pfs.go

package client

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"sync"

	"github.com/gogo/protobuf/types"
	"github.com/pachyderm/pachyderm/src/client/pfs"
	"github.com/pachyderm/pachyderm/src/client/pkg/grpcutil"
	"github.com/pachyderm/pachyderm/src/server/pkg/errutil"
)

// NewRepo creates a pfs.Repo.
func NewRepo(repoName string) *pfs.Repo {
	return &pfs.Repo{Name: repoName}
}

// NewBranch creates a pfs.Branch
func NewBranch(repoName string, branchName string) *pfs.Branch {
	return &pfs.Branch{
		Repo: NewRepo(repoName),
		Name: branchName,
	}
}

// NewCommit creates a pfs.Commit.
func NewCommit(repoName string, commitID string) *pfs.Commit {
	return &pfs.Commit{
		Repo: NewRepo(repoName),
		ID:   commitID,
	}
}

// NewCommitProvenance creates a pfs.CommitProvenance.
func NewCommitProvenance(repoName string, branchName string, commitID string) *pfs.CommitProvenance {
	return &pfs.CommitProvenance{
		Commit: NewCommit(repoName, commitID),
		Branch: NewBranch(repoName, branchName),
	}
}

// NewFile creates a pfs.File.
func NewFile(repoName string, commitID string, path string) *pfs.File {
	return &pfs.File{
		Commit: NewCommit(repoName, commitID),
		Path:   path,
	}
}

// NewObject creates a pfs.Object.
func NewObject(hash string) *pfs.Object {
	return &pfs.Object{
		Hash: hash,
	}
}

// NewBlock creates a pfs.Block.
func NewBlock(hash string) *pfs.Block {
	return &pfs.Block{
		Hash: hash,
	}
}

// NewTag creates a pfs.Tag.
func NewTag(name string) *pfs.Tag {
	return &pfs.Tag{
		Name: name,
	}
}

// CreateRepo creates a new Repo object in pfs with the given name. Repos are
// the top level data object in pfs and should be used to store data of a
// similar type. For example rather than having a single Repo for an entire
// project you might have separate Repos for logs, metrics, database dumps etc.
func (c APIClient) CreateRepo(repoName string) error {
	_, err := c.PfsAPIClient.CreateRepo(
		c.Ctx(),
		&pfs.CreateRepoRequest{
			Repo: NewRepo(repoName),
		},
	)
	return grpcutil.ScrubGRPC(err)
}

// InspectRepo returns info about a specific Repo.
func (c APIClient) InspectRepo(repoName string) (*pfs.RepoInfo, error) {
	resp, err := c.PfsAPIClient.InspectRepo(
		c.Ctx(),
		&pfs.InspectRepoRequest{
			Repo: NewRepo(repoName),
		},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return resp, nil
}

// ListRepo returns info about all Repos.
// provenance specifies a set of provenance repos, only repos which have ALL of
// the specified repos as provenance will be returned unless provenance is nil
// in which case it is ignored.
func (c APIClient) ListRepo() ([]*pfs.RepoInfo, error) {
	request := &pfs.ListRepoRequest{}
	repoInfos, err := c.PfsAPIClient.ListRepo(
		c.Ctx(),
		request,
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return repoInfos.RepoInfo, nil
}

// DeleteRepo deletes a repo and reclaims the storage space it was using. Note
// that as of 1.0 we do not reclaim the blocks that the Repo was referencing,
// this is because they may also be referenced by other Repos and deleting them
// would make those Repos inaccessible. This will be resolved in later
// versions.
// If "force" is set to true, the repo will be removed regardless of errors.
// This argument should be used with care.
func (c APIClient) DeleteRepo(repoName string, force bool) error {
	_, err := c.PfsAPIClient.DeleteRepo(
		c.Ctx(),
		&pfs.DeleteRepoRequest{
			Repo:  NewRepo(repoName),
			Force: force,
		},
	)
	return grpcutil.ScrubGRPC(err)
}

// StartCommit begins the process of committing data to a Repo. Once started
// you can write to the Commit with PutFile and when all the data has been
// written you must finish the Commit with FinishCommit. NOTE, data is not
// persisted until FinishCommit is called.
// branch is a more convenient way to build linear chains of commits. When a
// commit is started with a non empty branch the value of branch becomes an
// alias for the created Commit. This enables a more intuitive access pattern.
// When the commit is started on a branch the previous head of the branch is
// used as the parent of the commit.
func (c APIClient) StartCommit(repoName string, branch string) (*pfs.Commit, error) {
	commit, err := c.PfsAPIClient.StartCommit(
		c.Ctx(),
		&pfs.StartCommitRequest{
			Parent: &pfs.Commit{
				Repo: &pfs.Repo{
					Name: repoName,
				},
			},
			Branch: branch,
		},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return commit, nil
}

// BuildCommit builds a commit in a single call from an existing HashTree that
// has already been written to the object store. Note this is a more advanced
// pattern for creating commits that's mostly used internally.
func (c APIClient) BuildCommit(repoName string, branch string, parent string, treeObject string) (*pfs.Commit, error) {
	commit, err := c.PfsAPIClient.BuildCommit(
		c.Ctx(),
		&pfs.BuildCommitRequest{
			Parent: NewCommit(repoName, parent),
			Branch: branch,
			Tree:   &pfs.Object{Hash: treeObject},
		},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return commit, nil
}

// StartCommitParent begins the process of committing data to a Repo. Once started
// you can write to the Commit with PutFile and when all the data has been
// written you must finish the Commit with FinishCommit. NOTE, data is not
// persisted until FinishCommit is called.
// branch is a more convenient way to build linear chains of commits. When a
// commit is started with a non empty branch the value of branch becomes an
// alias for the created Commit. This enables a more intuitive access pattern.
// When the commit is started on a branch the previous head of the branch is
// used as the parent of the commit.
// parentCommit specifies the parent Commit, upon creation the new Commit will
// appear identical to the parent Commit, data can safely be added to the new
// commit without affecting the contents of the parent Commit. You may pass ""
// as parentCommit in which case the new Commit will have no parent and will
// initially appear empty.
func (c APIClient) StartCommitParent(repoName string, branch string, parentCommit string) (*pfs.Commit, error) {
	commit, err := c.PfsAPIClient.StartCommit(
		c.Ctx(),
		&pfs.StartCommitRequest{
			Parent: &pfs.Commit{
				Repo: &pfs.Repo{
					Name: repoName,
				},
				ID: parentCommit,
			},
			Branch: branch,
		},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return commit, nil
}

// FinishCommit ends the process of committing data to a Repo and persists the
// Commit. Once a Commit is finished the data becomes immutable and future
// attempts to write to it with PutFile will error.
func (c APIClient) FinishCommit(repoName string, commitID string) error {
	_, err := c.PfsAPIClient.FinishCommit(
		c.Ctx(),
		&pfs.FinishCommitRequest{
			Commit: NewCommit(repoName, commitID),
		},
	)
	return grpcutil.ScrubGRPC(err)
}

// InspectCommit returns info about a specific Commit.
func (c APIClient) InspectCommit(repoName string, commitID string) (*pfs.CommitInfo, error) {
	return c.inspectCommit(repoName, commitID, pfs.CommitState_STARTED)
}

// BlockCommit returns info about a specific Commit, but blocks until that
// commit has been finished.
func (c APIClient) BlockCommit(repoName string, commitID string) (*pfs.CommitInfo, error) {
	return c.inspectCommit(repoName, commitID, pfs.CommitState_FINISHED)
}

func (c APIClient) inspectCommit(repoName string, commitID string, blockState pfs.CommitState) (*pfs.CommitInfo, error) {
	commitInfo, err := c.PfsAPIClient.InspectCommit(
		c.Ctx(),
		&pfs.InspectCommitRequest{
			Commit:     NewCommit(repoName, commitID),
			BlockState: blockState,
		},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return commitInfo, nil
}

// ListCommit lists commits.
// If only `repo` is given, all commits in the repo are returned.
// If `to` is given, only the ancestors of `to`, including `to` itself,
// are considered.
// If `from` is given, only the descendents of `from`, including `from`
// itself, are considered.
// `number` determines how many commits are returned.  If `number` is 0,
// all commits that match the aforementioned criteria are returned.
func (c APIClient) ListCommit(repoName string, to string, from string, number uint64) ([]*pfs.CommitInfo, error) {
	var result []*pfs.CommitInfo
	if err := c.ListCommitF(repoName, to, from, number, func(ci *pfs.CommitInfo) error {
		result = append(result, ci)
		return nil
	}); err != nil {
		return nil, err
	}
	return result, nil
}

// ListCommitF lists commits, calling f with each commit.
// If only `repo` is given, all commits in the repo are returned.
// If `to` is given, only the ancestors of `to`, including `to` itself,
// are considered.
// If `from` is given, only the descendents of `from`, including `from`
// itself, are considered.
// `number` determines how many commits are returned.  If `number` is 0,
// all commits that match the aforementioned criteria are returned.
func (c APIClient) ListCommitF(repoName string, to string, from string, number uint64, f func(*pfs.CommitInfo) error) error {
	req := &pfs.ListCommitRequest{
		Repo:   NewRepo(repoName),
		Number: number,
	}
	if from != "" {
		req.From = NewCommit(repoName, from)
	}
	if to != "" {
		req.To = NewCommit(repoName, to)
	}
	stream, err := c.PfsAPIClient.ListCommitStream(c.Ctx(), req)
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	for {
		ci, err := stream.Recv()
		if err == io.EOF {
			break
		} else if err != nil {
			return grpcutil.ScrubGRPC(err)
		}
		if err := f(ci); err != nil {
			if err == errutil.ErrBreak {
				return nil
			}
			return err
		}
	}
	return nil
}

// ListCommitByRepo lists all commits in a repo.
func (c APIClient) ListCommitByRepo(repoName string) ([]*pfs.CommitInfo, error) {
	return c.ListCommit(repoName, "", "", 0)
}

// CreateBranch creates a new branch
func (c APIClient) CreateBranch(repoName string, branch string, commit string, provenance []*pfs.Branch) error {
	var head *pfs.Commit
	if commit != "" {
		head = NewCommit(repoName, commit)
	}
	_, err := c.PfsAPIClient.CreateBranch(
		c.Ctx(),
		&pfs.CreateBranchRequest{
			Branch:     NewBranch(repoName, branch),
			Head:       head,
			Provenance: provenance,
		},
	)
	return grpcutil.ScrubGRPC(err)
}

// InspectBranch returns information on a specific PFS branch
func (c APIClient) InspectBranch(repoName string, branch string) (*pfs.BranchInfo, error) {
	branchInfo, err := c.PfsAPIClient.InspectBranch(
		c.Ctx(),
		&pfs.InspectBranchRequest{
			Branch: NewBranch(repoName, branch),
		},
	)
	return branchInfo, grpcutil.ScrubGRPC(err)
}

// ListBranch lists the active branches on a Repo.
func (c APIClient) ListBranch(repoName string) ([]*pfs.BranchInfo, error) {
	branchInfos, err := c.PfsAPIClient.ListBranch(
		c.Ctx(),
		&pfs.ListBranchRequest{
			Repo: NewRepo(repoName),
		},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return branchInfos.BranchInfo, nil
}

// SetBranch sets a commit and its ancestors as a branch.
// SetBranch is deprecated in favor of CommitBranch.
func (c APIClient) SetBranch(repoName string, commit string, branch string) error {
	return c.CreateBranch(repoName, branch, commit, nil)
}

// DeleteBranch deletes a branch, but leaves the commits themselves intact.
// In other words, those commits can still be accessed via commit IDs and
// other branches they happen to be on.
func (c APIClient) DeleteBranch(repoName string, branch string, force bool) error {
	_, err := c.PfsAPIClient.DeleteBranch(
		c.Ctx(),
		&pfs.DeleteBranchRequest{
			Branch: NewBranch(repoName, branch),
			Force:  force,
		},
	)
	return grpcutil.ScrubGRPC(err)
}

// DeleteCommit deletes a commit.
func (c APIClient) DeleteCommit(repoName string, commitID string) error {
	_, err := c.PfsAPIClient.DeleteCommit(
		c.Ctx(),
		&pfs.DeleteCommitRequest{
			Commit: NewCommit(repoName, commitID),
		},
	)
	return grpcutil.ScrubGRPC(err)
}

// FlushCommit returns an iterator that returns commits that have the
// specified `commits` as provenance.  Note that the iterator can block if
// jobs have not successfully completed. This in effect waits for all of the
// jobs that are triggered by a set of commits to complete.
//
// If toRepos is not nil then only the commits up to and including those
// repos will be considered, otherwise all repos are considered.
//
// Note that it's never necessary to call FlushCommit to run jobs, they'll
// run no matter what, FlushCommit just allows you to wait for them to
// complete and see their output once they do.
func (c APIClient) FlushCommit(commits []*pfs.Commit, toRepos []*pfs.Repo) (CommitInfoIterator, error) {
	ctx, cancel := context.WithCancel(c.Ctx())
	stream, err := c.PfsAPIClient.FlushCommit(
		ctx,
		&pfs.FlushCommitRequest{
			Commits: commits,
			ToRepos: toRepos,
		},
	)
	if err != nil {
		cancel()
		return nil, grpcutil.ScrubGRPC(err)
	}
	return &commitInfoIterator{stream, cancel}, nil
}

// FlushCommitF calls f with commits that have the specified `commits` as
// provenance. Note that it can block if jobs have not successfully
// completed. This in effect waits for all of the jobs that are triggered by a
// set of commits to complete.
//
// If toRepos is not nil then only the commits up to and including those repos
// will be considered, otherwise all repos are considered.
//
// Note that it's never necessary to call FlushCommit to run jobs, they'll run
// no matter what, FlushCommitF just allows you to wait for them to complete and
// see their output once they do.
func (c APIClient) FlushCommitF(commits []*pfs.Commit, toRepos []*pfs.Repo, f func(*pfs.CommitInfo) error) error {
	stream, err := c.PfsAPIClient.FlushCommit(
		c.Ctx(),
		&pfs.FlushCommitRequest{
			Commits: commits,
			ToRepos: toRepos,
		},
	)
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	for {
		ci, err := stream.Recv()
		if err != nil {
			if err == io.EOF {
				return nil
			}
			return grpcutil.ScrubGRPC(err)
		}
		if err := f(ci); err != nil {
			return err
		}
	}
}

// FlushCommitAll returns commits that have the specified `commits` as
// provenance. Note that it can block if jobs have not successfully
// completed. This in effect waits for all of the jobs that are triggered by a
// set of commits to complete.
//
// If toRepos is not nil then only the commits up to and including those repos
// will be considered, otherwise all repos are considered.
//
// Note that it's never necessary to call FlushCommit to run jobs, they'll run
// no matter what, FlushCommitAll just allows you to wait for them to complete and
// see their output once they do.
func (c APIClient) FlushCommitAll(commits []*pfs.Commit, toRepos []*pfs.Repo) ([]*pfs.CommitInfo, error) {
	var result []*pfs.CommitInfo
	if err := c.FlushCommitF(commits, toRepos, func(ci *pfs.CommitInfo) error {
		result = append(result, ci)
		return nil
	}); err != nil {
		return nil, err
	}
	return result, nil
}

// CommitInfoIterator wraps a stream of commits and makes them easy to iterate.
type CommitInfoIterator interface {
	Next() (*pfs.CommitInfo, error)
	Close()
}

type commitInfoIterator struct {
	stream pfs.API_SubscribeCommitClient
	cancel context.CancelFunc
}

func (c *commitInfoIterator) Next() (*pfs.CommitInfo, error) {
	return c.stream.Recv()
}

func (c *commitInfoIterator) Close() {
	c.cancel()
	// this is completely retarded, but according to this thread it's
	// necessary for closing a server-side stream from the client side.
	// https://github.com/grpc/grpc-go/issues/188
	for {
		if _, err := c.stream.Recv(); err != nil {
			break
		}
	}
}

// SubscribeCommit is like ListCommit but it keeps listening for commits as
// they come in.
func (c APIClient) SubscribeCommit(repo string, branch string, from string, state pfs.CommitState) (CommitInfoIterator, error) {
	ctx, cancel := context.WithCancel(c.Ctx())
	req := &pfs.SubscribeCommitRequest{
		Repo:   NewRepo(repo),
		Branch: branch,
		State:  state,
	}
	if from != "" {
		req.From = NewCommit(repo, from)
	}
	stream, err := c.PfsAPIClient.SubscribeCommit(ctx, req)
	if err != nil {
		cancel()
		return nil, grpcutil.ScrubGRPC(err)
	}
	return &commitInfoIterator{stream, cancel}, nil
}

// SubscribeCommitF is like ListCommit but it calls a callback function with
// the results rather than returning an iterator.
func (c APIClient) SubscribeCommitF(repo, branch, from string, state pfs.CommitState, f func(*pfs.CommitInfo) error) error {
	req := &pfs.SubscribeCommitRequest{
		Repo:   NewRepo(repo),
		Branch: branch,
		State:  state,
	}
	if from != "" {
		req.From = NewCommit(repo, from)
	}
	stream, err := c.PfsAPIClient.SubscribeCommit(c.Ctx(), req)
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	for {
		ci, err := stream.Recv()
		if err != nil {
			return grpcutil.ScrubGRPC(err)
		}
		if err := f(ci); err != nil {
			return grpcutil.ScrubGRPC(err)
		}
	}
}

// PutObjectAsync puts a value into the object store asynchronously.
func (c APIClient) PutObjectAsync(tags []*pfs.Tag) (*PutObjectWriteCloserAsync, error) {
	w, err := c.newPutObjectWriteCloserAsync(tags)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return w, nil
}

// PutObject puts a value into the object store and tags it with 0 or more tags.
func (c APIClient) PutObject(_r io.Reader, tags ...string) (object *pfs.Object, _ int64, retErr error) {
	r := grpcutil.ReaderWrapper{_r}
	w, err := c.newPutObjectWriteCloser(tags...)
	if err != nil {
		return nil, 0, grpcutil.ScrubGRPC(err)
	}
	defer func() {
		if err := w.Close(); err != nil && retErr == nil {
			retErr = grpcutil.ScrubGRPC(err)
		}
		if retErr == nil {
			object = w.object
		}
	}()
	buf := grpcutil.GetBuffer()
	defer grpcutil.PutBuffer(buf)
	written, err := io.CopyBuffer(w, r, buf)
	if err != nil {
		return nil, 0, grpcutil.ScrubGRPC(err)
	}
	// return value set by deferred function
	return nil, written, nil
}

// PutObjectSplit is the same as PutObject except that the data is splitted
// into several smaller objects.  This is primarily useful if you'd like to
// be able to resume upload.
func (c APIClient) PutObjectSplit(_r io.Reader) (objects []*pfs.Object, _ int64, retErr error) {
	r := grpcutil.ReaderWrapper{_r}
	w, err := c.newPutObjectSplitWriteCloser()
	if err != nil {
		return nil, 0, grpcutil.ScrubGRPC(err)
	}
	defer func() {
		if err := w.Close(); err != nil && retErr == nil {
			retErr = grpcutil.ScrubGRPC(err)
		}
		if retErr == nil {
			objects = w.objects
		}
	}()
	buf := grpcutil.GetBuffer()
	defer grpcutil.PutBuffer(buf)
	written, err := io.CopyBuffer(w, r, buf)
	if err != nil {
		return nil, 0, grpcutil.ScrubGRPC(err)
	}
	// return value set by deferred function
	return nil, written, nil
}

// GetObject gets an object out of the object store by hash.
func (c APIClient) GetObject(hash string, writer io.Writer) error {
	getObjectClient, err := c.ObjectAPIClient.GetObject(
		c.Ctx(),
		&pfs.Object{Hash: hash},
	)
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	if err := grpcutil.WriteFromStreamingBytesClient(getObjectClient, writer); err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	return nil
}

// GetObjectReader returns a reader for an object in object store by hash.
func (c APIClient) GetObjectReader(hash string) (io.ReadCloser, error) {
	ctx, cancel := context.WithCancel(c.Ctx())
	getObjectClient, err := c.ObjectAPIClient.GetObject(
		ctx,
		&pfs.Object{Hash: hash},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return grpcutil.NewStreamingBytesReader(getObjectClient, cancel), nil
}

// ReadObject gets an object by hash and returns it directly as []byte.
func (c APIClient) ReadObject(hash string) ([]byte, error) {
	var buffer bytes.Buffer
	if err := c.GetObject(hash, &buffer); err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return buffer.Bytes(), nil
}

// GetObjects gets several objects out of the object store by hash.
func (c APIClient) GetObjects(hashes []string, offset uint64, size uint64, totalSize uint64, writer io.Writer) error {
	var objects []*pfs.Object
	for _, hash := range hashes {
		objects = append(objects, &pfs.Object{Hash: hash})
	}
	getObjectsClient, err := c.ObjectAPIClient.GetObjects(
		c.Ctx(),
		&pfs.GetObjectsRequest{
			Objects:     objects,
			OffsetBytes: offset,
			SizeBytes:   size,
			TotalSize:   totalSize,
		},
	)
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	if err := grpcutil.WriteFromStreamingBytesClient(getObjectsClient, writer); err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	return nil
}

// ReadObjects gets  several objects by hash and returns them directly as []byte.
func (c APIClient) ReadObjects(hashes []string, offset uint64, size uint64) ([]byte, error) {
	var buffer bytes.Buffer
	if err := c.GetObjects(hashes, offset, size, 0, &buffer); err != nil {
		return nil, err
	}
	return buffer.Bytes(), nil
}

// TagObject applies a tag to an existing object.
func (c APIClient) TagObject(hash string, tags ...string) error {
	var _tags []*pfs.Tag
	for _, tag := range tags {
		_tags = append(_tags, &pfs.Tag{Name: tag})
	}
	if _, err := c.ObjectAPIClient.TagObject(
		c.Ctx(),
		&pfs.TagObjectRequest{
			Object: &pfs.Object{Hash: hash},
			Tags:   _tags,
		},
	); err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	return nil
}

// ListObject lists objects stored in pfs.
func (c APIClient) ListObject(f func(*pfs.Object) error) error {
	listObjectClient, err := c.ObjectAPIClient.ListObjects(c.Ctx(), &pfs.ListObjectsRequest{})
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	for {
		object, err := listObjectClient.Recv()
		if err != nil {
			if err == io.EOF {
				return nil
			}
			return grpcutil.ScrubGRPC(err)
		}
		if err := f(object); err != nil {
			return err
		}
	}
}

// InspectObject returns info about an Object.
func (c APIClient) InspectObject(hash string) (*pfs.ObjectInfo, error) {
	value, err := c.ObjectAPIClient.InspectObject(
		c.Ctx(),
		&pfs.Object{Hash: hash},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return value, nil
}

// GetTag gets an object out of the object store by tag.
func (c APIClient) GetTag(tag string, writer io.Writer) error {
	getTagClient, err := c.ObjectAPIClient.GetTag(
		c.Ctx(),
		&pfs.Tag{Name: tag},
	)
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	if err := grpcutil.WriteFromStreamingBytesClient(getTagClient, writer); err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	return nil
}

// GetTagReader returns a reader for an object in object store by tag.
func (c APIClient) GetTagReader(tag string) (io.ReadCloser, error) {
	ctx, cancel := context.WithCancel(c.Ctx())
	getTagClient, err := c.ObjectAPIClient.GetTag(
		ctx,
		&pfs.Tag{Name: tag},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return grpcutil.NewStreamingBytesReader(getTagClient, cancel), nil
}

// ReadTag gets an object by tag and returns it directly as []byte.
func (c APIClient) ReadTag(tag string) ([]byte, error) {
	var buffer bytes.Buffer
	if err := c.GetTag(tag, &buffer); err != nil {
		return nil, err
	}
	return buffer.Bytes(), nil
}

// ListTag lists tags stored in pfs.
func (c APIClient) ListTag(f func(*pfs.ListTagsResponse) error) error {
	listTagClient, err := c.ObjectAPIClient.ListTags(c.Ctx(), &pfs.ListTagsRequest{IncludeObject: true})
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	for {
		listTagResponse, err := listTagClient.Recv()
		if err != nil {
			if err == io.EOF {
				return nil
			}
			return grpcutil.ScrubGRPC(err)
		}
		if err := f(listTagResponse); err != nil {
			return err
		}
	}
}

// Compact forces compaction of objects.
func (c APIClient) Compact() error {
	_, err := c.ObjectAPIClient.Compact(
		c.Ctx(),
		&types.Empty{},
	)
	return err
}

// PutFileClient is a client interface for putting files. There are 2
// implementations, 1 that does each file as a seperate request and one that
// does them all together in the same request.
type PutFileClient interface {
	// PutFileWriter writes a file to PFS.
	// NOTE: PutFileWriter returns an io.WriteCloser that you must call Close on when
	// you are done writing.
	PutFileWriter(repoName, commitID, path string) (io.WriteCloser, error)

	// PutFileSplitWriter writes multiple files to PFS by splitting up the data
	// that is written to it.
	// NOTE: PutFileSplitWriter returns an io.WriteCloser that you must call Close on when
	// you are done writing.
	PutFileSplitWriter(repoName string, commitID string, path string, delimiter pfs.Delimiter, targetFileDatums int64, targetFileBytes int64, headerRecords int64, overwrite bool) (io.WriteCloser, error)

	// PutFile writes a file to PFS from a reader.
	PutFile(repoName string, commitID string, path string, reader io.Reader) (_ int, retErr error)

	// PutFileOverwrite is like PutFile but it overwrites the file rather than
	// appending to it. overwriteIndex allows you to specify the index of the
	// object starting from which you'd like to overwrite. If you want to
	// overwrite the entire file, specify an index of 0.
	PutFileOverwrite(repoName string, commitID string, path string, reader io.Reader, overwriteIndex int64) (_ int, retErr error)

	// PutFileSplit writes a file to PFS from a reader.
	// delimiter is used to tell PFS how to break the input into blocks.
	PutFileSplit(repoName string, commitID string, path string, delimiter pfs.Delimiter, targetFileDatums int64, targetFileBytes int64, headerRecords int64, overwrite bool, reader io.Reader) (_ int, retErr error)

	// PutFileURL puts a file using the content found at a URL.
	// The URL is sent to the server which performs the request.
	// recursive allows for recursive scraping of some types URLs. For example on s3:// urls.
	PutFileURL(repoName string, commitID string, path string, url string, recursive bool, overwrite bool) error

	// Close must be called after you're done using a PutFileClient.
	// Further requests will throw errors.
	Close() error
}

type putFileClient struct {
	c      pfs.API_PutFileClient
	mu     sync.Mutex
	oneoff bool // indicates a one time use putFileClient
}

// NewPutFileClient returns a new client for putting files into pfs in a single request.
func (c APIClient) NewPutFileClient() (PutFileClient, error) {
	pfc, err := c.PfsAPIClient.PutFile(c.Ctx())
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return &putFileClient{c: pfc}, nil
}

func (c APIClient) newOneoffPutFileClient() (PutFileClient, error) {
	pfc, err := c.PfsAPIClient.PutFile(c.Ctx())
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return &putFileClient{c: pfc, oneoff: true}, nil
}

// PutFileWriter writes a file to PFS.
// NOTE: PutFileWriter returns an io.WriteCloser you must call Close on it when
// you are done writing.
func (c *putFileClient) PutFileWriter(repoName, commitID, path string) (io.WriteCloser, error) {
	return c.newPutFileWriteCloser(repoName, commitID, path, pfs.Delimiter_NONE, 0, 0, 0, nil)
}

// PutFileSplitWriter writes a multiple files to PFS by splitting up the data
// that is written to it.
// NOTE: PutFileSplitWriter returns an io.WriteCloser you must call Close on it when
// you are done writing.
func (c *putFileClient) PutFileSplitWriter(repoName string, commitID string, path string,
	delimiter pfs.Delimiter, targetFileDatums int64, targetFileBytes int64, headerRecords int64, overwrite bool) (io.WriteCloser, error) {
	// TODO(msteffen) add headerRecords
	var overwriteIndex *pfs.OverwriteIndex
	if overwrite {
		overwriteIndex = &pfs.OverwriteIndex{}
	}
	return c.newPutFileWriteCloser(repoName, commitID, path, delimiter, targetFileDatums, targetFileBytes, headerRecords, overwriteIndex)
}

// PutFile writes a file to PFS from a reader.
func (c *putFileClient) PutFile(repoName string, commitID string, path string, reader io.Reader) (_ int, retErr error) {
	return c.PutFileSplit(repoName, commitID, path, pfs.Delimiter_NONE, 0, 0, 0, false, reader)
}

// PutFileOverwrite is like PutFile but it overwrites the file rather than
// appending to it.  overwriteIndex allows you to specify the index of the
// object starting from which you'd like to overwrite.  If you want to
// overwrite the entire file, specify an index of 0.
func (c *putFileClient) PutFileOverwrite(repoName string, commitID string, path string, reader io.Reader, overwriteIndex int64) (_ int, retErr error) {
	writer, err := c.newPutFileWriteCloser(repoName, commitID, path, pfs.Delimiter_NONE, 0, 0, 0, &pfs.OverwriteIndex{Index: overwriteIndex})
	if err != nil {
		return 0, grpcutil.ScrubGRPC(err)
	}
	defer func() {
		if err := writer.Close(); err != nil && retErr == nil {
			retErr = err
		}
	}()
	written, err := io.Copy(writer, reader)
	return int(written), grpcutil.ScrubGRPC(err)
}

//PutFileSplit writes a file to PFS from a reader
// delimiter is used to tell PFS how to break the input into blocks
func (c *putFileClient) PutFileSplit(repoName string, commitID string, path string, delimiter pfs.Delimiter, targetFileDatums int64, targetFileBytes int64, headerRecords int64, overwrite bool, reader io.Reader) (_ int, retErr error) {
	writer, err := c.PutFileSplitWriter(repoName, commitID, path, delimiter, targetFileDatums, targetFileBytes, headerRecords, overwrite)
	if err != nil {
		return 0, grpcutil.ScrubGRPC(err)
	}
	defer func() {
		if err := writer.Close(); err != nil && retErr == nil {
			retErr = err
		}
	}()
	buf := grpcutil.GetBuffer()
	defer grpcutil.PutBuffer(buf)
	written, err := io.CopyBuffer(writer, reader, buf)
	return int(written), grpcutil.ScrubGRPC(err)
}

// PutFileURL puts a file using the content found at a URL.
// The URL is sent to the server which performs the request.
// recursive allow for recursive scraping of some types URLs for example on s3:// urls.
func (c *putFileClient) PutFileURL(repoName string, commitID string, path string, url string, recursive bool, overwrite bool) (retErr error) {
	c.mu.Lock()
	defer c.mu.Unlock()
	var overwriteIndex *pfs.OverwriteIndex
	if overwrite {
		overwriteIndex = &pfs.OverwriteIndex{}
	}
	if c.oneoff {
		defer func() {
			if err := grpcutil.ScrubGRPC(c.Close()); err != nil && retErr == nil {
				retErr = err
			}
		}()
	}
	if err := c.c.Send(&pfs.PutFileRequest{
		File:           NewFile(repoName, commitID, path),
		Url:            url,
		Recursive:      recursive,
		OverwriteIndex: overwriteIndex,
	}); err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	return nil
}

// Close must be called after you're done using a putFileClient.
// Further requests will throw errors.
func (c *putFileClient) Close() error {
	_, err := c.c.CloseAndRecv()
	return grpcutil.ScrubGRPC(err)
}

// PutFileWriter writes a file to PFS.
// NOTE: PutFileWriter returns an io.WriteCloser you must call Close on it when
// you are done writing.
func (c APIClient) PutFileWriter(repoName string, commitID string, path string) (io.WriteCloser, error) {
	pfc, err := c.newOneoffPutFileClient()
	if err != nil {
		return nil, err
	}
	return pfc.PutFileWriter(repoName, commitID, path)
}

// PutFileSplitWriter writes a multiple files to PFS by splitting up the data
// that is written to it.
// NOTE: PutFileSplitWriter returns an io.WriteCloser you must call Close on it when
// you are done writing.
func (c APIClient) PutFileSplitWriter(repoName string, commitID string, path string,
	delimiter pfs.Delimiter, targetFileDatums int64, targetFileBytes int64, headerRecords int64, overwrite bool) (io.WriteCloser, error) {
	pfc, err := c.newOneoffPutFileClient()
	if err != nil {
		return nil, err
	}
	return pfc.PutFileSplitWriter(repoName, commitID, path, delimiter, targetFileDatums, targetFileBytes, headerRecords, overwrite)
}

// PutFile writes a file to PFS from a reader.
func (c APIClient) PutFile(repoName string, commitID string, path string, reader io.Reader) (_ int, retErr error) {
	pfc, err := c.newOneoffPutFileClient()
	if err != nil {
		return 0, err
	}
	return pfc.PutFile(repoName, commitID, path, reader)
}

// PutFileOverwrite is like PutFile but it overwrites the file rather than
// appending to it.  overwriteIndex allows you to specify the index of the
// object starting from which you'd like to overwrite.  If you want to
// overwrite the entire file, specify an index of 0.
func (c APIClient) PutFileOverwrite(repoName string, commitID string, path string, reader io.Reader, overwriteIndex int64) (_ int, retErr error) {
	pfc, err := c.newOneoffPutFileClient()
	if err != nil {
		return 0, err
	}
	return pfc.PutFileOverwrite(repoName, commitID, path, reader, overwriteIndex)
}

//PutFileSplit writes a file to PFS from a reader
// delimiter is used to tell PFS how to break the input into blocks
func (c APIClient) PutFileSplit(repoName string, commitID string, path string, delimiter pfs.Delimiter, targetFileDatums int64, targetFileBytes int64, headerRecords int64, overwrite bool, reader io.Reader) (_ int, retErr error) {
	// TODO(msteffen) update
	pfc, err := c.newOneoffPutFileClient()
	if err != nil {
		return 0, err
	}
	return pfc.PutFileSplit(repoName, commitID, path, delimiter, targetFileDatums, targetFileBytes, headerRecords, overwrite, reader)
}

// PutFileURL puts a file using the content found at a URL.
// The URL is sent to the server which performs the request.
// recursive allow for recursive scraping of some types URLs for example on s3:// urls.
func (c APIClient) PutFileURL(repoName string, commitID string, path string, url string, recursive bool, overwrite bool) (retErr error) {
	pfc, err := c.newOneoffPutFileClient()
	if err != nil {
		return err
	}
	return pfc.PutFileURL(repoName, commitID, path, url, recursive, overwrite)
}

// CopyFile copys a file from one pfs location to another. It can be used on
// directories or regular files.
func (c APIClient) CopyFile(srcRepo, srcCommit, srcPath, dstRepo, dstCommit, dstPath string, overwrite bool) error {
	if _, err := c.PfsAPIClient.CopyFile(c.Ctx(),
		&pfs.CopyFileRequest{
			Src:       NewFile(srcRepo, srcCommit, srcPath),
			Dst:       NewFile(dstRepo, dstCommit, dstPath),
			Overwrite: overwrite,
		}); err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	return nil
}

// GetFile returns the contents of a file at a specific Commit.
// offset specifies a number of bytes that should be skipped in the beginning of the file.
// size limits the total amount of data returned, note you will get fewer bytes
// than size if you pass a value larger than the size of the file.
// If size is set to 0 then all of the data will be returned.
func (c APIClient) GetFile(repoName string, commitID string, path string, offset int64, size int64, writer io.Writer) error {
	if c.limiter != nil {
		c.limiter.Acquire()
		defer c.limiter.Release()
	}
	apiGetFileClient, err := c.getFile(repoName, commitID, path, offset, size)
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	if err := grpcutil.WriteFromStreamingBytesClient(apiGetFileClient, writer); err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	return nil
}

// GetFileReader returns a reader for the contents of a file at a specific Commit.
// offset specifies a number of bytes that should be skipped in the beginning of the file.
// size limits the total amount of data returned, note you will get fewer bytes
// than size if you pass a value larger than the size of the file.
// If size is set to 0 then all of the data will be returned.
func (c APIClient) GetFileReader(repoName string, commitID string, path string, offset int64, size int64) (io.Reader, error) {
	apiGetFileClient, err := c.getFile(repoName, commitID, path, offset, size)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return grpcutil.NewStreamingBytesReader(apiGetFileClient, nil), nil
}

// GetFileReadSeeker returns a reader for the contents of a file at a specific
// Commit that permits Seeking to different points in the file.
func (c APIClient) GetFileReadSeeker(repoName string, commitID string, path string) (io.ReadSeeker, error) {
	fileInfo, err := c.InspectFile(repoName, commitID, path)
	if err != nil {
		return nil, err
	}
	reader, err := c.GetFileReader(repoName, commitID, path, 0, 0)
	if err != nil {
		return nil, err
	}
	return &getFileReadSeeker{
		Reader: reader,
		file:   NewFile(repoName, commitID, path),
		offset: 0,
		size:   int64(fileInfo.SizeBytes),
		c:      c,
	}, nil
}

func (c APIClient) getFile(repoName string, commitID string, path string, offset int64,
	size int64) (pfs.API_GetFileClient, error) {
	return c.PfsAPIClient.GetFile(
		c.Ctx(),
		&pfs.GetFileRequest{
			File:        NewFile(repoName, commitID, path),
			OffsetBytes: offset,
			SizeBytes:   size,
		},
	)
}

// InspectFile returns info about a specific file.
func (c APIClient) InspectFile(repoName string, commitID string, path string) (*pfs.FileInfo, error) {
	return c.inspectFile(repoName, commitID, path)
}

func (c APIClient) inspectFile(repoName string, commitID string, path string) (*pfs.FileInfo, error) {
	fileInfo, err := c.PfsAPIClient.InspectFile(
		c.Ctx(),
		&pfs.InspectFileRequest{
			File: NewFile(repoName, commitID, path),
		},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return fileInfo, nil
}

// ListFile returns info about all files in a Commit under path.
func (c APIClient) ListFile(repoName string, commitID string, path string) ([]*pfs.FileInfo, error) {
	var result []*pfs.FileInfo
	if err := c.ListFileF(repoName, commitID, path, 0, func(fi *pfs.FileInfo) error {
		result = append(result, fi)
		return nil
	}); err != nil {
		return nil, err
	}
	return result, nil
}

// ListFileHistory returns info about all files and their history in a Commit under path.
func (c APIClient) ListFileHistory(repoName string, commitID string, path string, history int64) ([]*pfs.FileInfo, error) {
	var result []*pfs.FileInfo
	if err := c.ListFileF(repoName, commitID, path, history, func(fi *pfs.FileInfo) error {
		result = append(result, fi)
		return nil
	}); err != nil {
		return nil, err
	}
	return result, nil
}

// ListFileF returns info about all files in a Commit under path, calling f with each FileInfo.
func (c APIClient) ListFileF(repoName string, commitID string, path string, history int64, f func(fi *pfs.FileInfo) error) error {
	fs, err := c.PfsAPIClient.ListFileStream(
		c.Ctx(),
		&pfs.ListFileRequest{
			File:    NewFile(repoName, commitID, path),
			History: history,
		},
	)
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	for {
		fi, err := fs.Recv()
		if err == io.EOF {
			return nil
		} else if err != nil {
			return grpcutil.ScrubGRPC(err)
		}
		if err := f(fi); err != nil {
			if err == errutil.ErrBreak {
				return nil
			}
			return err
		}
	}
}

// GlobFile returns files that match a given glob pattern in a given commit.
// The pattern is documented here:
// https://golang.org/pkg/path/filepath/#Match
func (c APIClient) GlobFile(repoName string, commitID string, pattern string) ([]*pfs.FileInfo, error) {
	fs, err := c.PfsAPIClient.GlobFileStream(
		c.Ctx(),
		&pfs.GlobFileRequest{
			Commit:  NewCommit(repoName, commitID),
			Pattern: pattern,
		},
	)
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	var result []*pfs.FileInfo
	for {
		f, err := fs.Recv()
		if err == io.EOF {
			break
		} else if err != nil {
			return nil, grpcutil.ScrubGRPC(err)
		}
		result = append(result, f)
	}
	return result, nil
}

// GlobFileF returns files that match a given glob pattern in a given commit,
// calling f with each FileInfo. The pattern is documented here:
// https://golang.org/pkg/path/filepath/#Match
func (c APIClient) GlobFileF(repoName string, commitID string, pattern string, f func(fi *pfs.FileInfo) error) error {
	fs, err := c.PfsAPIClient.GlobFileStream(
		c.Ctx(),
		&pfs.GlobFileRequest{
			Commit:  NewCommit(repoName, commitID),
			Pattern: pattern,
		},
	)
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	for {
		fi, err := fs.Recv()
		if err == io.EOF {
			return nil
		} else if err != nil {
			return grpcutil.ScrubGRPC(err)
		}
		if err := f(fi); err != nil {
			if err == errutil.ErrBreak {
				return nil
			}
			return err
		}
	}
}

// DiffFile returns the difference between 2 paths, old path may be omitted in
// which case the parent of the new path will be used. DiffFile return 2 values
// (unless it returns an error) the first value is files present under new
// path, the second is files present under old path, files which are under both
// paths and have identical content are omitted.
func (c APIClient) DiffFile(newRepoName, newCommitID, newPath, oldRepoName,
	oldCommitID, oldPath string, shallow bool) ([]*pfs.FileInfo, []*pfs.FileInfo, error) {
	var oldFile *pfs.File
	if oldRepoName != "" {
		oldFile = NewFile(oldRepoName, oldCommitID, oldPath)
	}
	resp, err := c.PfsAPIClient.DiffFile(
		c.Ctx(),
		&pfs.DiffFileRequest{
			NewFile: NewFile(newRepoName, newCommitID, newPath),
			OldFile: oldFile,
			Shallow: shallow,
		},
	)
	if err != nil {
		return nil, nil, grpcutil.ScrubGRPC(err)
	}
	return resp.NewFiles, resp.OldFiles, nil
}

// WalkFn is the type of the function called for each file in Walk.
// Returning a non-nil error from WalkFn will result in Walk aborting and
// returning said error.
type WalkFn func(*pfs.FileInfo) error

// Walk walks the pfs filesystem rooted at path. walkFn will be called for each
// file found under path in lexicographical order. This includes both regular
// files and directories.
func (c APIClient) Walk(repoName string, commitID string, path string, f WalkFn) error {
	fs, err := c.PfsAPIClient.WalkFile(
		c.Ctx(),
		&pfs.WalkFileRequest{File: NewFile(repoName, commitID, path)})
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	for {
		fi, err := fs.Recv()
		if err == io.EOF {
			return nil
		} else if err != nil {
			return grpcutil.ScrubGRPC(err)
		}
		if err := f(fi); err != nil {
			if err == errutil.ErrBreak {
				return nil
			}
			return err
		}
	}
}

// DeleteFile deletes a file from a Commit.
// DeleteFile leaves a tombstone in the Commit, assuming the file isn't written
// to later attempting to get the file from the finished commit will result in
// not found error.
// The file will of course remain intact in the Commit's parent.
func (c APIClient) DeleteFile(repoName string, commitID string, path string) error {
	_, err := c.PfsAPIClient.DeleteFile(
		c.Ctx(),
		&pfs.DeleteFileRequest{
			File: NewFile(repoName, commitID, path),
		},
	)
	return err
}

type putFileWriteCloser struct {
	request *pfs.PutFileRequest
	sent    bool
	c       *putFileClient
}

func (c *putFileClient) newPutFileWriteCloser(repoName string, commitID string, path string, delimiter pfs.Delimiter, targetFileDatums int64, targetFileBytes int64, headerRecords int64, overwriteIndex *pfs.OverwriteIndex) (*putFileWriteCloser, error) {
	c.mu.Lock() // Unlocked in Close()
	return &putFileWriteCloser{
		request: &pfs.PutFileRequest{
			File:             NewFile(repoName, commitID, path),
			Delimiter:        delimiter,
			TargetFileDatums: targetFileDatums,
			TargetFileBytes:  targetFileBytes,
			HeaderRecords:    headerRecords,
			OverwriteIndex:   overwriteIndex,
		},
		c: c,
	}, nil
}

func (w *putFileWriteCloser) Write(p []byte) (int, error) {
	bytesWritten := 0
	for {
		// Buffer the write so that we don't exceed the grpc
		// MaxMsgSize. This value includes the whole payload
		// including headers, so we're conservative and halve it
		ceil := bytesWritten + grpcutil.MaxMsgSize/2
		if ceil > len(p) {
			ceil = len(p)
		}
		actualP := p[bytesWritten:ceil]
		if len(actualP) == 0 {
			break
		}
		w.request.Value = actualP
		if err := w.c.c.Send(w.request); err != nil {
			return 0, grpcutil.ScrubGRPC(err)
		}
		w.sent = true
		w.request.Value = nil
		// File must only be set on the first request containing data written to
		// that path
		// TODO(msteffen): can other fields be zeroed as well?
		w.request.File = nil
		bytesWritten += len(actualP)
	}
	return bytesWritten, nil
}

func (w *putFileWriteCloser) Close() (retErr error) {
	defer w.c.mu.Unlock()
	if w.c.oneoff {
		defer func() {
			if err := w.c.Close(); err != nil && retErr == nil {
				retErr = grpcutil.ScrubGRPC(err)
			}
		}()
	}
	// we always send at least one request, otherwise it's impossible to create
	// an empty file
	if !w.sent {
		if err := w.c.c.Send(w.request); err != nil {
			return grpcutil.ScrubGRPC(err)
		}
	}
	return nil
}

type putObjectWriteCloser struct {
	request *pfs.PutObjectRequest
	client  pfs.ObjectAPI_PutObjectClient
	object  *pfs.Object
}

func (c APIClient) newPutObjectWriteCloser(tags ...string) (*putObjectWriteCloser, error) {
	client, err := c.ObjectAPIClient.PutObject(c.Ctx())
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	var _tags []*pfs.Tag
	for _, tag := range tags {
		_tags = append(_tags, &pfs.Tag{Name: tag})
	}
	return &putObjectWriteCloser{
		request: &pfs.PutObjectRequest{
			Tags: _tags,
		},
		client: client,
	}, nil
}

func (w *putObjectWriteCloser) Write(p []byte) (int, error) {
	w.request.Value = p
	if err := w.client.Send(w.request); err != nil {
		return 0, grpcutil.ScrubGRPC(err)
	}
	w.request.Tags = nil
	return len(p), nil
}

func (w *putObjectWriteCloser) Close() error {
	var err error
	w.object, err = w.client.CloseAndRecv()
	return grpcutil.ScrubGRPC(err)
}

// PutObjectWriteCloserAsync wraps a put object call in an asynchronous buffered writer.
type PutObjectWriteCloserAsync struct {
	client    pfs.ObjectAPI_PutObjectClient
	request   *pfs.PutObjectRequest
	buf       []byte
	writeChan chan []byte
	errChan   chan error
	object    *pfs.Object
}

func (c APIClient) newPutObjectWriteCloserAsync(tags []*pfs.Tag) (*PutObjectWriteCloserAsync, error) {
	client, err := c.ObjectAPIClient.PutObject(c.Ctx())
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	w := &PutObjectWriteCloserAsync{
		client: client,
		request: &pfs.PutObjectRequest{
			Tags: tags,
		},
		buf:       grpcutil.GetBuffer()[:0],
		writeChan: make(chan []byte, 5),
		errChan:   make(chan error),
	}
	go func() {
		for buf := range w.writeChan {
			w.request.Value = buf
			if err := w.client.Send(w.request); err != nil {
				w.errChan <- err
				break
			}
			w.request.Tags = nil
			grpcutil.PutBuffer(buf[:cap(buf)])
		}
		close(w.errChan)
	}()
	return w, nil
}

// Write performs a write.
func (w *PutObjectWriteCloserAsync) Write(p []byte) (int, error) {
	var written int
	for len(w.buf)+len(p) > cap(w.buf) {
		// Write the bytes that fit into w.buf, then
		// remove those bytes from p.
		i := cap(w.buf) - len(w.buf)
		w.buf = append(w.buf, p[:i]...)
		if err := w.writeBuf(); err != nil {
			return 0, err
		}
		written += i
		p = p[i:]
		w.buf = grpcutil.GetBuffer()[:0]
	}
	w.buf = append(w.buf, p...)
	written += len(p)
	return written, nil
}

// Close closes the writer.
func (w *PutObjectWriteCloserAsync) Close() error {
	if err := w.writeBuf(); err != nil {
		return err
	}
	close(w.writeChan)
	err := <-w.errChan
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	w.object, err = w.client.CloseAndRecv()
	return grpcutil.ScrubGRPC(err)
}

func (w *PutObjectWriteCloserAsync) writeBuf() error {
	select {
	case err := <-w.errChan:
		if err != nil {
			return grpcutil.ScrubGRPC(err)
		}
	case w.writeChan <- w.buf:
	}
	return nil
}

// Object gets the pfs object for this writer.
// This can only be called when the writer is closed (the put object
// call is complete)
func (w *PutObjectWriteCloserAsync) Object() (*pfs.Object, error) {
	select {
	case err := <-w.errChan:
		if err != nil {
			return nil, grpcutil.ScrubGRPC(err)
		}
		return w.object, nil
	default:
		return nil, fmt.Errorf("attempting to get object before closing object writer")
	}
}

type putObjectSplitWriteCloser struct {
	request *pfs.PutObjectRequest
	client  pfs.ObjectAPI_PutObjectSplitClient
	objects []*pfs.Object
}

func (c APIClient) newPutObjectSplitWriteCloser() (*putObjectSplitWriteCloser, error) {
	client, err := c.ObjectAPIClient.PutObjectSplit(c.Ctx())
	if err != nil {
		return nil, grpcutil.ScrubGRPC(err)
	}
	return &putObjectSplitWriteCloser{
		request: &pfs.PutObjectRequest{},
		client:  client,
	}, nil
}

func (w *putObjectSplitWriteCloser) Write(p []byte) (int, error) {
	w.request.Value = p
	if err := w.client.Send(w.request); err != nil {
		return 0, grpcutil.ScrubGRPC(err)
	}
	return len(p), nil
}

func (w *putObjectSplitWriteCloser) Close() error {
	objects, err := w.client.CloseAndRecv()
	if err != nil {
		return grpcutil.ScrubGRPC(err)
	}
	w.objects = objects.Objects
	return nil
}

type getFileReadSeeker struct {
	io.Reader
	file   *pfs.File
	offset int64
	size   int64
	c      APIClient
}

func (r *getFileReadSeeker) Seek(offset int64, whence int) (int64, error) {
	getFileReader := func(offset int64) (io.Reader, error) {
		return r.c.GetFileReader(r.file.Commit.Repo.Name, r.file.Commit.ID, r.file.Path, offset, 0)
	}
	switch whence {
	case io.SeekStart:
		reader, err := getFileReader(offset)
		if err != nil {
			return r.offset, err
		}
		r.offset = offset
		r.Reader = reader
	case io.SeekCurrent:
		reader, err := getFileReader(r.offset + offset)
		if err != nil {
			return r.offset, err
		}
		r.offset += offset
		r.Reader = reader
	case io.SeekEnd:
		reader, err := getFileReader(r.size - offset)
		if err != nil {
			return r.offset, err
		}
		r.offset = r.size - offset
		r.Reader = reader
	}
	return r.offset, nil
}