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Signed-off-by: Derek Trider <[email protected]>
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Derek Trider
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Feb 19, 2020
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,204 @@ | ||
| /* | ||
| Copyright SecureKey Technologies Inc. All Rights Reserved. | ||
| SPDX-License-Identifier: Apache-2.0 | ||
| */ | ||
|
|
||
| package couchdbstore | ||
|
|
||
| import ( | ||
| "context" | ||
| "encoding/base64" | ||
| "encoding/json" | ||
| "errors" | ||
| "fmt" | ||
| "io/ioutil" | ||
| "sync" | ||
|
|
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| _ "github.com/go-kivik/couchdb" // The CouchDB driver | ||
| "github.com/go-kivik/kivik" | ||
|
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| "github.com/trustbloc/edge-core/pkg/storage" | ||
| ) | ||
|
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| // Provider represents an CouchDB implementation of the storage.Provider interface | ||
| type Provider struct { | ||
| hostURL string | ||
| couchDBClient *kivik.Client | ||
| dbs map[string]*CouchDBStore | ||
| mux sync.RWMutex | ||
| } | ||
|
|
||
| const ( | ||
| blankHostErrMsg = "hostURL for new CouchDB provider can't be blank" | ||
| failToCloseProviderErrMsg = "failed to close provider" | ||
| ) | ||
|
|
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| // NewProvider instantiates Provider | ||
| func NewProvider(hostURL string) (*Provider, error) { | ||
| if hostURL == "" { | ||
| return nil, errors.New(blankHostErrMsg) | ||
| } | ||
|
|
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| client, err := kivik.New("couch", hostURL) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
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| return &Provider{hostURL: hostURL, couchDBClient: client, dbs: map[string]*CouchDBStore{}}, nil | ||
| } | ||
|
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| // CreateStore creates a new store with the given name. | ||
| func (p *Provider) CreateStore(name string) error { | ||
| p.mux.Lock() | ||
| defer p.mux.Unlock() | ||
|
|
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| err := p.couchDBClient.CreateDB(context.Background(), name) | ||
|
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| return err | ||
| } | ||
|
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| // OpenStore opens an existing store with the given name and returns it. | ||
| func (p *Provider) OpenStore(name string) (storage.Store, error) { | ||
| p.mux.Lock() | ||
| defer p.mux.Unlock() | ||
|
|
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| // Check cache first | ||
| cachedStore, existsInCache := p.dbs[name] | ||
| if existsInCache { | ||
| return cachedStore, nil | ||
| } | ||
|
|
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| // If it's not in the cache, then let's ask the CouchDB server if it exists | ||
| existsOnServer, err := p.couchDBClient.DBExists(context.Background(), name) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| if !existsOnServer { | ||
| return nil, storage.ErrStoreNotFound | ||
| } | ||
|
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| db := p.couchDBClient.DB(context.Background(), name) | ||
|
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| // db.Err() won't return an error if the database doesn't exist, hence the need for the explicit DBExists call above | ||
| if dbErr := db.Err(); dbErr != nil { | ||
| return nil, dbErr | ||
| } | ||
|
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| store := &CouchDBStore{db: db} | ||
|
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| p.dbs[name] = store | ||
|
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| return store, nil | ||
| } | ||
|
|
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| // CloseStore closes a previously opened store. | ||
| func (p *Provider) CloseStore(name string) error { | ||
| p.mux.Lock() | ||
| defer p.mux.Unlock() | ||
|
|
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| store, exists := p.dbs[name] | ||
| if !exists { | ||
| return storage.ErrStoreNotFound | ||
| } | ||
|
|
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| delete(p.dbs, name) | ||
|
|
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| return store.db.Close(context.Background()) | ||
| } | ||
|
|
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| // Close closes the provider. | ||
| func (p *Provider) Close() error { | ||
| p.mux.Lock() | ||
| defer p.mux.Unlock() | ||
|
|
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| for _, store := range p.dbs { | ||
| err := store.db.Close(context.Background()) | ||
| if err != nil { | ||
| return fmt.Errorf(failToCloseProviderErrMsg+": %w", err) | ||
| } | ||
| } | ||
|
|
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| return p.couchDBClient.Close(context.Background()) | ||
| } | ||
|
|
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| // CouchDBStore represents a CouchDB-backed database. | ||
| type CouchDBStore struct { | ||
| db *kivik.DB | ||
| } | ||
|
|
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| // Put stores the given key-value pair in the store. | ||
| func (c *CouchDBStore) Put(k string, v []byte) error { | ||
| var valueToPut []byte | ||
| if isJSON(v) { | ||
| valueToPut = v | ||
| } else { | ||
| valueToPut = wrapTextAsCouchDBAttachment(v) | ||
| } | ||
|
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| _, err := c.db.Put(context.Background(), k, valueToPut) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
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| return nil | ||
| } | ||
|
|
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| func isJSON(textToCheck []byte) bool { | ||
| var js json.RawMessage | ||
| return json.Unmarshal(textToCheck, &js) == nil | ||
| } | ||
|
|
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| // Kivik has a PutAttachment method, but it requires creating a document first and then adding an attachment after. | ||
| // We want to do it all in one step, hence this manual stuff below. | ||
| func wrapTextAsCouchDBAttachment(textToWrap []byte) []byte { | ||
| encodedTextToWrap := base64.StdEncoding.EncodeToString(textToWrap) | ||
| return []byte(`{"_attachments": {"data": {"data": "` + encodedTextToWrap + `", "content_type": "text/plain"}}}`) | ||
| } | ||
|
|
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| // Get retrieves the value in the store associated with the given key. | ||
| func (c *CouchDBStore) Get(k string) ([]byte, error) { | ||
| destinationData := make(map[string]interface{}) | ||
|
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| row := c.db.Get(context.Background(), k) | ||
|
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| err := row.ScanDoc(&destinationData) | ||
| if err != nil { | ||
| if err.Error() == "Not Found: missing" { | ||
| return nil, storage.ErrValueNotFound | ||
| } | ||
|
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| return nil, err | ||
| } | ||
|
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| _, containsAttachment := destinationData["_attachments"] | ||
| if containsAttachment { | ||
| return c.getDataFromAttachment(k) | ||
| } | ||
|
|
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| // Stripping out the CouchDB-specific fields | ||
| delete(destinationData, "_id") | ||
| delete(destinationData, "_rev") | ||
|
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| strippedJSON, err := json.Marshal(destinationData) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
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| return strippedJSON, nil | ||
| } | ||
|
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| func (c *CouchDBStore) getDataFromAttachment(k string) ([]byte, error) { | ||
| // Original data was not JSON and so it was stored as an attachment | ||
| attachment, err := c.db.GetAttachment(context.Background(), k, "data") | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
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| data, err := ioutil.ReadAll(attachment.Content) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
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| return data, nil | ||
| } |
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