github.com/hasnat/dolt/go@v0.0.0-20210628190320-9eb5d843fbb7/libraries/doltcore/table/pk_reader.go (about)

     1  // Copyright 2020 Dolthub, 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  
    15  package table
    16  
    17  import (
    18  	"context"
    19  	"io"
    20  
    21  	"github.com/dolthub/go-mysql-server/sql"
    22  
    23  	"github.com/dolthub/dolt/go/libraries/doltcore/doltdb"
    24  	"github.com/dolthub/dolt/go/libraries/doltcore/row"
    25  	"github.com/dolthub/dolt/go/libraries/doltcore/schema"
    26  	"github.com/dolthub/dolt/go/libraries/doltcore/table/typed/noms"
    27  	"github.com/dolthub/dolt/go/store/types"
    28  )
    29  
    30  type pkTableReader struct {
    31  	iter types.MapIterator
    32  	sch  schema.Schema
    33  }
    34  
    35  var _ SqlTableReader = pkTableReader{}
    36  var _ TableReadCloser = pkTableReader{}
    37  
    38  // GetSchema implements the TableReader interface.
    39  func (rdr pkTableReader) GetSchema() schema.Schema {
    40  	return rdr.sch
    41  }
    42  
    43  // ReadRow implements the TableReader interface.
    44  func (rdr pkTableReader) ReadRow(ctx context.Context) (row.Row, error) {
    45  	key, val, err := rdr.iter.Next(ctx)
    46  
    47  	if err != nil {
    48  		return nil, err
    49  	} else if key == nil {
    50  		return nil, io.EOF
    51  	}
    52  
    53  	return row.FromNoms(rdr.sch, key.(types.Tuple), val.(types.Tuple))
    54  }
    55  
    56  // ReadSqlRow implements the SqlTableReader interface.
    57  func (rdr pkTableReader) ReadSqlRow(ctx context.Context) (sql.Row, error) {
    58  	key, val, err := rdr.iter.Next(ctx)
    59  
    60  	if err != nil {
    61  		return nil, err
    62  	} else if key == nil {
    63  		return nil, io.EOF
    64  	}
    65  
    66  	return noms.SqlRowFromTuples(rdr.sch, key.(types.Tuple), val.(types.Tuple))
    67  }
    68  
    69  // Close implements the TableReadCloser interface.
    70  func (rdr pkTableReader) Close(_ context.Context) error {
    71  	return nil
    72  }
    73  
    74  func newPkTableReader(ctx context.Context, tbl *doltdb.Table, sch schema.Schema, buffered bool) (pkTableReader, error) {
    75  	rows, err := tbl.GetRowData(ctx)
    76  	if err != nil {
    77  		return pkTableReader{}, err
    78  	}
    79  
    80  	return newPkTableReaderForRows(ctx, rows, sch, buffered)
    81  }
    82  
    83  func newPkTableReaderForRows(ctx context.Context, rows types.Map, sch schema.Schema, buffered bool) (pkTableReader, error) {
    84  	var err error
    85  	var iter types.MapIterator
    86  	if buffered {
    87  		iter, err = rows.Iterator(ctx)
    88  	} else {
    89  		iter, err = rows.BufferedIterator(ctx)
    90  	}
    91  	if err != nil {
    92  		return pkTableReader{}, err
    93  	}
    94  
    95  	return pkTableReader{
    96  		iter: iter,
    97  		sch:  sch,
    98  	}, nil
    99  }
   100  
   101  func newPkTableReaderFrom(ctx context.Context, tbl *doltdb.Table, sch schema.Schema, val types.Value) (SqlTableReader, error) {
   102  	rows, err := tbl.GetRowData(ctx)
   103  	if err != nil {
   104  		return nil, err
   105  	}
   106  
   107  	iter, err := rows.IteratorFrom(ctx, val)
   108  	if err != nil {
   109  		return nil, err
   110  	}
   111  
   112  	return pkTableReader{
   113  		iter: iter,
   114  		sch:  sch,
   115  	}, nil
   116  }
   117  
   118  type partitionTableReader struct {
   119  	SqlTableReader
   120  	remaining uint64
   121  }
   122  
   123  var _ SqlTableReader = &partitionTableReader{}
   124  
   125  func newPkTableReaderForPartition(ctx context.Context, tbl *doltdb.Table, sch schema.Schema, start, end uint64) (SqlTableReader, error) {
   126  	rows, err := tbl.GetRowData(ctx)
   127  	if err != nil {
   128  		return nil, err
   129  	}
   130  
   131  	iter, err := rows.BufferedIteratorAt(ctx, start)
   132  	if err != nil {
   133  		return nil, err
   134  	}
   135  
   136  	return &partitionTableReader{
   137  		SqlTableReader: pkTableReader{
   138  			iter: iter,
   139  			sch:  sch,
   140  		},
   141  		remaining: end - start,
   142  	}, nil
   143  }
   144  
   145  // ReadSqlRow implements the SqlTableReader interface.
   146  func (rdr *partitionTableReader) ReadSqlRow(ctx context.Context) (sql.Row, error) {
   147  	if rdr.remaining == 0 {
   148  		return nil, io.EOF
   149  	}
   150  	rdr.remaining -= 1
   151  
   152  	return rdr.SqlTableReader.ReadSqlRow(ctx)
   153  }