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pgx.go
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pgx.go
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//go:build go1.9
// +build go1.9
package pgx
import (
"context"
"database/sql"
"fmt"
"go.uber.org/atomic"
"io"
"io/ioutil"
nurl "net/url"
"regexp"
"strconv"
"strings"
"time"
"github.com/golang-migrate/migrate/v4"
"github.com/golang-migrate/migrate/v4/database"
"github.com/golang-migrate/migrate/v4/database/multistmt"
multierror "github.com/hashicorp/go-multierror"
"github.com/jackc/pgconn"
"github.com/jackc/pgerrcode"
_ "github.com/jackc/pgx/v4/stdlib"
)
func init() {
db := Postgres{}
database.Register("pgx", &db)
}
var (
multiStmtDelimiter = []byte(";")
DefaultMigrationsTable = "schema_migrations"
DefaultMultiStatementMaxSize = 10 * 1 << 20 // 10 MB
)
var (
ErrNilConfig = fmt.Errorf("no config")
ErrNoDatabaseName = fmt.Errorf("no database name")
ErrNoSchema = fmt.Errorf("no schema")
ErrDatabaseDirty = fmt.Errorf("database is dirty")
)
type Config struct {
MigrationsTable string
DatabaseName string
SchemaName string
migrationsSchemaName string
migrationsTableName string
StatementTimeout time.Duration
MigrationsTableQuoted bool
MultiStatementEnabled bool
MultiStatementMaxSize int
}
type Postgres struct {
// Locking and unlocking need to use the same connection
conn *sql.Conn
db *sql.DB
isLocked atomic.Bool
// Open and WithInstance need to guarantee that config is never nil
config *Config
}
func WithInstance(instance *sql.DB, config *Config) (database.Driver, error) {
if config == nil {
return nil, ErrNilConfig
}
if err := instance.Ping(); err != nil {
return nil, err
}
if config.DatabaseName == "" {
query := `SELECT CURRENT_DATABASE()`
var databaseName string
if err := instance.QueryRow(query).Scan(&databaseName); err != nil {
return nil, &database.Error{OrigErr: err, Query: []byte(query)}
}
if len(databaseName) == 0 {
return nil, ErrNoDatabaseName
}
config.DatabaseName = databaseName
}
if config.SchemaName == "" {
query := `SELECT CURRENT_SCHEMA()`
var schemaName string
if err := instance.QueryRow(query).Scan(&schemaName); err != nil {
return nil, &database.Error{OrigErr: err, Query: []byte(query)}
}
if len(schemaName) == 0 {
return nil, ErrNoSchema
}
config.SchemaName = schemaName
}
if len(config.MigrationsTable) == 0 {
config.MigrationsTable = DefaultMigrationsTable
}
config.migrationsSchemaName = config.SchemaName
config.migrationsTableName = config.MigrationsTable
if config.MigrationsTableQuoted {
re := regexp.MustCompile(`"(.*?)"`)
result := re.FindAllStringSubmatch(config.MigrationsTable, -1)
config.migrationsTableName = result[len(result)-1][1]
if len(result) == 2 {
config.migrationsSchemaName = result[0][1]
} else if len(result) > 2 {
return nil, fmt.Errorf("\"%s\" MigrationsTable contains too many dot characters", config.MigrationsTable)
}
}
conn, err := instance.Conn(context.Background())
if err != nil {
return nil, err
}
px := &Postgres{
conn: conn,
db: instance,
config: config,
}
if err := px.ensureVersionTable(); err != nil {
return nil, err
}
return px, nil
}
func (p *Postgres) Open(url string) (database.Driver, error) {
purl, err := nurl.Parse(url)
if err != nil {
return nil, err
}
// Driver is registered as pgx, but connection string must use postgres schema
// when making actual connection
// i.e. pgx://user:password@host:port/db => postgres://user:password@host:port/db
purl.Scheme = "postgres"
db, err := sql.Open("pgx", migrate.FilterCustomQuery(purl).String())
if err != nil {
return nil, err
}
migrationsTable := purl.Query().Get("x-migrations-table")
migrationsTableQuoted := false
if s := purl.Query().Get("x-migrations-table-quoted"); len(s) > 0 {
migrationsTableQuoted, err = strconv.ParseBool(s)
if err != nil {
return nil, fmt.Errorf("Unable to parse option x-migrations-table-quoted: %w", err)
}
}
if (len(migrationsTable) > 0) && (migrationsTableQuoted) && ((migrationsTable[0] != '"') || (migrationsTable[len(migrationsTable)-1] != '"')) {
return nil, fmt.Errorf("x-migrations-table must be quoted (for instance '\"migrate\".\"schema_migrations\"') when x-migrations-table-quoted is enabled, current value is: %s", migrationsTable)
}
statementTimeoutString := purl.Query().Get("x-statement-timeout")
statementTimeout := 0
if statementTimeoutString != "" {
statementTimeout, err = strconv.Atoi(statementTimeoutString)
if err != nil {
return nil, err
}
}
multiStatementMaxSize := DefaultMultiStatementMaxSize
if s := purl.Query().Get("x-multi-statement-max-size"); len(s) > 0 {
multiStatementMaxSize, err = strconv.Atoi(s)
if err != nil {
return nil, err
}
if multiStatementMaxSize <= 0 {
multiStatementMaxSize = DefaultMultiStatementMaxSize
}
}
multiStatementEnabled := false
if s := purl.Query().Get("x-multi-statement"); len(s) > 0 {
multiStatementEnabled, err = strconv.ParseBool(s)
if err != nil {
return nil, fmt.Errorf("Unable to parse option x-multi-statement: %w", err)
}
}
px, err := WithInstance(db, &Config{
DatabaseName: purl.Path,
MigrationsTable: migrationsTable,
MigrationsTableQuoted: migrationsTableQuoted,
StatementTimeout: time.Duration(statementTimeout) * time.Millisecond,
MultiStatementEnabled: multiStatementEnabled,
MultiStatementMaxSize: multiStatementMaxSize,
})
if err != nil {
return nil, err
}
return px, nil
}
func (p *Postgres) Close() error {
connErr := p.conn.Close()
dbErr := p.db.Close()
if connErr != nil || dbErr != nil {
return fmt.Errorf("conn: %v, db: %v", connErr, dbErr)
}
return nil
}
// https://www.postgresql.org/docs/9.6/static/explicit-locking.html#ADVISORY-LOCKS
func (p *Postgres) Lock() error {
return database.CasRestoreOnErr(&p.isLocked, false, true, database.ErrLocked, func() error {
aid, err := database.GenerateAdvisoryLockId(p.config.DatabaseName, p.config.migrationsSchemaName, p.config.migrationsTableName)
if err != nil {
return err
}
// This will wait indefinitely until the lock can be acquired.
query := `SELECT pg_advisory_lock($1)`
if _, err := p.conn.ExecContext(context.Background(), query, aid); err != nil {
return &database.Error{OrigErr: err, Err: "try lock failed", Query: []byte(query)}
}
return nil
})
}
func (p *Postgres) Unlock() error {
return database.CasRestoreOnErr(&p.isLocked, true, false, database.ErrNotLocked, func() error {
aid, err := database.GenerateAdvisoryLockId(p.config.DatabaseName, p.config.migrationsSchemaName, p.config.migrationsTableName)
if err != nil {
return err
}
query := `SELECT pg_advisory_unlock($1)`
if _, err := p.conn.ExecContext(context.Background(), query, aid); err != nil {
return &database.Error{OrigErr: err, Query: []byte(query)}
}
return nil
})
}
func (p *Postgres) Run(migration io.Reader) error {
if p.config.MultiStatementEnabled {
var err error
if e := multistmt.Parse(migration, multiStmtDelimiter, p.config.MultiStatementMaxSize, func(m []byte) bool {
if err = p.runStatement(m); err != nil {
return false
}
return true
}); e != nil {
return e
}
return err
}
migr, err := ioutil.ReadAll(migration)
if err != nil {
return err
}
return p.runStatement(migr)
}
func (p *Postgres) runStatement(statement []byte) error {
ctx := context.Background()
if p.config.StatementTimeout != 0 {
var cancel context.CancelFunc
ctx, cancel = context.WithTimeout(ctx, p.config.StatementTimeout)
defer cancel()
}
query := string(statement)
if strings.TrimSpace(query) == "" {
return nil
}
if _, err := p.conn.ExecContext(ctx, query); err != nil {
if pgErr, ok := err.(*pgconn.PgError); ok {
var line uint
var col uint
var lineColOK bool
line, col, lineColOK = computeLineFromPos(query, int(pgErr.Position))
message := fmt.Sprintf("migration failed: %s", pgErr.Message)
if lineColOK {
message = fmt.Sprintf("%s (column %d)", message, col)
}
if pgErr.Detail != "" {
message = fmt.Sprintf("%s, %s", message, pgErr.Detail)
}
return database.Error{OrigErr: err, Err: message, Query: statement, Line: line}
}
return database.Error{OrigErr: err, Err: "migration failed", Query: statement}
}
return nil
}
func computeLineFromPos(s string, pos int) (line uint, col uint, ok bool) {
// replace crlf with lf
s = strings.Replace(s, "\r\n", "\n", -1)
// pg docs: pos uses index 1 for the first character, and positions are measured in characters not bytes
runes := []rune(s)
if pos > len(runes) {
return 0, 0, false
}
sel := runes[:pos]
line = uint(runesCount(sel, newLine) + 1)
col = uint(pos - 1 - runesLastIndex(sel, newLine))
return line, col, true
}
const newLine = '\n'
func runesCount(input []rune, target rune) int {
var count int
for _, r := range input {
if r == target {
count++
}
}
return count
}
func runesLastIndex(input []rune, target rune) int {
for i := len(input) - 1; i >= 0; i-- {
if input[i] == target {
return i
}
}
return -1
}
func (p *Postgres) SetVersion(version int, dirty bool) error {
tx, err := p.conn.BeginTx(context.Background(), &sql.TxOptions{})
if err != nil {
return &database.Error{OrigErr: err, Err: "transaction start failed"}
}
query := `TRUNCATE ` + quoteIdentifier(p.config.migrationsSchemaName) + `.` + quoteIdentifier(p.config.migrationsTableName)
if _, err := tx.Exec(query); err != nil {
if errRollback := tx.Rollback(); errRollback != nil {
err = multierror.Append(err, errRollback)
}
return &database.Error{OrigErr: err, Query: []byte(query)}
}
// Also re-write the schema version for nil dirty versions to prevent
// empty schema version for failed down migration on the first migration
// See: https://github.com/golang-migrate/migrate/issues/330
if version >= 0 || (version == database.NilVersion && dirty) {
query = `INSERT INTO ` + quoteIdentifier(p.config.migrationsSchemaName) + `.` + quoteIdentifier(p.config.migrationsTableName) + ` (version, dirty) VALUES ($1, $2)`
if _, err := tx.Exec(query, version, dirty); err != nil {
if errRollback := tx.Rollback(); errRollback != nil {
err = multierror.Append(err, errRollback)
}
return &database.Error{OrigErr: err, Query: []byte(query)}
}
}
if err := tx.Commit(); err != nil {
return &database.Error{OrigErr: err, Err: "transaction commit failed"}
}
return nil
}
func (p *Postgres) Version() (version int, dirty bool, err error) {
query := `SELECT version, dirty FROM ` + quoteIdentifier(p.config.migrationsSchemaName) + `.` + quoteIdentifier(p.config.migrationsTableName) + ` LIMIT 1`
err = p.conn.QueryRowContext(context.Background(), query).Scan(&version, &dirty)
switch {
case err == sql.ErrNoRows:
return database.NilVersion, false, nil
case err != nil:
if e, ok := err.(*pgconn.PgError); ok {
if e.SQLState() == pgerrcode.UndefinedTable {
return database.NilVersion, false, nil
}
}
return 0, false, &database.Error{OrigErr: err, Query: []byte(query)}
default:
return version, dirty, nil
}
}
func (p *Postgres) Drop() (err error) {
// select all tables in current schema
query := `SELECT table_name FROM information_schema.tables WHERE table_schema=(SELECT current_schema()) AND table_type='BASE TABLE'`
tables, err := p.conn.QueryContext(context.Background(), query)
if err != nil {
return &database.Error{OrigErr: err, Query: []byte(query)}
}
defer func() {
if errClose := tables.Close(); errClose != nil {
err = multierror.Append(err, errClose)
}
}()
// delete one table after another
tableNames := make([]string, 0)
for tables.Next() {
var tableName string
if err := tables.Scan(&tableName); err != nil {
return err
}
if len(tableName) > 0 {
tableNames = append(tableNames, tableName)
}
}
if err := tables.Err(); err != nil {
return &database.Error{OrigErr: err, Query: []byte(query)}
}
if len(tableNames) > 0 {
// delete one by one ...
for _, t := range tableNames {
query = `DROP TABLE IF EXISTS ` + quoteIdentifier(t) + ` CASCADE`
if _, err := p.conn.ExecContext(context.Background(), query); err != nil {
return &database.Error{OrigErr: err, Query: []byte(query)}
}
}
}
return nil
}
// ensureVersionTable checks if versions table exists and, if not, creates it.
// Note that this function locks the database, which deviates from the usual
// convention of "caller locks" in the Postgres type.
func (p *Postgres) ensureVersionTable() (err error) {
if err = p.Lock(); err != nil {
return err
}
defer func() {
if e := p.Unlock(); e != nil {
if err == nil {
err = e
} else {
err = multierror.Append(err, e)
}
}
}()
// This block checks whether the `MigrationsTable` already exists. This is useful because it allows read only postgres
// users to also check the current version of the schema. Previously, even if `MigrationsTable` existed, the
// `CREATE TABLE IF NOT EXISTS...` query would fail because the user does not have the CREATE permission.
// Taken from https://github.com/mattes/migrate/blob/master/database/postgres/postgres.go#L258
query := `SELECT COUNT(1) FROM information_schema.tables WHERE table_schema = $1 AND table_name = $2 LIMIT 1`
row := p.conn.QueryRowContext(context.Background(), query, p.config.migrationsSchemaName, p.config.migrationsTableName)
var count int
err = row.Scan(&count)
if err != nil {
return &database.Error{OrigErr: err, Query: []byte(query)}
}
if count == 1 {
return nil
}
query = `CREATE TABLE IF NOT EXISTS ` + quoteIdentifier(p.config.migrationsSchemaName) + `.` + quoteIdentifier(p.config.migrationsTableName) + ` (version bigint not null primary key, dirty boolean not null)`
if _, err = p.conn.ExecContext(context.Background(), query); err != nil {
return &database.Error{OrigErr: err, Query: []byte(query)}
}
return nil
}
// Copied from lib/pq implementation: https://github.com/lib/pq/blob/v1.9.0/conn.go#L1611
func quoteIdentifier(name string) string {
end := strings.IndexRune(name, 0)
if end > -1 {
name = name[:end]
}
return `"` + strings.Replace(name, `"`, `""`, -1) + `"`
}