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// Copyright (C) 2019-2021 Algorand, Inc.
// This file is part of go-algorand
//
// go-algorand is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// go-algorand is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with go-algorand. If not, see <https://www.gnu.org/licenses/>.
package db
import (
"context"
"database/sql"
"errors"
"fmt"
)
// Migration is used to upgrade a database from one version to the next.
// The Migration slice is ordered and must contain all prior migrations
// in order to determine which need to be called.
type Migration func(ctx context.Context, tx *sql.Tx, newDatabase bool) error
// Initialize creates or upgrades a DB accessor in a new atomic context.
// The Migration slice is ordered and must contain all prior migrations
// in order to determine which need to be called.
func Initialize(accessor Accessor, migrations []Migration) error {
return accessor.Atomic(func(ctx context.Context, tx *sql.Tx) error {
return InitializeWithContext(ctx, tx, migrations)
})
}
// InitializeWithContext creates or upgrades a DB accessor.
func InitializeWithContext(ctx context.Context, tx *sql.Tx, migrations []Migration) error {
// check current database version
dbVersion, err := GetUserVersion(ctx, tx)
if err != nil {
return ErrUnableToRead
}
version := int32(len(migrations))
// if database version is greater than supported by current binary, write a warning. This would keep the existing
// fallback behavior where we could use an older binary iff the schema happen to be backward compatible.
if dbVersion > version {
return MakeErrUnknownVersion(dbVersion, version)
}
// if database is not up to date run migration functions.
if dbVersion < version {
var newDatabase bool
for i := dbVersion; i < version; i++ {
err = migrations[i](ctx, tx, newDatabase)
if err != nil && err != ErrNoOpMigration {
return MakeErrUpgradeFailure(dbVersion, i)
}
// Something like this is used by the account DB to conditionally skip things.
if i == 0 && err != ErrNoOpMigration {
newDatabase = true
}
// update version
_, err = SetUserVersion(ctx, tx, i+1)
if err != nil {
return MakeErrUpgradeFailure(dbVersion, i)
}
}
}
return nil
}
// ErrUnableToRead is returned when the accessor cannot be read.
var ErrUnableToRead = errors.New("unable to read database")
// ErrNoOpMigration is returned when there was no work for the migration to perform.
var ErrNoOpMigration = errors.New("migration no-op")
// ErrUnknownVersion is returned when a migration to the current version is not available.
type ErrUnknownVersion struct {
CurrentVersion int32
SupportedVersion int32
}
// Error implements the error interface.
func (err *ErrUnknownVersion) Error() string {
return fmt.Sprintf("database schema version is %d, but algod only supports up to %d", err.CurrentVersion, err.SupportedVersion)
}
// MakeErrUnknownVersion makes an ErrUnknownVersion.
func MakeErrUnknownVersion(currentVersion, supportedVersion int32) *ErrUnknownVersion {
return &ErrUnknownVersion{
CurrentVersion: currentVersion,
SupportedVersion: supportedVersion,
}
}
// ErrUpgradeFailure is returned when a migration returns an error.
type ErrUpgradeFailure struct {
SchemaVersionFrom int32
SchemaVersionTo int32
}
// Error implements the error interface.
func (err *ErrUpgradeFailure) Error() string {
return fmt.Sprintf("failed to upgrade database from schema %d to %d", err.SchemaVersionFrom, err.SchemaVersionTo)
}
// MakeErrUpgradeFailure makes an ErrUpgradeFailure.
func MakeErrUpgradeFailure(from, to int32) *ErrUpgradeFailure {
return &ErrUpgradeFailure{
SchemaVersionFrom: from,
SchemaVersionTo: to,
}
}
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