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postgres.go
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postgres.go
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package postgres
import (
"context"
"database/sql"
"fmt"
"strconv"
"strings"
"github.com/pkg/errors"
_ "github.com/lib/pq"
"github.com/mattermost/morph/drivers"
"github.com/mattermost/morph/models"
)
var (
driverName = "postgres"
defaultMigrationMaxSize = 10 * 1 << 20 // 10 MB
configParams = []string{
"x-migration-max-size",
"x-migrations-table",
"x-statement-timeout",
}
)
// The format is morph: followed by a comma separated list of values.
// For now, we are taking the whole string in a single constant.
// Later, if we need more values, we can split "morph:" to a separate constant.
const nonTransactionalPrefix = "morph:nontransactional"
type driverConfig struct {
drivers.Config
databaseName string
schemaName string
closeDBonClose bool
}
type postgres struct {
conn *sql.Conn
db *sql.DB
config *driverConfig
}
func WithInstance(dbInstance *sql.DB) (drivers.Driver, error) {
conn, err := dbInstance.Conn(context.Background())
if err != nil {
return nil, &drivers.DatabaseError{Driver: driverName, Command: "grabbing_connection", OrigErr: err, Message: "failed to grab connection to the database"}
}
driverConfig := getDefaultConfig()
if driverConfig.databaseName, err = currentDatabaseNameFromDB(conn, driverConfig); err != nil {
return nil, err
}
if driverConfig.schemaName, err = currentSchema(conn, driverConfig); err != nil {
return nil, err
}
return &postgres{
conn: conn,
db: dbInstance,
config: driverConfig,
}, nil
}
func Open(connURL string) (drivers.Driver, error) {
customParams, err := drivers.ExtractCustomParams(connURL, configParams)
if err != nil {
return nil, &drivers.AppError{Driver: driverName, OrigErr: err, Message: "failed to parse custom parameters from url"}
}
sanitizedConnURL, err := drivers.RemoveParamsFromURL(connURL, configParams)
if err != nil {
return nil, &drivers.AppError{Driver: driverName, OrigErr: err, Message: "failed to sanitize url from custom parameters"}
}
driverConfig, err := mergeConfigWithParams(customParams, getDefaultConfig())
if err != nil {
return nil, &drivers.AppError{Driver: driverName, OrigErr: err, Message: "failed to merge custom params to driver config"}
}
db, err := sql.Open(driverName, sanitizedConnURL)
if err != nil {
return nil, &drivers.DatabaseError{Driver: driverName, Command: "opening_connection", OrigErr: err, Message: "failed to open connection with the database"}
}
conn, err := db.Conn(context.Background())
if err != nil {
return nil, &drivers.DatabaseError{Driver: driverName, Command: "grabbing_connection", OrigErr: err, Message: "failed to grab connection to the database"}
}
if driverConfig.databaseName, err = extractDatabaseNameFromURL(connURL); err != nil {
return nil, &drivers.AppError{Driver: driverName, OrigErr: err, Message: "failed to extract database name from connection url"}
}
if driverConfig.schemaName, err = currentSchema(conn, driverConfig); err != nil {
return nil, err
}
driverConfig.closeDBonClose = true
return &postgres{
db: db,
config: driverConfig,
conn: conn,
}, nil
}
func currentSchema(conn *sql.Conn, config *driverConfig) (string, error) {
query := "SELECT CURRENT_SCHEMA()"
ctx, cancel := drivers.GetContext(config.StatementTimeoutInSecs)
defer cancel()
var schemaName string
if err := conn.QueryRowContext(ctx, query).Scan(&schemaName); err != nil {
return "", &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "failed to fetch current schema",
Command: "current_schema",
Query: []byte(query),
}
}
return schemaName, nil
}
func mergeConfigWithParams(params map[string]string, config *driverConfig) (*driverConfig, error) {
var err error
for _, configKey := range configParams {
if v, ok := params[configKey]; ok {
switch configKey {
case "x-migration-max-size":
if config.MigrationMaxSize, err = strconv.Atoi(v); err != nil {
return nil, errors.New(fmt.Sprintf("failed to cast config param %s of %s", configKey, v))
}
case "x-migrations-table":
config.MigrationsTable = v
case "x-statement-timeout":
if config.StatementTimeoutInSecs, err = strconv.Atoi(v); err != nil {
return nil, errors.New(fmt.Sprintf("failed to cast config param %s of %s", configKey, v))
}
}
}
}
return config, nil
}
func (pg *postgres) Ping() error {
ctx, cancel := drivers.GetContext(pg.config.StatementTimeoutInSecs)
defer cancel()
return pg.conn.PingContext(ctx)
}
func (pg *postgres) createSchemaTableIfNotExists() (err error) {
ctx, cancel := drivers.GetContext(pg.config.StatementTimeoutInSecs)
defer cancel()
createTableIfNotExistsQuery := fmt.Sprintf("CREATE TABLE IF NOT EXISTS %s (version bigint not null primary key, name varchar not null)", pg.config.MigrationsTable)
if _, err = pg.conn.ExecContext(ctx, createTableIfNotExistsQuery); err != nil {
return &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "failed while executing query",
Command: "create_migrations_table_if_not_exists",
Query: []byte(createTableIfNotExistsQuery),
}
}
return nil
}
func (postgres) DriverName() string {
return driverName
}
func (pg *postgres) Close() error {
if pg.conn != nil {
if err := pg.conn.Close(); err != nil {
return &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "failed to close database connection",
Command: "pg_conn_close",
Query: nil,
}
}
}
if pg.db != nil && pg.config.closeDBonClose {
if err := pg.db.Close(); err != nil {
return &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "failed to close database",
Command: "pg_db_close",
Query: nil,
}
}
pg.db = nil
}
pg.conn = nil
return nil
}
func (pg *postgres) Apply(migration *models.Migration, saveVersion bool) (err error) {
query := migration.Query()
ctx, cancel := drivers.GetContext(pg.config.StatementTimeoutInSecs)
defer cancel()
nonTransactional := strings.HasPrefix(query, "-- "+nonTransactionalPrefix)
// We wrap with a transaction only when there is no non-transactional prefix.
if !nonTransactional {
transaction, err := pg.conn.BeginTx(ctx, nil)
if err != nil {
return &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "error while opening a transaction to the database",
Command: "begin_transaction",
}
}
if err = executeQuery(ctx, transaction, query); err != nil {
return err
}
if saveVersion {
if err = executeQuery(ctx, transaction, pg.addMigrationQuery(migration)); err != nil {
return err
}
}
err = transaction.Commit()
if err != nil {
return &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "error while committing a transaction to the database",
Command: "commit_transaction",
}
}
} else {
_, err := pg.conn.ExecContext(ctx, query)
if err != nil {
return &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "failed to execute migration",
Command: "executing_query",
Query: []byte(query),
}
}
if saveVersion {
_, err = pg.conn.ExecContext(ctx, pg.addMigrationQuery(migration))
if err != nil {
return &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "failed to save version",
Command: "executing_query",
Query: []byte(query),
}
}
}
}
return nil
}
func (pg *postgres) AppliedMigrations() (migrations []*models.Migration, err error) {
if pg.conn == nil {
return nil, &drivers.AppError{
OrigErr: errors.New("driver has no connection established"),
Message: "database connection is missing",
Driver: driverName,
}
}
if err := pg.createSchemaTableIfNotExists(); err != nil {
return nil, err
}
query := fmt.Sprintf("SELECT version, name FROM %s", pg.config.MigrationsTable)
ctx, cancel := drivers.GetContext(pg.config.StatementTimeoutInSecs)
defer cancel()
var appliedMigrations []*models.Migration
var version uint32
var name string
rows, err := pg.conn.QueryContext(ctx, query)
if err != nil {
return nil, &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "failed to fetch applied migrations",
Command: "select_applied_migrations",
Query: []byte(query),
}
}
defer rows.Close()
for rows.Next() {
if err := rows.Scan(&version, &name); err != nil {
return nil, &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "failed to scan applied migration row",
Command: "scan_applied_migrations",
}
}
appliedMigrations = append(appliedMigrations, &models.Migration{
Name: name,
Version: version,
Direction: models.Up,
})
}
return appliedMigrations, nil
}
func (pg *postgres) addMigrationQuery(migration *models.Migration) string {
if migration.Direction == models.Down {
return fmt.Sprintf("DELETE FROM %s WHERE (Version=%d AND NAME='%s')", pg.config.MigrationsTable, migration.Version, migration.Name)
}
return fmt.Sprintf("INSERT INTO %s (version, name) VALUES (%d, '%s')", pg.config.MigrationsTable, migration.Version, migration.Name)
}
func executeQuery(ctx context.Context, transaction *sql.Tx, query string) error {
if _, err := transaction.ExecContext(ctx, query); err != nil {
if txErr := transaction.Rollback(); txErr != nil {
err = errors.Wrap(errors.New(err.Error()+txErr.Error()), "failed to execute query in migration transaction")
return &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Command: "rollback_transaction",
}
}
return &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "failed to execute migration",
Command: "executing_query",
Query: []byte(query),
}
}
return nil
}
func currentDatabaseNameFromDB(conn *sql.Conn, config *driverConfig) (string, error) {
query := "SELECT CURRENT_DATABASE()"
ctx, cancel := drivers.GetContext(config.StatementTimeoutInSecs)
defer cancel()
var databaseName string
if err := conn.QueryRowContext(ctx, query).Scan(&databaseName); err != nil {
return "", &drivers.DatabaseError{
OrigErr: err,
Driver: driverName,
Message: "failed to fetch database name",
Command: "current_database",
Query: []byte(query),
}
}
return databaseName, nil
}
func (pg *postgres) SetConfig(key string, value interface{}) error {
if pg.config != nil {
switch key {
case "StatementTimeoutInSecs":
n, ok := value.(int)
if ok {
pg.config.StatementTimeoutInSecs = n
return nil
}
return fmt.Errorf("incorrect value type for %s", key)
case "MigrationsTable":
n, ok := value.(string)
if ok {
pg.config.MigrationsTable = n
return nil
}
return fmt.Errorf("incorrect value type for %s", key)
}
}
return fmt.Errorf("incorrect key name %q", key)
}