blobserver

package
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 Go to latest Published: Jan 13, 2014 License: Apache-2.0 Imports: 15 Imported by: 0

Documentation

Overview

Package blobserver defines how raw blobs are stored and accessed.

Index

Constants

View Source 
const MaxBlobSize = constants.MaxBlobSize

MaxBlobSize is the size of a single blob in Camlistore.

Variables

View Source 
var ErrCorruptBlob = errors.New("corrupt blob; digest doesn't match")
View Source 
var ErrHandlerTypeNotFound = errors.New("requested handler type not loaded")
View Source 
var ErrNotImplemented = errors.New("not implemented")

ErrNotImplemented should be returned in methods where the function is not implemented

Functions

func CreateHandler 

func CreateHandler(typ string, loader Loader, config jsonconfig.Obj) (http.Handler, error)

CreateHandler instantiates an http Handler of type 'typ' from the provided JSON configuration, and finding peer handlers and configuration from the environment in 'loader'.

The handler 'typ' must have bee previously registered with RegisterHandlerConstructor.

func EnumerateAll 

func EnumerateAll(ctx *context.Context, src BlobEnumerator, fn func(blob.SizedRef) error) error

EnumerateAll runs fn for each blob in src. If fn returns an error, iteration stops and fn isn't called again. EnumerateAll will not return concurrently with fn.

func MergedEnumerate 

func MergedEnumerate(ctx *context.Context, dest chan<- blob.SizedRef, sources []Storage, after string, limit int) error

TODO: it'd be nice to make sources be []BlobEnumerator, but that makes callers more complex since assignable interfaces' slice forms aren't assignable.

func Receive 

func Receive(dst BlobReceiver, br blob.Ref, src io.Reader) (blob.SizedRef, error)

Receive wraps calling a BlobReceiver's ReceiveBlob method, additionally providing verification of the src digest, and also notifying the blob hub on success. The error will be ErrCorruptBlob if the blobref didn't match.

func ReceiveNoHash 

func ReceiveNoHash(dst BlobReceiver, br blob.Ref, src io.Reader) (blob.SizedRef, error)

func ReceiveString 

func ReceiveString(dst BlobReceiver, s string) (blob.SizedRef, error)

ReceiveString uploads the blob given by the string s to dst and returns its blobref and size.

func RegisterHandlerConstructor 

func RegisterHandlerConstructor(typ string, ctor HandlerConstructor)

RegisterHandlerConstructor registers an http Handler constructor function for a given handler type.

It is an error to register the same handler type twice.

func RegisterStorageConstructor 

func RegisterStorageConstructor(typ string, ctor StorageConstructor)

func StatBlob 

func StatBlob(bs BlobStatter, br blob.Ref) (sb blob.SizedRef, err error)

func WaitForBlob 

func WaitForBlob(storage interface{}, deadline time.Time, blobs []blob.Ref)

WaitForBlob waits until deadline for blobs to arrive. If blobs is empty, any blobs are waited on. Otherwise, those specific blobs are waited on. When WaitForBlob returns, nothing may have happened.

Types

type BlobEnumerator 

type BlobEnumerator interface {
	// EnumerateBobs sends at most limit SizedBlobRef into dest,
	// sorted, as long as they are lexigraphically greater than
	// after (if provided).
	// limit will be supplied and sanity checked by caller.
	// EnumerateBlobs must close the channel.  (even if limit
	// was hit and more blobs remain, or an error is returned, or
	// the ctx is canceled)
	EnumerateBlobs(ctx *context.Context,
		dest chan<- blob.SizedRef,
		after string,
		limit int) error
}

type BlobHub 

type BlobHub interface {

	// NotifyBlobReceived notes that a storage target has successfully received
	// a blob and asynchronously notifies registered listeners.
	//
	// If any synchronous receive hooks are registered, they're run before
	// NotifyBlobReceived returns and their error is returned.
	NotifyBlobReceived(blob.SizedRef) error

	// AddReceiveHook adds a hook that is synchronously run
	// whenever blobs are received.  All registered hooks are run
	// on each blob upload but if more than one returns an error,
	// NotifyBlobReceived will only return one of the errors.
	AddReceiveHook(func(blob.SizedRef) error)

	RegisterListener(ch chan<- blob.Ref)
	UnregisterListener(ch chan<- blob.Ref)

	RegisterBlobListener(blob blob.Ref, ch chan<- blob.Ref)
	UnregisterBlobListener(blob blob.Ref, ch chan<- blob.Ref)
}

func GetHub 

func GetHub(storage interface{}) BlobHub

GetHub return a BlobHub for the given storage implementation.

type BlobReceiveConfiger 

type BlobReceiveConfiger interface {
	BlobReceiver
	Configer
}

type BlobReceiver 

type BlobReceiver interface {
	// ReceiveBlob accepts a newly uploaded blob and writes it to
	// permanent storage.
	//
	// Implementations of BlobReceiver downstream of the HTTP
	// server can trust that the source isn't larger than
	// MaxBlobSize and that its digest matches the provided blob
	// ref. (If not, the read of the source will fail before EOF)
	//
	// To ensure those guarantees, callers of ReceiveBlob should
	// not call ReceiveBlob directly but instead use either
	// blobserver.Receive or blobserver.ReceiveString, which also
	// take care of notifying the BlobReceiver's "BlobHub"
	// notification bus for observers.
	ReceiveBlob(br blob.Ref, source io.Reader) (blob.SizedRef, error)
}

BlobReceiver is the interface for receiving

type BlobRemover 

type BlobRemover interface {
	// RemoveBlobs removes 0 or more blobs.  Removal of
	// non-existent items isn't an error.  Returns failure if any
	// items existed but failed to be deleted.
	// ErrNotImplemented may be returned for storage types not implementing removal.
	RemoveBlobs(blobs []blob.Ref) error
}

type BlobStatter 

type BlobStatter interface {
	// Stat checks for the existence of blobs, writing their sizes
	// (if found back to the dest channel), and returning an error
	// or nil.  Stat() should NOT close the channel.
	// TODO(bradfitz): redefine this to close the channel? Or document
	// better what the synchronization rules are.
	StatBlobs(dest chan<- blob.SizedRef, blobs []blob.Ref) error
}

type BlobStreamer 

type BlobStreamer interface {
	// StreamBlobs sends blobs to dest in unspecified order. It is
	// expected that a blobstorage implementing BlobStreamer will
	// send blobs to dest in the most efficient order
	// possible. StreamBlobs will stop sending blobs to dest and
	// return an opaque continuation token (in the string return
	// parameter) when the total size of the blobs it has sent
	// equals or exceeds limit. A succeeding call to StreamBlobs
	// should pass the string returned from the previous call in
	// contToken, or an empty string if the caller wishes to
	// receive blobs from "the start". StreamBlobs must
	// unconditionally close dest before returning, and it must
	// return if ctx.Done() becomes readable.
	StreamBlobs(ctx *context.Context, dest chan<- blob.Blob, contToken string, limitBytes int64) (nextContinueToken string, err error)
}

type Cache 

type Cache interface {
	blob.SeekFetcher
	BlobReceiver
	BlobStatter
}

Cache is the minimal interface expected of a blob cache.

type Config 

type Config struct {
	Writable    bool
	Readable    bool
	Deletable   bool
	CanLongPoll bool

	// the "http://host:port" and optional path (but without trailing slash) to have "/camli/*" appended
	URLBase       string
	HandlerFinder FindHandlerByTyper
}

type Configer 

type Configer interface {
	Config() *Config
}

type FetcherEnumerator 

type FetcherEnumerator interface {
	blob.StreamingFetcher
	BlobEnumerator
}

type FindHandlerByTyper 

type FindHandlerByTyper interface {
	// FindHandlerByType finds a handler by its handlerType and
	// returns its prefix and handler if it's loaded.  If it's not
	// loaded, the error will be ErrHandlerTypeNotFound.
	//
	// This is used by handlers to find siblings (such as the "ui" type handler)
	// which might have more knowledge about the configuration for discovery, etc.
	//
	// Note that if this is called during handler construction
	// time, only the prefix may be returned with a nil handler
	// and nil err.  Unlike GetHandler and GetStorage, this does
	// not cause the prefix to load immediately. At runtime (after
	// construction of all handlers), then prefix and handler will
	// both be non-nil when err is nil.
	FindHandlerByType(handlerType string) (prefix string, handler interface{}, err error)
}

type GenerationNotSupportedError 

type GenerationNotSupportedError string

A GenerationNotSupportedError explains why a Storage value implemented the Generationer interface but failed due to a wrapped Storage value not implementing the interface.

func (GenerationNotSupportedError) Error 

func (s GenerationNotSupportedError) Error() string

type Generationer 

type Generationer interface {
	// Generation returns a Storage's initialization time and
	// and unique random string (or UUID).  Implementations
	// should call ResetStorageGeneration on demand if no
	// information is known.
	// The error will be of type GenerationNotSupportedError if an underlying
	// storage target doesn't support the Generationer interface.
	StorageGeneration() (initTime time.Time, random string, err error)

	// ResetGeneration deletes the information returned by Generation
	// and re-generates it.
	ResetStorageGeneration() error
}

The optional Generationer interface is an optimization and paranoia facility for clients which can be implemented by Storage implementations.

If the client sees the same random string in multiple upload sessions, it assumes that the blobserver still has all the same blobs, and also it's the same server. This mechanism is not fundamental to Camlistore's operation: the client could also check each blob before uploading, or enumerate all blobs from the server too. This is purely an optimization so clients can mix this value into their "is this file uploaded?" local cache keys.

type HandlerConstructor 

type HandlerConstructor func(Loader, jsonconfig.Obj) (http.Handler, error)

A HandlerConstructor returns an http.Handler from a Loader environment and a configuration.

type HandlerIniter 

type HandlerIniter interface {
	InitHandler(FindHandlerByTyper) error
}

HandlerIniter is an optional interface which can be implemented by Storage or http.Handlers (from StorageConstructor or HandlerConstructor) to be called once all the handlers have been created.

type Loader 

type Loader interface {
	FindHandlerByTyper

	// MyPrefix returns the prefix of the handler currently being constructed.
	MyPrefix() string

	// GetHandlerType returns the handler's configured type, but does
	// not force it to start being loaded yet.
	GetHandlerType(prefix string) string // returns "" if unknown

	// GetHandler returns either a Storage or an http.Handler.
	// It forces the handler to be loaded and returns an error if
	// a cycle is created.
	GetHandler(prefix string) (interface{}, error)

	// GetStorage is like GetHandler but requires that the Handler be
	// a storage Handler.
	GetStorage(prefix string) (Storage, error)
}

type MaxEnumerateConfig 

type MaxEnumerateConfig interface {
	Storage

	// MaxEnumerate returns the max that this storage interface is
	// capable of enumerating at once.
	MaxEnumerate() int
}

MaxEnumerateConfig is an optional interface implemented by Storage interfaces to advertise their max value for how many items can be enumerated at once.

type NoImplStorage 

type NoImplStorage struct{}

NoImplStorage is an implementation of Storage that returns a not implemented error for all operations.

func (*NoImplStorage) EnumerateBlobs 

func (nis *NoImplStorage) EnumerateBlobs(ctx *context.Context, dest chan<- blob.SizedRef, after string, limit int) error

func (*NoImplStorage) Fetch 

func (nis *NoImplStorage) Fetch(blob.Ref) (file types.ReadSeekCloser, size int64, err error)

func (*NoImplStorage) FetchStreaming 

func (nis *NoImplStorage) FetchStreaming(blob.Ref) (file io.ReadCloser, size int64, err error)

func (*NoImplStorage) ReceiveBlob 

func (nis *NoImplStorage) ReceiveBlob(blob.Ref, io.Reader) (sb blob.SizedRef, err error)

func (*NoImplStorage) RemoveBlobs 

func (nis *NoImplStorage) RemoveBlobs(blobs []blob.Ref) error

func (*NoImplStorage) StatBlobs 

func (nis *NoImplStorage) StatBlobs(dest chan<- blob.SizedRef, blobs []blob.Ref) error

type ShutdownStorage 

type ShutdownStorage interface {
	Storage
	io.Closer
}

Optional interface for storage implementations which can be asked to shut down cleanly. Regardless, all implementations should be able to survive crashes without data loss.

type StatReceiver 

type StatReceiver interface {
	BlobReceiver
	BlobStatter
}

type Storage 

type Storage interface {
	blob.StreamingFetcher
	BlobReceiver
	BlobStatter
	BlobEnumerator
	BlobRemover
}

Storage is the interface that must be implemented by a blobserver storage type. (e.g. localdisk, s3, encrypt, shard, replica, remote)

func CreateStorage 

func CreateStorage(typ string, loader Loader, config jsonconfig.Obj) (Storage, error)

type StorageConfiger 

type StorageConfiger interface {
	Storage
	Configer
}

type StorageConstructor 

type StorageConstructor func(Loader, jsonconfig.Obj) (Storage, error)

A StorageConstructor returns a Storage implementation from a Loader environment and a configuration.

type StorageHandler 

type StorageHandler interface {
	Storage
	http.Handler
}

StorageHandler is a storage implementation that also exports an HTTP status page.

Source Files

View all Source files

Directories

Path Synopsis
Package cond registers the "cond" conditional blobserver storage type to select routing of get/put operations on blobs to other storage targets as a function of their content.
 Package cond registers the "cond" conditional blobserver storage type to select routing of get/put operations on blobs to other storage targets as a function of their content.
Package diskpacked registers the "diskpacked" blobserver storage type, storing blobs in sequence of monolithic data files indexed by a kvfile index.
 Package diskpacked registers the "diskpacked" blobserver storage type, storing blobs in sequence of monolithic data files indexed by a kvfile index.
Package encrypt registers the "encrypt" blobserver storage type which stores all blobs and metadata with AES encryption into other wrapped storage targets (e.g.
 Package encrypt registers the "encrypt" blobserver storage type which stores all blobs and metadata with AES encryption into other wrapped storage targets (e.g.
Package gethandler implements the HTTP handler for fetching blobs.
 Package gethandler implements the HTTP handler for fetching blobs.
google
cloudstorage
Package cloudstorage registers the "googlecloudstorage" blob storage type, storing blobs on Google Cloud Storage (not Google Drive).
 Package cloudstorage registers the "googlecloudstorage" blob storage type, storing blobs on Google Cloud Storage (not Google Drive).
drive
Package drive registers the "googledrive" blobserver storage type, storing blobs in a Google Drive folder.
 Package drive registers the "googledrive" blobserver storage type, storing blobs in a Google Drive folder.
drive/service
DriveService translates blobserver.Storage methods into Google Drive API methods.
 DriveService translates blobserver.Storage methods into Google Drive API methods.
Package handlers implements the HTTP interface to the Camlistore blob server.
 Package handlers implements the HTTP interface to the Camlistore blob server.
Package local implements functionality common to both the "localdisk" and "diskpacked" storage mechanisms.
 Package local implements functionality common to both the "localdisk" and "diskpacked" storage mechanisms.
Package localdisk registers the "filesystem" blobserver storage type, storing blobs in a forest of sharded directories at the specified root.
 Package localdisk registers the "filesystem" blobserver storage type, storing blobs in a forest of sharded directories at the specified root.
Package protocol contains types for Camlistore protocol types.
 Package protocol contains types for Camlistore protocol types.
Package remote registers the "remote" blobserver storage type, storing and fetching blobs from a remote Camlistore server, speaking the HTTP protocol.
 Package remote registers the "remote" blobserver storage type, storing and fetching blobs from a remote Camlistore server, speaking the HTTP protocol.
Package replica registers the "replica" blobserver storage type, providing synchronous replication to one more backends.
 Package replica registers the "replica" blobserver storage type, providing synchronous replication to one more backends.
Package s3 registers the "s3" blobserver storage type, storing blobs in an Amazon Web Services' S3 storage bucket.
 Package s3 registers the "s3" blobserver storage type, storing blobs in an Amazon Web Services' S3 storage bucket.
Package shard registers the "shard" blobserver storage type, predictably spraying out blobs out over the provided backends based on their blobref.
 Package shard registers the "shard" blobserver storage type, predictably spraying out blobs out over the provided backends based on their blobref.
Package stats contains an in-memory StatReceiver that only stores sizes of received blobs but not their contents.
 Package stats contains an in-memory StatReceiver that only stores sizes of received blobs but not their contents.
Package storagetest tests blobserver.Storage implementations
 Package storagetest tests blobserver.Storage implementations

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