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batcher_list.go
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/
batcher_list.go
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// Copyright (c) 2022 Gobalsky Labs Limited
//
// Use of this software is governed by the Business Source License included
// in the LICENSE.DATANODE file and at https://www.mariadb.com/bsl11.
//
// Change Date: 18 months from the later of the date of the first publicly
// available Distribution of this version of the repository, and 25 June 2022.
//
// On the date above, in accordance with the Business Source License, use
// of this software will be governed by version 3 or later of the GNU General
// Public License.
package sqlstore
import (
"context"
"fmt"
"github.com/jackc/pgx/v4"
)
type ListBatcher[T simpleEntity] struct {
pending []T
tableName string
columnNames []string
}
func NewListBatcher[T simpleEntity](tableName string, columnNames []string) ListBatcher[T] {
return ListBatcher[T]{
tableName: tableName,
columnNames: columnNames,
pending: make([]T, 0, 1000),
}
}
type simpleEntity interface {
ToRow() []interface{}
}
func (b *ListBatcher[T]) Add(entity T) {
b.pending = append(b.pending, entity)
}
func (b *ListBatcher[T]) Flush(ctx context.Context, connection Connection) ([]T, error) {
rows := make([][]interface{}, len(b.pending))
for i := 0; i < len(b.pending); i++ {
rows[i] = b.pending[i].ToRow()
}
copyCount, err := connection.CopyFrom(
ctx,
pgx.Identifier{b.tableName},
b.columnNames,
pgx.CopyFromRows(rows),
)
if err != nil {
return nil, fmt.Errorf("failed to copy %s entries into database:%w", b.tableName, err)
}
if copyCount != int64(len(b.pending)) {
return nil, fmt.Errorf("copied %d %s rows into the database, expected to copy %d",
copyCount,
b.tableName,
len(b.pending))
}
flushed := b.pending
b.pending = b.pending[:0]
return flushed, nil
}