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- /*
- Copyright 2016 Google LLC
-
- Licensed under the Apache License, Version 2.0 (the "License");
- you may not use this file except in compliance with the License.
- You may obtain a copy of the License at
-
- http://www.apache.org/licenses/LICENSE-2.0
-
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS,
- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- See the License for the specific language governing permissions and
- limitations under the License.
- */
-
- package bigtable
-
- import (
- "bytes"
- "fmt"
-
- btpb "google.golang.org/genproto/googleapis/bigtable/v2"
- )
-
- // A Row is returned by ReadRows. The map is keyed by column family (the prefix
- // of the column name before the colon). The values are the returned ReadItems
- // for that column family in the order returned by Read.
- type Row map[string][]ReadItem
-
- // Key returns the row's key, or "" if the row is empty.
- func (r Row) Key() string {
- for _, items := range r {
- if len(items) > 0 {
- return items[0].Row
- }
- }
- return ""
- }
-
- // A ReadItem is returned by Read. A ReadItem contains data from a specific row and column.
- type ReadItem struct {
- Row, Column string
- Timestamp Timestamp
- Value []byte
- }
-
- // The current state of the read rows state machine.
- type rrState int64
-
- const (
- newRow rrState = iota
- rowInProgress
- cellInProgress
- )
-
- // chunkReader handles cell chunks from the read rows response and combines
- // them into full Rows.
- type chunkReader struct {
- state rrState
- curKey []byte
- curFam string
- curQual []byte
- curTS int64
- curVal []byte
- curRow Row
- lastKey string
- }
-
- // newChunkReader returns a new chunkReader for handling read rows responses.
- func newChunkReader() *chunkReader {
- return &chunkReader{state: newRow}
- }
-
- // Process takes a cell chunk and returns a new Row if the given chunk
- // completes a Row, or nil otherwise.
- func (cr *chunkReader) Process(cc *btpb.ReadRowsResponse_CellChunk) (Row, error) {
- var row Row
- switch cr.state {
- case newRow:
- if err := cr.validateNewRow(cc); err != nil {
- return nil, err
- }
-
- cr.curRow = make(Row)
- cr.curKey = cc.RowKey
- cr.curFam = cc.FamilyName.Value
- cr.curQual = cc.Qualifier.Value
- cr.curTS = cc.TimestampMicros
- row = cr.handleCellValue(cc)
-
- case rowInProgress:
- if err := cr.validateRowInProgress(cc); err != nil {
- return nil, err
- }
-
- if cc.GetResetRow() {
- cr.resetToNewRow()
- return nil, nil
- }
-
- if cc.FamilyName != nil {
- cr.curFam = cc.FamilyName.Value
- }
- if cc.Qualifier != nil {
- cr.curQual = cc.Qualifier.Value
- }
- cr.curTS = cc.TimestampMicros
- row = cr.handleCellValue(cc)
-
- case cellInProgress:
- if err := cr.validateCellInProgress(cc); err != nil {
- return nil, err
- }
- if cc.GetResetRow() {
- cr.resetToNewRow()
- return nil, nil
- }
- row = cr.handleCellValue(cc)
- }
-
- return row, nil
- }
-
- // Close must be called after all cell chunks from the response
- // have been processed. An error will be returned if the reader is
- // in an invalid state, in which case the error should be propagated to the caller.
- func (cr *chunkReader) Close() error {
- if cr.state != newRow {
- return fmt.Errorf("invalid state for end of stream %q", cr.state)
- }
- return nil
- }
-
- // handleCellValue returns a Row if the cell value includes a commit, otherwise nil.
- func (cr *chunkReader) handleCellValue(cc *btpb.ReadRowsResponse_CellChunk) Row {
- if cc.ValueSize > 0 {
- // ValueSize is specified so expect a split value of ValueSize bytes
- if cr.curVal == nil {
- cr.curVal = make([]byte, 0, cc.ValueSize)
- }
- cr.curVal = append(cr.curVal, cc.Value...)
- cr.state = cellInProgress
- } else {
- // This cell is either the complete value or the last chunk of a split
- if cr.curVal == nil {
- cr.curVal = cc.Value
- } else {
- cr.curVal = append(cr.curVal, cc.Value...)
- }
- cr.finishCell()
-
- if cc.GetCommitRow() {
- return cr.commitRow()
- }
- cr.state = rowInProgress
- }
-
- return nil
- }
-
- func (cr *chunkReader) finishCell() {
- ri := ReadItem{
- Row: string(cr.curKey),
- Column: string(cr.curFam) + ":" + string(cr.curQual),
- Timestamp: Timestamp(cr.curTS),
- Value: cr.curVal,
- }
- cr.curRow[cr.curFam] = append(cr.curRow[cr.curFam], ri)
- cr.curVal = nil
- }
-
- func (cr *chunkReader) commitRow() Row {
- row := cr.curRow
- cr.lastKey = cr.curRow.Key()
- cr.resetToNewRow()
- return row
- }
-
- func (cr *chunkReader) resetToNewRow() {
- cr.curKey = nil
- cr.curFam = ""
- cr.curQual = nil
- cr.curVal = nil
- cr.curRow = nil
- cr.curTS = 0
- cr.state = newRow
- }
-
- func (cr *chunkReader) validateNewRow(cc *btpb.ReadRowsResponse_CellChunk) error {
- if cc.GetResetRow() {
- return fmt.Errorf("reset_row not allowed between rows")
- }
- if cc.RowKey == nil || cc.FamilyName == nil || cc.Qualifier == nil {
- return fmt.Errorf("missing key field for new row %v", cc)
- }
- if cr.lastKey != "" && cr.lastKey >= string(cc.RowKey) {
- return fmt.Errorf("out of order row key: %q, %q", cr.lastKey, string(cc.RowKey))
- }
- return nil
- }
-
- func (cr *chunkReader) validateRowInProgress(cc *btpb.ReadRowsResponse_CellChunk) error {
- if err := cr.validateRowStatus(cc); err != nil {
- return err
- }
- if cc.RowKey != nil && !bytes.Equal(cc.RowKey, cr.curKey) {
- return fmt.Errorf("received new row key %q during existing row %q", cc.RowKey, cr.curKey)
- }
- if cc.FamilyName != nil && cc.Qualifier == nil {
- return fmt.Errorf("family name %q specified without a qualifier", cc.FamilyName)
- }
- return nil
- }
-
- func (cr *chunkReader) validateCellInProgress(cc *btpb.ReadRowsResponse_CellChunk) error {
- if err := cr.validateRowStatus(cc); err != nil {
- return err
- }
- if cr.curVal == nil {
- return fmt.Errorf("no cached cell while CELL_IN_PROGRESS %v", cc)
- }
- if cc.GetResetRow() == false && cr.isAnyKeyPresent(cc) {
- return fmt.Errorf("cell key components found while CELL_IN_PROGRESS %v", cc)
- }
- return nil
- }
-
- func (cr *chunkReader) isAnyKeyPresent(cc *btpb.ReadRowsResponse_CellChunk) bool {
- return cc.RowKey != nil ||
- cc.FamilyName != nil ||
- cc.Qualifier != nil ||
- cc.TimestampMicros != 0
- }
-
- // Validate a RowStatus, commit or reset, if present.
- func (cr *chunkReader) validateRowStatus(cc *btpb.ReadRowsResponse_CellChunk) error {
- // Resets can't be specified with any other part of a cell
- if cc.GetResetRow() && (cr.isAnyKeyPresent(cc) ||
- cc.Value != nil ||
- cc.ValueSize != 0 ||
- cc.Labels != nil) {
- return fmt.Errorf("reset must not be specified with other fields %v", cc)
- }
- if cc.GetCommitRow() && cc.ValueSize > 0 {
- return fmt.Errorf("commit row found in between chunks in a cell")
- }
- return nil
- }
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