) *StringIterator {
	return c.internalClient.ListTopicSubscriptions(ctx, req, opts...)
}

// ListTopicSnapshots lists the names of the snapshots on this topic. Snapshots are used in
// Seek (at https://cloud.google.com/pubsub/docs/replay-overview) operations,
// which allow you to manage message acknowledgments in bulk. That is, you can
// set the acknowledgment state of messages in an existing subscription to the
// state captured by a snapshot.
func (c *PublisherClient) ListTopicSnapshots(ctx context.Context, req *pubsubpb.ListTopicSnapshotsRequest, opts ...gax.CallOption) *StringIterator {
	return c.internalClient.ListTopicSnapshots(ctx, req, opts...)
}

// DeleteTopic deletes the topic with the given name. Returns NOT_FOUND if the topic
// does not exist. After a topic is deleted, a new topic may be created with
// the same name; this is an entirely new topic with none of the old
// configuration or subscriptions. Existing subscriptions to this topic are
// not deleted, but their topic field is set to _deleted-topic_.
func (c *PublisherClient) DeleteTopic(ctx context.Context, req *pubsubpb.DeleteTopicRequest, opts ...gax.CallOption) error {
	return c.internalClient.DeleteTopic(ctx, req, opts...)
}

// DetachSubscription detaches a subscription from this topic. All messages retained in the
// subscription are dropped. Subsequent Pull and StreamingPull requests
// will return FAILED_PRECONDITION. If the subscription is a push
// subscription, pushes to the endpoint will stop.
func (c *PublisherClient) DetachSubscription(ctx context.Context, req *pubsubpb.DetachSubscriptionRequest, opts ...gax.CallOption) (*pubsubpb.DetachSubscriptionResponse, error) {
	return c.internalClient.DetachSubscription(ctx, req, opts...)
}

// GetIamPolicy gets the access control policy for a resource. Returns an empty policy
// if the resource exists and does not have a policy set.
func (c *PublisherClient) GetIamPolicy(ctx context.Context, req *iampb.GetIamPolicyRequest, opts ...gax.CallOption) (*iampb.Policy, error) {
	return c.internalClient.GetIamPolicy(ctx, req, opts...)
}

// SetIamPolicy sets the access control policy on the specified resource. Replaces
// any existing policy.
//
// Can return NOT_FOUND, INVALID_ARGUMENT, and PERMISSION_DENIED
// errors.
func (c *PublisherClient) SetIamPolicy(ctx context.Context, req *iampb.SetIamPolicyRequest, opts ...gax.CallOption) (*iampb.Policy, error) {
	return c.internalClient.SetIamPolicy(ctx, req, opts...)
}

// TestIamPermissions returns permissions that a caller has on the specified resource. If the
// resource does not exist, this will return an empty set of
// permissions, not a NOT_FOUND error.
//
// Note: This operation is designed to be used for building
// permission-aware UIs and command-line tools, not for authorization
// checking. This operation may “fail open” without warning.
func (c *PublisherClient) TestIamPermissions(ctx context.Context, req *iampb.TestIamPermissionsRequest, opts ...gax.CallOption) (*iampb.TestIamPermissionsResponse, error) {
	return c.internalClient.TestIamPermissions(ctx, req, opts...)
}

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

	// flag to opt out of default deadlines via GOOGLE_API_GO_EXPERIMENTAL_DISABLE_DEFAULT_DEADLINE
	disableDeadlines bool

	// Points back to the CallOptions field of the containing PublisherClient
	CallOptions **PublisherCallOptions

	// The gRPC API client.
	publisherClient pubsubpb.PublisherClient

	iamPolicyClient iampb.IAMPolicyClient

	// The x-goog-* metadata to be sent with each request.
	xGoogMetadata metadata.MD
}

// NewPublisherClient creates a new publisher client based on gRPC.
// The returned client must be Closed when it is done being used to clean up its underlying connections.
//
// The service that an application uses to manipulate topics, and to send
// messages to a topic.
func NewPublisherClient(ctx context.Context, opts ...option.ClientOption) (*PublisherClient, error) {
	clientOpts := defaultPublisherGRPCClientOptions()
	if newPublisherClientHook != nil {
		hookOpts, err := newPublisherClientHook(ctx, clientHookParams{})
		if err != nil {
			return nil, err
		}
		clientOpts = append(clientOpts, hookOpts...)
	}

	disableDeadlines, err := checkDisableDeadlines()
	if err != nil {
		return nil, err
	}

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

	c := &publisherGRPCClient{
		connPool:         connPool,
		disableDeadlines: disableDeadlines,
		publisherClient:  pubsubpb.NewPublisherClient(connPool),
		CallOptions:      &client.CallOptions,
		iamPolicyClient:  iampb.NewIAMPolicyClient(connPool),
	}
	c.setGoogleClientInfo()

	client.internalClient = c

	return &client, nil
}

// Connection returns a connection to the API service.
//
// Deprecated.
func (c *publisherGRPCClient) 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 *publisherGRPCClient) setGoogleClientInfo(keyval ...string) {
	kv := append([]string{"gl-go", versionGo()}, keyval...)
	kv = append(kv, "gapic", versionClient, "gax", gax.Version, "grpc", grpc.Version)
	c.xGoogMetadata = metadata.Pairs("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 *publisherGRPCClient) Close() error {
	return c.connPool.Close()
}

func (c *publisherGRPCClient) CreateTopic(ctx context.Context, req *pubsubpb.Topic, opts ...gax.CallOption) (*pubsubpb.Topic, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 60000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "name", url.QueryEscape(req.GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((*c.CallOptions).CreateTopic[0:len((*c.CallOptions).CreateTopic):len((*c.CallOptions).CreateTopic)], opts...)
	var resp *pubsubpb.Topic
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.publisherClient.CreateTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *publisherGRPCClient) UpdateTopic(ctx context.Context, req *pubsubpb.UpdateTopicRequest, opts ...gax.CallOption) (*pubsubpb.Topic, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 60000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "topic.name", url.QueryEscape(req.GetTopic().GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((*c.CallOptions).UpdateTopic[0:len((*c.CallOptions).UpdateTopic):len((*c.CallOptions).UpdateTopic)], opts...)
	var resp *pubsubpb.Topic
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.publisherClient.UpdateTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *publisherGRPCClient) Publish(ctx context.Context, req *pubsubpb.PublishRequest, opts ...gax.CallOption) (*pubsubpb.PublishResponse, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 60000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "topic", url.QueryEscape(req.GetTopic())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((*c.CallOptions).Publish[0:len((*c.CallOptions).Publish):len((*c.CallOptions).Publish)], opts...)
	var resp *pubsubpb.PublishResponse
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.publisherClient.Publish(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *publisherGRPCClient) GetTopic(ctx context.Context, req *pubsubpb.GetTopicRequest, opts ...gax.CallOption) (*pubsubpb.Topic, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 60000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "topic", url.QueryEscape(req.GetTopic())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((*c.CallOptions).GetTopic[0:len((*c.CallOptions).GetTopic):len((*c.CallOptions).GetTopic)], opts...)
	var resp *pubsubpb.Topic
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.publisherClient.GetTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *publisherGRPCClient) ListTopics(ctx context.Context, req *pubsubpb.ListTopicsRequest, opts ...gax.CallOption) *TopicIterator {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "project", url.QueryEscape(req.GetProject())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((*c.CallOptions).ListTopics[0:len((*c.CallOptions).ListTopics):len((*c.CallOptions).ListTopics)], opts...)
	it := &TopicIterator{}
	req = proto.Clone(req).(*pubsubpb.ListTopicsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*pubsubpb.Topic, string, error) {
		var resp *pubsubpb.ListTopicsResponse
		req.PageToken = pageToken
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.publisherClient.ListTopics(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetTopics(), 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 *publisherGRPCClient) ListTopicSubscriptions(ctx context.Context, req *pubsubpb.ListTopicSubscriptionsRequest, opts ...gax.CallOption) *StringIterator {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "topic", url.QueryEscape(req.GetTopic())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((*c.CallOptions).ListTopicSubscriptions[0:len((*c.CallOptions).ListTopicSubscriptions):len((*c.CallOptions).ListTopicSubscriptions)], opts...)
	it := &StringIterator{}
	req = proto.Clone(req).(*pubsubpb.ListTopicSubscriptionsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]string, string, error) {
		var resp *pubsubpb.ListTopicSubscriptionsResponse
		req.PageToken = pageToken
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.publisherClient.ListTopicSubscriptions(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetSubscriptions(), 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 *publisherGRPCClient) ListTopicSnapshots(ctx context.Context, req *pubsubpb.ListTopicSnapshotsRequest, opts ...gax.CallOption) *StringIterator {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "topic", url.QueryEscape(req.GetTopic())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((*c.CallOptions).ListTopicSnapshots[0:len((*c.CallOptions).ListTopicSnapshots):len((*c.CallOptions).ListTopicSnapshots)], opts...)
	it := &StringIterator{}
	req = proto.Clone(req).(*pubsubpb.ListTopicSnapshotsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]string, string, error) {
		var resp *pubsubpb.ListTopicSnapshotsResponse
		req.PageToken = pageToken
		if pageSize > math.MaxInt32 {
			req.PageSize = math.MaxInt32
		} else {
			req.PageSize = int32(pageSize)
		}
		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
			var err error
			resp, err = c.publisherClient.ListTopicSnapshots(ctx, req, settings.GRPC...)
			return err
		}, opts...)
		if err != nil {
			return nil, "", err
		}

		it.Response = resp
		return resp.GetSnapshots(), 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 *publisherGRPCClient) DeleteTopic(ctx context.Context, req *pubsubpb.DeleteTopicRequest, opts ...gax.CallOption) error {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 60000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "topic", url.QueryEscape(req.GetTopic())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((*c.CallOptions).DeleteTopic[0:len((*c.CallOptions).DeleteTopic):len((*c.CallOptions).DeleteTopic)], opts...)
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		_, err = c.publisherClient.DeleteTopic(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	return err
}

func (c *publisherGRPCClient) DetachSubscription(ctx context.Context, req *pubsubpb.DetachSubscriptionRequest, opts ...gax.CallOption) (*pubsubpb.DetachSubscriptionResponse, error) {
	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
		cctx, cancel := context.WithTimeout(ctx, 60000*time.Millisecond)
		defer cancel()
		ctx = cctx
	}
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "subscription", url.QueryEscape(req.GetSubscription())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((*c.CallOptions).DetachSubscription[0:len((*c.CallOptions).DetachSubscription):len((*c.CallOptions).DetachSubscription)], opts...)
	var resp *pubsubpb.DetachSubscriptionResponse
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.publisherClient.DetachSubscription(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *publisherGRPCClient) GetIamPolicy(ctx context.Context, req *iampb.GetIamPolicyRequest, opts ...gax.CallOption) (*iampb.Policy, error) {
	ctx = insertMetadata(ctx, c.xGoogMetadata)
	opts = append((*c.CallOptions).GetIamPolicy[0:len((*c.CallOptions).GetIamPolicy):len((*c.CallOptions).GetIamPolicy)], opts...)
	var resp *iampb.Policy
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.iamPolicyClient.GetIamPolicy(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *publisherGRPCClient) SetIamPolicy(ctx context.Context, req *iampb.SetIamPolicyRequest, opts ...gax.CallOption) (*iampb.Policy, error) {
	ctx = insertMetadata(ctx, c.xGoogMetadata)
	opts = append((*c.CallOptions).SetIamPolicy[0:len((*c.CallOptions).SetIamPolicy):len((*c.CallOptions).SetIamPolicy)], opts...)
	var resp *iampb.Policy
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.iamPolicyClient.SetIamPolicy(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *publisherGRPCClient) TestIamPermissions(ctx context.Context, req *iampb.TestIamPermissionsRequest, opts ...gax.CallOption) (*iampb.TestIamPermissionsResponse, error) {
	ctx = insertMetadata(ctx, c.xGoogMetadata)
	opts = append((*c.CallOptions).TestIamPermissions[0:len((*c.CallOptions).TestIamPermissions):len((*c.CallOptions).TestIamPermissions)], opts...)
	var resp *iampb.TestIamPermissionsResponse
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
		var err error
		resp, err = c.iamPolicyClient.TestIamPermissions(ctx, req, settings.GRPC...)
		return err
	}, opts...)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// 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
}

// TopicIterator manages a stream of *pubsubpb.Topic.
type TopicIterator struct {
	items    []*pubsubpb.Topic
	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 []*pubsubpb.Topic, nextPageToken string, err error)
}

// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
func (it *TopicIterator) 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 *TopicIterator) Next() (*pubsubpb.Topic, error) {
	var item *pubsubpb.Topic
	if err := it.nextFunc(); err != nil {
		return item, err
	}
	item = it.items[0]
	it.items = it.items[1:]
	return item, nil
}

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

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