110 lines
3.1 KiB
Go
110 lines
3.1 KiB
Go
// Copyright 2020 The Matrix.org Foundation C.I.C.
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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 sqlutil
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import (
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"database/sql"
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"errors"
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"fmt"
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"runtime"
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)
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// ErrUserExists is returned if a username already exists in the database.
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var ErrUserExists = errors.New("Username already exists")
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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()
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} else {
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return txn.Rollback()
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}
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}
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// EndTransactionWithCheck ends a transaction and overwrites the error pointer if its value was nil.
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// If the transaction succeeded then it is committed, otherwise it is rolledback.
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// Designed to be used with defer (see EndTransaction otherwise).
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func EndTransactionWithCheck(txn Transaction, succeeded *bool, err *error) {
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if e := EndTransaction(txn, succeeded); e != nil && *err == nil {
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*err = e
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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 fmt.Errorf("sqlutil.WithTransaction.Begin: %w", err)
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}
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succeeded := false
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defer EndTransactionWithCheck(txn, &succeeded, &err)
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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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// 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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func SQLiteDriverName() string {
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if runtime.GOOS == "js" {
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return "sqlite3_js"
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}
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return "sqlite3"
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}
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