53 lines
1.3 KiB
Go
53 lines
1.3 KiB
Go
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// Copyright 2018 New Vector Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package storage
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import (
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"context"
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"database/sql"
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)
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const txnIDSchema = `
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-- Keeps a count of the current transaction ID
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CREATE SEQUENCE IF NOT EXISTS txn_id_counter START 1;
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`
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const selectTxnIDSQL = "SELECT nextval('txn_id_counter')"
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type txnStatements struct {
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selectTxnIDStmt *sql.Stmt
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}
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func (s *txnStatements) prepare(db *sql.DB) (err error) {
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_, err = db.Exec(txnIDSchema)
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if err != nil {
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return
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}
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if s.selectTxnIDStmt, err = db.Prepare(selectTxnIDSQL); err != nil {
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return
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}
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return
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}
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// selectTxnID selects the latest ascending transaction ID
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func (s *txnStatements) selectTxnID(
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ctx context.Context,
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) (txnID int, err error) {
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err = s.selectTxnIDStmt.QueryRowContext(ctx).Scan(&txnID)
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return
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}
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