[yunqa.de] Re: How to correctly avoid 'database is locked' in multi user
- From: Delphi Inspiration <delphi@xxxxxxxx>
- To: yunqa@xxxxxxxxxxxxx
- Date: Sat, 12 Jan 2013 23:00:31 +0100
On 11.01.2013 20:37, H M wrote:
> I tried uploading this a few hours ago but it didn't seem to make it to
> the list. Here it is again without the .exe files in the zip in case that was
> the
> reason.
Thanks for your efforts. Did you receive an error message? For the future,
please know that I do not need *.exe compiled applications to debug and
reproduce problems.
Your code is correct. However, it revealed that for multi-statement SQL run on
a database with a reserved lock, sqlite3_exec_with_callback() incorrectly
returns SQLITE_OK instead of SQLITE_BUSY.
To solve, please replace the sqlite3_exec_with_callback() implementation in
DISQLite3Database.pas with the following:
function sqlite3_exec_with_callback(
const ADBHandle: sqlite3_ptr;
const ASQL: Utf8String;
const ACallback: TDISQLite3_Callback_{$IFDEF SUPPORTS_DEFAULTPARAMS} =
nil{$ENDIF};
const AUserData: Pointer{$IFDEF SUPPORTS_DEFAULTPARAMS} = nil{$ENDIF}):
Integer;
var
CallbackResult: Boolean;
SqlStart, SqlTail: PUtf8Char;
SqlLength: C_int;
Stmt: sqlite3_stmt_ptr;
begin
if not Assigned(ADBHandle) then
begin
Result := SQLITE_MISUSE;
Exit;
end;
SqlLength := Length(ASQL);
if SqlLength = 0 then
begin
Result := SQLITE_OK;
Exit;
end;
SqlStart := Pointer(ASQL);
repeat
Result := sqlite3_prepare_v2(ADBHandle, SqlStart, SqlLength + 1, @Stmt,
@SqlTail);
if Result <> SQLITE_OK then
Break;
if Assigned(Stmt) then
begin
try
CallbackResult := True;
Result := sqlite3_step(Stmt);
if Assigned(ACallback) and (Result and $FF = SQLITE_ROW) then
repeat
CallbackResult := ACallback(Stmt, AUserData);
if not CallbackResult then
Break;
Result := sqlite3_step(Stmt);
until Result and $FF <> SQLITE_ROW;
finally
Result := sqlite3_finalize(Stmt);
end;
if not CallbackResult then
Result := SQLITE_ABORT;
end;
if Result <> SQLITE_OK then
Break;
Dec(SqlLength, SqlTail - SqlStart);
if SqlLength <= 0 then
Break;
SqlStart := SqlTail;
until False;
end;
Thanks for the report,
Ralf
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