gotosocial/vendor/github.com/ncruces/go-sqlite3/txn.go

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package sqlite3
import (
"context"
"errors"
"fmt"
"math/rand"
"runtime"
"strconv"
"strings"
"github.com/ncruces/go-sqlite3/internal/util"
"github.com/tetratelabs/wazero/api"
)
// Txn is an in-progress database transaction.
//
// https://sqlite.org/lang_transaction.html
type Txn struct {
c *Conn
}
// Begin starts a deferred transaction.
//
// https://sqlite.org/lang_transaction.html
func (c *Conn) Begin() Txn {
// BEGIN even if interrupted.
err := c.txnExecInterrupted(`BEGIN DEFERRED`)
if err != nil {
panic(err)
}
return Txn{c}
}
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// BeginConcurrent starts a concurrent transaction.
//
// Experimental: requires a custom build of SQLite.
//
// https://sqlite.org/cgi/src/doc/begin-concurrent/doc/begin_concurrent.md
func (c *Conn) BeginConcurrent() (Txn, error) {
err := c.Exec(`BEGIN CONCURRENT`)
if err != nil {
return Txn{}, err
}
return Txn{c}, nil
}
// BeginImmediate starts an immediate transaction.
//
// https://sqlite.org/lang_transaction.html
func (c *Conn) BeginImmediate() (Txn, error) {
err := c.Exec(`BEGIN IMMEDIATE`)
if err != nil {
return Txn{}, err
}
return Txn{c}, nil
}
// BeginExclusive starts an exclusive transaction.
//
// https://sqlite.org/lang_transaction.html
func (c *Conn) BeginExclusive() (Txn, error) {
err := c.Exec(`BEGIN EXCLUSIVE`)
if err != nil {
return Txn{}, err
}
return Txn{c}, nil
}
// End calls either [Txn.Commit] or [Txn.Rollback]
// depending on whether *error points to a nil or non-nil error.
//
// This is meant to be deferred:
//
// func doWork(db *sqlite3.Conn) (err error) {
// tx := db.Begin()
// defer tx.End(&err)
//
// // ... do work in the transaction
// }
//
// https://sqlite.org/lang_transaction.html
func (tx Txn) End(errp *error) {
recovered := recover()
if recovered != nil {
defer panic(recovered)
}
if *errp == nil && recovered == nil {
// Success path.
if tx.c.GetAutocommit() { // There is nothing to commit.
return
}
*errp = tx.Commit()
if *errp == nil {
return
}
// Fall through to the error path.
}
// Error path.
if tx.c.GetAutocommit() { // There is nothing to rollback.
return
}
err := tx.Rollback()
if err != nil {
panic(err)
}
}
// Commit commits the transaction.
//
// https://sqlite.org/lang_transaction.html
func (tx Txn) Commit() error {
return tx.c.Exec(`COMMIT`)
}
// Rollback rolls back the transaction,
// even if the connection has been interrupted.
//
// https://sqlite.org/lang_transaction.html
func (tx Txn) Rollback() error {
return tx.c.txnExecInterrupted(`ROLLBACK`)
}
// Savepoint is a marker within a transaction
// that allows for partial rollback.
//
// https://sqlite.org/lang_savepoint.html
type Savepoint struct {
c *Conn
name string
}
// Savepoint establishes a new transaction savepoint.
//
// https://sqlite.org/lang_savepoint.html
func (c *Conn) Savepoint() Savepoint {
// Names can be reused; this makes catching bugs more likely.
name := saveptName() + "_" + strconv.Itoa(int(rand.Int31()))
err := c.txnExecInterrupted(fmt.Sprintf("SAVEPOINT %q;", name))
if err != nil {
panic(err)
}
return Savepoint{c: c, name: name}
}
func saveptName() (name string) {
defer func() {
if name == "" {
name = "sqlite3.Savepoint"
}
}()
var pc [8]uintptr
n := runtime.Callers(3, pc[:])
if n <= 0 {
return ""
}
frames := runtime.CallersFrames(pc[:n])
frame, more := frames.Next()
for more && (strings.HasPrefix(frame.Function, "database/sql.") ||
strings.HasPrefix(frame.Function, "github.com/ncruces/go-sqlite3/driver.")) {
frame, more = frames.Next()
}
return frame.Function
}
// Release releases the savepoint rolling back any changes
// if *error points to a non-nil error.
//
// This is meant to be deferred:
//
// func doWork(db *sqlite3.Conn) (err error) {
// savept := db.Savepoint()
// defer savept.Release(&err)
//
// // ... do work in the transaction
// }
func (s Savepoint) Release(errp *error) {
recovered := recover()
if recovered != nil {
defer panic(recovered)
}
if *errp == nil && recovered == nil {
// Success path.
if s.c.GetAutocommit() { // There is nothing to commit.
return
}
*errp = s.c.Exec(fmt.Sprintf("RELEASE %q;", s.name))
if *errp == nil {
return
}
// Fall through to the error path.
}
// Error path.
if s.c.GetAutocommit() { // There is nothing to rollback.
return
}
// ROLLBACK and RELEASE even if interrupted.
err := s.c.txnExecInterrupted(fmt.Sprintf(`
ROLLBACK TO %[1]q;
RELEASE %[1]q;
`, s.name))
if err != nil {
panic(err)
}
}
// Rollback rolls the transaction back to the savepoint,
// even if the connection has been interrupted.
// Rollback does not release the savepoint.
//
// https://sqlite.org/lang_transaction.html
func (s Savepoint) Rollback() error {
// ROLLBACK even if interrupted.
return s.c.txnExecInterrupted(fmt.Sprintf("ROLLBACK TO %q;", s.name))
}
func (c *Conn) txnExecInterrupted(sql string) error {
err := c.Exec(sql)
if errors.Is(err, INTERRUPT) {
old := c.SetInterrupt(context.Background())
defer c.SetInterrupt(old)
err = c.Exec(sql)
}
return err
}
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// TxnState determines the transaction state of a database.
//
// https://sqlite.org/c3ref/txn_state.html
func (c *Conn) TxnState(schema string) TxnState {
var ptr uint32
if schema != "" {
defer c.arena.mark()()
ptr = c.arena.string(schema)
}
r := c.call("sqlite3_txn_state", uint64(c.handle), uint64(ptr))
return TxnState(r)
}
// CommitHook registers a callback function to be invoked
// whenever a transaction is committed.
// Return true to allow the commit operation to continue normally.
//
// https://sqlite.org/c3ref/commit_hook.html
func (c *Conn) CommitHook(cb func() (ok bool)) {
var enable uint64
if cb != nil {
enable = 1
}
c.call("sqlite3_commit_hook_go", uint64(c.handle), enable)
c.commit = cb
}
// RollbackHook registers a callback function to be invoked
// whenever a transaction is rolled back.
//
// https://sqlite.org/c3ref/commit_hook.html
func (c *Conn) RollbackHook(cb func()) {
var enable uint64
if cb != nil {
enable = 1
}
c.call("sqlite3_rollback_hook_go", uint64(c.handle), enable)
c.rollback = cb
}
// UpdateHook registers a callback function to be invoked
// whenever a row is updated, inserted or deleted in a rowid table.
//
// https://sqlite.org/c3ref/update_hook.html
func (c *Conn) UpdateHook(cb func(action AuthorizerActionCode, schema, table string, rowid int64)) {
var enable uint64
if cb != nil {
enable = 1
}
c.call("sqlite3_update_hook_go", uint64(c.handle), enable)
c.update = cb
}
func commitCallback(ctx context.Context, mod api.Module, pDB uint32) (rollback uint32) {
if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB && c.commit != nil {
if !c.commit() {
rollback = 1
}
}
return rollback
}
func rollbackCallback(ctx context.Context, mod api.Module, pDB uint32) {
if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB && c.rollback != nil {
c.rollback()
}
}
func updateCallback(ctx context.Context, mod api.Module, pDB uint32, action AuthorizerActionCode, zSchema, zTabName uint32, rowid uint64) {
if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB && c.update != nil {
schema := util.ReadString(mod, zSchema, _MAX_NAME)
table := util.ReadString(mod, zTabName, _MAX_NAME)
c.update(action, schema, table, int64(rowid))
}
}
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// CacheFlush flushes caches to disk mid-transaction.
//
// https://sqlite.org/c3ref/db_cacheflush.html
func (c *Conn) CacheFlush() error {
r := c.call("sqlite3_db_cacheflush", uint64(c.handle))
return c.error(r)
}