gotosocial/vendor/github.com/ncruces/go-sqlite3/conn.go
kim 1e7b32490d
[experiment] add alternative wasm sqlite3 implementation available via build-tag (#2863)
This allows for building GoToSocial with [SQLite transpiled to WASM](https://github.com/ncruces/go-sqlite3) and accessed through [Wazero](https://wazero.io/).
2024-05-27 17:46:15 +02:00

427 lines
12 KiB
Go

package sqlite3
import (
"context"
"fmt"
"math"
"net/url"
"strings"
"time"
"github.com/ncruces/go-sqlite3/internal/util"
"github.com/ncruces/go-sqlite3/vfs"
"github.com/tetratelabs/wazero/api"
)
// Conn is a database connection handle.
// A Conn is not safe for concurrent use by multiple goroutines.
//
// https://sqlite.org/c3ref/sqlite3.html
type Conn struct {
*sqlite
interrupt context.Context
pending *Stmt
busy func(int) bool
log func(xErrorCode, string)
collation func(*Conn, string)
authorizer func(AuthorizerActionCode, string, string, string, string) AuthorizerReturnCode
update func(AuthorizerActionCode, string, string, int64)
commit func() bool
rollback func()
wal func(*Conn, string, int) error
arena arena
handle uint32
}
// Open calls [OpenFlags] with [OPEN_READWRITE], [OPEN_CREATE], [OPEN_URI] and [OPEN_NOFOLLOW].
func Open(filename string) (*Conn, error) {
return newConn(filename, OPEN_READWRITE|OPEN_CREATE|OPEN_URI|OPEN_NOFOLLOW)
}
// OpenFlags opens an SQLite database file as specified by the filename argument.
//
// If none of the required flags is used, a combination of [OPEN_READWRITE] and [OPEN_CREATE] is used.
// If a URI filename is used, PRAGMA statements to execute can be specified using "_pragma":
//
// sqlite3.Open("file:demo.db?_pragma=busy_timeout(10000)")
//
// https://sqlite.org/c3ref/open.html
func OpenFlags(filename string, flags OpenFlag) (*Conn, error) {
if flags&(OPEN_READONLY|OPEN_READWRITE|OPEN_CREATE) == 0 {
flags |= OPEN_READWRITE | OPEN_CREATE
}
return newConn(filename, flags)
}
type connKey struct{}
func newConn(filename string, flags OpenFlag) (conn *Conn, err error) {
sqlite, err := instantiateSQLite()
if err != nil {
return nil, err
}
defer func() {
if conn == nil {
sqlite.close()
}
}()
c := &Conn{sqlite: sqlite}
c.arena = c.newArena(1024)
c.ctx = context.WithValue(c.ctx, connKey{}, c)
c.handle, err = c.openDB(filename, flags)
if err != nil {
return nil, err
}
return c, nil
}
func (c *Conn) openDB(filename string, flags OpenFlag) (uint32, error) {
defer c.arena.mark()()
connPtr := c.arena.new(ptrlen)
namePtr := c.arena.string(filename)
flags |= OPEN_EXRESCODE
r := c.call("sqlite3_open_v2", uint64(namePtr), uint64(connPtr), uint64(flags), 0)
handle := util.ReadUint32(c.mod, connPtr)
if err := c.sqlite.error(r, handle); err != nil {
c.closeDB(handle)
return 0, err
}
if flags|OPEN_URI != 0 && strings.HasPrefix(filename, "file:") {
var pragmas strings.Builder
if _, after, ok := strings.Cut(filename, "?"); ok {
query, _ := url.ParseQuery(after)
for _, p := range query["_pragma"] {
pragmas.WriteString(`PRAGMA `)
pragmas.WriteString(p)
pragmas.WriteString(`;`)
}
}
if pragmas.Len() != 0 {
pragmaPtr := c.arena.string(pragmas.String())
r := c.call("sqlite3_exec", uint64(handle), uint64(pragmaPtr), 0, 0, 0)
if err := c.sqlite.error(r, handle, pragmas.String()); err != nil {
err = fmt.Errorf("sqlite3: invalid _pragma: %w", err)
c.closeDB(handle)
return 0, err
}
}
}
c.call("sqlite3_progress_handler_go", uint64(handle), 100)
return handle, nil
}
func (c *Conn) closeDB(handle uint32) {
r := c.call("sqlite3_close_v2", uint64(handle))
if err := c.sqlite.error(r, handle); err != nil {
panic(err)
}
}
// Close closes the database connection.
//
// If the database connection is associated with unfinalized prepared statements,
// open blob handles, and/or unfinished backup objects,
// Close will leave the database connection open and return [BUSY].
//
// It is safe to close a nil, zero or closed Conn.
//
// https://sqlite.org/c3ref/close.html
func (c *Conn) Close() error {
if c == nil || c.handle == 0 {
return nil
}
c.pending.Close()
c.pending = nil
r := c.call("sqlite3_close", uint64(c.handle))
if err := c.error(r); err != nil {
return err
}
c.handle = 0
return c.close()
}
// Exec is a convenience function that allows an application to run
// multiple statements of SQL without having to use a lot of code.
//
// https://sqlite.org/c3ref/exec.html
func (c *Conn) Exec(sql string) error {
c.checkInterrupt()
defer c.arena.mark()()
sqlPtr := c.arena.string(sql)
r := c.call("sqlite3_exec", uint64(c.handle), uint64(sqlPtr), 0, 0, 0)
return c.error(r, sql)
}
// Prepare calls [Conn.PrepareFlags] with no flags.
func (c *Conn) Prepare(sql string) (stmt *Stmt, tail string, err error) {
return c.PrepareFlags(sql, 0)
}
// PrepareFlags compiles the first SQL statement in sql;
// tail is left pointing to what remains uncompiled.
// If the input text contains no SQL (if the input is an empty string or a comment),
// both stmt and err will be nil.
//
// https://sqlite.org/c3ref/prepare.html
func (c *Conn) PrepareFlags(sql string, flags PrepareFlag) (stmt *Stmt, tail string, err error) {
if len(sql) > _MAX_SQL_LENGTH {
return nil, "", TOOBIG
}
defer c.arena.mark()()
stmtPtr := c.arena.new(ptrlen)
tailPtr := c.arena.new(ptrlen)
sqlPtr := c.arena.string(sql)
r := c.call("sqlite3_prepare_v3", uint64(c.handle),
uint64(sqlPtr), uint64(len(sql)+1), uint64(flags),
uint64(stmtPtr), uint64(tailPtr))
stmt = &Stmt{c: c}
stmt.handle = util.ReadUint32(c.mod, stmtPtr)
if sql := sql[util.ReadUint32(c.mod, tailPtr)-sqlPtr:]; sql != "" {
tail = sql
}
if err := c.error(r, sql); err != nil {
return nil, "", err
}
if stmt.handle == 0 {
return nil, "", nil
}
return stmt, tail, nil
}
// DBName returns the schema name for n-th database on the database connection.
//
// https://sqlite.org/c3ref/db_name.html
func (c *Conn) DBName(n int) string {
r := c.call("sqlite3_db_name", uint64(c.handle), uint64(n))
ptr := uint32(r)
if ptr == 0 {
return ""
}
return util.ReadString(c.mod, ptr, _MAX_NAME)
}
// Filename returns the filename for a database.
//
// https://sqlite.org/c3ref/db_filename.html
func (c *Conn) Filename(schema string) *vfs.Filename {
var ptr uint32
if schema != "" {
defer c.arena.mark()()
ptr = c.arena.string(schema)
}
r := c.call("sqlite3_db_filename", uint64(c.handle), uint64(ptr))
return vfs.OpenFilename(c.ctx, c.mod, uint32(r), vfs.OPEN_MAIN_DB)
}
// ReadOnly determines if a database is read-only.
//
// https://sqlite.org/c3ref/db_readonly.html
func (c *Conn) ReadOnly(schema string) (ro bool, ok bool) {
var ptr uint32
if schema != "" {
defer c.arena.mark()()
ptr = c.arena.string(schema)
}
r := c.call("sqlite3_db_readonly", uint64(c.handle), uint64(ptr))
return int32(r) > 0, int32(r) < 0
}
// GetAutocommit tests the connection for auto-commit mode.
//
// https://sqlite.org/c3ref/get_autocommit.html
func (c *Conn) GetAutocommit() bool {
r := c.call("sqlite3_get_autocommit", uint64(c.handle))
return r != 0
}
// LastInsertRowID returns the rowid of the most recent successful INSERT
// on the database connection.
//
// https://sqlite.org/c3ref/last_insert_rowid.html
func (c *Conn) LastInsertRowID() int64 {
r := c.call("sqlite3_last_insert_rowid", uint64(c.handle))
return int64(r)
}
// SetLastInsertRowID allows the application to set the value returned by
// [Conn.LastInsertRowID].
//
// https://sqlite.org/c3ref/set_last_insert_rowid.html
func (c *Conn) SetLastInsertRowID(id int64) {
c.call("sqlite3_set_last_insert_rowid", uint64(c.handle), uint64(id))
}
// Changes returns the number of rows modified, inserted or deleted
// by the most recently completed INSERT, UPDATE or DELETE statement
// on the database connection.
//
// https://sqlite.org/c3ref/changes.html
func (c *Conn) Changes() int64 {
r := c.call("sqlite3_changes64", uint64(c.handle))
return int64(r)
}
// TotalChanges returns the number of rows modified, inserted or deleted
// by all INSERT, UPDATE or DELETE statements completed
// since the database connection was opened.
//
// https://sqlite.org/c3ref/total_changes.html
func (c *Conn) TotalChanges() int64 {
r := c.call("sqlite3_total_changes64", uint64(c.handle))
return int64(r)
}
// ReleaseMemory frees memory used by a database connection.
//
// https://sqlite.org/c3ref/db_release_memory.html
func (c *Conn) ReleaseMemory() error {
r := c.call("sqlite3_db_release_memory", uint64(c.handle))
return c.error(r)
}
// GetInterrupt gets the context set with [Conn.SetInterrupt],
// or nil if none was set.
func (c *Conn) GetInterrupt() context.Context {
return c.interrupt
}
// SetInterrupt interrupts a long-running query when a context is done.
//
// Subsequent uses of the connection will return [INTERRUPT]
// until the context is reset by another call to SetInterrupt.
//
// To associate a timeout with a connection:
//
// ctx, cancel := context.WithTimeout(context.TODO(), 100*time.Millisecond)
// conn.SetInterrupt(ctx)
// defer cancel()
//
// SetInterrupt returns the old context assigned to the connection.
//
// https://sqlite.org/c3ref/interrupt.html
func (c *Conn) SetInterrupt(ctx context.Context) (old context.Context) {
// Is it the same context?
if ctx == c.interrupt {
return ctx
}
// A busy SQL statement prevents SQLite from ignoring an interrupt
// that comes before any other statements are started.
if c.pending == nil {
c.pending, _, _ = c.Prepare(`WITH RECURSIVE c(x) AS (VALUES(0) UNION ALL SELECT x FROM c) SELECT x FROM c`)
}
old = c.interrupt
c.interrupt = ctx
if old != nil && old.Done() != nil && (ctx == nil || ctx.Err() == nil) {
c.pending.Reset()
}
if ctx != nil && ctx.Done() != nil {
c.pending.Step()
}
return old
}
func (c *Conn) checkInterrupt() {
if c.interrupt != nil && c.interrupt.Err() != nil {
c.call("sqlite3_interrupt", uint64(c.handle))
}
}
func progressCallback(ctx context.Context, mod api.Module, pDB uint32) (interrupt uint32) {
if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB &&
c.interrupt != nil && c.interrupt.Err() != nil {
interrupt = 1
}
return interrupt
}
// BusyTimeout sets a busy timeout.
//
// https://sqlite.org/c3ref/busy_timeout.html
func (c *Conn) BusyTimeout(timeout time.Duration) error {
ms := min((timeout+time.Millisecond-1)/time.Millisecond, math.MaxInt32)
r := c.call("sqlite3_busy_timeout", uint64(c.handle), uint64(ms))
return c.error(r)
}
func timeoutCallback(ctx context.Context, mod api.Module, pDB uint32, count, tmout int32) (retry uint32) {
if c, ok := ctx.Value(connKey{}).(*Conn); ok &&
(c.interrupt == nil || c.interrupt.Err() == nil) {
const delays = "\x01\x02\x05\x0a\x0f\x14\x19\x19\x19\x32\x32\x64"
const totals = "\x00\x01\x03\x08\x12\x21\x35\x4e\x67\x80\xb2\xe4"
const ndelay = int32(len(delays) - 1)
var delay, prior int32
if count <= ndelay {
delay = int32(delays[count])
prior = int32(totals[count])
} else {
delay = int32(delays[ndelay])
prior = int32(totals[ndelay]) + delay*(count-ndelay)
}
if delay = min(delay, tmout-prior); delay > 0 {
time.Sleep(time.Duration(delay) * time.Millisecond)
retry = 1
}
}
return retry
}
// BusyHandler registers a callback to handle [BUSY] errors.
//
// https://sqlite.org/c3ref/busy_handler.html
func (c *Conn) BusyHandler(cb func(count int) (retry bool)) error {
var enable uint64
if cb != nil {
enable = 1
}
r := c.call("sqlite3_busy_handler_go", uint64(c.handle), enable)
if err := c.error(r); err != nil {
return err
}
c.busy = cb
return nil
}
func busyCallback(ctx context.Context, mod api.Module, pDB uint32, count int32) (retry uint32) {
if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB && c.busy != nil &&
(c.interrupt == nil || c.interrupt.Err() == nil) {
if c.busy(int(count)) {
retry = 1
}
}
return retry
}
func (c *Conn) error(rc uint64, sql ...string) error {
return c.sqlite.error(rc, c.handle, sql...)
}
// DriverConn is implemented by the SQLite [database/sql] driver connection.
//
// It can be used to access SQLite features like [online backup].
//
// [online backup]: https://sqlite.org/backup.html
type DriverConn interface {
Raw() *Conn
}