retail/apiv2/catalog_client.go - gocloud - Git at Google

 // 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 retail

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

 	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"
 	retailpb "google.golang.org/genproto/googleapis/cloud/retail/v2"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/protobuf/proto"
 )

 var newCatalogClientHook clientHook

 // CatalogCallOptions contains the retry settings for each method of CatalogClient.
 type CatalogCallOptions struct {
 	ListCatalogs  []gax.CallOption
 	UpdateCatalog []gax.CallOption
 }

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

 func defaultCatalogCallOptions() *CatalogCallOptions {
 	return &CatalogCallOptions{
 		ListCatalogs: []gax.CallOption{
 			gax.WithRetry(func() gax.Retryer {
 				return gax.OnCodes([]codes.Code{
 					codes.Unavailable,
 					codes.DeadlineExceeded,
 				}, gax.Backoff{
 					Initial:    100 * time.Millisecond,
 					Max:        60000 * time.Millisecond,
 					Multiplier: 1.30,
 				})
 			}),
 		},
 		UpdateCatalog: []gax.CallOption{
 			gax.WithRetry(func() gax.Retryer {
 				return gax.OnCodes([]codes.Code{
 					codes.Unavailable,
 					codes.DeadlineExceeded,
 				}, gax.Backoff{
 					Initial:    100 * time.Millisecond,
 					Max:        60000 * time.Millisecond,
 					Multiplier: 1.30,
 				})
 			}),
 		},
 	}
 }

 // internalCatalogClient is an interface that defines the methods availaible from Retail API.
 type internalCatalogClient interface {
 	Close() error
 	setGoogleClientInfo(...string)
 	Connection() *grpc.ClientConn
 	ListCatalogs(context.Context, *retailpb.ListCatalogsRequest, ...gax.CallOption) *CatalogIterator
 	UpdateCatalog(context.Context, *retailpb.UpdateCatalogRequest, ...gax.CallOption) (*retailpb.Catalog, error)
 }

 // CatalogClient is a client for interacting with Retail API.
 // Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
 //
 // Service for managing catalog configuration.
 type CatalogClient struct {
 	// The internal transport-dependent client.
 	internalClient internalCatalogClient

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

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

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

 // ListCatalogs lists all the Catalogs associated with
 // the project.
 func (c *CatalogClient) ListCatalogs(ctx context.Context, req *retailpb.ListCatalogsRequest, opts ...gax.CallOption) *CatalogIterator {
 	return c.internalClient.ListCatalogs(ctx, req, opts...)
 }

 // UpdateCatalog updates the Catalogs.
 func (c *CatalogClient) UpdateCatalog(ctx context.Context, req *retailpb.UpdateCatalogRequest, opts ...gax.CallOption) (*retailpb.Catalog, error) {
 	return c.internalClient.UpdateCatalog(ctx, req, opts...)
 }

 // catalogGRPCClient is a client for interacting with Retail API over gRPC transport.
 //
 // Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
 type catalogGRPCClient 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 CatalogClient
 	CallOptions **CatalogCallOptions

 	// The gRPC API client.
 	catalogClient retailpb.CatalogServiceClient

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

 // NewCatalogClient creates a new catalog service client based on gRPC.
 // The returned client must be Closed when it is done being used to clean up its underlying connections.
 //
 // Service for managing catalog configuration.
 func NewCatalogClient(ctx context.Context, opts ...option.ClientOption) (*CatalogClient, error) {
 	clientOpts := defaultCatalogGRPCClientOptions()
 	if newCatalogClientHook != nil {
 		hookOpts, err := newCatalogClientHook(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 := CatalogClient{CallOptions: defaultCatalogCallOptions()}

 	c := &catalogGRPCClient{
 		connPool:         connPool,
 		disableDeadlines: disableDeadlines,
 		catalogClient:    retailpb.NewCatalogServiceClient(connPool),
 		CallOptions:      &client.CallOptions,
 	}
 	c.setGoogleClientInfo()

 	client.internalClient = c

 	return &client, nil
 }

 // Connection returns a connection to the API service.
 //
 // Deprecated.
 func (c *catalogGRPCClient) 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 *catalogGRPCClient) 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 *catalogGRPCClient) Close() error {
 	return c.connPool.Close()
 }

 func (c *catalogGRPCClient) ListCatalogs(ctx context.Context, req *retailpb.ListCatalogsRequest, opts ...gax.CallOption) *CatalogIterator {
 	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "parent", url.QueryEscape(req.GetParent())))
 	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
 	opts = append((*c.CallOptions).ListCatalogs[0:len((*c.CallOptions).ListCatalogs):len((*c.CallOptions).ListCatalogs)], opts...)
 	it := &CatalogIterator{}
 	req = proto.Clone(req).(*retailpb.ListCatalogsRequest)
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*retailpb.Catalog, string, error) {
 		var resp *retailpb.ListCatalogsResponse
 		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.catalogClient.ListCatalogs(ctx, req, settings.GRPC...)
 			return err
 		}, opts...)
 		if err != nil {
 			return nil, "", err
 		}

 		it.Response = resp
 		return resp.GetCatalogs(), 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 *catalogGRPCClient) UpdateCatalog(ctx context.Context, req *retailpb.UpdateCatalogRequest, opts ...gax.CallOption) (*retailpb.Catalog, 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", "catalog.name", url.QueryEscape(req.GetCatalog().GetName())))
 	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
 	opts = append((*c.CallOptions).UpdateCatalog[0:len((*c.CallOptions).UpdateCatalog):len((*c.CallOptions).UpdateCatalog)], opts...)
 	var resp *retailpb.Catalog
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
 		resp, err = c.catalogClient.UpdateCatalog(ctx, req, settings.GRPC...)
 		return err
 	}, opts...)
 	if err != nil {
 		return nil, err
 	}
 	return resp, nil
 }

 // CatalogIterator manages a stream of *retailpb.Catalog.
 type CatalogIterator struct {
 	items    []*retailpb.Catalog
 	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 []*retailpb.Catalog, nextPageToken string, err error)
 }

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

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

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

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

	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"
	retailpb "google.golang.org/genproto/googleapis/cloud/retail/v2"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/metadata"
	"google.golang.org/protobuf/proto"
	)

	var newCatalogClientHook clientHook

	// CatalogCallOptions contains the retry settings for each method of CatalogClient.
	type CatalogCallOptions struct {
	ListCatalogs []gax.CallOption
	UpdateCatalog []gax.CallOption
	}

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

	func defaultCatalogCallOptions() *CatalogCallOptions {
	return &CatalogCallOptions{
	ListCatalogs: []gax.CallOption{
	gax.WithRetry(func() gax.Retryer {
	return gax.OnCodes([]codes.Code{
	codes.Unavailable,
	codes.DeadlineExceeded,
	}, gax.Backoff{
	Initial: 100 * time.Millisecond,
	Max: 60000 * time.Millisecond,
	Multiplier: 1.30,
	})
	}),
	},
	UpdateCatalog: []gax.CallOption{
	gax.WithRetry(func() gax.Retryer {
	return gax.OnCodes([]codes.Code{
	codes.Unavailable,
	codes.DeadlineExceeded,
	}, gax.Backoff{
	Initial: 100 * time.Millisecond,
	Max: 60000 * time.Millisecond,
	Multiplier: 1.30,
	})
	}),
	},
	}
	}

	// internalCatalogClient is an interface that defines the methods availaible from Retail API.
	type internalCatalogClient interface {
	Close() error
	setGoogleClientInfo(...string)
	Connection() *grpc.ClientConn
	ListCatalogs(context.Context, retailpb.ListCatalogsRequest, ...gax.CallOption) CatalogIterator
	UpdateCatalog(context.Context, retailpb.UpdateCatalogRequest, ...gax.CallOption) (retailpb.Catalog, error)
	}

	// CatalogClient is a client for interacting with Retail API.
	// Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
	//
	// Service for managing catalog configuration.
	type CatalogClient struct {
	// The internal transport-dependent client.
	internalClient internalCatalogClient

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

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

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

	// ListCatalogs lists all the Catalogs associated with
	// the project.
	func (c CatalogClient) ListCatalogs(ctx context.Context, req retailpb.ListCatalogsRequest, opts ...gax.CallOption) *CatalogIterator {
	return c.internalClient.ListCatalogs(ctx, req, opts...)
	}

	// UpdateCatalog updates the Catalogs.
	func (c CatalogClient) UpdateCatalog(ctx context.Context, req retailpb.UpdateCatalogRequest, opts ...gax.CallOption) (*retailpb.Catalog, error) {
	return c.internalClient.UpdateCatalog(ctx, req, opts...)
	}

	// catalogGRPCClient is a client for interacting with Retail API over gRPC transport.
	//
	// Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
	type catalogGRPCClient 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 CatalogClient
	CallOptions **CatalogCallOptions

	// The gRPC API client.
	catalogClient retailpb.CatalogServiceClient

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

	// NewCatalogClient creates a new catalog service client based on gRPC.
	// The returned client must be Closed when it is done being used to clean up its underlying connections.
	//
	// Service for managing catalog configuration.
	func NewCatalogClient(ctx context.Context, opts ...option.ClientOption) (*CatalogClient, error) {
	clientOpts := defaultCatalogGRPCClientOptions()
	if newCatalogClientHook != nil {
	hookOpts, err := newCatalogClientHook(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 := CatalogClient{CallOptions: defaultCatalogCallOptions()}

	c := &catalogGRPCClient{
	connPool: connPool,
	disableDeadlines: disableDeadlines,
	catalogClient: retailpb.NewCatalogServiceClient(connPool),
	CallOptions: &client.CallOptions,
	}
	c.setGoogleClientInfo()

	client.internalClient = c

	return &client, nil
	}

	// Connection returns a connection to the API service.
	//
	// Deprecated.
	func (c catalogGRPCClient) 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 *catalogGRPCClient) 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 *catalogGRPCClient) Close() error {
	return c.connPool.Close()
	}

	func (c catalogGRPCClient) ListCatalogs(ctx context.Context, req retailpb.ListCatalogsRequest, opts ...gax.CallOption) *CatalogIterator {
	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "parent", url.QueryEscape(req.GetParent())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((c.CallOptions).ListCatalogs[0:len((c.CallOptions).ListCatalogs):len((*c.CallOptions).ListCatalogs)], opts...)
	it := &CatalogIterator{}
	req = proto.Clone(req).(*retailpb.ListCatalogsRequest)
	it.InternalFetch = func(pageSize int, pageToken string) ([]*retailpb.Catalog, string, error) {
	var resp *retailpb.ListCatalogsResponse
	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.catalogClient.ListCatalogs(ctx, req, settings.GRPC...)
	return err
	}, opts...)
	if err != nil {
	return nil, "", err
	}

	it.Response = resp
	return resp.GetCatalogs(), 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 catalogGRPCClient) UpdateCatalog(ctx context.Context, req retailpb.UpdateCatalogRequest, opts ...gax.CallOption) (*retailpb.Catalog, 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", "catalog.name", url.QueryEscape(req.GetCatalog().GetName())))
	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
	opts = append((c.CallOptions).UpdateCatalog[0:len((c.CallOptions).UpdateCatalog):len((*c.CallOptions).UpdateCatalog)], opts...)
	var resp *retailpb.Catalog
	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
	var err error
	resp, err = c.catalogClient.UpdateCatalog(ctx, req, settings.GRPC...)
	return err
	}, opts...)
	if err != nil {
	return nil, err
	}
	return resp, nil
	}

	// CatalogIterator manages a stream of *retailpb.Catalog.
	type CatalogIterator struct {
	items []*retailpb.Catalog
	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 []*retailpb.Catalog, nextPageToken string, err error)
	}

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

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

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