/
memo.go
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/
memo.go
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// Copyright 2023 The Cockroach Authors
//
// 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.
//
// SPDX-License-Identifier: Apache-2.0
// Package memo implements a simple kv store with string keys.
package memo
import (
"context"
"github.com/cockroachdb/cdc-sink/internal/types"
"github.com/cockroachdb/cdc-sink/internal/util/retry"
"github.com/jackc/pgx/v5"
"github.com/pkg/errors"
)
// Memo is a key store that persists a value associated to a key.
type Memo struct {
stagingPool *types.StagingPool
sql struct {
get string
update string
}
}
var _ types.Memo = (*Memo)(nil)
const (
schema = `
CREATE TABLE IF NOT EXISTS %[1]s (
key STRING NOT NULL PRIMARY KEY,
value BYTES NOT NULL
)`
updateTemplate = `UPSERT INTO %[1]s (key, value) VALUES ($1, $2)`
getTemplate = `SELECT value FROM %[1]s WHERE key = $1`
)
// Get retrieves a value given a key or nil if it does not exist.
func (m *Memo) Get(ctx context.Context, tx types.StagingQuerier, key string) ([]byte, error) {
var ret []byte
err := retry.Retry(ctx, m.stagingPool, func(ctx context.Context) error {
err := tx.QueryRow(
ctx,
m.sql.get,
key,
).Scan(&ret)
return errors.WithStack(err)
})
if errors.Is(err, pgx.ErrNoRows) {
err = nil
}
return ret, err
}
// Put stores the key-value in the target database
func (m *Memo) Put(ctx context.Context, tx types.StagingQuerier, key string, value []byte) error {
return retry.Retry(ctx, m.stagingPool, func(ctx context.Context) error {
_, err := tx.Exec(
ctx,
m.sql.update,
key,
value,
)
return err
})
}