Merge pull request #35 from rqlite/changeset-support

Add support for Sessions and Changesets

Author: otoolep

sqlite3.go

@@ -27,6 +27,8 @@ package sqlite3
 #cgo CFLAGS: -DSQLITE_ENABLE_DBSTAT_VTAB
 #cgo CFLAGS: -DSQLITE_MEMDB_DEFAULT_MAXSIZE=2147483648
 #cgo CFLAGS: -DSQLITE_ENABLE_GEOPOLY=1
+#cgo CFLAGS: -DSQLITE_ENABLE_SESSION
+#cgo CFLAGS: -DSQLITE_ENABLE_PREUPDATE_HOOK
 #cgo CFLAGS: -Wno-deprecated-declarations
 #cgo openbsd CFLAGS: -I/usr/local/include
 #cgo openbsd LDFLAGS: -L/usr/local/lib

sqlite3_session.go

@@ -0,0 +1,190 @@
+//go:build !sqlite_omit_session
+// +build !sqlite_omit_session
+
+package sqlite3
+
+/*
+#cgo CFLAGS: -DSQLITE_ENABLE_SESSION -DSQLITE_ENABLE_PREUPDATE_HOOK
+#cgo LDFLAGS: -lm
+*/
+
+/*
+#ifndef USE_LIBSQLITE3
+#include "sqlite3-binding.h"
+#else
+#include <sqlite3.h>
+#endif
+#include <stdlib.h>
+#include <stdint.h>
+*/
+import "C"
+import (
+	"fmt"
+	"unsafe"
+)
+
+type Session struct {
+	session *C.sqlite3_session
+}
+
+// CreateSession creates a new session object.
+func (c *SQLiteConn) CreateSession(dbName string) (*Session, error) {
+	cDbName := C.CString(dbName)
+	defer C.free(unsafe.Pointer(cDbName))
+
+	var session *C.sqlite3_session
+	rc := C.sqlite3session_create(c.db, cDbName, &session)
+	if rc != C.SQLITE_OK {
+		return nil, fmt.Errorf("sqlite3session_create: %s", C.GoString(C.sqlite3_errstr(rc)))
+	}
+	return &Session{session: session}, nil
+}
+
+// AttachSession attaches a session object to a table or all tables.
+func (s *Session) AttachSession(tableName string) error {
+	var cTableName *C.char
+	if tableName != "" {
+		cTableName = C.CString(tableName)
+		defer C.free(unsafe.Pointer(cTableName))
+	}
+
+	rc := C.sqlite3session_attach(s.session, cTableName)
+	if rc != C.SQLITE_OK {
+		return fmt.Errorf("sqlite3session_attach: %s", C.GoString(C.sqlite3_errstr(rc)))
+	}
+	return nil
+}
+
+// Delete deletes a session object.
+func (s *Session) DeleteSession() error {
+	if s.session != nil {
+		C.sqlite3session_delete(s.session)
+		s.session = nil
+	}
+	return nil
+}
+
+// Changeset represents a changeset object.
+type Changeset struct {
+	b []byte
+}
+
+// NewChangeset returns a changeset from a session object.
+func NewChangeset(s *Session) (*Changeset, error) {
+	var nChangeset C.int
+	var pChangeset unsafe.Pointer
+
+	rc := C.sqlite3session_changeset(s.session, &nChangeset, &pChangeset)
+	if rc != C.SQLITE_OK {
+		return nil, fmt.Errorf("sqlite3session_changeset: %s", C.GoString(C.sqlite3_errstr(rc)))
+	}
+	defer C.sqlite3_free(pChangeset)
+
+	// Copy the changeset buffer to a Go byte slice, because cgo
+	// does not support Go slices with C memory.
+	changeset := C.GoBytes(pChangeset, nChangeset)
+	return &Changeset{b: changeset}, nil
+}
+
+// ChangesetIterator represents a changeset iterator object.
+type ChangesetIterator struct {
+	iter *C.sqlite3_changeset_iter
+}
+
+// NewChangesetIterator creates a new changeset iterator object.
+func NewChangesetIterator(cs *Changeset) (*ChangesetIterator, error) {
+	var iter *C.sqlite3_changeset_iter
+	ptr := unsafe.Pointer(nil)
+	if len(cs.b) > 0 {
+		ptr = unsafe.Pointer(&cs.b[0])
+	}
+	rc := C.sqlite3changeset_start(&iter, C.int(len(cs.b)), ptr)
+	if rc != C.SQLITE_OK {
+		return nil, fmt.Errorf("sqlite3changeset_start: %s", C.GoString(C.sqlite3_errstr(rc)))
+	}
+	return &ChangesetIterator{iter: iter}, nil
+}
+
+// Next moves the changeset iterator to the next change.
+func (ci *ChangesetIterator) Next() (bool, error) {
+	rc := C.sqlite3changeset_next(ci.iter)
+	if rc == C.SQLITE_DONE {
+		return false, nil // No more changes
+	}
+	if rc != C.SQLITE_ROW {
+		return false, fmt.Errorf("sqlite3changeset_next: %s", C.GoString(C.sqlite3_errstr(rc)))
+	}
+	return true, nil
+}
+
+// Op returns the current Operation from a Changeset Iterator
+func (ci *ChangesetIterator) Op() (tblName string, numCol int, oper int, indirect bool, err error) {
+	var tableName *C.char
+	var nCol C.int
+	var op C.int
+	var ind C.int
+
+	rc := C.sqlite3changeset_op(ci.iter, &tableName, &nCol, &op, &ind)
+	if rc != C.SQLITE_OK {
+		return "", 0, 0, false, fmt.Errorf("sqlite3changeset_op: %s", C.GoString(C.sqlite3_errstr(rc)))
+	}
+	return C.GoString(tableName), int(nCol), int(op), ind != 0, nil
+}
+
+// Old retrieves the old value for the specified column in the change payload.
+func (ci *ChangesetIterator) Old(dest []any) error {
+	return ci.row(dest, true)
+}
+
+// New retrieves the new value for the specified column in the change payload.
+func (ci *ChangesetIterator) New(dest []any) error {
+	return ci.row(dest, false)
+}
+
+// Finalize deletes a changeset iterator.
+func (ci *ChangesetIterator) Finalize() error {
+	if ci.iter != nil {
+		rc := C.sqlite3changeset_finalize(ci.iter)
+		ci.iter = nil
+		if rc != C.SQLITE_OK {
+			return fmt.Errorf("sqlite3changeset_finalize: %s", C.GoString(C.sqlite3_errstr(rc)))
+		}
+	}
+	return nil
+}
+
+// New retrieves the new value for the specified column in the change payload.
+func (ci *ChangesetIterator) row(dest []any, old bool) error {
+	var val *C.sqlite3_value
+	var rc C.int
+	for i := 0; i < len(dest); i++ {
+		fn := ""
+		if old {
+			fn = "old"
+			rc = C.sqlite3changeset_old(ci.iter, C.int(i), &val)
+		} else {
+			fn = "new"
+			rc = C.sqlite3changeset_new(ci.iter, C.int(i), &val)
+		}
+		if rc != C.SQLITE_OK {
+			return fmt.Errorf("sqlite3changeset_%s: %s", fn, C.GoString(C.sqlite3_errstr(rc)))
+		}
+
+		switch C.sqlite3_value_type(val) {
+		case C.SQLITE_INTEGER:
+			dest[i] = int64(C.sqlite3_value_int64(val))
+		case C.SQLITE_FLOAT:
+			dest[i] = float64(C.sqlite3_value_double(val))
+		case C.SQLITE_BLOB:
+			len := C.sqlite3_value_bytes(val)
+			blobptr := C.sqlite3_value_blob(val)
+			dest[i] = C.GoBytes(blobptr, len)
+		case C.SQLITE_TEXT:
+			cstrptr := unsafe.Pointer(C.sqlite3_value_text(val))
+			dest[i] = C.GoString((*C.char)(cstrptr))
+		case C.SQLITE_NULL:
+			dest[i] = nil
+		}
+	}
+	return nil
+}