Improve SetInterrupt performance.

Author: ncruces

blob.go

@@ -42,7 +42,7 @@ func (c *Conn) OpenBlob(db, table, column string, row int64, write bool) (*Blob,
 		flags = 1
 	}
 
-	c.checkInterrupt(c.handle)
+	c.checkInterrupt()
 	rc := res_t(c.call("sqlite3_blob_open", stk_t(c.handle),
 		stk_t(dbPtr), stk_t(tablePtr), stk_t(columnPtr),
 		stk_t(row), stk_t(flags), stk_t(blobPtr)))
@@ -253,7 +253,7 @@ func (b *Blob) Seek(offset int64, whence int) (int64, error) {
 //
 // https://sqlite.org/c3ref/blob_reopen.html
 func (b *Blob) Reopen(row int64) error {
-	b.c.checkInterrupt(b.c.handle)
+	b.c.checkInterrupt()
 	err := b.c.error(res_t(b.c.call("sqlite3_blob_reopen", stk_t(b.handle), stk_t(row))))
 	b.bytes = int64(int32(b.c.call("sqlite3_blob_bytes", stk_t(b.handle))))
 	b.offset = 0

conn.go

@@ -25,7 +25,6 @@ type Conn struct {
 	*sqlite
 
 	interrupt  context.Context
-	pending    *Stmt
 	stmts      []*Stmt
 	busy       func(context.Context, int) bool
 	log        func(xErrorCode, string)
@@ -41,7 +40,9 @@ type Conn struct {
 	busylst time.Time
 	arena   arena
 	handle  ptr_t
-	nprogr  uint8
+	pending ptr_t
+	stepped bool
+	gosched uint8
 }
 
 // Open calls [OpenFlags] with [OPEN_READWRITE], [OPEN_CREATE] and [OPEN_URI].
@@ -133,7 +134,6 @@ func (c *Conn) openDB(filename string, flags OpenFlag) (ptr_t, error) {
 			}
 		}
 		if pragmas.Len() != 0 {
-			c.checkInterrupt(handle)
 			pragmaPtr := c.arena.string(pragmas.String())
 			rc := res_t(c.call("sqlite3_exec", stk_t(handle), stk_t(pragmaPtr), 0, 0, 0))
 			if err := c.sqlite.error(rc, handle, pragmas.String()); err != nil {
@@ -167,8 +167,8 @@ func (c *Conn) Close() error {
 		return nil
 	}
 
-	c.pending.Close()
-	c.pending = nil
+	c.call("sqlite3_finalize", stk_t(c.pending))
+	c.pending = 0
 
 	rc := res_t(c.call("sqlite3_close", stk_t(c.handle)))
 	if err := c.error(rc); err != nil {
@@ -187,7 +187,7 @@ func (c *Conn) Exec(sql string) error {
 	defer c.arena.mark()()
 	sqlPtr := c.arena.string(sql)
 
-	c.checkInterrupt(c.handle)
+	c.checkInterrupt()
 	rc := res_t(c.call("sqlite3_exec", stk_t(c.handle), stk_t(sqlPtr), 0, 0, 0))
 	return c.error(rc, sql)
 }
@@ -211,16 +211,16 @@ func (c *Conn) PrepareFlags(sql string, flags PrepareFlag) (stmt *Stmt, tail str
 	defer c.arena.mark()()
 	stmtPtr := c.arena.new(ptrlen)
 	tailPtr := c.arena.new(ptrlen)
-	sqlPtr := c.arena.string(sql)
+	textPtr := c.arena.string(sql)
 
-	c.checkInterrupt(c.handle)
+	c.checkInterrupt()
 	rc := res_t(c.call("sqlite3_prepare_v3", stk_t(c.handle),
-		stk_t(sqlPtr), stk_t(len(sql)+1), stk_t(flags),
+		stk_t(textPtr), stk_t(len(sql)+1), stk_t(flags),
 		stk_t(stmtPtr), stk_t(tailPtr)))
 
-	stmt = &Stmt{c: c}
+	stmt = &Stmt{c: c, sql: sql}
 	stmt.handle = util.Read32[ptr_t](c.mod, stmtPtr)
-	if sql := sql[util.Read32[ptr_t](c.mod, tailPtr)-sqlPtr:]; sql != "" {
+	if sql := sql[util.Read32[ptr_t](c.mod, tailPtr)-textPtr:]; sql != "" {
 		tail = sql
 	}
 
@@ -344,40 +344,44 @@ func (c *Conn) SetInterrupt(ctx context.Context) (old context.Context) {
 	old = c.interrupt
 	c.interrupt = ctx
 
-	if ctx == old || ctx.Done() == old.Done() {
+	if ctx == old {
 		return old
 	}
 
-	// A busy SQL statement prevents SQLite from ignoring an interrupt
+	// An active SQL statement prevents SQLite from ignoring an interrupt
 	// that comes before any other statements are started.
-	if c.pending == nil {
+	if c.pending == 0 {
 		defer c.arena.mark()()
 		stmtPtr := c.arena.new(ptrlen)
-		loopPtr := c.arena.string(`WITH RECURSIVE c(x) AS (VALUES(0) UNION ALL SELECT x FROM c) SELECT x FROM c`)
-		c.call("sqlite3_prepare_v3", stk_t(c.handle), stk_t(loopPtr), math.MaxUint64,
+		textPtr := c.arena.string(`SELECT 0 UNION ALL SELECT 0`)
+		c.call("sqlite3_prepare_v3", stk_t(c.handle), stk_t(textPtr), math.MaxUint64,
 			stk_t(PREPARE_PERSISTENT), stk_t(stmtPtr), 0)
-		c.pending = &Stmt{c: c}
-		c.pending.handle = util.Read32[ptr_t](c.mod, stmtPtr)
+		c.pending = util.Read32[ptr_t](c.mod, stmtPtr)
 	}
 
-	if old.Done() != nil && ctx.Err() == nil {
-		c.pending.Reset()
-	}
-	if ctx.Done() != nil {
-		c.pending.Step()
+	if c.stepped && ctx.Err() == nil {
+		c.call("sqlite3_reset", stk_t(c.pending))
+		c.stepped = false
+	} else {
+		c.checkInterrupt()
 	}
 	return old
 }
 
-func (c *Conn) checkInterrupt(handle ptr_t) {
-	if c.interrupt.Err() != nil {
-		c.call("sqlite3_interrupt", stk_t(handle))
+func (c *Conn) checkInterrupt() {
+	if c.interrupt.Err() == nil {
+		return
+	}
+	if !c.stepped {
+		c.call("sqlite3_step", stk_t(c.pending))
+		c.stepped = true
 	}
+	c.call("sqlite3_interrupt", stk_t(c.handle))
 }
 
 func progressCallback(ctx context.Context, mod api.Module, _ ptr_t) (interrupt int32) {
 	if c, ok := ctx.Value(connKey{}).(*Conn); ok {
-		if c.nprogr++; c.nprogr%16 == 0 {
+		if c.gosched++; c.gosched%16 == 0 {
 			runtime.Gosched()
 		}
 		if c.interrupt.Err() != nil {

func.go

@@ -284,10 +284,10 @@ func returnArgs(p *[]Value) {
 }
 
 type aggregateFunc struct {
-	ctx  Context
-	arg  []Value
 	next func() (struct{}, bool)
 	stop func()
+	ctx  Context
+	arg  []Value
 }
 
 func (a *aggregateFunc) Step(ctx Context, arg ...Value) {

stmt.go

@@ -106,7 +106,7 @@ func (s *Stmt) Busy() bool {
 //
 // https://sqlite.org/c3ref/step.html
 func (s *Stmt) Step() bool {
-	s.c.checkInterrupt(s.c.handle)
+	s.c.checkInterrupt()
 	rc := res_t(s.c.call("sqlite3_step", stk_t(s.handle)))
 	switch rc {
 	case _ROW: