Don Newton | 379ae25 | 2019-04-01 12:17:06 -0400 | [diff] [blame^] | 1 | package driver |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "errors" |
| 6 | "strings" |
| 7 | |
| 8 | "github.com/mongodb/mongo-go-driver/x/bsonx/bsoncore" |
| 9 | ) |
| 10 | |
| 11 | // ListCollectionsBatchCursor is a special batch cursor returned from ListCollections that properly |
| 12 | // handles current and legacy ListCollections operations. |
| 13 | type ListCollectionsBatchCursor struct { |
| 14 | legacy bool |
| 15 | bc *BatchCursor |
| 16 | currentBatch []byte |
| 17 | err error |
| 18 | } |
| 19 | |
| 20 | // NewListCollectionsBatchCursor creates a new non-legacy ListCollectionsCursor. |
| 21 | func NewListCollectionsBatchCursor(bc *BatchCursor) (*ListCollectionsBatchCursor, error) { |
| 22 | if bc == nil { |
| 23 | return nil, errors.New("batch cursor must not be nil") |
| 24 | } |
| 25 | return &ListCollectionsBatchCursor{bc: bc}, nil |
| 26 | } |
| 27 | |
| 28 | // NewLegacyListCollectionsBatchCursor creates a new legacy ListCollectionsCursor. |
| 29 | func NewLegacyListCollectionsBatchCursor(bc *BatchCursor) (*ListCollectionsBatchCursor, error) { |
| 30 | if bc == nil { |
| 31 | return nil, errors.New("batch cursor must not be nil") |
| 32 | } |
| 33 | return &ListCollectionsBatchCursor{legacy: true, bc: bc}, nil |
| 34 | } |
| 35 | |
| 36 | // ID returns the cursor ID for this batch cursor. |
| 37 | func (lcbc *ListCollectionsBatchCursor) ID() int64 { |
| 38 | return lcbc.bc.ID() |
| 39 | } |
| 40 | |
| 41 | // Next indicates if there is another batch available. Returning false does not necessarily indicate |
| 42 | // that the cursor is closed. This method will return false when an empty batch is returned. |
| 43 | // |
| 44 | // If Next returns true, there is a valid batch of documents available. If Next returns false, there |
| 45 | // is not a valid batch of documents available. |
| 46 | func (lcbc *ListCollectionsBatchCursor) Next(ctx context.Context) bool { |
| 47 | if !lcbc.bc.Next(ctx) { |
| 48 | return false |
| 49 | } |
| 50 | |
| 51 | if !lcbc.legacy { |
| 52 | lcbc.currentBatch = lcbc.bc.currentBatch |
| 53 | return true |
| 54 | } |
| 55 | |
| 56 | batch := lcbc.bc.currentBatch |
| 57 | lcbc.currentBatch = lcbc.currentBatch[:0] |
| 58 | var doc bsoncore.Document |
| 59 | var ok bool |
| 60 | for { |
| 61 | doc, batch, ok = bsoncore.ReadDocument(batch) |
| 62 | if !ok { |
| 63 | break |
| 64 | } |
| 65 | |
| 66 | doc, lcbc.err = lcbc.projectNameElement(doc) |
| 67 | if lcbc.err != nil { |
| 68 | return false |
| 69 | } |
| 70 | lcbc.currentBatch = append(lcbc.currentBatch, doc...) |
| 71 | } |
| 72 | |
| 73 | return true |
| 74 | } |
| 75 | |
| 76 | // Batch will append the current batch of documents to dst. RequiredBytes can be called to determine |
| 77 | // the length of the current batch of documents. |
| 78 | // |
| 79 | // If there is no batch available, this method does nothing. |
| 80 | func (lcbc *ListCollectionsBatchCursor) Batch(dst []byte) []byte { |
| 81 | return append(dst, lcbc.currentBatch...) |
| 82 | } |
| 83 | |
| 84 | // RequiredBytes returns the number of bytes required for the current batch. |
| 85 | func (lcbc *ListCollectionsBatchCursor) RequiredBytes() int { return len(lcbc.currentBatch) } |
| 86 | |
| 87 | // Err returns the latest error encountered. |
| 88 | func (lcbc *ListCollectionsBatchCursor) Err() error { |
| 89 | if lcbc.err != nil { |
| 90 | return lcbc.err |
| 91 | } |
| 92 | return lcbc.bc.Err() |
| 93 | } |
| 94 | |
| 95 | // Close closes this batch cursor. |
| 96 | func (lcbc *ListCollectionsBatchCursor) Close(ctx context.Context) error { return lcbc.bc.Close(ctx) } |
| 97 | |
| 98 | // project out the database name for a legacy server |
| 99 | func (*ListCollectionsBatchCursor) projectNameElement(rawDoc bsoncore.Document) (bsoncore.Document, error) { |
| 100 | elems, err := rawDoc.Elements() |
| 101 | if err != nil { |
| 102 | return nil, err |
| 103 | } |
| 104 | |
| 105 | var filteredElems []byte |
| 106 | for _, elem := range elems { |
| 107 | key := elem.Key() |
| 108 | if key != "name" { |
| 109 | filteredElems = append(filteredElems, elem...) |
| 110 | continue |
| 111 | } |
| 112 | |
| 113 | name := elem.Value().StringValue() |
| 114 | collName := name[strings.Index(name, ".")+1:] |
| 115 | filteredElems = bsoncore.AppendStringElement(filteredElems, "name", collName) |
| 116 | } |
| 117 | |
| 118 | var filteredDoc []byte |
| 119 | filteredDoc = bsoncore.BuildDocument(filteredDoc, filteredElems) |
| 120 | return filteredDoc, nil |
| 121 | } |