github.com/uber/kraken@v0.1.4/lib/backend/client.go (about)

     1  // Copyright (c) 2016-2019 Uber Technologies, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  package backend
    15  
    16  import (
    17  	"fmt"
    18  	"io"
    19  
    20  	"github.com/uber/kraken/core"
    21  )
    22  
    23  var _factories = make(map[string]ClientFactory)
    24  
    25  // ClientFactory creates backend client given name.
    26  type ClientFactory interface {
    27  	Create(config interface{}, authConfig interface{}) (Client, error)
    28  }
    29  
    30  // Register registers new Factory with corresponding backend client name.
    31  func Register(name string, factory ClientFactory) {
    32  	_factories[name] = factory
    33  }
    34  
    35  // getFactory returns backend client factory given client name.
    36  func getFactory(name string) (ClientFactory, error) {
    37  	factory, ok := _factories[name]
    38  	if !ok {
    39  		return nil, fmt.Errorf("no backend client defined with name %s", name)
    40  	}
    41  	return factory, nil
    42  }
    43  
    44  // Client defines an interface for accessing blobs on a remote storage backend.
    45  //
    46  // Implementations of Client must be thread-safe, since they are cached and
    47  // used concurrently by Manager.
    48  type Client interface {
    49  	// Stat returns blob info for name. All implementations should return
    50  	// backenderrors.ErrBlobNotFound when the blob was not found.
    51  	//
    52  	// Stat is useful when we need to quickly know if a blob exists (and maybe
    53  	// some basic information about it), without downloading the entire blob,
    54  	// which may be very large.
    55  	Stat(namespace, name string) (*core.BlobInfo, error)
    56  
    57  	// Upload uploads src into name.
    58  	Upload(namespace, name string, src io.Reader) error
    59  
    60  	// Download downloads name into dst. All implementations should return
    61  	// backenderrors.ErrBlobNotFound when the blob was not found.
    62  	Download(namespace, name string, dst io.Writer) error
    63  
    64  	// List lists entries whose names start with prefix.
    65  	List(prefix string, opts ...ListOption) (*ListResult, error)
    66  }