102 lines
2.8 KiB
Go
102 lines
2.8 KiB
Go
// Copyright 2017 Vector Creations 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 common
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import (
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"database/sql"
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"fmt"
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"github.com/lib/pq"
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)
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// A Transaction is something that can be committed or rolledback.
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type Transaction interface {
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// Commit the transaction
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Commit() error
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// Rollback the transaction.
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Rollback() error
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}
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// EndTransaction ends a transaction.
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// If the transaction succeeded then it is committed, otherwise it is rolledback.
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// You MUST check the error returned from this function to be sure that the transaction
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// was applied correctly. For example, 'database is locked' errors in sqlite will happen here.
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func EndTransaction(txn Transaction, succeeded *bool) error {
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if *succeeded {
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return txn.Commit() // nolint: errcheck
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} else {
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return txn.Rollback() // nolint: errcheck
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}
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}
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// WithTransaction runs a block of code passing in an SQL transaction
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// If the code returns an error or panics then the transactions is rolledback
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// Otherwise the transaction is committed.
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func WithTransaction(db *sql.DB, fn func(txn *sql.Tx) error) (err error) {
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txn, err := db.Begin()
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if err != nil {
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return
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}
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succeeded := false
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defer func() {
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err2 := EndTransaction(txn, &succeeded)
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if err == nil && err2 != nil { // failed to commit/rollback
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err = err2
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}
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}()
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err = fn(txn)
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if err != nil {
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return
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}
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succeeded = true
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return
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}
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// TxStmt wraps an SQL stmt inside an optional transaction.
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// If the transaction is nil then it returns the original statement that will
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// run outside of a transaction.
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// Otherwise returns a copy of the statement that will run inside the transaction.
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func TxStmt(transaction *sql.Tx, statement *sql.Stmt) *sql.Stmt {
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if transaction != nil {
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statement = transaction.Stmt(statement)
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}
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return statement
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}
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// IsUniqueConstraintViolationErr returns true if the error is a postgresql unique_violation error
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func IsUniqueConstraintViolationErr(err error) bool {
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pqErr, ok := err.(*pq.Error)
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return ok && pqErr.Code == "23505"
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}
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// Hack of the century
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func QueryVariadic(count int) string {
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return QueryVariadicOffset(count, 0)
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}
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func QueryVariadicOffset(count, offset int) string {
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str := "("
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for i := 0; i < count; i++ {
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str += fmt.Sprintf("$%d", i+offset+1)
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if i < (count - 1) {
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str += ", "
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}
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}
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str += ")"
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return str
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}
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