distribution/docs/storage/driver/rados/rados.go
Richard Scothern e79324edd8 Add a generic error type to capture non-typed errors
Signed-off-by: Richard Scothern <richard.scothern@gmail.com>
2015-11-03 11:19:44 -08:00

633 lines
14 KiB
Go

// +build include_rados
package rados
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"io/ioutil"
"path"
"strconv"
log "github.com/Sirupsen/logrus"
"github.com/docker/distribution/context"
storagedriver "github.com/docker/distribution/registry/storage/driver"
"github.com/docker/distribution/registry/storage/driver/base"
"github.com/docker/distribution/registry/storage/driver/factory"
"github.com/docker/distribution/uuid"
"github.com/noahdesu/go-ceph/rados"
)
const driverName = "rados"
// Prefix all the stored blob
const objectBlobPrefix = "blob:"
// Stripes objects size to 4M
const defaultChunkSize = 4 << 20
const defaultXattrTotalSizeName = "total-size"
// Max number of keys fetched from omap at each read operation
const defaultKeysFetched = 1
//DriverParameters A struct that encapsulates all of the driver parameters after all values have been set
type DriverParameters struct {
poolname string
username string
chunksize uint64
}
func init() {
factory.Register(driverName, &radosDriverFactory{})
}
// radosDriverFactory implements the factory.StorageDriverFactory interface
type radosDriverFactory struct{}
func (factory *radosDriverFactory) Create(parameters map[string]interface{}) (storagedriver.StorageDriver, error) {
return FromParameters(parameters)
}
type driver struct {
Conn *rados.Conn
Ioctx *rados.IOContext
chunksize uint64
}
type baseEmbed struct {
base.Base
}
// Driver is a storagedriver.StorageDriver implementation backed by Ceph RADOS
// Objects are stored at absolute keys in the provided bucket.
type Driver struct {
baseEmbed
}
// FromParameters constructs a new Driver with a given parameters map
// Required parameters:
// - poolname: the ceph pool name
func FromParameters(parameters map[string]interface{}) (*Driver, error) {
pool, ok := parameters["poolname"]
if !ok {
return nil, fmt.Errorf("No poolname parameter provided")
}
username, ok := parameters["username"]
if !ok {
username = ""
}
chunksize := uint64(defaultChunkSize)
chunksizeParam, ok := parameters["chunksize"]
if ok {
chunksize, ok = chunksizeParam.(uint64)
if !ok {
return nil, fmt.Errorf("The chunksize parameter should be a number")
}
}
params := DriverParameters{
fmt.Sprint(pool),
fmt.Sprint(username),
chunksize,
}
return New(params)
}
// New constructs a new Driver
func New(params DriverParameters) (*Driver, error) {
var conn *rados.Conn
var err error
if params.username != "" {
log.Infof("Opening connection to pool %s using user %s", params.poolname, params.username)
conn, err = rados.NewConnWithUser(params.username)
} else {
log.Infof("Opening connection to pool %s", params.poolname)
conn, err = rados.NewConn()
}
if err != nil {
return nil, err
}
err = conn.ReadDefaultConfigFile()
if err != nil {
return nil, err
}
err = conn.Connect()
if err != nil {
return nil, err
}
log.Infof("Connected")
ioctx, err := conn.OpenIOContext(params.poolname)
log.Infof("Connected to pool %s", params.poolname)
if err != nil {
return nil, err
}
d := &driver{
Ioctx: ioctx,
Conn: conn,
chunksize: params.chunksize,
}
return &Driver{
baseEmbed: baseEmbed{
Base: base.Base{
StorageDriver: d,
},
},
}, nil
}
// Implement the storagedriver.StorageDriver interface
func (d *driver) Name() string {
return driverName
}
// GetContent retrieves the content stored at "path" as a []byte.
func (d *driver) GetContent(ctx context.Context, path string) ([]byte, error) {
rc, err := d.ReadStream(ctx, path, 0)
if err != nil {
return nil, err
}
defer rc.Close()
p, err := ioutil.ReadAll(rc)
if err != nil {
return nil, err
}
return p, nil
}
// PutContent stores the []byte content at a location designated by "path".
func (d *driver) PutContent(ctx context.Context, path string, contents []byte) error {
if _, err := d.WriteStream(ctx, path, 0, bytes.NewReader(contents)); err != nil {
return err
}
return nil
}
// ReadStream retrieves an io.ReadCloser for the content stored at "path" with a
// given byte offset.
type readStreamReader struct {
driver *driver
oid string
size uint64
offset uint64
}
func (r *readStreamReader) Read(b []byte) (n int, err error) {
// Determine the part available to read
bufferOffset := uint64(0)
bufferSize := uint64(len(b))
// End of the object, read less than the buffer size
if bufferSize > r.size-r.offset {
bufferSize = r.size - r.offset
}
// Fill `b`
for bufferOffset < bufferSize {
// Get the offset in the object chunk
chunkedOid, chunkedOffset := r.driver.getChunkNameFromOffset(r.oid, r.offset)
// Determine the best size to read
bufferEndOffset := bufferSize
if bufferEndOffset-bufferOffset > r.driver.chunksize-chunkedOffset {
bufferEndOffset = bufferOffset + (r.driver.chunksize - chunkedOffset)
}
// Read the chunk
n, err = r.driver.Ioctx.Read(chunkedOid, b[bufferOffset:bufferEndOffset], chunkedOffset)
if err != nil {
return int(bufferOffset), err
}
bufferOffset += uint64(n)
r.offset += uint64(n)
}
// EOF if the offset is at the end of the object
if r.offset == r.size {
return int(bufferOffset), io.EOF
}
return int(bufferOffset), nil
}
func (r *readStreamReader) Close() error {
return nil
}
func (d *driver) ReadStream(ctx context.Context, path string, offset int64) (io.ReadCloser, error) {
// get oid from filename
oid, err := d.getOid(path)
if err != nil {
return nil, err
}
// get object stat
stat, err := d.Stat(ctx, path)
if err != nil {
return nil, err
}
if offset > stat.Size() {
return nil, storagedriver.InvalidOffsetError{Path: path, Offset: offset}
}
return &readStreamReader{
driver: d,
oid: oid,
size: uint64(stat.Size()),
offset: uint64(offset),
}, nil
}
func (d *driver) WriteStream(ctx context.Context, path string, offset int64, reader io.Reader) (totalRead int64, err error) {
buf := make([]byte, d.chunksize)
totalRead = 0
oid, err := d.getOid(path)
if err != nil {
switch err.(type) {
// Trying to write new object, generate new blob identifier for it
case storagedriver.PathNotFoundError:
oid = d.generateOid()
err = d.putOid(path, oid)
if err != nil {
return 0, err
}
default:
return 0, err
}
} else {
// Check total object size only for existing ones
totalSize, err := d.getXattrTotalSize(ctx, oid)
if err != nil {
return 0, err
}
// If offset if after the current object size, fill the gap with zeros
for totalSize < uint64(offset) {
sizeToWrite := d.chunksize
if totalSize-uint64(offset) < sizeToWrite {
sizeToWrite = totalSize - uint64(offset)
}
chunkName, chunkOffset := d.getChunkNameFromOffset(oid, uint64(totalSize))
err = d.Ioctx.Write(chunkName, buf[:sizeToWrite], uint64(chunkOffset))
if err != nil {
return totalRead, err
}
totalSize += sizeToWrite
}
}
// Writer
for {
// Align to chunk size
sizeRead := uint64(0)
sizeToRead := uint64(offset+totalRead) % d.chunksize
if sizeToRead == 0 {
sizeToRead = d.chunksize
}
// Read from `reader`
for sizeRead < sizeToRead {
nn, err := reader.Read(buf[sizeRead:sizeToRead])
sizeRead += uint64(nn)
if err != nil {
if err != io.EOF {
return totalRead, err
}
break
}
}
// End of file and nothing was read
if sizeRead == 0 {
break
}
// Write chunk object
chunkName, chunkOffset := d.getChunkNameFromOffset(oid, uint64(offset+totalRead))
err = d.Ioctx.Write(chunkName, buf[:sizeRead], uint64(chunkOffset))
if err != nil {
return totalRead, err
}
// Update total object size as xattr in the first chunk of the object
err = d.setXattrTotalSize(oid, uint64(offset+totalRead)+sizeRead)
if err != nil {
return totalRead, err
}
totalRead += int64(sizeRead)
// End of file
if sizeRead < sizeToRead {
break
}
}
return totalRead, nil
}
// Stat retrieves the FileInfo for the given path, including the current size
func (d *driver) Stat(ctx context.Context, path string) (storagedriver.FileInfo, error) {
// get oid from filename
oid, err := d.getOid(path)
if err != nil {
return nil, err
}
// the path is a virtual directory?
if oid == "" {
return storagedriver.FileInfoInternal{
FileInfoFields: storagedriver.FileInfoFields{
Path: path,
Size: 0,
IsDir: true,
},
}, nil
}
// stat first chunk
stat, err := d.Ioctx.Stat(oid + "-0")
if err != nil {
return nil, err
}
// get total size of chunked object
totalSize, err := d.getXattrTotalSize(ctx, oid)
if err != nil {
return nil, err
}
return storagedriver.FileInfoInternal{
FileInfoFields: storagedriver.FileInfoFields{
Path: path,
Size: int64(totalSize),
ModTime: stat.ModTime,
},
}, nil
}
// List returns a list of the objects that are direct descendants of the given path.
func (d *driver) List(ctx context.Context, dirPath string) ([]string, error) {
files, err := d.listDirectoryOid(dirPath)
if err != nil {
return nil, err
}
keys := make([]string, 0, len(files))
for k := range files {
if k != dirPath {
keys = append(keys, path.Join(dirPath, k))
}
}
return keys, nil
}
// Move moves an object stored at sourcePath to destPath, removing the original
// object.
func (d *driver) Move(ctx context.Context, sourcePath string, destPath string) error {
// Get oid
oid, err := d.getOid(sourcePath)
if err != nil {
return err
}
// Move reference
err = d.putOid(destPath, oid)
if err != nil {
return err
}
// Delete old reference
err = d.deleteOid(sourcePath)
if err != nil {
return err
}
return nil
}
// Delete recursively deletes all objects stored at "path" and its subpaths.
func (d *driver) Delete(ctx context.Context, objectPath string) error {
// Get oid
oid, err := d.getOid(objectPath)
if err != nil {
return err
}
// Deleting virtual directory
if oid == "" {
objects, err := d.listDirectoryOid(objectPath)
if err != nil {
return err
}
for object := range objects {
err = d.Delete(ctx, path.Join(objectPath, object))
if err != nil {
return err
}
}
} else {
// Delete object chunks
totalSize, err := d.getXattrTotalSize(ctx, oid)
if err != nil {
return err
}
for offset := uint64(0); offset < totalSize; offset += d.chunksize {
chunkName, _ := d.getChunkNameFromOffset(oid, offset)
err = d.Ioctx.Delete(chunkName)
if err != nil {
return err
}
}
// Delete reference
err = d.deleteOid(objectPath)
if err != nil {
return err
}
}
return nil
}
// URLFor returns a URL which may be used to retrieve the content stored at the given path.
// May return an UnsupportedMethodErr in certain StorageDriver implementations.
func (d *driver) URLFor(ctx context.Context, path string, options map[string]interface{}) (string, error) {
return "", storagedriver.ErrUnsupportedMethod{}
}
// Generate a blob identifier
func (d *driver) generateOid() string {
return objectBlobPrefix + uuid.Generate().String()
}
// Reference a object and its hierarchy
func (d *driver) putOid(objectPath string, oid string) error {
directory := path.Dir(objectPath)
base := path.Base(objectPath)
createParentReference := true
// After creating this reference, skip the parents referencing since the
// hierarchy already exists
if oid == "" {
firstReference, err := d.Ioctx.GetOmapValues(directory, "", "", 1)
if (err == nil) && (len(firstReference) > 0) {
createParentReference = false
}
}
oids := map[string][]byte{
base: []byte(oid),
}
// Reference object
err := d.Ioctx.SetOmap(directory, oids)
if err != nil {
return err
}
// Esure parent virtual directories
if createParentReference {
return d.putOid(directory, "")
}
return nil
}
// Get the object identifier from an object name
func (d *driver) getOid(objectPath string) (string, error) {
directory := path.Dir(objectPath)
base := path.Base(objectPath)
files, err := d.Ioctx.GetOmapValues(directory, "", base, 1)
if (err != nil) || (files[base] == nil) {
return "", storagedriver.PathNotFoundError{Path: objectPath}
}
return string(files[base]), nil
}
// List the objects of a virtual directory
func (d *driver) listDirectoryOid(path string) (list map[string][]byte, err error) {
return d.Ioctx.GetAllOmapValues(path, "", "", defaultKeysFetched)
}
// Remove a file from the files hierarchy
func (d *driver) deleteOid(objectPath string) error {
// Remove object reference
directory := path.Dir(objectPath)
base := path.Base(objectPath)
err := d.Ioctx.RmOmapKeys(directory, []string{base})
if err != nil {
return err
}
// Remove virtual directory if empty (no more references)
firstReference, err := d.Ioctx.GetOmapValues(directory, "", "", 1)
if err != nil {
return err
}
if len(firstReference) == 0 {
// Delete omap
err := d.Ioctx.Delete(directory)
if err != nil {
return err
}
// Remove reference on parent omaps
if directory != "" {
return d.deleteOid(directory)
}
}
return nil
}
// Takes an offset in an chunked object and return the chunk name and a new
// offset in this chunk object
func (d *driver) getChunkNameFromOffset(oid string, offset uint64) (string, uint64) {
chunkID := offset / d.chunksize
chunkedOid := oid + "-" + strconv.FormatInt(int64(chunkID), 10)
chunkedOffset := offset % d.chunksize
return chunkedOid, chunkedOffset
}
// Set the total size of a chunked object `oid`
func (d *driver) setXattrTotalSize(oid string, size uint64) error {
// Convert uint64 `size` to []byte
xattr := make([]byte, binary.MaxVarintLen64)
binary.LittleEndian.PutUint64(xattr, size)
// Save the total size as a xattr in the first chunk
return d.Ioctx.SetXattr(oid+"-0", defaultXattrTotalSizeName, xattr)
}
// Get the total size of the chunked object `oid` stored as xattr
func (d *driver) getXattrTotalSize(ctx context.Context, oid string) (uint64, error) {
// Fetch xattr as []byte
xattr := make([]byte, binary.MaxVarintLen64)
xattrLength, err := d.Ioctx.GetXattr(oid+"-0", defaultXattrTotalSizeName, xattr)
if err != nil {
return 0, err
}
if xattrLength != len(xattr) {
context.GetLogger(ctx).Errorf("object %s xattr length mismatch: %d != %d", oid, xattrLength, len(xattr))
return 0, storagedriver.PathNotFoundError{Path: oid}
}
// Convert []byte as uint64
totalSize := binary.LittleEndian.Uint64(xattr)
return totalSize, nil
}